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The purpose of this research was to determine the fatty acid composition of lipids as compared to those of normal tissue. The altered molecular structure of these lipids could cause changes in the plasma membrane fluidity and membrane integrity producing the membrane characteristics associated with carcinomas.Plasma membranes-were isolated by differential centrifugation from both tumor and normal tissue from Strong A female mice. The lipids were extracted, separated by thin-layer chromatography, saponified and the fatty acid methyl esters identified and quantified by gas chromatography. The lipids were separated into four classes, cholesterol esters, triglycerides, free fatty acids and phospholipids. The carcinoma samples exhibited a reduction in the fatty acids of 10 to 14, carbons in chain length by as much as 32 percent. The level of palmitic acid increased in the tumor fractions as much as double the normal amount. The level of palmitoleic acid also increased in the tumor fractions nearly proportional to the palmitic acid. The stearic acid content in the tumor fractions increased as did the oleic acid in three of the four lipid classes, again nearly proportional to the stearic acid. Levels as high as 29 percent of henicosanoic acid in some normal tissue samples were found, but the carcinoma samples exhibited no higher than 10 percent. The increased production of heptadecadienoic acid in the carcinoma fractions along with the appearance of eicosatrienoic acid when only low scattered amounts were found in the normal fractions indicated that a shift in fatty acid biosynthesis has occurred, it would appear that in the carcinoma, the biosynthetic pathway for synthesis of fatty acids in the plasma membranes shifted from a de novo to a chain elongation pathway as the principal route.

The insulin-dependent uptake of glucose by adipose and muscle tissues is accomplished through the regulated vesicle trafficking of the GLUT4 glucose transporter to the plasma membrane. The distal trafficking events comprising the tethering, docking and fusion of GLUT4 vesicles with the plasma membrane are poorly defined, but represent vital steps in this pathway. This dissertation encompasses a series of complementary studies that have provided new insights into how these events are regulated in the adipocyte. The Sec1p homologue Munc18c, is believed to play a central role in the docking of GLUT4 vesicles by controlling SNARE complex assembly. Munc18c was shown to bind the t-SNARE Syntaxin4 and form a stable complex in vivo. Protein binding studies demonstrated that Munc18c interacts with Syntaxin4 via an evolutionarily conserved N-terminal binding mode and the formation of the Munc18c/Syntaxin4 hetero-dimer was shown to promote SNARE complex assembly. In contrast to previous reports, I propose that Munc18c is positive regulator of SNARE assembly and vesicle docking. The exocyst complex is thought to promote the tethering of exocytic GLUT4 vesicles with the plasma membrane. Yeast two-hybrid screens revealed interactions between the exocyst subunits Sec6 and Exo70 and the SNARE-associated proteins Munc18c and Snapin, respectively. Snapin was subsequently shown to have a novel role in GLUT4 trafficking. These interactions suggest Munc18c and Snapin provide a course for cross-talk between the exocyst complex and the SNAREs to stimulate GLUT4 vesicle tethering and docking. In addition to its interactions with Munc18c and Snapin, the exocyst was also found to interact with the GTP-bound form of RalA, a small GTPase regulated by insulin. RalA was almost exclusively localised to the plasma membrane of the adipocyte and a novel role for the RalA/exocyst interaction in GLUT4 trafficking was demonstrated. Specifically, overexpression of a GTP-deficient RalA mutant significantly inhibited insulin-stimulated GLUT4 appearance on the plasma membrane. In addition to its role in GLUT4 trafficking, a novel role for RalA was demonstrated in insulin release from pancreatic -cells, indicating that RalA may represent a universal component of regulated exocytosis. It is becoming increasingly apparent that vesicle trafficking events from yeast to mammals rely on similar protein complexes which communicate through multiple protein interactions, ensuring vesicle transport is highly coupled. Similarly, the Munc18c studies demonstrate that while mammalian cells have evolved to fulfil specialised functions throughout the body, some proteins appear to have retained the biochemical properties of their ancestors, emphasing the importance of this family of proteins throughout eukaryotic vesicle transport. In contrast, proteins such as RalA have evolved only in higher eukaryotes and appear to play a universal role in vesicle transport despite vast differences in the specialised functioning of mammalian cells.

Thesis (D. Sc.)--Faculty of Science, University of Adelaide, 1990. / Published works [representing] original research conducted during the various phases of [his] academic development--Pref. Includes bibliographical references.

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics, and Mathematical Physics, 1993. / Includes bibliographical references (leaves 154-163).

Thesis (Ph.D.) in Chemical Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 97-105).

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 123-137). Also available on the Internet.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed June 17, 2008). PDF text: xiii, 146 p. : ill. (some col.) ; 4 Mb. UMI publication number: AAT 3295233. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 123-137). Also available on the Internet.