Subtilase cytotoxin (SubAB) is the prototype of a novel class of AB₅ cytotoxins produced by Shiga-toxigenic Escherichia coli (STEC). The A subunit (SubA) is a serine protease that cleaves the ER chaperone BiP causing cell death by a previouslyundetermined mechanism. The B subunits of AB₅toxins typically recognise host cell glycan receptors and direct the subcellular transport of the A subunit. Although the function of SubA and its intracellular substrate have been elucidated, the B subunit (SubB) is relatively uncharacterised. The subcellular trafficking pathway of SubAB was initially examined. SubAB conjugated to Oregon Green 488 (SubAB-OG) was internalised by Vero cells by 5 min, and co-localised with its ER target BiP within 30 min. When Vero cells were incubated with SubAB-OG and either Alexa Fluor 594-conjugated Cholera toxin B subunit (CtxBAF594) or Texas Red-conjugated Shiga toxin B subunit (StxB-TR), individual cells exhibited differential toxin uptake. This was shown to be cell cycle-dependent, in which, SubAB-OG was preferentially internalised by cells migrating through G1 and early S phases. In contrast, CtxB-AF594 was taken up by cells in S through M phases and by a majority of cells in G1, while StxB-TR endocytosis occurred in cells traversing G1. Fluorescent SubAB co-localised with the clathrin marker transferrin, but not with Caveolin-1 (a marker for cholesterol-associated caveolae) and was subsequently trafficked via a retrograde pathway to the TGN, Golgi and ER. The clathrin inhibitor phenylarsine oxide prevented SubAB entry and BiP cleavage in SubAB-treated Vero, HeLa and N2A cells, while cholesterol depletion did not, demonstrating that, unlike either Stx or Ctx, SubAB internalisation is exclusively clathrin-dependent. Identification of the SubB receptor was initially approached using toxin overlay assays in which Vero cell glycolipid extracts were separated by thin-layer chromatography and overlaid with SubAB. SubAB exhibited a high affinity for particular acidic species in the ganglioside fraction. However, none co-migrated with commercial glycolipid standards. SubAB-OG also exhibited an affinity for the oligosaccharide structures of chimeric LPS from GM₂ and GM₃ bacterial receptor mimic constructs in an LPS toxin overlay assay. Glycan array analysis revealed that SubB possessed a unique affinity for carbohydrate receptors with a terminal Neu5Gcα(2→3)Galβ disaccharide. Monovalent receptor analogues with distal Neu5Gc or Neu5Gcα(2→3)Galβ and highly-sialylated α₁-AGP did not prevent endocytosis of SubAB-OG, BiP cleavage or cytotoxicity in Vero cells. This indicated that SubAB has a greater affinity for the host cell receptors than the receptor analogues and may engage multiple receptors displayed on a lipid bilayer. In addition to mediating toxin binding and subcellular trafficking, CtxB and StxB can also potentiate the immune response to co-administered antigen. Accordingly, the systemic immunomodulatory properties of SubB administered by the i.p. route were assessed in mice. Using SubAA₂₇₂ as a bystander antigen, SubB significantly increased mouse anti-SubAA₂₇₂ titres to levels that were comparable to those obtained using Alum adjuvant. However, when admixed with structurally-unrelated OVA, SubB did not significantly affect anti-OVA titres whereas Alum and CtxB did. This indicated that SubB may function as a systemic carrier protein (rather than an adjuvant) for particular antigens. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1363363 / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2009

<p>Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.</p>

<p>Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.</p>

Magister Scientiae - MSc / Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy. / South Africa