The sodium-calcium exchanger (NCX) is a countertransporter of Na+ and Ca2+ across most cell membranes. It has been identified as an essential component of Ca2+ homeostasis in physiological and disease conditions in both cardiovascular and neurological settings. The exchanger not only transports Na+ and Ca2+, but is also regulated by these ions. Although ionic regulatory profiles differ between NCX isoforms, similar regulatory domains have been identified. Previous structure-function studies have determined key residues within these domains, particularly in the eXchanger Inhibitory Peptide region (XIP) and the Ca2+ binding domains (CBD1/2), which have a direct impact on ionic regulation of the outward exchange currents. Recent structural studies of the Ca2+ binding domains of NCX1 suggest a mechanism by which Ca2+ binding would not only be essential for activation of current but may also influence Na+-dependent inactivation. The alternative splice region is located within the Ca2+ binding domain and may play a role in mediating these regulatory phenotypes. Previous studies have demonstrated that specific combinations of the mutually-exclusive and cassette exons are associated with profound effects on ionic regulation in NCX1. This study focuses on examining the mechanisms by which the alternative splice region, in combination with specific regulatory domains, modulates exchange activity in two isoforms, NCX1 and NCX2. Chimaeric and mutant constructs in the alternative splice region were expressed in Xenopus oocytes and outward Na+-Ca2+ exchange activity was assessed using the giant, excised patch clamp technique. Substitution of the region corresponding to the mutually exclusive exon in either exchanger greatly reduced the extent of Na+-dependent inactivation, independently of intracellular Ca2+ concentrations. However, replacement of both the region corresponding to the mutually exclusive exon A and the XIP region reestablishes a wild-type profile in NCX2. The first mutually exclusive exon is therefore critical in determining Na+ and Ca2+-dependent regulatory properties. Furthermore, non-conserved residues within the XIP region may be essential in maintaining the structural stability of the Na+-dependent inactive state of NCX1, and by interacting with the mutually exclusive exon, may contribute to the structure-function relationship and the distinct regulatory phenotype of each Na+-Ca2+ exchanger variant and isoform.

As a result of transcriptional editing, Ebola virus (EBOV) produces multiple soluble products from its glycoprotein gene, the primary product of which is the secreted glycoprotein (sGP), in addition to the membrane-bound viral spike protein GP1,2. A lack of leukocyte infiltration is observed during EBOV infection, which is thought to allow virus replication to proceed unchecked and thus represents a significant role in the immunopathology of the disease. Currently the only know function of sGP is that it has an anti-inflammatory effect on endothelial cells treated with TNF-α, an effect that has been hypothesized to interfere with recruitment or extravasation of leukocytes. To better characterize this anti-inflammatory function, a link between sGP structure and function was sought. Mass spectrometry (MS) analysis of recombinant sGP demonstrated that it is a parallel-orientated disulphide-linked homodimer that contains Cys53-C53’ and Cys306-C306’ intermolecular disulphide bonds. In addition to being glycosylated with complex N-glycans, sGP also contained a novel post-translation modification, termed C-mannosylation. C-mannosylation was not required for the anti-inflammatory function of sGP; however, glycine mutations at amino acids 53 and 306 resulted in the complete loss of the anti-inflammatory effect on TNF-α treated endothelial cells. Thus, a specific structure mediated by intermolecular disulphide bonds is required for the proposed anti-inflammatory function of sGP, suggesting that this effect is the result of a specific interaction. The spike protein GP1,2, also contains C-mannosylation motifs. MS analysis of GP1,2 indicated that GP1 was C-mannosylated, while two adjacent motifs in the membrane proximal region (MPER) of GP2 were not. The infectious virus-like particle (iVLP) assay, a system for investigating virus particle assembly and entry, was utilized to determine the functional importance of these conserved tryptophans. Elimination of the C-mannosylation motif, which resides in an external loop region of GP1, increased reporter activity, suggesting that particle entry is enhanced and this region may interact with the cell surface despite being outside of the receptor binding site. Decreased reporter activity was observed for all MPER mutants, with multiple MPER tryptophan mutations resulting in decreased GP1,2 incorporation. These data place the MPER tryptophan residues in an important role for glycoprotein incorporation and particle entry. Given the tryptophan content and location is similar to the MPER of HIV gp41, where these residues are required for glycoprotein incorporation and fusion, the MPER of EBOV GP2 may function similarly.

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This dissertation explains the increasingly homogenous institutional and policy framework of Official Development Assistance. Whereas multilateral actors like the World Bank or the issue of civil society involvement in development have been substantially researched and discussed, less attention has been paid to the institutions of bilateral donor agencies and the processes by which they arrive at common policy positions. It is of great importance to better understand how donors arrive at these consensus policy positions, essentially limiting development possibilities worldwide. Engaged with the literatures on world polity theory, development assistance, and social movements, this dissertation examines the social processes which explain this growing uniformity among major bilateral development assistance donor agencies. This research adopts a mixed-methods approach of both quantitative and qualitative methods to illustrate the working of world polity influences on nation-state donor agencies. Event history analysis techniques at the macro level are used to show the influence of world society on donor states, then the relationships identified in this quantitative analysis are used to frame two in-depth qualitative case studies on gender and security policy among three countries, Canada, Sweden, and the United States. My results show that despite different national contexts, there are common social processes and mechanisms of globalisation that promote conformity and isomorphism among donor countries. Five primary social processes are identified: (1) internalisation and certification; (2) donor agency embeddedness with civil society; (3) bureaucratic activism; (4) catalyt / L'objet de cette thèse est d'expliquer les raisons pour lesquelles le cadre politique et institutionnel de l'aide publique au développement devient de plus en plus homogène. Si les organismes multilatéraux (comme la Banque mondiale) et la participation de la société civile dans le développement ont fait l'objet de nombreux débats et d'études approfondies, il en est tout autrement pour les institutions des organismes donateurs bilatéraux et les processus via lesquels ils aboutissent à une position politique commune. Il est donc primordial de mieux comprendre comment les donateurs parviennent à ces consensus politiques qui limitent avant tout les possibilités de développement dans le monde. À travers l'étude de la littérature portant sur la théorie de la politie planétaire, sur l'aide au développement et sur les mouvements sociaux, cette thèse examine les processus sociaux qui expliquent l'uniformité croissante parmi les principaux organismes donateurs d'aide bilatérale au développement. Cette recherche se fonde sur une approche méthodologique mixte, à la fois quantitative et qualitative, pour démontrer comment la politie planétaire influence les organismes donateurs des États-nations. Des techniques de macro-analyse des transitions sont employées pour montrer l'influence de la société mondiale sur les États donateurs. Les relations identifiées dans cette analyse quantitative sont ensuite utilisées pour formuler deux études de cas détaillées, l'une sur les politiques en matière d'égalité entre les sexes et l'autre sur les politiques de sécurité, dans trois pays : le Canada, la Suède et les États-Unis d'Amérique. Mes résultat

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