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No description available.

Membrane fusion plays a crucial role in many biological processes from virus infection to release of neurotransmitters (Hughson 1999). Membrane -bound surface glycoproteins are involved in the fusion process. The enveloped animal virus infection is initiated by interactions between the virus and the cell membrane through the surface glycoproteins called fusion glycoproteins (Eckert and Kim 2001). The fusion glycoproteins are responsible for both receptor binding and membrane fusion activity. The fusion proteins are characterized by a large ectodomain containing fusion peptides, a transmembrane (TM) domain, and a cytoplasimic domain. The viruses can enter cells either at neutral pH or at acidic pH. When exposed to appropriate conditions, the fusion protein undergoes conformational changes, which in turn drives the fusion process. The fusion glycoproteins can be classified as Class I and Class II fusion proteins (Lescar eta/. 2001 ). The Class I fusion proteins are synthesized as a precursor molecule, which then undergoes proteolytic cleavage to generate a mature molecule containing the hydrophobic fusion peptide at the N -terminal. The class II fusion glycoproteins are not synthesized as precursor molecules, and they have internal fusion peptides. The vesicular stomatitis virus (VSV) glycoprotein G is a class Ill fusion protein. It has a neutral internal fusion peptide and upon exposure to low pH, the protein undergoes reversible conformational change (Gaudin 2000, Yao eta/. 2003). A 62kDa soluble ectodomain of VSV G (Gs) has been generated by limited trypsin digestion. The SDS PAGE gel electrophoresis indicates that the trypsin has possibly cleaved near the transmembrane (TM) domain. Liposome binding experiment suggests that Gs can bind to liposomes in a pH dependent manner. Liposome fusion studied by RET assay suggests that the Gs can induce significant amount of hemifusion. However, it failed to induce any content mixing mainly due to considerable amount of membrane leakage activity. This indicates that the binding to the membrane through the TM domain is required for complete membrane fusion. Unlike TBE E soluble ectodomain, Gs can form dimers and trimers at neutral and fusion active pH. Light scattering experiment shows that the aggregation of Gs increases with a decrease in pH. The conformational change with changes in pH was evident from the trypsin sensitivity assay and CD spectroscopy. It was observed that Gs became resistant to trypsin digestion at low pH and a-helicity content of the molecule increased upon lowering the pH. However, the maximum amount of a-helicity was observed at pH 6. The removal of the TM domain also shifts the optimum fusion pH towards more acidic pH in comparison to VSV G. These results indicate that the TM domain is not required for the oligomerization of G protein, but some role has been reserved for the TM domain during membrane fusion. The CD spectroscopic data also indicated that the G protein undergoes structural rearrangement between pH 7.4-6, which could be responsible for the exposure of fusion peptide and subsequent target membrane binding. / Thesis / Master of Science (MSc)

The Uncinate Fasciculus (UF) is a white matter association tract responsible for connecting the frontal and temporal lobes of the brain. Its location, general shape, and estimated projections have been visualized and analyzed at low-resolution via diffusion tensor imaging (DTI) in many studies, allowing for a basic understanding of the pathway and its potential functions. Despite this, the microstructural properties of this white matter highway are still relatively unknown as we can estimate characteristics such as myelination and pathway density from low-resolution imaging, but we cannot gain a deeper understanding of the fine characteristics that allow the pathway to function in health and how those features are disrupted in disease. To address this gap, we examined six post-mortem tissue samples, featuring approximately 12,000 axons of the temporal segment of the UF (adjacent to the amygdala and hippocampus) from neurotypical controls. We used high-resolution microscopy to systematically sample and study the microstructure of myelinated axons to characterize the UF for future comparisons to disease states, like Autism Spectrum Disorder (ASD). We provide novel characterization of the microstructure of the UF in both hemispheres, examining density, size, myelination, and trajectories of axons in healthy adult tissue. Our data revealed hemispheric trends of axon characteristics that align with previous imaging studies, including slight left hemispheric asymmetry in regard to density and myelination and a small increase in trajectory variability in the right hemisphere. In addition, like values found previously in the Corpus Callosum, the distribution of thin and medium axons was much higher than thick axons. Our findings provide a more in-depth understanding of the microstructural characteristics of the UF at the level of single axons, providing context for white matter anisotropy and diffusivity estimates from previous DTI studies through values such as myelin thickness, area fraction, and axon trajectory. This structural framework of this pathway can be used to compare with results from in vivo imaging studies, and to provide a basis for comparison with pathological states in the future. / 2026-06-06T00:00:00Z

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

In this diploma thesis, capillary columns with an inner diameter of 530 microns filled with gel particles were prepared. These columns are intended for gel chromatography. Three various methods of filling were used for their preparation. The first method was based on filling of wet particles in suspension with the organic solvent, followed by drying and swelling of particles with water into the form of gel. The second method used filling of wet particles in the suspension form with the aqueous phase. The last method started with suction of dry gel particles by air and continued with their subsequent swelling with water into the form of the gel. The prepared columns have been compared analysing hyaluronic acid and thiourea. The basic parameters specified for the gel column chromatography were determined by using phenylalanine. The pressure characteristics depending on the flow rate of mobile phase were used to compare the quality of packing of the columns prepared by various methods.

In this work first we characterize two nondegenerate positive random variables X and Y to be gammally distributed with the same scale parameter under the assumptions X/Y}|Y~B(p,q) and E((Y-X)^k|X)=b for some fixed integer k>1 and constant b. Among others characterizations of the gamma and beta distributions based on some special quadratic forms of conditional moments are also investigated.

Thesis (M. Mus.)--University of Melbourne, 1978. / Typescript (photocopy). Includes bibliographical references (leaves [279]-283) and index.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 294-299).

The presented study tries to reveal the evolutionary history of polyploid complex Galium pusillum aiming on a rare czech endemic species G. sudeticum, an ideal model to study allopatric speciation in the context of Central European (post)glacial development. The species G. sudeticum grows in Krkonose Mts. and on serpentines in western Bohemia (Slavkovský les) more than 200 kilometers away. Our morphological and molecular data suggest a clearly different history of its two isolated areas. The populations in Krkonose Mts. are probable relics of mountainous species G. anisophyllon which was there on its northern border of occurence and hybridized with lowland species G. valdepilosum during postglacial vegetations shifts. This fact is well supported by intermediate position of Krkonose Mts. populations in both morphological and molecular AFLP analyses and by sharing the same chloroplast haplotype with geographically close lowland populations. On the other hand the serpentine lowland populations in western Bohemia are both morphologicaly and genetically indistinguishable from G. valdepilosum. Distinct genetic lineage of few populations belonging to G. valdepilosum (incl. one traditionaly referred as G. sudeticum) was found in western Bohemia and Bavaria, located on relic stands (calcareous and serpentine...