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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Eggshell Membrane Proteins provide Innate Immune Protection

Cordeiro, Cristianne January 2015 (has links)
The microbiological safety of avian eggs is a major concern for the poultry industry and for consumers due to the potential for severe impacts on public health. Innate immune defense is formed by proteins with antimicrobial and immune-modulatory activities and ensures the protection of the chick embryo against pathogens. The objective of this project was to identify the chicken eggshell membrane (ESM) proteins that play a role in these innate immune defense mechanisms. We hypothesized that ESM Ovocalyxin-36 (OCX-36) is a pattern recognition protein, and characterized purified ESM OCX-36. OCX-36 has antimicrobial activity against S. aureus and binds E. coli lipopolysaccharide (LPS) and S. aureus lipoteichoic acid (LTA). We additionally investigated the OCX-36 nonsynonymous single nucleotide polymorphisms (SNPs) at cDNA position 211. The corresponding isoforms (proline-71 or serine-71) were purified from eggs collected from genotyped homozygous hens. A significant difference between Pro-71 and Ser-71 OCX-36s for S. aureus LTA binding activity was observed. From these experiments, we confirmed the hypothesis that OCX-36 is a pattern recognition molecule. We also found that OCX-36 has anti-endotoxin properties and is a macrophage immunostimulator to produce NO and TNF-α. Digested OCX-36 down-regulated the expression of genes involved in LPS signaling and inflammatory responses. Moreover, OCX-36-derived peptides inhibited the production of LPS-induced pro-inflammatory mediators associated with endotoxemia in vivo. Quantitative proteomics analysis of ESMs was performed to evaluate changes in ESM protein abundance during chick embryonic development. Bioinformatics analysis revealed enrichment of proteins associated with antimicrobial and immune protection, vascularization, calcium mobilization and lipid transport, which are vital for chick embryonic development. In unfertilized eggs, protease inhibitors and antimicrobial proteins were enriched. In summary, the ESMs are enriched in proteins with antimicrobial, antioxidant and immune-modulatory properties, which aid in the development of the chick embryo and protect the embryo and unfertilized egg against pathogen invasion.
2

Antimicrobial Proteins for Human Health

Berhane, Nahom Ahferom January 2018 (has links)
Bacteria are one of the largest causes of human disease, with millions of deaths every year attributed to bacterial infections, and they have become more difficult to tackle with the widespread emergence of antibiotic resistance. In this thesis, I describe my studies that pursued two approaches: one focus was on using antimicrobial histones as an alternative to treatment for antibiotic resistant bacteria; in another approach the recombinant version of an eggshell cuticle protein was expressed and purified for testing against food-safety pathogens. One major pathogen that is contributing to this challenge of antibiotic resistance is Staphylococcus aureus. The methicillin-resistant strain of S. aureus leads to increased hospital stays and increased mortality in patients. The impact of such pathogens is worsened when bacteria form surface-attached aggregates known as biofilms. Development of new approaches to eradicate antibiotic- resistant biofilms will benefit human health. This study looked at an alternative method to eradicate bacteria compared to traditional antibiotics. Histones with antimicrobial activity were extracted from chicken blood and tested against methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus biofilm (MSSA and MRSA). The histone mixture completely eradicated both strains in biofilm form at relatively low concentrations. In addition, the histone mixture also displayed fast kill kinetics against planktonic forms of the two strains. Finally, the interaction of the histone mixture with the bacterial membrane in MRSA biofilms was observed by scanning electron microscopy (SEM). Bacteria treated with the histone mixture showed clear morphological changes, including pore formation and cell collapse. Therefore, the histone mixture purified from chicken red blood cells could prove to be a good alternative to traditional antibiotics for protection against antibiotic-resistant strains of bacteria in their planktonic and biofilm forms. Reduction of food-borne illness is another important aspect in the promotion of human health. A significant contributor to food-borne illness is contaminated table eggs. The unfertilized egg can be contaminated by a variety of pathogens including Salmonella spp. and Bacillus spp. The egg is protected by the eggshell which is traversed by respiratory pores that are normally covered by a cuticle plug to restrict pathogen entry. This cuticle consists of several proteins including ovocaxlyin-32 (OCX-32). OCX-32 has a large number of naturally occurring haplotypes due non-synonymous single nucleotide polymorphisms (SNPs). In this study, the goal was to express five of the most common haplotypes of OCX-32 in Escherichia coli and purify the recombinant protein for assay of its antimicrobial activity. Five constructs that contain the cDNA of common OCX-32 haplotypes (A, B, C, D, and O) with a histidine tag at the C-terminus were generated. The constructs were subcloned into pGEX4T-1 vector which encodes Glutathione-S-transferase (GST) upstream of the multiple cloning site. My study developed methods to optimize the expression conditions, and to increase the solubility of the recombinant protein. Various expression strains of E. coli and solubility buffers were tested. In addition, the construct was subcloned into a plasmid containing the small ubiquitin-like modifier (SUMO) fusion tag; the solubility of the new SUMO-OCX-32 haplotype A recombinant fusion protein was evaluated. The best results were obtained by slow dialysis refolding of denatured SUMO-OCX-32 fusion protein. This recombinant protein showed almost complete solubility with minimal precipitation and was tested against the egg-related pathogen, Bacillus cereus. Unfortunately, the SUMO-OCX-32 recombinant protein did not inhibit growth of B. cereus. In my studies reported in this thesis, two very different approaches were taken. A histone mixture was isolated from an abundant starting material, which proved to be highly effective and promising in the eradication of S. aureus biofilms at relatively low concentrations. Alternatively, expression of a soluble recombinant protein for functional activity assay was very challenging and required the optimization of a number of methods to prepare soluble protein for testing. One of the methods tested proved effective in obtaining large amounts of soluble protein. However, further developmental work will be essential to determine if this approach is a viable strategy in acquiring functional protein.
3

Gamybinių užsakymų projektavimo ir valdymo programinė įranga / Manufacturing Orders Design and Management Software

Kičas, Rolandas 27 May 2005 (has links)
This master thesis analyses principle manufacturing order design and management methods and schemas. They are practicaly applied in developing software for product‘s graphical-informational model management, feature management, technological data and rules specification and description, product‘s material list creation and estimation. The developed software is suited for both large and small manufacturing corporations, that specializes in plastic or wooden windows, doors, garage gates, glass fillings production. The system may be adjusted to various manufacturing technologies. These software development methods and technologies were applied during system design and implementation: Dynamic System Development Method (DSDM), Object Oriented (OO) Design and Programming, Component Based System Engineering Method (CBSE), Computer-Aided Design/Computer-Aided Manufacturing Methods, eXtensible Markup Language (XML). Created software was tested with real technological data. Systems suites functional and non-functional specifiaction. Experimets show that the product is more flexible than it‘s previous version.

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