One of the most effective immunological interventions for human disease prevention is the administration of anti-red blood cell (RBC) IgG, more specifically, anti-D IgG, for prevention of hemolytic disease of the fetus and newborn (HDN), a serious and potentially fatal condition caused by the maternal immune response against the Rhesus (Rh) blood group system D antigen on fetal RBC. Despite its widespread clinical use, the mechanism of the suppressive anti-RBC IgG effect is not fully understood. In a murine model of immunity to foreign RBCs, transfusion of mice with IgG-opsonized RBCs strongly attenuated the antibody response compared to transfusion of untreated RBCs. This model was used to study the anti-RBC IgG effect on the host immune response. Contrary to the predominant theories of the anti-D effect, here it is shown that IgG-mediated RBC clearance is not sufficient for the attenuation of antibody responses. IgG-opsonized RBCs internalized by the mononuclear phagocytic cells could stimulate T and B cell responses against RBC antigens. This thesis also shows that the adaptive tolerance at the T or B cell level is not the reason for the attenuation of the antibody response. Instead, IgG selectively prevented the appearance of antigen-primed RBC-specific B cells and, surprisingly, induced the host B cell response against the IgG in complex with RBCs. These results suggest that the inability of RBC-specific B cells to recognize and present RBC-specific epitopes may explain the inhibitory IgG effect.

Bacteriophage Lambda (λ) has played a historical role as an essential model contributing to our current understanding of molecular genetics. Lambda’s major capsid protein “gpD” occurs on each capsid at 405 to 420 copies per phage in homotrimeric form and functions to stabilize the head and likely to compact the genomic DNA. The interesting conformation of this protein allows for its exploitation through the genetic fusion of peptides or proteins to either the amino or carboxy terminal end of gpD, while retaining phage assembly functionality and viability. The lytic nature of λ and the conformation of gpD in capsid assembly makes this display system superior to other display options. Despite previous reports of λ as a phage display candidate, decorative control of the phage remains an elusive concept. The primary goal of this study was to design and construct a highly controllable head decoration system governed by two genetic conditional regulation systems; plasmid-mediated temperature sensitive repressor expression and bacterial conditional amber mutation suppression. The historical λ Dam15 conditional allele results in a truncated gpD fragment when translated in nonsuppressor, wild-type E. coli cells, resulting in unassembled, nonviable progeny. I sequenced the Dam15 allele, identifying an amber (UAG) translational stop at the 68th codon. Employing this mutant in combination with a newly created isogenic cellular background utilizing the amber suppressors SupD (Serine), SupE (Glutamine), SupF (Tyrosine) and Sup— (wild type), we sought to control the level of incorporation of undecorated gpD products. As a second dimension, I constructed two separate temperature-inducile plasmids whereby expression of either D or D::eGFP was governed by the λ strong λ CI[Ts]857 temperature-sensitive repressor and expressed from the λ PL strong promoter. Our aim was to measure the decoration of the λ capsid by a D::gfp fusion under varying conditions regulated by both temperature and presence of suppression. This was achieved utilizing this controllable system, enabling the measurement of a variable number of fusions per phage based on diverse genetic and physical environments without significantly compromising phage viability. Surprisingly, both SupE and SupF showed similar levels of Dam15 suppression, even though sequencing data indicated that only SupE could restore the native gpD sequence at amino acid 68 (Q). In contrast, SupD (S), conferred very weak levels of suppression, but imparted an environment for very high decoration of gpD::eGFP per capsid, even at lower (repressed) temperatures. The presence of albeit few wild-type gpD molecules allowed for an even greater display than that of the perceived “100%” decoration scenario provided by the nonsuppressor strain. It appears that the lack of wild-type gpD does not allow for the space required to display the maximum number of fusions and in turn creates an environment that affects both phage assembly and therefore phage viability. Finally, the use of Western blotting, confirmed the presence of gpD::eGFP fusion decoration by employing a polyclonal anti-eGFP antibody. The significance of this work relates to the unique structure of λ’s capsid and its ability to exploit gpD in the design of controlled expression, which is guiding future research examining the fusion of different therapeutic peptides and proteins. Furthermore this approach has important implications specifically for the design of novel vaccines and delivery vehicles for targeted gene therapy in which steric hindrance and avidity are important concerns. The execution of this project employed basic bacterial genetics, phage biology and molecular biology techniques in the construction of bacterial strains and plasmids and the characterization of the phage display system.

Defence Research and Development Canada - Atlantic is currently under a project arrangement with Sweden and Holland to investigate new or emerging fire suppression technologies in naval applications. One possible outcome of this project arrangement could be the identification of a safe and effective Halon 1301 replacement suppression agent within the respective navies. The subject area Canada has agreed to investigate is aerosol fire extinguishing agent technologies. Although aerosols have been shown to be effective in suppressing demonstration fires, to date there has been little systematic scientific research into fire suppression using aerosol particulates. Therefore, there is a need for more in depth investigation of some of the commercial aerosol products available on the market to determine their fire suppression efficacy in naval applications, as well as any potential negative impacts that the aerosol may have on personnel, equipment and the environment. Aerosol suppression systems range from small handheld grenade extinguishers to large fitted and remotely activated aerosol dispersal units. The fire research and testing presented in this thesis looks specifically at the efficacy and safe use of two variants of the small handheld aerosol extinguishers, while also assessing aerosol agent suppression technologies overall. The Royal Canadian Navy (RCN) currently uses a two tiered response to fire, consisting of first response by a Rapid Response Team (RRT), followed by full response by an Attack Team (AT). A Rapid Attack Team (RAT) has been introduced as an intermediate response team. To enhance efficiency of the RRTs or RATs, handheld aerosol units, in this evaluation the Dry Sprinkler Powder Aerosol (DSPA) and StatX fire knock down aerosol extinguishers, could potentially be stored throughout the ship or transported by the teams to a fire scene and used to control, suppress or even extinguish a fire prior to the AT arriving on the scene, particularly in the case of smaller enclosure fires. To fully evaluate their potential for use in this capacity, it is important to carefully study the suppression efficacy of these units under conditions similar to those in which they would be deployed, as well as to better understand their impact on a fire environment in terms of important parameters such as compartment temperature reduction, visibility, oxygen concentration, aerosol particulate dwell time, and toxicity. In terms of operational issues related to deployment of these pyrotechnic tools onboard RCN vessels, it is critical to assess the requirements for extinguisher safe storage and to gain an understanding of the incendiary potential of the units, as well as post suppression overhaul, smoke/agent clearing and compartment gas free certification. The thesis includes a description of the experimental design, measurement techniques, and key results and conclusions for each of the 26 full-scale simulated marine enclosure live fire tests that were conducted. In general, handheld aerosol extinguishers have proven to be effective for fire control and even suppression under certain circumstances. They can improve the fire safety of RCN vessels when used correctly. Experimental data measured that relate to the consequences of accidental discharge and incendiary potential can also be used to ensure naval applications are safe and effective.

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Differential gene expression plays a key role in developmental pathways within an organism. Examples of such pathways include primary sex determination signaling and the formation of secondary sexual characteristics. This dissertation is focused on the use of suppression subtractive hybridization (SSH) to identify genes that are differentially expressed and involved in some aspect of sexual development in the Mediterranean fruit fly (medfly), Ceratitis capitata. In the course ofthis project, a method for sexing individual specimens from pre-adult stages was developed. This method was used to collect sex-specific RNAs at different developmental stages for use in SSH. A total of25 subtraction products were obtained across all the stages examined. Analysis of these products revealed that approximately half were similar to cytoplasmic ribosomal proteins and mitochondrial ribosomal RNA The remaining products represent putative medfly homologs of other previously identified genes or potentially novel genes One ofthe subtraction products, representing a potentially novel gene, was characterized in detail. This gene, named mapotge', represents a novel medfly gene that appears to encode a polypeptide of 299 amino acids. The N-terminus of this polypeptide contains a BTB-POZ domain. This domain functions as a protein-protein interaction motif found in a wide range of organisms from humans to Drosophila that mediates protein dimerization and oligomerization. The temporal expression pattern of mapotge' was determined using RT-PCR and Northern blot analysis. These revealed that the transcript is expressed throughout embryogenesis in both females and males, and in adult females that are > 0.5 days post-eclosion. Minimal expression is observed in female and male third instar larvae, early pupae, and in adult males. Studies were also initiated to characterize the representation of additioual sequences containing a BTB-POZ domain in the medfly genome. This was performed using Southern blot analysis and degenerate primers for the polymerase chain reaction (PCR). These results indicate the presence of at least three sequences in the medfly, in addition to 'mapotge', that contain a BTB-POZ domain. Potential evolutionary relationships ofthe BTB-POZ domain sequences from the medfly and other insect species were also analyzed.

Effective antenna selection and deployment strategies are important for reducing co-channel interference in indoor wireless systems. Low-cost solutions are essential, and strategies that utilise simple antennas (such as directional patches) are advantageous from this perspective. However, performance is always an issue and the improvements achievable through clever antenna deployment need to be quantified. In this thesis, an experimental investigation of indoor propagation comparing the performance of directional antennas and multiple-element arrays (MEAs) with omni-directional antennas is reported. Estimation of the performance of a direct sequence code division multiple access (DS-CDMA) system operating in a variety of deployment scenarios allows the identification of a range of performance-limiting factors and the optimal deployment strategies. It is shown that the orientation of single-element directional antennas can significantly impact on system performance compared to omni-directional antennas in traditional systems. The deployment of MEAs with an active diversity combining scheme can further improve system performance by more than one order of magnitude. From the perspective of system planning, the choice of antenna selection and deployment options depends on the current and future demand for system performance and the financial resources available. An evolutionary path has been proposed to provide a smooth transition from conventional (low-cost) to high-performance (high-cost) antenna systems as demand dictates. Other performance-limiting factors in indoor wireless systems include the physical environment and external interference. It is also shown that electromagnetically-opaque obstacles in the environment can amplify the effectiveness of the antenna deployment by acting as physical zone boundaries that restrict interference. External interference has been shown to cause a significant degradation to the performance of an indoor system when the carrier-to-external-interference ratio (CEIR) is below 30 dB. This performance degradation can be minimised by appropriate antenna deployment, although the optimum antenna orientations depends on the strength of the external interference.

Effective antenna selection and deployment strategies are important for reducing co-channel interference in indoor wireless systems. Low-cost solutions are essential, and strategies that utilise simple antennas (such as directional patches) are advantageous from this perspective. However, performance is always an issue and the improvements achievable through clever antenna deployment need to be quantified. In this thesis, an experimental investigation of indoor propagation comparing the performance of directional antennas and multiple-element arrays (MEAs) with omni-directional antennas is reported. Estimation of the performance of a direct sequence code division multiple access (DS-CDMA) system operating in a variety of deployment scenarios allows the identification of a range of performance-limiting factors and the optimal deployment strategies. It is shown that the orientation of single-element directional antennas can significantly impact on system performance compared to omni-directional antennas in traditional systems. The deployment of MEAs with an active diversity combining scheme can further improve system performance by more than one order of magnitude. From the perspective of system planning, the choice of antenna selection and deployment options depends on the current and future demand for system performance and the financial resources available. An evolutionary path has been proposed to provide a smooth transition from conventional (low-cost) to high-performance (high-cost) antenna systems as demand dictates. Other performance-limiting factors in indoor wireless systems include the physical environment and external interference. It is also shown that electromagnetically-opaque obstacles in the environment can amplify the effectiveness of the antenna deployment by acting as physical zone boundaries that restrict interference. External interference has been shown to cause a significant degradation to the performance of an indoor system when the carrier-to-external-interference ratio (CEIR) is below 30 dB. This performance degradation can be minimised by appropriate antenna deployment, although the optimum antenna orientations depends on the strength of the external interference.

Effective antenna selection and deployment strategies are important for reducing co-channel interference in indoor wireless systems. Low-cost solutions are essential, and strategies that utilise simple antennas (such as directional patches) are advantageous from this perspective. However, performance is always an issue and the improvements achievable through clever antenna deployment need to be quantified. In this thesis, an experimental investigation of indoor propagation comparing the performance of directional antennas and multiple-element arrays (MEAs) with omni-directional antennas is reported. Estimation of the performance of a direct sequence code division multiple access (DS-CDMA) system operating in a variety of deployment scenarios allows the identification of a range of performance-limiting factors and the optimal deployment strategies. It is shown that the orientation of single-element directional antennas can significantly impact on system performance compared to omni-directional antennas in traditional systems. The deployment of MEAs with an active diversity combining scheme can further improve system performance by more than one order of magnitude. From the perspective of system planning, the choice of antenna selection and deployment options depends on the current and future demand for system performance and the financial resources available. An evolutionary path has been proposed to provide a smooth transition from conventional (low-cost) to high-performance (high-cost) antenna systems as demand dictates. Other performance-limiting factors in indoor wireless systems include the physical environment and external interference. It is also shown that electromagnetically-opaque obstacles in the environment can amplify the effectiveness of the antenna deployment by acting as physical zone boundaries that restrict interference. External interference has been shown to cause a significant degradation to the performance of an indoor system when the carrier-to-external-interference ratio (CEIR) is below 30 dB. This performance degradation can be minimised by appropriate antenna deployment, although the optimum antenna orientations depends on the strength of the external interference.

Effective antenna selection and deployment strategies are important for reducing co-channel interference in indoor wireless systems. Low-cost solutions are essential, and strategies that utilise simple antennas (such as directional patches) are advantageous from this perspective. However, performance is always an issue and the improvements achievable through clever antenna deployment need to be quantified. In this thesis, an experimental investigation of indoor propagation comparing the performance of directional antennas and multiple-element arrays (MEAs) with omni-directional antennas is reported. Estimation of the performance of a direct sequence code division multiple access (DS-CDMA) system operating in a variety of deployment scenarios allows the identification of a range of performance-limiting factors and the optimal deployment strategies. It is shown that the orientation of single-element directional antennas can significantly impact on system performance compared to omni-directional antennas in traditional systems. The deployment of MEAs with an active diversity combining scheme can further improve system performance by more than one order of magnitude. From the perspective of system planning, the choice of antenna selection and deployment options depends on the current and future demand for system performance and the financial resources available. An evolutionary path has been proposed to provide a smooth transition from conventional (low-cost) to high-performance (high-cost) antenna systems as demand dictates. Other performance-limiting factors in indoor wireless systems include the physical environment and external interference. It is also shown that electromagnetically-opaque obstacles in the environment can amplify the effectiveness of the antenna deployment by acting as physical zone boundaries that restrict interference. External interference has been shown to cause a significant degradation to the performance of an indoor system when the carrier-to-external-interference ratio (CEIR) is below 30 dB. This performance degradation can be minimised by appropriate antenna deployment, although the optimum antenna orientations depends on the strength of the external interference.