Mobile group II introns are retroelements that site-specifically insert into DNA target sequences. The group II intron mobility pathway is mediated by a ribonucleoprotein particle (RNP) composed of excised intron RNA and an intron-encoded protein (IEP). The intron lariat inserts at a specific DNA target sequence and is then reverse transcribed by the IEP. Both the intron RNA and IEP are required for DNA target site recognition. I have identified the contact sites within the IEP responsible for recognition of two key positions in the DNA target, T+5 and T-23. IEP recognition of T+5 in the 3'-exon is required for endonuclease cleavage of the bottom-strand of the DNA target site, which generates a primer used for initiation of reverse transcription of the intron. The T+5 base is contacted by G498 in the LtrA DNA-binding domain and nearby residues, particularly K499, potentially bolster this interaction. Recognition of T-23 in the distal 5'-exon is required for initial recognition of the DNA target site by the RNP. The T533 side-chain contacts the T-23 base and the L534 side-chain may also contribute to recognition through hydrophobic interactions with the C5 methyl group. A mutant, L534H, that switches target site specificity to T-23G has been characterized. In order for the RNP to make these and other contacts in the 5'- and 3'-exons simultaneously, the DNA must be bent. I have dissected the role of DNA bending in the intron mobility pathway and found that the DNA is bent at two progressively larger angles as the reaction proceeds. The predominant bend angle at earlier time points places the bottom-strand DNA cleavage site at the protein endonuclease active site. The predominant bend angle of later time points places the cleaved DNA site at the RT domain active site for initiation of reverse transcription of intron cDNA. Finally, in a practical application of group II intron mobility, I have used reprogrammed group II introns ("targetrons") to target two genes in Bacillus subtilis to demonstrate the suitability of targetron technology for gene targeting in the Gram-positive Bacillus genus. / text

This dissertation studies the impact of World War II on the development of the American economy after 1940. Scholars have long-debated the economic consequences of the war, particularly with reference to the macroeconomy and often relying on standard measures of aggregate economic performance. The approach in this dissertation is to study the microeconomic implications of mobilization for World War II. Specifically, the three main chapters address the following questions: What were the human capital costs of the manpower mobilization for young women? Did industrial mobilization promote the growth and diversification of manufacturing in the American South? How much did government spending on supply contracts contribute to migration and the change in the structure of wages between 1940 and 1950? The first chapter provides an overview of America's twentieth century wars and surveys the literature on the impact of World War II. In the second chapter, I find that greater exposure to manpower mobilization decreased young women's educational attainment initially, with important implications for family formation and labor market performance. From the analysis of the third chapter I conclude that the war led to modest reallocation of manufacturing activity toward high value- added sectors, but the war most likely did not create the modern industrial South. In the final chapter I provide evidence that migration induced by World War II played a role in reshaping the structure of wages during the 1940s. Together, the chapters provide important nuance and revisions to our understanding of World War II.

Several active flow control, as well as passive flow control, schemes were applied to a modified Glauert II "laminar" airfoil section. Zero mass-flux oscillatory suction and blowing and net mass-flux steady suction, or steady blowing were applied through a segmented spanwise slot. Static and dynamic pressures were measured. Pressures around the main element and within the wake were analyzed in order to gauge the performance through aerodynamic coefficients. Unsteady AFC was found to be effective as well as efficient. Several flow visualization techniques were used to aid the static analysis of the pressure distributions. Separation bubbles, recirculation zones, jump in stagnation location, spanwise-, and streamwise vortices were visualized. The present research attempts to quantify the control efficacy of unsteady zero mass-flux control and it's ability to reattach the flow and/or prevent separation. The concave curvature of the ramp was of concern as were the flow instabilities present due to the concavity.

No description available.

The objective of this thesis is to explore the synthesis and characterization of high quality binary ZnTe nanowires with great potential for development of optoelectronic devices including high efficiency photovoltaic cells for energy conversion and high sensitivity photodetectors for green fluorescent protein bioimaging at single molecule level. To systematically explore the fabrication process for high quality nanowires, a chemical vapour deposition system was built for nanowire growth. Computational fluid dynamics simulations were used to optimize the reactor and growth parameters. The simulations were validated by experimental measurements. Room temperature photoluminescence measurements showed that high crystal quality with very low defects by single step growth was achieved. This single step growth technique makes a great improvement compared to the reported growth followed by annealing, which achieved equivalent crystal quality. This simplification could be of use in large scale synthesis of nanowires. The simulation results also showed that reactant species concentration is a key factor influencing the growth. A metal-organic chemical vapour deposition system was thus built to independently control reactant concentrations for ZnTe nanowire growth. Temperature-dependent photoluminescence measurements of as-grown ZnTe nanowires showed a strong near band-edge emission. In addition, a deep level oxygen-related band was observed for the first time. From the detailed analysis of thermal quenching of the photoluminescence, it was shown that the deep level emission was partially from the intermediate band of the material. This is of great importance due to the theoretical absorption efficiency that is as high as 63% for intermediate band materials, which is more than two times of that of current single junction concentrators, and few materials possessing this property. Individual ZnTe nanowires, grown after optimization, were patterned and contacted, and their conductivity and photoconductivity were measured at room temperature. A single ZnTe nanowire serving as a photodetector was shown to have the highest reported visible responsivity of 360 A/W (at 530 nm), and a gain of 8,640 (at 3 V bias). The responsivity is roughly 18 times higher than that of silicon avalanche photodiodes. This demonstrates that ZnTe nanowires are strong candidates for single photon detection.

Atliktas palyginamasis dviejų kompleksinių sistemų - Cu|Cu(II), glicinas ir Cu|Cu(II), maleino rūgštis - elektrocheminių charakteristikų tyrimas. Nustatytos maleino rūgšties tirpalų pusiausvyrinės charakteristikos. Kiekybiniam titravimo kreivių aprašymui išvestos lygtys, kuriose įvertinti medžiagų bei krūvių balansai bei atsižvelgta į praskiedimo efektus. Jų taikymas pH-metrinių duomenų analizei davė tokias maleato anijonų protonizacijos konstantų reikšmes: log = 6,05, log = 7,48. Nustatyta, kad tirpaluose su 0,3 M K2SO4 priedu protonizuotų ligando formų stabilumas sumažėja (log = 5,75, log = 7,30). Cu(II) maleatinių kompleksų stabilumui nustatyti panaudotas spektrofotometrijos metodas ir pasiūlyta duomenų analizės procedūra. Ji remiasi kiekybiniu absorbcijos spektrų aprašymu, taikant lygtis, išplaukiančias iš valdomo harmoninio osciliatoriaus teorijos. Išanalizavus įvairių sudėčių tirpalų absorbcijos maksimumo dydžius, prieita išvados, kad rūgščiose terpėse vyrauja monoligandinis kompleksas, kurio koncentracinė stabilumo konstanta log b1 = 2,2. Atlikta sistemos Cu|Cu(II), maleino rūgštis pusiausvyrų termodinaminė analizė. Nustatyta, kad esant metalinio vario ir tirpalų sąlyčiui, sistemoje galimi gilūs virsmai, kurių metu iki 90 % Cu(II) transformuojasi į Cu(I). Teorines išvadas patvirtina eksperimentiniai duomenys, gauti spektrofotometrijos ir elektrocheminės kvarco kristalo mikrogravimetrijos metodais. Įvertinti Cu korozijos bei fazinių Cu2O sluoksnių susidarymo... [toliau žr. visą tekstą] / A comparative investigation of electrochemical characteristics of two complex systems, viz. Cu|Cu(II), glycine and Cu|Cu(II), maleic acid, was carried out. The equations were obtained for quantitative description of pH-metric and spectrophotometric data, which were used for determination of equilibrium characteristics in Cu(II)-maleic acid solutions. Thermodynamic analysis shows that deep changes are possible in this system resulting in 90 % transform of Cu(II) into Cu(I). The rates of Cu corrosion and Cu2O formation are estimated to be of the same order (nmol cm-2 s-1). Regularities of formal electrochemical kinetics, which account for the mass transport of chemically interacting particles and for step-wise charge transfer process, are suitable for interpretation of voltammetric data of the Cu|Cu(II), glycine system. Kinetic parameters Cu(II) glycinate complex depend on the nature of the supporting electrolyte: the exchange current density decreases and the cathodic charge transfer coefficient increases in the sequence: Li+ - Na+ - K+ - Cs+. To enhance the Cu(I) generation in maleic acid system, the pre-electrolysis procedure was applied. It was found that its effect depends on solution pH. Applied theoretical model describes satisfactorily the steady-state voltammetric characteristics of Cu|Cu(II), maleic acid system, but some contradictory results were obtained in the case of time-dependent processes. Theoretical and experimental problems to be solved are discussed.

RNA polymerase II, the polymerase responsible for transcribing protein coding genes in eukaryotes, possesses an ability to discriminate between correct (complementary to the DNA template) and incorrect substrates (selectivity), and as well as remove incorrect substrates that have been erroneously incorporated into the nascent RNA transcript (proofreading). Although these features of pol II are not as robust as those observed for DNA polymerases, the accurate utilization of genetic information is of obvious importance to the cell. The role of the small RNA polymerase II subunit Rpb9 in transcriptional proofreading was assessed in vitro. Transcription elongation complexes in which the 3'-end of the RNA is not complementary to the DNA template have a dramatically reduced rate of elongation, which provides a fidelity checkpoint at which the error can be removed. The efficiency of such proofreading depends on competing rates of error propagation (extending the RNA chain without removing the error) and error excision, a process that is facilitated by TFIIS. In the absence of Rpb9, the rate of error propagation is increased by 2- to 3-fold in numerous sequence contexts, compromising the efficiency of proofreading. In addition, the rate and extent of TFIIS-mediated error excision is also significantly compromised in the absence of Rpb9. In at least some sequence contexts, Rpb9 appears to enhance TFIIS-mediated error excision by facilitating efficient formation of a conformation necessary for RNA cleavage. If a transcription error is propagated by addition of a nucleotide to the mismatched 3'-end, the rate of further elongation increases but remains much slower than that of a complex with a fully base-paired RNA, which provides a second potential fidelity checkpoint. The absence of Rpb9 also affects both error propagation and TFIIS-mediated error excision at this potential fidelity checkpoint in a manner that compromises transcriptional fidelity. The trigger loop, a mobile structural element of the largest subunit of RNA polymerase II is important for maintaining fidelity. The pol II specific toxin α-amanitin targets the trigger loop, and was used to distinguish trigger loop -independent and -dependent Rpb9 functions, in vitro. Rpb9 decreases the correct nt extension rate when trigger loop movement is restricted by α-amanitin. This occurs in the context of a RNA with a matched or mismatched 3’-end, which indicates that Rpb9’s contribution to correct nt extension occurs in a manner independent of the trigger loop. In addition, the effect on mismatch extension indicates that the trigger loop is not required for Rpb9 to facilitate recognition of proofreading ‘checkpoints’ after mismatches occur. Rpb9 also decreases the rate of misincorporation, but this effect is dependent on the trigger loop. Rpb9’s role in selectivity was tested by utilizing several assays to estimate nt discrimination. Rpb9 does not have a significant effect on nt discrimination for the sequence contexts tested, which suggests the role Rpb9 plays in fidelity is in large part due to its proofreading capabilities. Lastly, the charged residues of Rpb9’s C-terminal “loop” region, proposed in the prevailing model to be important for trigger loop interaction, are dispensable for Rpb9 function in vivo and in vitro.

Exposure to benzene, a ubiquitous environmental pollutant, has been linked to leukemogenesis, although the mechanism of benzene initiated carcinogenesis remains unclear. It has been proposed that benzene can be bioactivated to toxic metabolites such as 1,4 benzoquinone (BQ), which can alter signalling pathways and affect chromosomal integrity. BQ has been shown to increase the activity of c-Myb, which is an important transcription factor involved in hematopoiesis, cell proliferation, and cell differentiation. The c-Myb protein also increases topoisomerase IIα (topo IIα) promoter activity specifically in cell lines with hematopoietic origin. Topo II is a critical nuclear enzyme that removes torsional strain by cleaving, untangling and religating double-stranded DNA. Since topo II mediates DNA strand breaks, aberrant topo II activity or increased protein levels may increase the formation of DNA strand breaks, leaving the cell susceptible to mutational events. I hypothesize that BQ increases c-Myb activity, which in turn increases topo IIα promoter activity resulting in increased DNA strand breaks. Using luciferase reporter assays in K-562 cells (human chronic myeloid leukemic cells) I confirmed that BQ exposure (25 and 37 µM) caused an increase in c-Myb activity after 24 hours. Contradictory to previous findings, overexpression of exogenous c-Myb or a polypeptide consisting of c-Myb’s DNA binding domain (DBD), which competitively inhibits the binding of endogenous c-Myb to DNA, did not affect topo IIα promoter activity. However, BQ exposure (37 µM for 24 hours) caused a significant increase in topo IIα promoter activity, which could be blocked by the overexpression of the DBD polypeptide. Western immunoblotting analysis did not show any significant increases in topo IIα protein levels in cells exposed to 37 µM BQ for 24 hours. Overall, this study suggests that BQ exposure increases topo IIα promoter activity through the c-Myb signalling pathway and furthers our understanding of BQ-mediated toxicity. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2008-01-02 14:09:00.011

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

El presente trabajo propone conocer el rol de la CaMKII en la vía de señalización que conduce a la apoptosis inducida por AngII. Hipótesis de Trabajo: Nuestra hipótesis de trabajo es que la CaMKII está involucrada en la muerte celular por apoptosis inducida por AngII en el miocardio. Objetivos específicos: • Ratificar la inducción de apoptosis por AngII en nuestros preparados experimentales, a través de parámetros morfológicos, inmunohistoquímicos y bioquímicos. • Determinar si la CaMKII participa en la vía apoptótica inducida por AngII y en ese caso, investigar la cascada de señales intracelulares involucradas en su activación, realizando ensayos con inhibidores farmacológicos específicos de los posibles mediadores intracelulares, en combinación con medidas de Ca<SUP>+2</SUP> intracelular y ROS. • Determinar los blancos moleculares de la CaMKII, a través de los cuales la vía apoptótica se hace efectiva.