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The developmental processes of lymphopoiesis generate mature B lymphocytes from hematopoietic stem cells through increasingly restricted intermediates. Networks of transcription factors regulate these cell fate choices and are composed of both ubiquitously expressed and B lineage-specific factors. E-protein transcription factors are encoded by the three genes E2A, E2-2 (SEF2-1), and HEB. The E2A gene is required for B cell development and encodes the alternatively spliced proteins E12 and E47. During B lymphocyte development, the cells have to pass several checkpoints verifying the functionality of their antigen receptors. Early in the development, the expression of a pre-B cell receptor (pre-BCR) with membrane-bound immunoglobulin (Ig) heavy chain protein associated with surrogate light chain (SLC) proteins is a critical checkpoint that monitors for functional Ig heavy chain rearrangement. Signaling from the pre-BCR induces survival and a limited clonal expansion. Here it is shown that pre-BCR signaling rapidly down-regulates the SLCs l5 and VpreB and also the co-receptor CD19. Ca2+ signaling and E2A were shown to be essential for this regulation. E2A mutated in its binding site for the Ca2+ sensor protein calmodulin (CaM), and thus with CaM-resistant DNA binding, makes l5, VpreB and CD19 expression resistant to the inhibition following pre-BCR stimulation. Thus, Ca2+ down-regulates SLC and CD19 gene expression upon pre-BCR stimulation through inhibition of E2A by Ca2+/CaM. A general negative feedback regulation of the pre-BCR proteins as well as many co-receptors and proteins in signal pathways from the receptor was also shown. After the ordered recombination of Ig heavy chain gene segments, also Ig light chain gene segments are recombined together to create antibody diversity. The recombinations are orchestrated by the recombination activating gene (RAG) enzymes, other enzymes that cleave/mutate/assemble DNA of the Ig loci, and the transcription factor Pax5. A key feature of the immune system is the concept that one lymphocyte has only one antigen specificity that can be selected for or against. This requires that only one of the alleles of genes for Ig chains is made functional. The mechanism of this allelic exclusion has however been an enigma. Here pre-BCR signaling was shown to down-regulate several components of the recombination machinery including RAG1 and RAG2 through CaM inhibition of E2A. Furthermore, E2A, Pax5 and the RAGs were shown to be in a complex bound to key sequences on the IgH gene before pre-BCR stimulation and instead bound to CaM after this stimulation. Thus, the recombination complex is directly released through CaM inhibition of E2A. Upon encountering antigens, B cells must adapt to produce a highly specific and potent antibody response. Somatic hypermutation (SH), which introduces point mutations in the variable regions of Ig genes, can increase the affinity for antigen, and antibody effector functions can be altered by class switch recombination (CSR), which changes the expressed constant region exons. Activation-induced cytidine deaminase (AID) is the mutagenic antibody diversification enzyme that is essential for both SH and CSR. The AID enzyme has to be tightly controlled as it is a powerful mutagen. BCR signaling, which signals that good antibody affinity has been reached, was shown to inhibit AID gene expression through CaM inhibition of E2A.  SH increases the antigen binding strength by many orders of magnitude. Each round of SH leads to one or a few mutations, followed by selection for increased affinity. Thus, BCR signaling has to enable selection for successive improvements in antibodies (Ab) over an extremely broad range of affinities. Here the BCR is shown to be subject to general negative feedback regulation of the receptor proteins as well as many co-receptors and proteins in signal pathways from the receptor. Thus, the BCR can down-regulate itself to enable sensitive detection of successive improvements in antigen affinity. Furthermore, the feedback inhibition of the BCR signalosome and most of its protein, and most other gene regulations by BCR stimulation, is through inhibition of E2A by Ca2+/CaM. Differentiation to Ab-secreting plasmablasts and plasma cells is antigen-driven. The interaction of antigen with the membrane-bound Ab of the BCR is critical in determining which clones enter the plasma cell response. Genome-wide analysis showed that differentiation of B cells to Ab-secreting cell is induced by BCR stimulation through very fast regulatory events, and induction of IRF-4 and down-regulation of Pax5, Bcl-6, MITF, Ets-1, Fli-1 and Spi-B gene expressions were identified as immediate early events. Ca2+ signaling through CaM inhibition of E2A was essential for these rapid down-regulations of immediate early genes after BCR stimulation in initiation of plasma cell differentiation.

BACKGROUND: The research deals with the effect of the Student Rag Community Service's (SRCS) Pick–A–Leader programme on adolescents in a disadvantaged community. The SRCS has been in existence for 30 years and the Student Representative Council of the North–West University: Potchefstroom Campus, has authorised them to promote voluntary ativities for charity in Potchefstroom and its surrounding areas. The SJGD annually presents various programmes to communities in Potchefstroom; however, these programmes have not thus far been formally evaluated. One of these projects is the Pick–A–Leader (PAL) programme which focuses on leadership– and skills development for adolescents in a disadvantaged community. This study concentrates on the evaluation of the PAL–programme. AIM: The primary aim of this study was to determine the effect of the PAL–programme on the adolescents in a disadvantaged community. METHOD: The nature of the investigation was exploratory and descriptive. Mixed methodology was applied in this study. A quasi–experimental design was used in the form of a comparative pre– and post–test design. Focus groups and a number of measuring instruments were used to gather data. Participants in the experimental groups consisted of 45 grade 11 learners from 3 schools in a disadvantaged community of Potchefstroom. Members of the comparative groups also numbered 45 and were grade 11 learners from the same 3 schools as those in the experimental groups. RESULT: It was concluded that the SRCS PAL–programme had an effect on the adolescents. / Thesis (M.A. (MW))--North-West University, Potchefstroom Campus, 2011.

BACKGROUND: The research deals with the effect of the Student Rag Community Service's (SRCS) Pick–A–Leader programme on adolescents in a disadvantaged community. The SRCS has been in existence for 30 years and the Student Representative Council of the North–West University: Potchefstroom Campus, has authorised them to promote voluntary ativities for charity in Potchefstroom and its surrounding areas. The SJGD annually presents various programmes to communities in Potchefstroom; however, these programmes have not thus far been formally evaluated. One of these projects is the Pick–A–Leader (PAL) programme which focuses on leadership– and skills development for adolescents in a disadvantaged community. This study concentrates on the evaluation of the PAL–programme. AIM: The primary aim of this study was to determine the effect of the PAL–programme on the adolescents in a disadvantaged community. METHOD: The nature of the investigation was exploratory and descriptive. Mixed methodology was applied in this study. A quasi–experimental design was used in the form of a comparative pre– and post–test design. Focus groups and a number of measuring instruments were used to gather data. Participants in the experimental groups consisted of 45 grade 11 learners from 3 schools in a disadvantaged community of Potchefstroom. Members of the comparative groups also numbered 45 and were grade 11 learners from the same 3 schools as those in the experimental groups. RESULT: It was concluded that the SRCS PAL–programme had an effect on the adolescents. / Thesis (M.A. (MW))--North-West University, Potchefstroom Campus, 2011.

Of key importance for metamodelling are appropriate modelling formalisms. Most metamodelling languages permit the development of metamodels that specify tree-structured models enriched with semantics like constraints, references and operations, which extend the models to graphs. However, often the semantics of these semantic constructs is not part of the metamodel, i.e., it is unspeci ed. Therefore, we propose to reuse well-known compiler construction techniques to specify metamodel semantics. To be more precise, we present the application of reference attribute grammars (RAGs) for metamodel semantics and analyse commonalities and differences. Our focus is to pave the way for such a combination, by exemplifying why and how the metamodelling and attribute grammar (AG) world can be combined and by investigating a concrete example - the combination of the Eclipse Modelling Framework (EMF) and JastAdd, an AG evaluator generator.

Chris Marker, (1921-2012) qui photographie et filme des lieux divers dans le monde entier, avait pour thème de prédilection la ville. En effet, ce lieu de circulation et de mobilité, dépassant toutes les clôtures, se prête particulièrement aux œuvres markériennes, caractérisées par l’entrecroisement de différents espace-temps, et par l’expérience de l’altérité. En étant à la fois cinéaste et voyageur, les images de la ville capturées par Marker se caractérisent par le déplacement, en particulier par l’expérience de la flânerie, qui constitue un élément essentiel de la réflexion philosophique sur la ville moderne de Walter Benjamin (1892-1940). Pour cette raison, cette thèse est consacrée à l’analyse des œuvres de Marker autour du thème de la flânerie. Ainsi, au cours de trois parties, nous travaillerons des concepts reliées à la flânerie : le seuil, l’allégorie, et le chiffonnier. Ces travaux thématiques nous aideront à comprendre la stratification complexe de l’espace-temps, le caractère transitoire, et l’art de l’assemblage dans les images markériennes. Ces recherches sont finalement élargies à la notion de la navigation comme version renouvelée de flânerie, pour analyser l’espace de L’Ouvroir, le monde virtuel crée sur Second Life par Marker dans sa dernière période. Par conséquence, à la lumière des problématiques abordées par la flânerie, on comprend que la création artistique de Marker est fondée sur la quête continuelle de nouvelles expérience visuelles qui remettent en question la modernité et la représentation cinématographique. / Chris Marker (1921-2012) is a filmmaker, who took photos and filmed various places by travelling all over the world. The city had been one of the important subjects for Marker’s works. Suppose every metropolis is essentially a limitless place, filled with flow and mobility, Marker’s works, described as intersection of different time and space and “otherness,” can be said that they inherit the nature of metropolis. Being filmmaker and traveler, Marker’s images of city are often characterized by “moving”, particularly by the experience of flânerie (stroll), which constitutes element of philosophical reflection of modern city by Walter Benjamin (1892-1940). In order to make this point clear, this dissertation deals with the films of Marker using Benjamin’s concept flânerie, as a major analyzing concept. Using four key concepts, threshold, allegory, and rag-and-bone man related to the experience of flânerie, this dissertation dissects the complex stratification of “space-time”, the “ephemeral character”, and the “art of collecting” in the images of Marker. Also, bringing the new concept “navigation”, as a renewed version of flânerie, the space of L’Ouvroir, the territorialities of Second Life, created in Marker’s last years of his life is analyzed. As a result, in the light of the issues raised by flânerie, we understand that Chris Marker problematizes the modernity and the system of cinematic representation based on the continual search for new visual experience.

Haematological cancers like leukemia and lymphoma are characterized by genetic abnormalities, specifically chromosomal translocations. Analyses of the translocation breakpoint regions in patients have shown that some loci in the genome are more susceptible to breakage than others. However, very little is known about the mechanism of generation of many such chromosomal translocations. In the present study, we have attempted to understand the mechanism of fragility of three regions, which are prone to breaks during translocations in follicular lymphoma (FL) and T-cell leukemia. The t(14;18) translocation in FL is one of the most common chromosomal translocations. Most breaks on chromosome 18 are located at the 3’ UTR of the BCL2 gene and are broadly classified into three clusters, namely major breakpoint region (mbr), minor breakpoint cluster region (mcr) and the intermediate cluster region (icr). The RAG complex has been shown to cleave BCL2 mbr by recognizing an altered DNA structure. In the present study, by using a gel based assay, nature of the non-B DNA structure at BCL2 mbr was identified as parallel intramolecular G-quadruplex. Various studies including circular dichroism (CD), mutagenesis, DMS modification assay and 1H NMR showed the presence of three guanine tetrads in the structure. Further, evidence was also found for the formation of such a G-quadruplex structure within mammalian cells. In an effort to characterize the mechanism of fragility of mcr, a unique pattern of RAG cleavage was observed in a sequence dependent manner. Three independent nicks of equal efficiency were generated by RAGs at the cryptic sequence, “CCACCTCT”, at mcr and at a cytosine upstream of it, unlike a single specific nick at the 5’ of heptamer during V(D)J rearrangement. Interestingly, RAG nicking at mcr occured in the presence of both Mg2+ and Mn2+. Using recombination assay, followed by sequencing of the junctions, we find that mcr can recombine with standard RSS in vivo, albeit at a very low frequency. Mutations to this novel motif abolish recombination at the mcr within the cells. In order to determine the prevalence of t(14;18) translocation in the healthy Indian population, nested PCR approach followed by Southern hybridization was used. Results showed 34% prevalence of t(14;18) translocation in the Indian population. Although, no gender based difference was observed, an age dependent increase was found in adults. Further, presence of the t(14;18) transcripts was also detected. The mechanism underlying the fragility of the t(10;14) translocation involving HOX11 gene in T-cell leukemia is not known. Using primer extension assays on a plasmid DNA containing HOX11 breakpoint region, presence of consistent pause sites corresponding to two G-quadruplex forming regions, flanking the patient breakpoints, were detected. These replication blocks were dependent on K+ ions. Native gel shift assays, mutation analysis, S1 nuclease and CD, further revealed formation of intermolecular G-quadruplexes, unlike the BCL2 mbr. Further, sodium bisulfite modification assay indicated the presence of such structures in the genomic DNA within cells. Hence, we propose that two independent G-quadruplex structures formed in the HOX11 gene could interact with each other, thereby resulting in fragility of the intervening sequences, where majority of the patient breakpoints are mapped. Overall, this study has attempted to understand the role of both sequence and structure of DNA, in generating chromosomal fragility during t(14;18) translocation in FL and t(10;14) translocation in T-cell leukemia. These results may facilitate future studies in unraveling the mechanism leading to genomic instability in other lymphoid cancers.

Since the beginning of the early 20th century bed rugs have been interesting research objects, but only in passing researchers have paid attention to rugs woven with rags. Noone has taken a closer look upon the reasons why people have woven these rugs. What does the materials of the rag – like recycled garments and interior textiles in the form of clothing rags – have to tell about the times when these rugs were woven? Did the rag rugs have any specific function or were the materials available and therefore used? The main sources of information are 21 rag rugs from Roslagen in Uppland, with a varied amount of rags. They were woven during the latter half of 19th century, and estate inventories from Väddö- and Häverö Ship District have altogether given some answers to the primary question of this paper: in wich way can the examined bed rugs bear witness to the use and value of recycled textile materials and the view of these in the context of the community where they were manufactured and used? This research doesn´t give an answer to whether these rugs have any particular function or not. Instead these rag rugs can be looked upon as representing a general development of the society towards an increasing amount of textiles surplus material. This being due an increasing consumption of factory-made clothing and textiles, manufactured in factories, as well as the paper mills development from producing paper made of cellulose rather than textile waste. To this we can add a principle lingering on from the 19th century, of domestic production and a thrift of resources. This resulted in an obvious recycling of discarded textiles. The home weaving of interior textiles was still strong by the end of the 19th century, and in Rosagen there was also a long tradition of weaving and of using rugs in the beds. At the same time there was, in the coastal regions of Roslagen, a local need for warming covers in boats and boat houses. This demand was related to the shooting of seals and other hunting in the coastal areas, as well as in the fishing- and maritime trades.

The objectives of the research study are to review existing subnational credit rating methodologies and their applicability in the South African context, to develop the quantitative parts of credit rating methodologies for two provincial departments (Department of Health and Department of Education) that best predict future payment behaviour, to test the appropriateness of the proposed methodologies and to construct the datasets needed. The literature study includes background information regarding the uniqueness of South Africa’s provinces and credit rating methodologies in general. This is followed by information on subnational credit rating methodologies, including a review of existing subnational credit rating methodologies and an assessment of the applicability of the information provided in the South African context. Lastly, the applicable laws and regulations within the South African regulatory framework are provided. The knowledge gained from the literature study is applied to the data that have been collected to predict the two departments’ future payment behaviour. Linear regression modelling is used to identify the factors that best predict future payment behaviour and to assign weights to the identified factors in a scientific manner. The resulting payment behaviour models can be viewed as the quantitative part of the credit ratings. This is followed by a discussion on further investigations to improve the models. The developed models (both the simple and the advanced models) are tested with regard to prediction accuracies using RAG (Red, Amber or Green) statuses. This is followed by recommendations regarding future model usage that conclude that the department-specific models outperform the generic models in terms of prediction accuracies. / PhD (Risk analysis), North-West University, Potchefstroom Campus, 2015

The objectives of the research study are to review existing subnational credit rating methodologies and their applicability in the South African context, to develop the quantitative parts of credit rating methodologies for two provincial departments (Department of Health and Department of Education) that best predict future payment behaviour, to test the appropriateness of the proposed methodologies and to construct the datasets needed. The literature study includes background information regarding the uniqueness of South Africa’s provinces and credit rating methodologies in general. This is followed by information on subnational credit rating methodologies, including a review of existing subnational credit rating methodologies and an assessment of the applicability of the information provided in the South African context. Lastly, the applicable laws and regulations within the South African regulatory framework are provided. The knowledge gained from the literature study is applied to the data that have been collected to predict the two departments’ future payment behaviour. Linear regression modelling is used to identify the factors that best predict future payment behaviour and to assign weights to the identified factors in a scientific manner. The resulting payment behaviour models can be viewed as the quantitative part of the credit ratings. This is followed by a discussion on further investigations to improve the models. The developed models (both the simple and the advanced models) are tested with regard to prediction accuracies using RAG (Red, Amber or Green) statuses. This is followed by recommendations regarding future model usage that conclude that the department-specific models outperform the generic models in terms of prediction accuracies. / PhD (Risk analysis), North-West University, Potchefstroom Campus, 2015