<p>Asthma involves a systemic element that includes the mobilization and lung-accumulation of bone marrow-derived endothelial progenitor cells (EPC). This traffic may be driven by the stromal cell derived factor-1α (SDF-1α)/CXCR4 axis, where SDF1-α is a potent progenitor cell chemoattractant.</p> <p>Interfering with EPC lung-accumulation by administering AMD3100, a CXCR4 antagonist, was previously shown to be associated with the modulation of airway angiogenesis and airway hyperresponsiveness. However, since eosinophils express CXCR4, it is unknown whether AMD3100 acted directly on EPC or indirectly through its anti-inflammatory effects on eosinophils.</p> <p>We investigated the role that eosinophilic inflammation plays in the lung-homing of EPCs and airway angiogenesis in allergic asthmatic response by utilizing eosinophil deficient (PHIL) mice.</p> <p>Wild-type BALB/c (WT) and PHIL mice underwent a chronic house dust mite (HDM) exposure protocol. Treatment groups were administered AMD3100. Outcome measurements were made 24hrs post final exposure and included: flow cytometry to enumerate lung-extracted EPCs, immunostaining for von Willebrand factor to assess bronchial vascularity, bronchoalveolar lavage for airway inflammation, haematoxylin and eosin stain to enumerate eosinophils, picrosirius red stain to assess collagen deposition, and measurement of airway resistance to increasing intranasal doses of methacholine.</p> <p>HDM exposed mice had a significant increase in EPC lung accumulation, bronchial vascularity, airway inflammation, collagen deposition and airway hyperresponsiveness (AHR) in both WT and PHIL groups, with some indices at lower levels in PHIL mice. Concurrent treatment with AMD3100 significantly attenuated EPC lung homing, bronchial vascularity, eosinophil numbers in lung tissue and AHR, but not collagen deposition in WT mice. AMD3100 treatment significantly attenuated all indices in PHIL mice.</p> <p>The findings of this study show that, EPC-driven angiogenesis and the development of AHR in allergic airway responses are independent of eosinophils, the presence of these cells, however, may have a role in worsening of the pathology of allergic airways disease.</p> / Master of Science (MSc)

The effect of a free-living stage in host-parasite coevolution: a skink mite phylogenetic study in New Zealand. During the last decade, phylogenetic trees have even been used to compare ecologically related taxa such as parasites and their hosts, and are used to determine their level of coevolution or reciprocal adaptation in time. Diverse coevolutionary events have been detected for this ecological association, where generally the parasite has been regarded as one that feeds exclusively on the host and is likely to cospeciate with it. A different coevolutionary pattern might occur when the parasite has a free-living stage in its life cycle, in which the parasite may have the opportunity to abandon its host and successfully colonise a new species (host-switching) making cospeciation less likely. Many New Zealand skinks are infested with a parasitic mite, Odontacarus sp. (Prostigmata: Leeuwenhoekiidae), which becomes free-living as an adult. The genetic variation of these mites found on four hosts was analyzed for host- parasite coevolutionary events. The hosts were the McCann’s skink and the common skink in coastal Birdling Flat, Canterbury, plus these species and the Grand and Otago skinks in Macraes Flat, Central Otago, South Island, New Zealand. The genetic variation of fast evolving nuclear Internal Transcribed Spacers 2 and mitochondrial Cytochrome c Oxidase I in Odontacarus mites found on these hosts was determined by PCR and DNA sequencing and phylogenetic trees were built using the computer programs PAUP*4 and MrBayes 3. The results show that mite haplotypes only had a significant geographical division and no host-related differences. In Birdling Flat, the COI haplotypes were represented in two groups that infested both regional hosts and had 5.7 % divergence. The same individual mites belonged to a single ITS 2 haplotype, thus indicating a historical geographical division between two populations that now interbreed successfully. The Macraes Flat mites were divided into two COI haplotypes with 2.4% divergence and internal nodes, which showed greater genetic variability than the Birdling Flat populations. The Macraes Flat mites formed two ITS 2 haplotypes with 6% divergence. This greater geographical structure of the Otago mites is probably due to the older age of the mainland area compared to the recently exposed coastal locality of Birdling Flat. The COI haplotypes from the two different regions had a mean distance of 15.5%, with an earlier divergence time than that known for the hosts. For both genes, the haplotypes from different regions had 100% bootstrap support and the parasite showed no host specificity. Mites of the different COI and ITS haplotypes were found on most of the host species that were sampled in Canterbury and Otago. The results of this study suggest that a free-living stage in a parasite’s life cycle can favour coevolutionary events such as inertia (failure to speciate) and host-switching, probably as a result of resource-tracking of the parasite. NB: Electronic files contained on CD to accompany print copy are not included with this version of the thesis.

The two-spotted spider mite (TSM), Tetranychus urticae Koch, is an important pest of many greenhouse and field crops worldwide. The development of resistance in TSM populations to chemical acaricides, allied with public health concerns about pesticide residues, has motivated the search for alternative control measures to suppress the pest. Hyphomycetous fungi are promising agents for mite control and the fungus Beauveria bassiana (Bb) (Balsamo) Vuillemin was investigated in this study as a biocontrol agent. The principal objectives of this study comprised: a) screening Bb strains for their pathogenicity against T. urticae; b) testing the effect of adjuvants on the efficacy of Bb; c) studying the effect of plant type on persistence of Bb and the efficacy of control of Bb against T. urticae; d) evaluating the field efficacy of Bb applications against T. urticae; e) testing the compatibility of Bb with selected fungicides; and f) assessing the synergy between Bb and soluble silicon for T. urticae control. Screening bioassays of sixty-two strains of Bb identified the two most effective strains, PPRI 7315 (R289) and PPRI 7861 (R444), that caused mortality levels of more than 80% of adult mites at 9 d post-inoculation with 2 × 108 conidia ml-1. These strains performed significantly better than the Bb commercial strain PPRI 5339, in laboratory bioassays. The two strains also attacked mite eggs, causing 53.4% and 55.5% reduction in egg hatchability at 2 × 108 conidia ml-1 respectively. However, PPRI 7861 showed relatively higher production of conidia in culture and was, therefore, selected for further trials under greenhouse and field conditions. Greenhouse evaluations of the effects of two adjuvants (Break-thru® and a paraffin oil-based emulsion) on efficacy of Bb demonstrated a higher efficacy of the biocontrol agent (BCA) when it was applied with Break-thru® or the oil solution than with water alone. Moreover, Bb conidia applied in Break-thru® solution resulted in greater control of TSM than conidia applied in the mineral oil. There was also a dose-response effect and the control of TSM by Bb increased when the concentration of conidia was increased. The control of TSM by Bb in beans (Phaseolus vulgaris L), cucumber (Cucumis sativus L.), eggplant (Solanum melongena L.), maize (Zea mays L.) and tomato (Solanum lycopersicum L.) was tested in greenhouse trials. On these crops, the persistence of conidia declined over time. The rate of decline was significantly higher on maize. However, TSM mortality was positively correlated with the amount of conidia deposited on leaves immediately after spraying, rather than their persistence over time. Higher levels of mortality of TSM due to Bb application were observed on beans, cucumber and eggplants, suggesting that the type of crop must be taken into consideration when Bb is applied as a BCA. Field efficacy of Bb against mites was evaluated in two trials on eggplants. Based on assessment of population densities of mites and leaf damage assessments; both trials showed that the strain PPRI 7861 controlled TSM in the field. Two commonly used fungicides, azoxystrobin and flutriafol, were investigated in vitro tests on culture medium and laboratory bioassays on detached bean leaves (Phaseolus vulgaris L.) for their effects on Bb. Azoxystrobin (a strobilurin) was less harmful to Bb while flutriafol was found to be inhibitory. Another important finding of this study was the substantial enhancement of Bb efficacy by soluble silicon. When Bb was combined with soluble Si, the control of TSM was better than when either of the two products was applied alone. Moreover, application of soluble Si as a plant fertilizer in hydroponic water nutrient increased accumulation of peroxidase, polyphenoloxidase and phenylalanine ammonia-lyase enzymes in leaves of plants infested with TSM. Increased activity of these defense enzymes in leaves deters feeding behaviour of mites. We suggested that feeding stress renders them susceptible to Bb infection, which would explain the synergy observed between the two agents. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

A feminist examination of the life of the Afrikaans poet Ingrid Jonker is preceded by a look at the conventional literary biography with its unique dual nature: scientific enquiry combined with the art of storytelling, which is aptly called “fiction under oath” (Gutiérrez 1992: 49). Subsequently, an overview of the theoretical basis of feminist ideology and literary approaches is presented with the emphasis on the psychoanalytical point of departure, which views women’s marginalized position as social instead of biological in origin, and therefore as changeable. Biography owes its important place in contemporary women’s writing to the fact that it documents the history and experience of women in the patriarchal system. Feminist biographers, influenced by Postmodernism, force the genre from its traditionally linear form and narrow focus on a famous, usually male subject. The result is a more fluid, cyclical portrayal of (usually) influential women, shedding more light on the social, domestic and personal spheres. Because this kind of biography does not claim to be authoritative, the biographer’s personal contribution and her methods are made explicit. The intuitive and experimental nature of feminist biography makes it suitable for an intertextual and even interdisciplinary approach. Jonker’s life is analysed against the background of a folk tale, The Red Shoes, which is an allegory for the sacrifice of the instinctive creative self or archetypal “wildish woman”. Ancient myths, which narratives of almost every culture share, are seen as responsible for the tenacious survival of the patriarchy through time, social change, and across cultural boundaries. For this reason, feminists see the creation of new myths or infusing old myths with new meaning as the key to women’s emancipation. Against this background, the following subtexts also act as shaping elements in the Ingrid Jonker biography: · The concept of a person’s life “script” unfolding according to repetitive messages laid down in the unconscious by authority figures; · The “conspiracy” between a biographee and her biographers in forming her public image; and · Six archetypes in the Jungian idiom that characterise a person’s journey to spiritual maturity, Examined with these subtexts in mind, Ingrid Jonker’s life story unfolds as follows: A poet in conflict with her time and “abandoned” by her parents, is displaced in pre-adolescence from a unstructured rural milieu where her instinctive creativity was allowed to develop freely, to a highly structured, limiting and artificial urban environment. She seems prophetically destined for a tragic end. Her obsession with death is fed by an inability to have meaningful relationships and to adjust to society’s double standards. Ever the victim of imagined or real betrayal, she joins the ranks of other female artists who follow the same destructive archetypal pattern. She is spurred on not only by her own feral recklessness, but also by other artists who are inspired by her flirtation with death. Upcoming generations are mesmerised by her “moth around a flame” life and, like children, ask time and again for the disastrous though darkly romantic story with its mythical proportions, which turned Jonker into an icon. In doing so, they manage their own collectively unconscious fear of the annihilation of death. The Red Shoes links with Kristeva’s distinction between semiotic and symbolic language. The former is non-rational, intuitive and signifies the maternal whereas the latter represents language that is masculine, rational, linear and therefore patriarchal and logocentric. / Dissertation (MA (Afrikaans))--University of Pretoria, 2005. / Afrikaans / unrestricted

The problem statement mainly deals with the curtailment of the high function status of Afrikaans in South Africa since 1994 as this has a negative impact on the six million mother tongue speakers of Afrikaans as well as on non-mother tongue speakers for whom the language has an instrumental value. The question is raised as to whether myth making around Afrikaans can be held partly responsible for this loss in status. The term “myth” and the impact of myths are looked into. “Myth” is not used in this thesis as a “story without ground” (as in the dictionary definition), but, according to the work of Jung, Campbell, Leroux, Malan and others, as a story/narrative that gives voice to man’s search for meaning and significance. The main points of departure are: · The viewpoint of the well-known twentieth-century mythologist, Joseph Campbell, who states: “Myths are stories of our search through the ages for truth, for meaning, for significance (Campbell in Flowers 1988:5); and · The statement of Malan (1978:39) namely that myth has always been the way in which man has tried to explain the sense, significance and purpose of the cosmos by means of a simple narrative. Myth making within groups (Anderson 1991: “imagined communities”) is viewed and the role of of political myth making explicitly stated. In this regard the statement of Leonard Thompson is relevant. Thompson (1985:3) points to two kinds of myths, namely: 1) “conservative myths” (for example about the origins of a group); and 2) “radical myths” (that aim to discredit the regime of “the other”). In the discourse about myths around Afrikaans the point of departure is that the specific myth is regarded as positive or negative in terms of its impact on the status and position of Afrikaans in South Africa. The two “main” myths around Afrikaans are discussed by exemplification and by means of anecdotes and the impact of the said myths on Afrikaans is evaluated. The two myths are: · Afrikaans as mythical binding force in Afrikaner nationalism in (mainly) the first fifty years of the twentieth century; and · Afrikaans as metaphorical language of the oppressor, especially in the period of institutionalized apartheid. The impact of the above myths within various Afrikaans systems (among others the historiography and literature of Afrikaans and the school syllabi) is furthermore exemplified with the purpose of indicating how great this impact has been. Finally the question is asked: ”And now, Afrikaans?” (with acknowledgement to the title of a publication by Hans du Plessis, 1992: “En nou, Afrikaans?”). The conclusion is that the status of Afrikaans in the so-called high language functions is daily under more pressure as a result of the hegemony of English in the country. There should be rational and firm negotiations about this unconstitutional curtailment of the rights of Afrikaans. The speakers of Afrikaans can, however, help to preserve the language by: 1. Living with the myths around Afrikaans in the sense that they develop and demonstrate understanding and empathy for the myths of other groups; 2. Using Afrikaans daily for all functions, especially seeing that Afrikaans is indeed suitably developed to meet any need; and 3. Working towards new myth making around Afrikaans, by – among other things – pointing to the fact that Afrikaans, as a language of Africa, has a greater claim to national language status in South Africa than the international language, English. / Thesis (DLitt (Afrikaans))--University of Pretoria, 2005. / Afrikaans / unrestricted