Dissertations / Theses on the topic 'Candida africana'

<p>Autism is a pervasive developmental disorder (PDD) that&rsquo<br>s incidence is approximately 1 in 158. It is four times more prevalent in males than females and is believed to be caused by both genetic and environmental factors. Research indicates that several genes are involved in autism and it is believed that these genes act together to produce autism. Many genes implicated in this disorder are involved with brain structure formation and brain functioning. Studies have identified the reelin (RELN) gene as necessary for proper formation of brain, which indicates that RELN abnormalities could contribute to the aetiology of several neurogenetic diseases such as schizophrenia, bipolar and autism. The aims of the study were (i) to genotype two SNPs (exonic rs3622691 and intronic rs736707) in the RELN gene using Taqman&reg<br>SNP Genotyping assays to detect association with autism in three distinct South African (SA) ethnic groups (Black, Caucasian and Mixed), and (ii) to detect candidate genes that are over and under-expressed in the samples taken from a SA Caucasian autistic group and compare those with samples taken from a healthy Caucasian group using cDNA microarray. The Taqman&reg<br>study indicated significant association for the intronic SNP, rs736707, with a p-value of 0.0009 in the total SA group. More so, the Mixed group displayed the highest significance amongst the ethnic groups, with a p-value of 0.00014. The microarray study yielded 21 genes with 95% significance in the Caucasian sample group. Most genes were hypothetical proteins and formed part of the FAM90A family. The LOC83459 showed the highest level of expression in the autistic samples, while the BTNL8 gene was shown to be highly suppressed in the control samples.</p>

Dissertation (PhD)--University of Stellenbosch, 2007.<br>ENGLISH ABSTRACT: Obsessive-compulsive disorder is a severe, debilitating psychiatric disorder for which the underlying molecular aetiology still remains unclear. Evidence from family studies have suggested that OCD may be caused by a complex interplay of environmental and genetic factors. In order to identify the genetic factors that mediate OCD susceptibility, several genetic association studies have been undertaken, which have yielded inconsistent findings. Moreover, the majority of these studies have focused on a small number of candidate genes that encode components of the serotonin and dopamine neurotransmitter pathways. However, based on the complexity of clinical manifestations observed in OCD, it is likely that its pathogenesis is mediated by a broader complex of interrelated neurotransmitter systems and signal transduction pathways; consequently there is a need to identify and assess novel candidate genes. One method of identifying such novel OCD candidate genes is by utilising knowledge of diseases with phenomenological overlap with OCD, which lend themselves to better genetic dissection through linkage analysis and animal studies. Genetic loci for such disorders, identified though linkage analysis, could potentially harbour novel OCD candidate genes, while genes implicated through animal models may lead to the identification of additional susceptibility genes through delineation of pathways by, for instance, interactome analysis. One such disorder is schizophrenia, which manifests overlap in both symptoms and brain circuits with OCD. In schizophrenia, in addition to several case-control association studies having been performed, linkage data, studies of chromosomal aberrations and animal models have led to the identification of many chromosomal regions that may contain genes involved in its aetiology and thus may also contain OCD candidate genes. In the present investigation, this approach was employed using previously reported schizophrenia susceptibility loci to identify novel OCD candidate genes. All genes residing in each of these loci were catalogued and individually analysed using a battery of bioinformatic techniques in order to assess their potential candidature for OCD susceptibility. These analyses yielded 13 credible OCD candidate genes.Additional candidates were sought using information regarding a well-defined schizophrenia animal model, the heterozygous reeler mouse, that exhibits neurodevelopmental, neuroanatomical and behavioural abnormalities, similar to those displayed by patients with schizophrenia. The phenotype of these mice is caused by a mutation in Reln, which encodes reelin, a large extracellular matrix protein that plays a pivotal role in the ordered migration of neurons during the development of laminar brain structures. The fact that both reelin protein and mRNA levels have been shown to be reduced in post-mortem brain sections of schizophrenic patients, coupled with the observed behaviour and neurochemical similarities between the heterozygous reeler mouse and schizophrenic patients suggests that reelin may be involved in the pathogenesis of schizophrenia and hence also OCD. Furthermore, genes encoding proteins that interact with reelin may thus also be considered plausible candidate genes for both schizophrenia and OCD. For this reason, novel reelin-interacting proteins were sought using the N-terminal reeler-domain of reelin, a domain only found in proteins involved in neuronal migration, as “bait” in a yeast twohybrid screen of a foetal brain cDNA library. Putative reelin ligands were subsequently reevaluated using co-immunopreciptitation and mammalian two-hybrid analysis to corroborate the yeast two-hybrid findings. Results of these analyses showed that WDR47, a WD40-repeat domain protein, interacts with reelin via its reeler-domain; therefore, the gene encoding this ligand protein, as well as RELN itself, was also considered a credible OCD candidate gene. Each of the candidate genes identified using the afore-mentioned strategies were assessed for their potential role in the aetiology of OCD by case-control association studies of a cohort of Afrikaner OCD patients and control individuals. Statistically significant associations were detected for two genes, DLX6 and SYN3, with the disorder. These associations are exciting as they may point to novel mechanisms involved in OCD development. The identification of WDR47 as a novel reelin-interacting protein has significant implications for our understanding of reelin-dependant signalling. Using this protein as the starting point, further novel components of the reelin signalling pathway may be unravelled, an investigation which may lead to the identification of novel roles for reelin in neurodevelopment. Such novel components may, of course, also be considered OCD and schizophrenia candidate genes, which may, in turn, augment the existing knowledge of the pathophysiologies of OCD, schizophrenia and other neurodevelopmental disorders. Taken together, the current study yielded exciting results that warrants follow-up investigation in future. The identification of DLX6 and SYN3 as novel OCD susceptibility genes as well as the identification of WDR47 as a reelin-interacting protein may provide investigators with alternative avenues of research into potential pathological mechanisms involved both in OCD and schizophrenia, which may ultimately lead to alternative pharmacotherapy.<br>AFRIKAANSE OPSOMMING: Obsessiewe kompulsiewe steuring (OKS) is `n ernstige, verswakkende psigiatriese steuring waarvan die onderliggende molekulêre etiologie steeds onbekend is. Bewyse verkry vanuit familiestudies het voorgestel dat OKS moontlik veroorsaak word deur `n komplekse interaksie van omgewings en genetiese faktore. Om die genetiese faktore te identifiseer wat OKS vatbaarheid veroorsaak, is `n hele aantal genetiese assosiasie studies onderneem, wat teenstrydige resultate gelewer het. Wat meer is, die grootste hoeveelheid van hierdie studies het gefokus op `n klein aantal kandidaatgene wat vir komponente van die serotonien en dopamine neurotransmittor weë enkodeer. Dit is egter, gebaseer op die kompleksiteit van die kliniese manifestasies wat waargeneem word in OKS, heel moontlik dat die patogenisiteit van die siekte bemiddel word deur `n breër kompleks van interverwante neurotransmittor sisteme en seintransduksie weë. Daar is dus `n behoefte na die identifikasie en ondersoek van nuwe kandidaatgene. Een metode om sulke nuwe OKS kandidaatgene te identifiseer, is deur die gebruik van bestaande kennis oor siektes wat fenomenologiese ooreenkomste het met OKS, siektes wat makliker geneties ontleed kan word deur koppelingsanalises en dierestudies. Genetiese lokusse vir sulke versteurings, geïdentifiseer deur koppelingsanalises, het die potensiaal om nuwe OKS kandidaatgene in te sluit, terwyl gene wat geïmpliseer word deur dierestudies mag lei tot die identifisering van bykomende vatbaarheidsgene deur die ondersoek van weë deur, byvoorbeeld, interaktoom analises. `n Voorbeeld van so `n versteuring is skisofrenie, wat in manifestasie oorvleuel in beide simptome en breinstroombane met OKS. In skisofrenie het, addisioneel tot verskeie geval-kontrole assosiasiestudies wat gedoen is, koppelingsdata, studies van chromosomale afwykings en dierestudies gelei tot die identifikasie van verskeie chromosomale gebiede wat gene mag bevat wat betrokke kan wees in die etiologie van die siekte, en dus ook OKS kandidaatgene mag bevat. In die huidige ondersoek is hierdie benadering gevolg en is gebruik gemaak van voorheen gerapporteerde skisofrenie vatbaarheidslokusse om nuwe OKS kandidaatgene te identifiseer. Alle gene wat in hierdie lokusse voorkom is gekatalogiseer en individueel geanaliseer deur gebruik te maak van `n battery van bioinformatika tegnieke om hul potensiaal as kandidate vir OKS vatbaarheid te bepaal. Hierdie analise het 13 geloofwaardige OKS kandidate opgelewer. Addisionele kandidate is gesoek deur inligting van `n goed gedefinieerde skisofrenie dieremodel te gebruik, naamlik die heterosigotiese “reeler” muismodel, wat neuro-ontwikkelings-, neuroanatomiese- en gedragsabnormaliteite vertoon, soortgelyk aan dié wat voorkom by pasiënte met skisofrenie. Die feit dat daar aangetoon is dat beide reelin protein en bRNS vlakke verlaag is in post-mortem brein seksies van skisofrenie pasiënte, gekoppel aan die gedrags- en neurochemiese ooreenkomste wat gesien word tussen heterosigotiese “reeler” muise en skisofrenie pasiënte, stel voor dat reelin betrokke is by die patogenese van skisofrenie en dus ook OKS. Vir hierdie rede is nuwe proteïene gesoek wat `n interaksie met reelin toon, deur gebruik te maak van die N-terminale reeler-domein van reelin, `n domein wat slegs gevind word in proteïene wat betrokke is by neuronale migrasie, as “aas” in `n gis-twee-hibried sifting van `n fetale brein cDNS biblioteek. Vermeende reelin ligande is vervolgens herevalueer deur gebruik te maak van koimmunopresipitasie en soogdier twee-hibried analises om die gis-twee-hibried bevindings te bevestig. Resultate van hierdie analises het getoon dat daar interaksie is tussen WDR47, `n WD40-herhalingsdomein protein, met reelin via sy reeler-domein. Die geen wat hierdie ligand protein enkodeer, sowel as RELN self, is dus beskou as ‘n geloofwaardige OKS kandidaatgeen. Elkeen van die kandidaatgene wat geïdentifiseer is deur gebruik te maak van bogenoemde strategieë is ondersoek vir `n potensiële rol in die etiologie van OKS deur gebruik te maak van geval-kontrole assosiasie studies met `n groep Afrikaner OKVS pasiënte en kontrole individue. Statisties-betekenisvolle assosiasies met die versteuring is vasgestel vir twee gene, DLX6 en SYN3. Hierdie assosiasies is opwindend aangesien hul nuwe meganismes betrokke by OKS ontwikkeling mag aantoon. Die identifikasie van WDR47 as ‘n nuwe protein wat interaksie met reelin vertoon, het betekenisvolle implikasies vir die verstaan van reelin-afhanklike seining. Deur hierdie proteïn as die beginpunt te gebruik kan vêrdere nuwe komponente van die reelin seinweg ontdek word, `n ondersoek wat mag lei tot die identifisering van nuwe funksies vir reelin in neuro-ontwikkeling. Sulke nuwe komponente mag, natuurlik, ook in aanmerking kom as OKS en skisofrenie kandidaatgene, wat op sy beurt weer die bestaande kennis van die patofisiologie van OKS, skisofrenie en ander neuro-ontwikkelings versteurings mag verbreed. In samevatting, hierdie studie het opwindende resultate gelewer wat opvolgondersoeke in die toekoms regverdig. Die identifikasie van DLX6 en Syn3 as nuwe OKS vatbaarheidsgene, sowel as die identifisering van WDR47 as ‘n protein wat interaksie vertoon met reelin, mag aan navorsers alternatiewe navorsingsweë voorsien om die moontlike patologiese meganismes wat betrokke is by beide OKS en skisofrenie te ondersoek, wat uiteindelik mag lei tot alternatiewe farmakoterapie.

Includes bibliographical references.<br>Sustainable diversification and the biological viability of selected aquaculture species are now viewed as being crucial factors that must be assessed in order to introduce the candidate species into commercial production. The biological feasibility of white stumpnose, Rhabdosargus globiceps,as a potential aquaculture candidate, was assessed by examining the ability of the broodstock to be manipulated to spawn in captivity and the viability of the larvae from 0 days post hatch (DPH) to 30 DPH under varied conditions. These factors are recognised as the most significant bottlenecks of development for a potential aquaculture candidate. A compressed photothermal cycle successfully brought about the reproductive maturation of both male and female broodstock. The natural, seasonal reproduction cycle, of the population of Rhabdosargus globiceps in Langebaan Lagoon, and manipulated cycles were comparable with regard to oocyte maturation. Under the compressed cycle an increase in the plasma estradiol 17ß concentration correlated with the increase in oocyte diameter and the presence of late vitellogenic and hydrated oocytes. Reproductively mature broodstock were injected twice with LH-RHa on a 24 hour interval, which successfully induced spawning over four consecutive 24 hour periods. This method of manipulation and induction of spawning was successful twice and the resultant eggs and larvae were used to examine the ontogeny and the optimal rearing temperature of Rhabdosargus globiceps. In the first larval rearing experiment the stages of development from egg to 30 DPH larvae were recorded at 20°C and showed similar developmental stages as other sea bream aquaculture species. The developmental stages were noted as being highly influenced by the available food sources with elevated mortalities recorded during the transitional phase between endogenous food reserves and exogenous feeding. The growth pattern showed the same reduced growth present for other successfully cultured sea bream larvae, suggesting that first feeding and swimbladder inflation was relatively successful. At 30 DPH the larvae reached a mean total length of 11.14 ± 0.44 mm. To determine the optimal rearing temperature and the effect of temperature on embryonic development eggs were placed at three different incubation temperatures (25°C, 20°C and 15°C) and the timing to the developmental stages was recorded from 0 DPH to 30 DPH. Measurements indicated that the larvae reached and exceeded their thermal tolerance at 25°C, with larvae only surviving to 6 DPH at this temperature, while at 20°C the larvae had better growth, and significantly earlier indications and higher percentages of feeding, swimbladder inflation and notochord flexion than at 15°C. The results suggest that the highest quality larvae are achieved at a rearing temperature of 20°C. This thesis describes the induction of spawning and larval rearing of Rhabdosargus globiceps. The ontogeny of the larvae as well as the critical stages of first feeding, swimbladder inflation and notochord flexion are discussed and described in detail. Overall, the life cycle from adult to juvenile was successfully closed and the experiments showed very positive results regarding Rhabdosargus globiceps’ biological capacity and feasibility to become a potential aquaculture candidate in South Africa.

Water hyacinth, Eichhornia crassipes Mart. Solms-Laubach (Pontederiaceae), a freefloating aquatic macrophyte of Neotropical origin, was introduced into South Africa as an ornamental aquarium plant in the early 1900’s. By the 1970’s it had reached pest proportions in dams and rivers around the country. Due to the sustainability, cost efficiency and low environmental risk associated with biological control, this has been a widely used method in an attempt to reduce infestations to below the threshold where they cause economic and ecological damage. To date, five arthropod and one pathogen biocontrol agents have been introduced for the control of water hyacinth but their impact has been variable. It is believed that their efficacy is hampered by the presence of highly eutrophic systems in South Africa in which plant growth is prolific and the negative effects of herbivory are therefore mitigated. It is for these reasons that new, potentially more damaging biocontrol agents are being considered for release. The water hyacinth grasshopper, Cornops aquaticum Brüner (Orthoptera: Acrididae), which is native to South America and Mexico, was brought into quarantine in Pretoria, South Africa in 1995. Although the grasshopper was identified as one of the most damaging insects associated with water hyacinth in its native range, it has not been considered as a biocontrol agent for water hyacinth anywhere else in the world. After extensive host-range testing which revealed it to be safe for release, a release permit for this candidate agent was issued in 2007. However, host specificity testing is no longer considered to be the only important component of pre-release screening of candidate biocontrol agents. Investigating biological and ecological aspects of the plant-herbivore system that will assist in determination of potential establishment, efficacy and the ability to build up good populations in the recipient environment are some of the important factors. This thesis is a pre-release evaluation of C. aquaticum to determine whether it is sufficiently damaging to water hyacinth to warrant its release. It investigated interactions between the grasshopper and water hyacinth under a range of nutrient conditions found in South African water bodies as well as the impact of the grasshopper on the competitive performance of water hyacinth. Both plant growth rates and the response of water hyacinth to herbivory by the grasshopper were influenced by nutrient availability to the plants. The ability of water hyacinth to compensate for loss of tissue through herbivory was greater under eutrophic nutrient conditions. However, a negative linear relationship was found between grasshopper biomass and water hyacinth performance parameters such as biomass accumulation and leaf production, even under eutrophic conditions. Water hyacinth’s compensatory ability in terms of its potential to mitigate to detrimental effects of insect feeding was dependent on the amount of damage caused by herbivory by the grasshopper. Plant biomass and the competitive ability of water hyacinth in relation to another freefloating aquatic weed species were reduced by C. aquaticum under eutrophic nutrient conditions, in a short space of time. It was also found that grasshopper feeding and characteristics related to their population dynamics such as fecundity and survival were significantly influenced by water nutrient availability and that environmental nutrient availability will influence the control potential of this species should it be released in South Africa. Cornops aquaticum shows promise as a biocontrol agent for water hyacinth but additional factors that were not investigated in this study such as compatibility with the South African climate and the current water hyacinth biocontrol agents need to be combined with these data to make a decision on its release. Possible management options for this species if it is to be introduced into South Africa are discussed.

Thesis (PhD (Medicine. Internal Medicine))--Stellenbosch University, 2008.<br>Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in Western countries, extending from steatosis (FLD) to steatohepatitis (NASH). Differentiation between NASH and nonprogressive NAFLD is difficult on clinical grounds therefore a need exists to identify reliable biomarkers of disease progression. The aims of the study were 1) to describe the disease profile of NAFLD/NASH in South African patients of the Western Cape, 2) to investigate the metabolic derangements associated with this condition, including insulin resistance, lipid abnormalities and liver fibrogenesis, and 3) to assess the possible involvement of candidate genes in relation to the disease phenotype in the patient cohort. A total of 233 patients (73% female) were enrolled in this study, consisting of 69% Cape Coloured, 25% Caucasian, 5% Black and 1% Asian individuals. All subjects were obese or overweight based on the assessment of body mass index (BMI). Screening for NAFLD identified 182 patients (87%) with ultrasonographical evidence of fatty infiltration and/or hepatomegaly. Liver biopsies were performed on patients with persistently abnormal liver functions and/or hepatomegaly. NAFLD was confirmed histologically in 111 patients of whom 36% had NASH and 17% advanced liver fibrosis. None of the Black patients had advanced fibrosis.

The lyssavirus genus of the Rhabdovirus family is divided into seven genotypes. Genotype 3, Mokola virus, has only been found on the African continent, and has been reported to infect rodents, cats, dogs and humans. The first Mokola virus identification in South Africa was made in 1970, on the east coast of the KwaZulu-Natal province. After 25 years, Mokola virus was again identified in three cats, 650 km south-west of the previous isolation. In 1997 two more Mokola infections were identified in Pinetown, only about 23 km south-west of the 1970 isolation. Phylogenetic analysis of the nucleic acid sequences of the nucleoprotein gene region of the Mokola genome, indicated that the Mokola viruses from the same geographical region were more closely related, irrespective of the time of isolation. The identification of these two distinct clusters of Mokola in South Africa leads i us to believe that this virus is more widespread than previously thought, but that the reservoir host species remains to be identified. Genotype 1 in the Rhabdovirus family, rabies virus, is found on all continents, except Australia, New Zealand, Papua New Guinea, Japan, Hawaii, Taiwan, United Kingdom, Ireland, etc. An ongoing rabies enzootic in southern Africa is associated with two genetically distinct groups of viruses, called the canid biotype (infecting carnivores of the family Canidae) and the viverrid biotype (infecting carnivores of the subfamily Viverrinae). We identified the first cases of spillover of canid biotype virus into viverrid hosts, using monoclonal antibody and nucleic acid sequence analysis. Genetic analysis of the G-L intergenic region of the rabies virus genome, showed that these spillover events do not bring about any significant change on this part of the virus genome. All of these spillover isolates maintained a typical canid virus phylogeny. Rabies viruses associated with the family Viverridae form a highly diverse group of viruses, which can be divided into four distinct phylogenetic groups, each associated with a specific geographical area in South Africa. The canid biotype of rabies virus is divided into three specific groups, based on geographic location and the associated reservoir species, namely KwaZulu-Natal province (with domestic dogs as its main vector), the western parts of South Africa (bat-eared foxes) and the northern parts of South Africa (black-backed jackals). In order to determine the degree of genetic change in the virus over a period of time, we identified two endemic canid rabies regions (KwaZulu-Natal and the northern parts of South Africa) and analysed the nucleic acid sequence variation 0f the viruses over 15 years. Phylogenetic analysis of the variable G-L intergenic region of t e virus genome indicated that the canid rabies biotype changed less than 1% over the period studied. This implies that the highly diverse viverrid biotype has been circulating in the southern African wildlife for a very long time. In order to obtain a faster, more economical, and reliable method for rabies virus biotype identification, a competitive, hemi-nested PCR assay was developed. In a single tube, two biotype specific oligonucleotides (developed by Jaftha, 1997), and a common downstream primer were -used in the biotype specific, second round amplification. The specific virus biotypes were identified on the basis of specific amplicon sizes for each biotype. A third biotype specific primer was designed to target a region of the Nucleoprotein gene, this primer was used in a second round hemi-nested reaction. Despite having been designed to specifically amplify canid biotype viruses, this primer amplified all rabies biotypes non¬specifically. We conclude that the nucleoprotein genes are too conserved to make this part of the genome a good target for a biotype-specific PCR diagnostic assay.<br>Dissertation (MSc (Agric) Microbiology)--University of Pretoria, 1997.<br>Microbiology and Plant Pathology<br>unrestricted

Lantana camara (lantana), a thicket-forming shrub, a number of different varieties of which were introduced into South Africa as ornamental plants but which has become a serious invasive weed. Conventional control measures for lantana are expensive and ineffective and it has therefore been targeted for biological control since 1961. To date, eleven biological control agent species have become established on lantana in South Africa. However, most agents persist at low densities and only occasionally impact plant populations. Three species regularly cause significant damage, but only reach sufficiently high numbers by midsummer after populations crash during the winter. Overall, the impact of the biological control programme on the weed is negligible and this has been ascribed to the poor selection of agents for release, the accumulation of native parasitoids, differences in insect preference for different varieties of the weed and variable climatic conditions over the weed’s range. This study suggests that the importance of varietal preferences has been over-estimated. A predictive bioclimatic modelling technique showed that most of the agents established in South Africa have a wide climatic tolerance and that the redistribution and importation of new climatypes of these agents will not improve the level of control. Additional agents are required to improve the biocontrol in the temperate conditions, and also to increase damage in the sub-tropical areas where most of the agents are established and where the weed retains its leaves year round. New candidate agents that possess biological attributes that favour a high intrinsic rate of increase, a high impact per individual and that improve the synchrony between the weed and the agent in climatic conditions that promote the seasonal leaflessness of plants should receive prior consideration. A survey in Jamaica indicated that additional biological control agents are available in the region of origin but that care should be taken to prioritise the most effective agents. The various selection systems currently available in weed biocontrol produce contradictory results in the priority assigned to candidate agents and a new selection system is proposed. The biology and host range of two new candidate natural enemies, the leaf-galling weevil, Coelocephalapion camarae and the leaf-sucking mirid, Falconia intermedia were investigated for the biocontrol of lantana. The studies indicated that these have considerable biocontrol potential, in that the weevil has a wide climatic tolerance and has the potential to survive the host leaflessness typical of temperate conditions, while the mirid has a high intrinsic rate of increase, and the potential for several generations a year. Both agents caused a high level of damage to the leaves, with the weevil galling the vascular tissue in the leaf-petiole and the mirid causing chlorotic speckling of the leaves. During laboratory trials both agents accepted indigenous species in the genus Lippia. However, under multiple choice conditions these agents showed a significant and strong oviposition preference for lantana. A risk assessment and post release field trials indicated that F. intermedia is likely to attack some Lippia species in the presence of lantana, but the levels of damage are predicted to be relatively low. A possible low incidence of damage to indigenous species was considered a justifiable ‘trade-off’ for the potentially marked impact on L. camara. Preference and performance studies on the two candidate agents suggested that most of the South African lantana varieties are suitable host plants. The mirid preferred certain varieties in multiple choice experiments, but this is unlikely to affect its impact under field conditions. Permission for release was accordingly sought for both species. Finally, the challenges facing the biological control programme and the potential for improving the control of L. camara in South Africa are considered.

Pereskia aculeata Miller (Cactaceae) is a damaging invasive alien plant in South Africa that has negative impacts to indigenous biodiversity and ecosystem functioning. Mechanical and chemical control are not effective against P. aculeata so biological control is considered the only viable option. Two biological control agents, the leaf-feeding beetle Phenrica guerini Bechyne (Chrysomelidae) and the stem-wilting bug Catorhintha schaffneri (Coreidae), have been released in South Africa thus far. Post-release evaluations have indicated that P. guerini will not reduce P. aculeata densities to acceptable levels alone, while C. schaffneri was released very recently, so it is too soon to determine how effective that agent will be. Even if C. schaffneri is extremely damaging, it is likely that further agents will be required to reduce the densities of P. aculeata to acceptable levels within a reasonable time-scale. Additional agents should target the woody stems of P. aculeata which are not impacted by the damage of either of the released agents. Pereskiophaga brasiliensis Anderson (Curculionidae) is a promising potential candidate agent that feeds on the thick woody stems of the plant in the larval stage. Climatic matching, genetic matching and field based host specificity observations all indicated that P. brasiliensis was a promising candidate. In this study, the impact of P. brasiliensis to the target weed, P. aculeata, was quantified under quarantine conditions to determine whether it was sufficiently damaging to warrant release. This was followed by host specificity testing to determine whether P. brasiliensis was suitably host specific for release in South Africa. Impact studies indicated that P. brasiliensis was damaging to P. aculeata at insect densities that would be expected in the field. Pereskiophaga brasiliensis reduced the number of leaves of P. aculeata to a greater extent than it reduced shoot lengths, but both plant parameters were significantly reduced due to the feeding damage from the insect. This suggests that the damage from P. brasiliensis may be compatible with that of C. schaffneri which reduces shoot length to a greater degree than the number of leaves. Pereskiophaga brasiliensis is therefore sufficiently damaging to warrant release, and although interaction studies with the other agents would be required, it is expected that it should complement other existing agents. Although P. brasiliensis is sufficiently damaging, at present the host specificity data indicates that it is not suitably specific for release in South Africa because oviposition and larval development to the adult stage was recorded on both indigenous and alien plant species within the families Cactaceae and Basellaceae. This non-target feeding was recorded during no-choice tests, which are very conservative, but significant non-target damage and development to the adult stage was recorded on an indigenous plant from a different family to the target weed. Further host specificity testing, including paired and multiple choice tests, are required to confirm the broad host range of P. brasiliensis. Other biological control agents that damage the woody stems of P. aculeata should be considered. The stem-borer, Acanthodoxus machacalis (Cerambycidae) is considered the most promising of the other candidate agents as it can be sourced from a climatically matched region where genetically suitable P. aculeata plants are found, it is sufficiently damaging to the woody stems of P. aculeata and there is no evidence that the species has a broad host range. Acanthodoxus machacalis should be sourced from Rio de Janeiro, Brazil, and imported into quarantine in South Africa for host specificity testing.

Includes bibliographical references (leaves 151-173).<br>A root-feeding, Mexican flea beetle, Longitarsus bethae Savini & Escalona 2005 (Coleoptera: Chrysomelidae: Alticinae), was evaluated in quarantine as a candidate biological control agent for the noxious weed, Lantana camara L. (Verbenaceae). The premise was that L. bethae would only be released if it could be ascertained that it was: (i) safe for non-target plants; (ii) likely to inflict significant damage on the target weed; and (ii) capable of surviving under the various (abiotic and biotic) environmental conditions in its new range.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology<br>The present study includes the use of a green synthetic method to prepare copper and silver nanoparticles using chitosan, aqueous extracts of Camellia sinensis, Combretum molle and Melia azedarach linn leaves. This study aims to investigate the influence of capping and precursor concentration on the properties of silver nanoparticles with emphasis on the medicinal plants chosen. The effect of capping agent on the properties of copper nanoparticles is also investigated. The phytochemical properties of plant extracts and the antimicrobial activity of the synthesized particles were also studied; this was achieved by using microdilution bioassay. Decoction method was used to extract secondary metabolites from plant leaves. Preliminary phytochemical screening carried out on the aqueous extracts of the plant leaves showed the presence of tannins, proteins, flavonoids, phenols, and carbohydrates. The total phenolic and flavonoids content of the aqueous extract was determined using spectroscopic methods. The highest phenolic content was found in the aqueous extract of Combretum molle (135 mg/g), and the highest flavonoid content was found in the aqueous extract of Camellia sinensis (0.4 mg/g). Characterization was done by a combination of spectroscopic, microscopy and XRD techniques. Both the size and shape of the synthesized silver nanoparticles were dependent on the identity of the capping molecule, precursor and capping agent concentration as depicted from their TEM and XRD results. Silver nanoparticles were found to be predominantly spherical. The capping agent concentration was also found to influence the degree of agglomeration, with an increase in capping agent concentration giving lesser agglomeration. FTIR spectral analysis showed that silver nanoparticles interact with bioactive compounds found in the plants through the hydroxyl functional group. Other shapes including diamond were observed for the effect of precursor concentration. The XRD micrographs revealed a face-centered cubic geometry and the phase remained the same with an increase in precursor concentration. The synthesized silver nanoparticles were all blue shifted compared to the bulk material. The TEM results revealed that copper nanoparticles with different sizes and shapes were successfully synthesized. All the prepared copper and silver nanoparticles showed satisfactory antifungal and antibacterial activity against Candida albicans, Cryptococcus neoformans, Staphylococcus aureus, Enterococcus faecalis, Klebsiella pneumonia and Pseudomonas aeruginosa. The capping molecules used in this study also showed some antibacterial and antifungal activity against the selected strains. However nanoparticles performed better than these capping molecules. Both silver and copper nanoparticles were found to be more active against gram-negative bacteria compared to gram-positive bacteria. Amongst all the prepared silver nanoparticles Combretum molle capped nanoparticles were found to be the most active nanoparticles. Also with copper nanoparticles, it was found that Combretum molle capped nanoparticles were the most active nanoparticles. Between the two metal nanoparticles, silver nanoparticles showed high antibacterial and antifungal activity compared to copper nanoparticles. The antioxidant activity of silver nanoparticles was assessed using 2.2-diphenyl-1-picrylhydrazyl. Silver nanoparticles were found to have some antioxidant activity. However, the capping molecules were found to be more active than the synthesized nanoparticles. This observation is attributed to the presence of some bioactive compounds in the plant extracts.

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2019<br>Até hoje já foram conduzidos em Portugal alguns estudos epidemiológicos focados na caracterização da candidemia invasiva, no entanto, pouco se sabe sobre qual o padrão de colonização das espécies do género Candida em nichos considerados não estéreis onde estas espécies podem existir como comensais. Estudos recentes têm demonstrado o papel importante que as populações comensais podem desenvolver enquanto focos de infeção invasiva. Nesse sentido, neste trabalho foi analisada a frequência de isolamentos de Candida spp. em mais de 1000 isolados recolhidos de amostras estéreis e não estéreis em 5 grandes centros hospitalares e num conjunto de Postos de Recolha da área de Lisboa. Para além da caracterização da frequência dos isolados das espécies nos diferentes produtos, foi analisada a suscetibilidade de um conjunto alargado destes isolados a 3 antifúngicos com relevância na prática clínica, anfotericina B, fluconazol e voriconazol. No geral, os resultados obtidos confirmam a elevada prevalência de C. albicans enquanto espécie colonizadora de amostras estéreis e não estéreis. Apesar disso, uma percentagem significativa de isolados (26 %) pertencentes a espécies Candida não-albicans foi observada, com ênfase para as espécies C. glabrata (14 %), C. parapsilosis (5 %) e C. tropicalis (4 %). Esta distribuição é consistente com os resultados reportados em estudos epidemiológicos desenvolvidos anteriormente em Portugal e ao redor do mundo. A prevalência de resistência aos antifúngicos observada foi baixa em todas as espécies (0,36 %) tendo sido possível identificar pelo menos 1 isolado de C. glabrata, recolhido de exsudado vaginal, resistente a fluconazol e voriconazol. Tentou-se verificar se este fenótipo de resistência estaria subjacente à existência de mutações de ganho de função na sequência do regulador transcricional CgPdr1 tendo-se identificado 3 mutações, nomeadamente, V91I, L98S e D243N.<br>To date, some epidemiological studies focused on cases of invasive candidemia have been conducted in Portugal, however, little is known about what the pattern of colonization of species of the genus Candida in niches considered non-sterile where this species can exist as commensals. Recent studies have shown the important role that commensal population can develop as foci of invasive infections. In this sense, in this work it was examined the frequency of isolation of Candida spp. in more than 1000 isolates collected from sterile and non-sterile samples in 5 major hospital centers and in a set of Collection stations of the Lisbon area. Besides the characterization of the frequency of species isolates in the different products, it was also tested the susceptibility to 3 antifungals with relevance in the clinical practice, amphotericin B, fluconazol and voriconazol. In general, the results obtained confirmed the high prevalence of C. albicans while colonizer species in sterile and non-sterile samples. Nevertheless, a significant percentage of isolates (26 %) belonging to non-Candida albicans Candida species was also observed with emphasis on C. glabrata (14 %), C. parapsilosis (5 %) and C. tropicalis (4 %). This distribution is consistent with the results reported in other epidemiological surveys undertaken in Portugal and worldwide. The incidence of resistance to antifungals observed was low in every species (0,36 %) and it was possible to identify at least 1 C. glabrata isolate, from a vaginal niche, resistant to fluconazol and voriconazol. It was attempted to verify if this phenotype of resistance would be underlying the existence of gain of functions mutations in the transcriptional regulator CgPDR1 sequence and 3 mutations were identified, namely, V91I, L98S e D243N.<br>Instituto Superior Técnico da Universidade de Lisboa; Farmácia Ibéria

Candida species were discovered more than a century ago as a causative organism of oral thrush. In HIV patients, the presence of oral candidiasis has been shown to be the earliest opportunistic infection. Candidiasis lesions associated with HIV infections are primarily a reflection of the specific change of the host's immune response caused by the virus. Studies of AIDS all over the world show that 58-81% of all patients contract a fungal infection at some time during the primordial stage or after developing AIDS and 10-20% have died as a direct consequence of fungal infections. Twenty four South African medicinal plants were screened using a modification of the NCCSL broth microdilution antifungal test against Candida albicans standard strain ATCC 10231 and two clinical isolates from a 5-month- old baby and an adult. This assay was performed in order to find a traditional remedy to treat oral candidiasis. Of all the screened plants Allium sativum L., Glycyrrhiza glabra L., Polygala myrtifolia L. and Tulbaghia violacea L. aqueous extracts were found to have the best activity. Allium sativum and Tulbaghia violacea aqueous bulb extracts had MIC values of 0.56 mgml-1 and 3.25 mgml-1 respectively, whilst Polygala myrtifolia leaf extracts and Glycyrrhiza glabra rhizome extracts had MIC values of 1.56 mgml-1 and 3.25 mgml-1 respectively when tested against the isolate from a 5-month-old baby, which was the most susceptible of the isolates used. All the extracts had higher MIC values against the standard strain (ATTC 10231), which was the least susceptible to the extracts used. Stability testing was performed on fresh aqueous extracts of A. sativum, G. glabra, T. violacea and P. myrtifolia stored at 4°C, 23°C and 33°C over a period of one week, to determine the stability of the extracts in solution. All A. sativum extracts maintained stability for three days in solution, whilst T. violacea extracts remained stable for only two days in solution. TLC fingerprinting of A. sativum and T. violacea extracts indicated the presence of the known antibacterial and antifungal compound allicin. The activity of allicin and other active compounds was observed by using the bioautographic assay, which was performed on these extracts. P. myrtifolia and G. glabra extracts lost stability 24 hours after preparation at all tested temperatures. However, it was clear with the four plant extracts tested that storage of solutions at higher temperatures reduced their activity and stability. The unpleasant taste and smell of A. sativum and G. glabra could however not be masked, since the intake of these two extracts would result in HIV patients being recognised. These two plants where therefore not considered for further investigation. G. glabra and P. myrtifolia are both saponin containing plants. These could be the active constituents responsible for the anticandidal action. G. glabra is known for its biological activity as an antibacterial agent, whilst other Polygala species have been reported to possess antifungal saponins. Although P. myrtifolia and G. glabra are not stable for more than 24 hours, they do not have an unpleasant smell or taste. These plants are therefore further investigated for use as oral mouthwash in clinics and homes.<br>Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Philosophiae Doctor - PhD<br>One of the most common HIV-associated opportunistic infections is candidiasis, caused by Candida albicans or other Candida species. In immune suppressed subjects, this commensal organism can cause an increase in patient morbidity and mortality due to oropharyngeal or systemic dissemination. Limited information exists on the prevalence and antifungal susceptibility of Candida species in the African continent, the most HIV-affected region globally and home to new and emerging drug resistant Candida species. The mechanisms of Candida drug resistance in the African continent have also not been described. In this study, 255 Candida species isolated from the oral mucosa of HIV-positive South African and Cameroonian patients were identified using differential and chromogenic media and their drug susceptibility profiles tested using the disk diffusion method and the TREK Sensititre system, an automated broth microdilution method. Candida cell wall fractions were run on SDSPAGE and HPLC-MS with the aim of identifying peptides specifically expressed by antifungal drug resistant isolates. Comparisons between the two groups of isolates revealed differences in Candida species prevalence and drug susceptibility with interesting associations observed between specific drug resistance and duration of ARV therapy. This study showed that fluconazole, the drug of choice for the treatment of candidiasis in the African continent, is not an effective therapy for most cases of Candida infection, and suggests that regional surveillance be implemented in the continent. A multiple-drug resistant Candida strain was identified in this study, a finding that has not previously been documented. The use of proteomics tools allowed for the identification of peptides involved in drug resistance and the elucidation of Candida colonization mechanisms in HIV-infected African patients.

African horse sickness (AHS) is a lethal disease of horses. The aetiological agent is African horsesickness virus (AHSV) (genus Orbivirus; family: Reoviridae). Immunity to all nine serotypes is needed for full protection. The AHSV virion is composed of seven structural proteins and 10 dsRNA genes. The outer capsid protein, VP2, determines the serotype and elicits protective neutralising antibodies (NAbs). The existing polyvalent attenuated vaccine has some drawbacks. The most important ones are the exclusion of serotypes 5 and 9. Also, vaccinated and naturally infected horses cannot be differentiated. This impedes the international movement of horses. Recombinant su.bunit vaccines should solve both problems. Previously, it was established that baculovirus-expressed AHSV VP2 induces NAbs and partial protection. The main aim of this investigation was to improve the level of protection and develop a prototype VP2-based AHSV -5 vaccine to supplement the current attenuated vaccine and pave the way for developing a VP2-based subunit vaccine that incorporates all nine AHSV serotypes. Preliminary challenge experiments in horses indicated that AHSV -5 rVP2 provides incomplete protection against a lethal AHSV-5 challenge. Probable causes and solutions for this problem had to be sought. Analysis of the baculovirus-expressed AHSV-5 VP2 showed that most (ca. 90 %) is aggregated and that only the soluble part (ca. 10 %) elicits NAbs in guinea pigs and full protection in horses. Preliminary small-scale production studies indicated that solubility of the AHSV-5 rVP2 could be improved considerably by optimising in vitro infection conditions. A significant finding was that the safety and efficacy of soluble AHSV -5 rVP2 is determined by the adjuvant used. Saponin-based adjuvants rendered the best results, albeit with dose-related side effects in horses. Saponin Q was tolerated best. These results for the first time implicated AHSV VP2 in stimulating a protective cell-mediated immunity. Based on these results, it is recommended that a candidate AHSV-5 VP2-based subunit vaccine, consisting of 50 µg rVP2 and 3.0 mg Saponin Q for the primary immunisation followed by a 50 µµg rVP2 and 0.6 mg Saponin Q booster, be formulated for the purpose of field trials. The knowledge generated during this study, combined with the recent cloning of the VP2 genes of all nine AHSV serotypes, provides a route for the development of a complete recombinant vaccine that will offer protection against all nine AHSV serotypes and could well free the restraint on the import and export of horses to and from South Africa.<br>Thesis (PhD (Microbiology))--University of Pretoria, 2005.<br>Biochemistry<br>unrestricted

Plant-feeding mites represent major pests in agriculture that are of importance to crops world-wide, as large populations of mites reduce the quality and quantity of yields. Alternatives to the use of pesticides are needed due to their negative effects and bio-control agents (predatory mites) remain advantages as they suppress spider mites and other plant pests. This study aims to determine species status of plant-feeding and predatory mites on plants of the family Solanaceae and to apply morphological and molecular data to determine phylogenetic relationships among economically important Phytoseiidae, Stigmaeidae and Tetranychidae. The material for this study was collected through plant beating and specimens were preserved in 75% and 96% ethanol respectively and mounted in Heinz’s PVA medium on microscope slides. A survey was conducted during peak seasons to provide enough samples of pest and predatory species. Morphological analysis was performed and initial results indicate that 94% of the species identified were parasitic and 6% were predatory, which led to a predator:prey ratio of 1:17, where Tetranychus evansi Baker & Pritchard had the highest frequency of appearance. A modified Qiagen DNeasy tissue kit extraction protocol was used and Polymerase Chain Reaction was performed to amplify ribosomal ITS and mitochondrial COI gene fragments. The nucleotide sequence of a 700-bp fragment for ITS was determined by direct sequencing as well as for a 700-bp and 800-bp fragments for COI. The resulting data included 4 isolates that corresponded morphologically and molecularly with Phytoseiidae and 10 with Stigmaeidae. The phylogenetic trees agreed with the morphological data. For species that lack morphological descriptions in GenBank and are not placed within expected clades, one has to accept the possibility of miss identification and highlights the need to combine morphological and molecular approaches to guarantee solid species diagnosis. Ultimately, Solanaceae contain various parasitic mites, but predators seem low in numbers. This could be problamatic in finding effective bio-control agents.<br>MSc (Zoology), North-West University, Potchefstroom Campus, 2015

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.<br>Title from title screen (site viewed September 08, 2009). PDF text: ix, 270 p. : col. ill. ; 2 Mb. UMI publication number: AAT 3354712 . Includes bibliographical references. Also available in microfilm and microfiche formats.

A research report submitted to the Faculty of Humanities, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Arts in Translation (Option Interpreting) Johannesburg, 2017<br>The aim of this research project is to examine the feasibility of using technology such as email and YouTube in pre-assessing potential interpreting students. This research project investigates existing pre-assessment methods and proposes a method for online interpreter pre-assessment. Pre-assessment for candidate interpreters is essential, but no standard or universal pre-assessment test exists. Scholars agree on several aspects that should be tested for, yet institutions providing interpreter training conduct pre-assessment tests differently. Generally, pre-assessment testing involves a jury or panel interviewing the potential student and observing him/her perform interpreting-related tasks. Pre-assessment by jury assessment presents several logistical and financial challenges for the institution conducting pre-assessment as well as the potential student. In poor regions such as Africa, this could prevent potentially viable interpreting students from attending pre-assessment tests. This research project investigates current pre-assessment practices in order to determine the skills generally tested for in pre-assessment tests, as well as the methods used for assessing these skills. Based on this investigation, an online delivery method is developed and evaluated in order to determine the extent to which online pre-assessment could be used as an alternative to using a jury for pre-assessment testing. Wits Language School in Johannesburg, South Africa is used as a pilot study for online interpreter pre-assessment: Interpreting students who applied for study, were given the option of online pre-assessment. After the pre-assessment, students attended a course in interpreting and their performance in the pre-assessment test was compared with their performance in the examination for the course. These results along with interviews and questionnaires provide useful information regarding the feasibility of online interpreter pre-assessment.<br>MT 2018

Tese de mestrado em Microbiologia Clínica, apresentada à Faculdade de Medicina da Universidade de Lisboa, 2009<br>Viruses are obligate intracellular parasites and, as a consequence of many years of coevolution with their hosts, have evolved genes/strategies to manipulate and/or evade host cell biology and immune responses. Many of these viral evasion genes code for proteins that are non-essential for virus replication in vitro. They may, however, be considered as valuable ready made tools to extend, explore and manipulate the regulation of the basic cellular processes that they manipulate. African swine fever virus (ASFV) is a devastative acute pathogen of domestic pigs, principally in Africa where due to progressive urbanization and informal pig rearing, endemicity is growing. In its wild life hosts, both vertebrate (warthog and bush pig) and invertebrate (soft tick), however, the virus has evolved many genes to escape the full ferocity of the host immune response and is non-pathogenic. This project has focused on one such strategy, specifically, the ASFV gene I329L, which has been demonstrated to inhibit TLR signaling. Two important future possibilities have been defined by this work: 1) The demonstration that I329L is a non-essential virus gene will permit construction of an I329L deletion-mutant virus and work towards this has commenced with the successful subcloning of the flanking regions of I329L into the necessary transfer vector. The I329L deletion virus will further our understanding of the role of I329L in the pathogenesis of the ASFV infection and may justify the testing of an I329L deletion mutant as a vaccine. 2) The demonstration that I329L functions in mouse macrophages and the subsequent construction of a macrophage restricted I329L transgenic mouse will provide an in vivo system to determine the role of I329L in healthy and infected macrophages.<br>Os Vírus são parasitas intracelulares que como consequência de evoluírem em conjunto com os seus hospedeiros, desenvolveram estratégias/genes de manipulação e/ou evasão das células e resposta imunitária do hospedeiro. Muitos destes genes de evasão codificam proteínas que são não essenciais para a replicação do vírus in vitro. Podem, no entanto ser consideradas ferramentas úteis no estudo e manipulação da regulação dos processos celulares que manipulam. O vírus da Peste Suína Africana (PSA) é um patogénio que causa doença aguda em porcos domésticos, principalmente em África, onde o seu estado endémico é cada vez maior devido principalmente a uma urbanização progressiva e também à criação doméstica de porcos. No entanto, nos seus hospedeiros selvagens tanto vertebrados como invertebrados, o vírus desenvolveu estratégias e genes que lhe permitem evadir fortes respostas imunitárias, sendo não-patogénico. Este projecto foca-se no estudo de um gene do ASFV, o I329L, no qual já foram previamente feitos estudos no nosso laboratório que demonstraram que inibe a via de sinalização TLR. Foram definidas duas abordagens para o estudo deste gene neste projecto: 1) A demonstração de que o I329L é um gene viral não essencial que permite a construção de um vírus de delecção mutante, tendo o trabalho neste sentido começado pela clonagem bem sucedida das regiões que flanqueiam o gene no vector de transferência apropriado. O vírus mutante para o I329L permitirá a melhor compreensão das funções deste gene na patogenicidade da infecção e poderá justificar a construção de uma vacina mutante por delecção. 2) A demonstração de que o I329L mantém a sua função em macrófagos de ratinho e a subsequente construção de um ratinho transgénico com expressão de I329L restrita a macrófagos, proporcionam um sistema in vivo que permitirá avaliar o papel do I329L em macrófagos infectados e não infectados.

Research was undertaken to discover and study trypanosome proteins that may play important roles in host-parasite or vector-parasite interactions. The methods used mass spectrometry based proteomics ideally suited for analysis of low abundance molecules. First, isobaric tags were used to monitor changes in proteins expression throughout the life cycle of Trypanosoma congolense, an economically important livestock pathogen. This was the first large scale survey of protein expression in trypanosomes. In addition to generating protein expression data for approximately 2000 different parasite proteins, 6 previously undescribed T. congolense proteins were discovered. Several of the proteins with interesting expression trends were selected for molecular characterization and monoclonal antibody derivation. Second, immunoenrichment and mass spectrometry were used to identify the cognate antigen recognized by a T. congolense-specific monoclonal antibody. The antigen, a flagellar calcium binding protein, was expressed as a recombinant protein and used to test its utility as a potential serodiagnostic antigen for diagnosis of T. congolense infections. Third, a “deep-mining” protein discovery mass spectrometric method was used to identify trypanosome proteins present in the plasma of late-stage African sleeping sickness patients. A total of 254 trypanosome proteins were unequivocally identified by tandem mass spectrometry. These findings are unprecedented since never before have such a large number of pathogen proteins been discovered in human blood using a non-biased approach (i.e. without using a targeted assay). The proteins discovered provide insights into host-parasite interactions and are strong candidates as targets for new diagnostic assays.<br>Graduate

Escherichia coli diarrhoea is the most important source of mortality in piglets. The most frequently isolated strain in enterotoxigenic E. coli diarrhoea is F4ab/ac. Recent studies in South Africa reported non-fimbrial strains such as PAA and EAST-1 to be prevalent. The objective of the study was to determine whether there are breed differences among pigs with respect to E. coli adhesion phenotypes and correlate them to polymorphisms at selected candidate genes in the South African population. A total of 225 pigs aged 3-12 weeks of the imported (Large White, Landrace and Duroc), local and crossbreds, were sampled from the Eastern Cape and Limpopo provinces of South Africa and genotyped for PCR-RFLP polymorphisms at four candidate genes associated with E. coli F4ab/ac resistance/susceptibility. These genes were Mucin 4 (MUC4), Mucin 13, (MUC13), Mucin 20 (MUC20) and Transferrin Receptor (TFRC). The TFRC and MUC13 genes were less polymorphic, the C allele was close to fixation and the homozygous CC genotype was the most frequent in all three pig populations. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for the TFRC locus. The g.8227G>C polymorphism in MUC4 segregated in all three breeds and the marker was moderately polymorphic. There was a significant difference (P <0.05) in genotypic distribution amongst breeds for MUC4.The g.191C>T polymorphism in MUC20 segregated in the local and crossbred pigs and was close to fixation in the imported pigs. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for MUC20, which was moderately polymorphic. There was a reduction in heterozygosity in both the TFRC and MUC13 loci, although MUC4 and MUC20 genes had higher heterozygosity levels. The MUC4 gene had a negative FIS value, indicating outbreeding at this locus. The MUC20, MUC13 and TFRC genes had a positive FIS value, indicating inbreeding at these loci. Overall, the studied population was outbred. Imported pigs in TFRC and MUC20 deviated from Hardy-Weinberg equilibrium (HWE). All breeds were in HWE at the MUC4 and MUC13 genes. There was no linkage disequilibrium observed amongst the analysed loci. iv A total of 109 piglets of three breeds (Large White, indigenous and crossbred) aged 3-5 weeks, were investigated for the susceptibility to E. coli F4, PAA strains and EAST-1 toxin. Adhesion tests were conducted on pig intestinal cells, which were viewed under a phase contrast microscope. Three phenotypes were identified as, adhesive, weakly adhesive and non-adhesive. There was a significant association (P <0.05) between breed and level of adherence of the F4 and PAA strains. Highest frequencies of adhesion phenotypes were observed in the indigenous pigs for both F4 and PAA E. coli strains. Large White pigs had the lowest frequency of non-adhesion in F4 and PAA E. coli strains. The F4 strain had a higher (P <0.05) level of adherence compared to PAA and EAST-1 in Large White pigs. Age of pigs had a significant effect on the level of E. coli adherence in indigenous and crossbred pigs (P <0.05). Adhesion of F4 and EAST-1 was higher in weaned indigenous and crossbred pigs, respectively, than in suckling piglets. There was no significant difference between F4 adhesion and the genotypes at all four candidate genes genotypes. The study showed that both imported and local pig populations carry receptors and are susceptible to F4, PAA and EAST-1 E. coli infections. Indigenous pigs were less susceptible than Large White to E. coli infection. Although polymorphic and segregating in the populations, the MUC4 g.8227G>C and MUC20 g.191C>T mutations were not associated with the adhesion phenotypes and cannot be used in the selection of susceptible animals.<br>M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

The aim of this research was (1) to provide empirical data of learning potential and English language proficiency for work performance; (2) to establish whether race and gender influence work performance; (3) to evaluate practical utility and to propose recommendations for selection purposes. The Learning Potential Computerised Adaptive Test and the English Literacy Skills Assessment were used as measuring instruments to measure learning potential and English language proficiency respectively. Work performance data were obtained from the normal performance data system of the company where the research was conducted. ANOVA results showed differences between race and gender groupings. A regression analysis confirmed the predictive validity of learning potential and English language proficiency on work performance. The Spearman rho correlation coefficient (p < 0.05) showed a significant positive correlation between the investigated variables<br>Industrial & Organisational Psychology<br>M. A. (Industrial & Organisational Psychology)

D. Tech. Food Technology.<br>Discusses a range of lactobacilli and bifidobacteria were isolated from functional food products and pharmaceutical preparations and also obtained from culture collections. They were then subjected to phylogenetic analysis for accurate identification and classification and the probiotic properties of the organisms was evaluated. The isolates were then screened for inhibitory activity against a range of pathogenic bacteria and Candida albicans strains. Selected isolates that were found to have the necessary inhibitory and probiotic properties were recommended for inclusion in an envisaged synbiotic, maize-based beverage that would, in a subsequent study, be subjected to a nutritional intervention trial aimed at alleviating oral thrush in human patients. The specific objectives: to investigate and illustrate the superiority of rpoA and pheS gene sequencing compared to 16S rRNA gene sequencing in the identification and phylogenic assignment of Lactobacillus isolates ; to determine the precision of selected protein-coding gene sequencing in comparison with 16S rRNA gene sequencing for the discrimination and phylogenetic analysis of Bifidobacterium isolates ; to investigate the probiotic properties of selected bacterial strains in terms of antibacterial activity, anti-Candida activity, acid resistance, bile tolerance and antibiotic resistance ; to determine the potential of Lactobacillus isolates to inhibit the growth of each of seven Candida albicans strains in fermented maize gruel and to establish the factors contributing to Candida inhibition and to determine the antimicrobial and antioxidant activity of intracellular extracts and to elucidate compounds in methanol extracts from selected Lactobacillus strains.

<p>This dissertation examines the topic of social perceptions regarding political candidates at the intersection of race and gender. Within this project I analyze 1) the degree to which stereotypes are held at different points of this intersection; 2) the degree to which these stereotypes can be influenced by way of priming via common news reporting messages; and 3) the ways in which these stereotypes and perceptions influence evaluations of Black female political candidates and their electoral prospects. In order to examine these issues, I utilize data from two surveys I have designed: the 2011 Social Cognition and Evaluation Survey and the 2012 Political Candidate Evaluation and Social Beliefs Survey. The former gathers information regarding social and personal perceptions of "average" and "elite" Black women, White women, Black men, and White men, and the ways in which negative intersectional priming messages can influence the evaluation of each of these groups. The latter survey includes an embedded experiment in which respondents participate in two mock elections and candidate evaluations. One mock election includes a Black female with a relatively dark complexion as the fixed candidate and the other includes a Black female with a relatively light complexion as the fixed candidate, with each competing against either a White male, White female, or Black male opponent. Based on the data from the aforementioned surveys, I find that people engage in stereotyping in an intersectional, rather than a one-dimensional, manner. Consequently, Black women at different social status levels and with differing skin tones are subject to distinct intensities of the attribution of racialized, gendered, and intersectional stereotypes. In turn, the ways in which the voting public evaluates them as political candidates are influenced by these stereotypes.</p><br>Dissertation

Those who take the Great Commission of Christ seriously realise that enlarging today's mission force is crucial. The Two-thirds World church is in a prime position to meet the need. Cross-cultural mission training would greatly enhance and accelerate the fulfilling of Christ's final mandate to the Church. As founding director of Missions Exposure and Training (MET), a Christian ministry located in Pretoria, South Africa, the author of the thesis lays out the details of the programme for the reader. MET is the case study being considered, with particular emphasis placed on Missionary Candidate School (MCS), the backbone of MET. Before MET is introduced, the thesis begins with the challenge facing the universal Church today: the need to strengthen and enlarge the current mission force. The theological implications of Jesus Christ's mandate to the Church, the missionary purpose of the Church, as well as eschatological concerns build a strong argument for the need of a larger mission force. Demographic changes taking place within the Church mean that Two-thirds World Christians should be considered as a primary resource for cross-cultural mission endeavours. To maximise the potential of the new recruits, which the writer refers to as 'missionary candidates,' further discussion is given for the need of systematic training and equipping of Two-thirds World missionaries. After describing MET and MCS, the programme is critically evaluated. MCS is proven to be effective in training African men and women for intercultural Christian mission service, and as such it becomes a model worth investigating. The clear findings that result from the candid evaluation, and assessments made in light of current theological and missiological issues, should prove to be beneficial to those developing programmes with the purpose of training and equipping Two-thirds World missionaries.<br>Christian Spirituality, Church History and Missiology<br>D. Th. (Missiology)

The central purpose of this dissertation is to discuss different ways in which land and the broader natural environment has been used as a vehicle or medium in art-making, with a specific focus on the works of Jenny Cullinan and Lynne Hull and the candidate. The work centres on artworks that are in the landscape, of the landscape, in the earth, of the earth or predominantly concerned with ecological issues and the inter-relatedness of all living systems. It is argued that artworks included under the general appellation land or environmental art may be widely divergent in character, notwithstanding threads of commonality and convergence. In addition, the often fluid or ambiguous nature of the terminology associated with this area of investigation has necessitated some definition of key terms.<br>Thesis (M.A.)-University of Natal, Pietermaritzburg, 2001.

The purpose of this study was to explore and describe the experiences of Recognition of Prior Learning (RPL) nursing candidates related to the four-year comprehensive nursing training programme at a Nursing Education Institution in Gauteng. To this end an exploratory descriptive qualitative research design was undertaken. The research sample comprised of 13 purposefully selected participants. Face-to-face individual interviews, using open-ended questions (Grand tour), were used to collect data, which was analysed using Tesch’s approach. Findings from the study highlighted the challenges faced by nursing RPL candidates as adult students. These included challenges related to their theoretical learning as well as their clinical facility experiences. Based on the study results, recommendations were formulated in assisting them to successfully and timeously complete their nursing programme<br>Health Studies<br>M.A. (Nursing Science)

At the 2007 General Synod of the Dutch Reformed Church a compromise resolution was accepted regarding homosexual members. This resolution, inter alia, requires of gay ministers to remain celibate as a prerequisite to be legitimated. This research is a qualitative inquiry to evaluate the impact which this resolution has on the lives of gay ministers and gay candidate ministers. Narrative and postfoundational perspectives were obtained by interviewing six gay ministers and/or candidate ministers as coresearchers, and also by engaging in dialogue with inter-disciplinary experts from Sociology, Psychology and Law. This research traced the history of the Resolution, while the patriarchal and heteronormative discourses underlying the formulation were discussed. These discourses still sustain the Resolution. Interwoven in the Resolution are contradictions and double standards based on prejudice, leading to discrimination against gay ministers and gay candidate ministers. A literature study on prejudice and discrimination revealed many of the negative impacts these have on people on the margins of society. A literature review on gay marriages suggested that gay unions and gay marriages were known from pre-modern times. With the changing of the socio-political climates since pre-modern times till today, attitudes towards gay unions/marriages seemed to havethat the Bible does not categorically say anything about committed, monogamous gay unions or gay marriages. The focus of this research was to determine the impacts of the Resolution on gay ministers and gay candidate ministers. From their stories certain themes revealing the impacts were co-constructed by the co-researchers and the researcher. According to a negotiated meaning-making process a fragile and incomplete understanding of the gay ministers’ and gay candidate ministers’ immense suffering due to their experience of rejection and humiliation by the DRC was formulated. This reiterated the Shame of being gay. In terms of the discrimination levelled against gay ministers, it could, according to the Constitution of South Africa, be regarded as fair. This research suggested that the fairness of the discrimination should be revisited. changed. A study of the biblical texts led to the tentative and incomplete understanding<br>Thesis (PhD)--University of Pretoria, 2015.<br>gm2015<br>Practical Theology<br>PhD<br>Unrestricted