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Blessing or curse? : an evaluation of the African Growth Opportunity Act

  • Authors: Matenga, Lloyd
  • Date: 2017
  • Subjects: United States -- African Growth and Opportunity Act Tariff preferences Terms of trade
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: http://hdl.handle.net/10353/8825 , vital:33667
  • Description: The core of the commercial relations between the United States (US) and Sub-Saharan African (SSA) countries is primarily based on the advancement of unilateral preferential treatment as envisaged under the African Growth and Opportunity Act (AGOA). AGOA is a bipartisan US legislation promulgated to govern the North-South agreement between the US and SSA countries. Notably, AGOA can be categorized as an exception to the Most Favored Nation (MFN) clause of the General Agreement on Tariffs and Trade (GATT) and consequently under the legal framework of the World Trade Organisation (WTO). The US through the AGOA Extension and Enhancement Act (TPEA) has prolonged the lifespan of AGOA to 2025 in consonance with AGOA and other relevant US legislation. However, there is an ongoing debate as to whether AGOA is working to the advantage or benefit of the eligible SSA countries. This is due to several problematic issues which inter alia relate to the legitimacy of the unilateral preferential treatment, the applicable Rules of Origin (RoO) and the requirement for adoption of robust intellectual property protection regimes as impediments to the enjoyment of AGOA duty and quota free benefits. This study will thus examine the pertinent legal issues underpinning the granting of unilateral preferential treatment in favour of the SSA countries under AGOA and assess the extent to which AGOA complies with or fulfills the purposes and objects of the Enabling Clause.
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  • Date Issued: 2017

Browsing as a demographic bottleneck in a semi-arid savanna: the effect of size and age on compensatory responses of Vachellia karroo seedlings after simulated herbivory

  • Authors: Perumal, Lavinia
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/4899 , vital:20741
  • Description: Savannas are characterised by a continuous grass layer with scattered trees at varying densities. This vegetation structure is determined by several interacting factors, including fire, herbivory, resource competition and atmospheric CO2 concentration. The preservation of savanna biomes is important and a shift towards a woody biome threatens savanna globally. Bush encroachment which describes the shift towards domination of savannas by C3 woody plants, is especially acute in southern Africa. In semi-arid rangelands, encroachment progresses to dense thickets dominated by thorny and unpalatable bushes and trees. There is evidence that bush encroachment is driven by a reduction in fire and browsing events as well as their interaction. Despite browsing having strong effects on African savannas its isolated role in maintaining tree-grass coexistence has not received as much attention as the role of fire. Therefore the overall aim of this study was to examine the effects of browsing on seedlings of a commonly encroaching species, Vachellia karroo. Browsing was hypothesized to be a demographic release bottleneck for bush encroachment in a semiarid (MAP ~550mm) savanna in the Eastern Cape of South Africa, where fire has been historically rare. In a single study I explored the fate of V. karroo seedlings (less than a year old) following browsing in sub canopy and inter canopy microhabitats. Additionally, I explored how the fate of a seedling changed under high and low tree cover. Firstly, I investigated the type, intensity and frequency of herbivory, from both small and large herbivores, which seedlings were subjected to. Results revealed that browsing was severe and frequent with the majority of seedlings browsed more than twice over a 12 month period. Large browsers such as kudu and impala caused high seedling mortality (46%) while smaller browsers such as invertebrates were more effective at suppressing growth. Microhabitat had little impact on seedling survival, but significantly influenced plant compensatory growth. Reduced seedling growth following browsing was observed in the sub-canopy in comparison to seedling growth in full sunlight in the intercanopy, suggesting V.karroo may be shade intolerant. Secondly, the effect of tree cover on browsed seedlings was determined by quantifying browsing frequency and intensity at high and low tree cover. No differences in browsing intensity and frequency were observed between high and low tree cover. However, high tree cover due to bush encroachment limited seedling above ground growth. The aim of the second study was to investigate how V.karroo survival and growth were influenced by its age and size following simulated browsing. I explored this aim through field and greenhouse experiments. I was particularly interested in testing how plant sensitivity to varying defoliation intensities of repeated browsing varied with plant age (known ages of 6, 12, 16 and 30 weeks). There were large differences in mortality between the different age groups. Furthermore, age interacted with repeated browsing and negatively influenced seedling survival and regrowth. Older seedlings (16 and 30 week old) had greater survival and higher browsing frequencies resulted in greater mortality and reduced growth. The threshold age after which seedlings become more tolerant to herbivory occurs at an age of 28 weeks. Seedlings less than six weeks old experiencing intense (100 % defoliation)browsing had a very low probability (33%) of survival following just a single defoliation. Interestingly, all 16 week old seedlings regrew most of their foliage following a moderate (50%) defoliation with some plants overcompensating for leaf loss. The field study revealed two distinct demographic stages based on age and size (seedlings< 9 mm and saplings >9 mm in stem basal diameter (SBD)). Browsing had a strong negative effect on seedlings, resulting in reduced investment in leaf biomass. These findings suggest plant size and age can be used as robust predictors of a plants vulnerability to browsing. An increase in tree cover requires successful transitions of seedlings to saplings (also known as release). The results of this study suggest that in semi-arid savannas, browsing can impact tree cover through imposing a release bottleneck for tree seedlings and to lesser extent saplings. By limiting tree growth plants are kept in a disturbance trap and will therefore be exposed to not only browsers but fire. These findings also have important implications for tree-grass coexistence dynamics, suggesting that specific size and browsing thresholds should be considered in savanna management.
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  • Date Issued: 2017

Buchu and Bobotie in the Boland : culinary heritage in Franschhoek, Western Cape

  • Authors: Deavin, Candace
  • Date: 2017
  • Subjects: Food habits -- South Africa -- Franschhoek -- Cross-cultural studies Plants, Edible -- South Africa -- Franschhoek
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/22254 , vital:29923
  • Description: From a confit tomato and potato tumbleweed with buchu to a cured snoek terrine rolled in wilde kruie and Cape bobotie puff pastry with blatjang, chefs that mix indigenous plants and local cuisine with European inspiration and training have proved popular in Franschhoek’s restaurants. In this boland town, the particular constructions of heritage through food, not only showcases regional flavours, but gestures towards the search for an elusive place-based ‘South African’ cuisine that is seen to be rooted in the land. Harkening back to old culinary practices and drawing from their own heritages, Franschhoek’s chefs are foraging, butchering, gathering, growing, fermenting, pickling and cooking over open fires with renewed vigour as they attempt to ground their cuisine, and indeed, themselves, in the soil around them. This thesis considers how, through the culinary repertoire of chefs in Franschhoek, food is constructed as heritage. Within this I look at what heritages are considered desirable, how food’s sensory and symbolic properties are used to their full potential, and who is behind these constructions of culinary heritage. Following on from this, I explore postcolonial and post-apartheid anxieties of place and belonging, as well as desired and emergent identities that are expressed through this culinary heritage.
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  • Date Issued: 2017

Calibration and imaging with variable radio sources

  • Authors: Mbou Sob, Ulrich Armel
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/37977 , vital:24721
  • Description: Calibration of radio interferometric data is one of the most important steps that are required to produce high dynamic range radio maps with high fidelity. However, naive calibration (inaccurate knowledge of the sky and instruments) leads to the formation of calibration artefacts: the generation of spurious sources and the deformations in the structure of extended sources. A particular class of calibration artefacts, called ghost sources, which results from calibration with incomplete sky models has been extensively studied by Grobler et al. (2014, 2016) and Wijnholds et al. (2016). They developed a framework which can be used to predict the fluxes and positions of ghost sources. This work uses the approach initiated by these authors to study the calibration artefacts and ghost sources that are produced when variable sources are not considered in sky models during calibration. This work investigates both long-term and short-term variability and uses the root mean square (rms) and power spectrum as metrics to evaluate the “quality” of the residual visibilities obtained through calibration. We show that the overestimation and underestimation of source flux density during calibration produces similar but symmetrically opposite results. We show that calibration artefacts from sky model errors are not normally distributed. This prevents them from being removed by employing advanced techniques, such as stacking. The power spectrums measured from the residuals with a variable source was significantly higher than those from residuals without a variable source. This implies advanced calibration techniques and sky model completeness will be required for studies such as probing the Epoch of Reoinization, where we seek to detect faint signals below thermal noise.
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  • Date Issued: 2017

Carbon credit restoration projects in the Eastern Cape province of South Africa: considerations for sustainable local economic development

  • Authors: Polak, James Samuel
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/8069 , vital:21349
  • Description: Although global climate change has been identified as a serious global economic, social, and environmental threat to society, national governments have been slow to respond on a global scale. Environmental economic theory offers market-based solutions to address climate change efficiently through carbon control regimes, such as carbon taxation and cap-and-trade policy. A major political milestone was reached when an international agreement entered into force in 2008, known the Kyoto Protocol, which incorporated a market-based solution to address climate change on a global scale. This allowed a global market for emissions to form through the Clean Development Mechanism. Although the Kyoto Protocol aimed to address a global issue on a global scale through a single global market for emissions, fragmented sovereign cap-and-trade schemes have since emerged in the form of national and regional emission markets, commonly referred to as carbon markets. The Clean Development Mechanism offered the opportunity to generate carbon credits through carbon offset projects, such as carbon restoration projects. Although the Kyoto Protocol did not achieve the objective of forming an internationally accepted global carbon control regime, it seems to have set a trend of including offset programs in newly emerging carbon control regimes, such as South Africa’s proposed carbon tax. This study set out to assess the extent to which carbon control regimes are enabling sustainable local economic development, based on carbon restoration projects in the Eastern Cape province of South Africa using Portulacaria afra, commonly known as spekboom. As a starting point, this study assessed the current state of the international carbon markets using significant international cap-and-trade based markets as examples. Based on Newell et al.’s (2013) selection of significant carbon markets and data availability, the United States’ Regional Greenhouse Gas Initiative and the European Union’s Emission Trading Scheme were selected. Historical, current and forecasted supply and demand data were gathered from Thomson Reuters’ Point Carbon research division. Further, historical futures and spot market price and volume data were gathered from the markets to compare how prices have fared over time. The Clean Development Mechanism’s market for Certified Emission Reduction credits was used for comparative purposes. The markets were found to be systemically oversupplied, leading to systemically low prices. The systemic oversupply in credits provides a limited incentive to initiate carbon offset projects, however, South Africa’s proposed carbon tax may be able to stimulate demand for domestic offset projects. Key success factors established through a comparative literature review on local economic development theory were incorporated into key informant interviews. The results were then analysed through the lens of Connelly’s (2007) model for sustainable development to provide recommendations for sustainable local economic development, regarding carbon restoration projects in the Eastern Cape using P. afra. The following opportunities were identified: the planting of P. afra on degraded land has the potential to mitigate climate change, offer water benefits to the surrounding communities, and promote biodiversity regeneration. There is potential for economic growth through job creation and the economic multiplier effect. Government funding is available and voluntary offset agreements do exist, eliminating a large portion of the cumbersome accreditation requirements. These projects also offer potential for social justice through the government funding requirements which stipulate that youth and women should be given preference for employment, potentially helping to alleviate inequality. The funding further stipulates that employees should be trained in transferable skills, offering potential for capacity building and social capital accumulation through education. These transferable skills include skills geared towards encouraging entrepreneurialism. Corresponding challenges were also found: excessive overgrazing through pastoralism has rendered some land degraded beyond restoration. Opportunists may resort to planting P. afra outside of the subtropical Albany Thicket biome to which it is endemic, leading to potential biodiversity loss rather than gains. Sufficient buy-in is required from private landowners for these projects to be sustainable, however, the projects entail a large opportunity cost to farmers as returns take at least 5 to 6 years. This may render these projects undesirable to most landowners and provides scope for free-riding, should pastoralists not have to bear the full costs of the project and property rights not be enforced through land user agreements. The projects require an exorbitant amount of upfront funding. Cash flow received from the projects does not extend in perpetuity. Requirements for social justice pertain only to government funded projects. A working model, generating and selling carbon credits through land restoration using P. afra, has not yet been established. As it stands, these carbon restoration projects are still highly speculative and carry a significant amount of investment risk, given the high mortality and low growth rates associated with the current planting method. The current systemic oversupply of carbon. credits in the international markets signal that returns from carbon credits are set to be low, at least until the oversupply issues are resolved. Should these challenges be overcome, carbon restoration projects using P. afra may have the potential to bolster sustainable local economic development in the impoverished regions of province as well as provide a locally-driven adaptation and mitigation strategy to address global climate change.
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  • Date Issued: 2017

Cardiovascular disease risk in Black and Caucasian females: an Eastern Cape sample

  • Authors: Remsing, Sandra Claudia
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/40737 , vital:25021
  • Description: The purpose of this study was to investigate cardiovascular disease risk in Black and Caucasian urban working females of the Makana region of the Eastern Cape. One- hundred and sixty six age-matched urban-working individuals (Black n = 88; Caucasian n = 78) voluntarily participated in this cross-sectional study. Cardiovascular disease risk was assessed in four categories: 1) obesity, classified as ‘morphological risk’, 2) blood pressure, classified as ‘cardiovascular risk’, 3) diet, physical activity, smoking, and alcohol consumption, classified as ‘lifestyle risk’, and 4) education and income, classified as ‘socioeconomic factors’. Results showed that Black females were significantly (p<0.01) heavier than Caucasian females and categorized as ‘obese’ according to BMI classifications (31.19 ± 8.09 kg.m2 and 25.90 ±4.67 kg.m2, respectively). Black females also presented with significantly (p<0.01) higher waist circumferences and waist-to-stature ratios, further confirming the obesity prevalence in this group. When accounting for those who were on anti-hypertensive mediation, Black females additionally presented with significantly (p<0.05) higher blood pressure, categorizing them as ‘pre-hypertensive’ (MAP = 98 ± 16 mmHg and 85 ± 11 mmHg, respectively). These results therefore placed Black females at increased cardiovascular disease risk compared to Caucasian females. With respect to lifestyle factors, Black females consumed significantly (p<0.05) more kilojoules carbohydrates, and total sugar than Caucasian females, and expended more physical activity MET- minutes per week (2688.86 ± 1486.56 MET-minutes and 1828.27 ± 2238.10 MET- minutes, respectively). However, reduced validity of physical activity data as well as poor dietary recall limited the interpretations of these findings. In addition, despite significant differences between smoking and alcohol consumption between groups, the majority of both Black and Caucasian females reported being non-smokers and consumed alcohol minimally. Thus, these were concluded to be unlikely contributors to cardiovascular disease risk in these samples. Socioeconomic results nevertheless expectedly showed that Black females were significantly (p<0.05) less educated, and subsequently earned lower incomes. It was thus concluded that this may be a likely contributor to higher cardiovascular risk in Black females. Future recommendations include the incorporation of exercise intensity measures as well as objective measures of habitual diet. This is in order to get a clearer understanding of the impact of these lifestyle factors on cardiovascular disease risk.
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  • Date Issued: 2017

Challenges in distribution of old age pensions in Lesotho

  • Authors: Sejanamane, Nkhahle Daniel
  • Date: 2017
  • Subjects: Old age pensions -- Lesotho Aging -- Economic aspects -- Lesotho , Defined contribution pension plans -- Lesotho Retirement income -- Lesotho
  • Language: English
  • Type: Thesis , Masters , MPhil
  • Identifier: http://hdl.handle.net/10948/20477 , vital:29293
  • Description: The research set out to explore the nature of challenges in distribution of old age pensions in Lesotho. Poor institutional capacity failed the implementing agency, the Department of Pensions; to set up competent administrative structures to run run the pensions effectively and efficiently. A number of challenges have been identified, some of which were: inadequate supervision of the paying officers, fraud by workers and community agents, missing funds, insufficient resources, inadequate administrative capacity, overworked employees, faulty targeting, soft and discriminatory approach to non-compliance with rules and multiple use of identity documents by recipients. On the other hand, a number of opportunities have been identified to counteract the challenges. The main recommendation of the study was the engagement of mobile phone-based money transfer facilities to transfer the old age pensions from the government to the recipients. The Department of Pensions should make use of baseline database like information from civil registration agency like the Ministry of Home Affairs to confirm the validity of the pension recipients. Other recommendations included moving the division of old age pensions from the Pensions Department to the Ministry of Social Development which is the controlling body for other forms of social grants in Lesotho. The Ministry of Social Development is regarded as well equipped with qualified staff and facilities to deal with vulnerable people like the elderly.
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  • Date Issued: 2017

Characterisation and cryopreservation of semen from indigenous Namaqua Afrikaner sheep breed, in comparison with Dorper and Dohne Merino breeds

  • Authors: Letsoalo, Phutiane Thomas
  • Date: 2017
  • Subjects: Merino sheep Dorper sheep Semen
  • Language: English
  • Type: Thesis , Masters , Animal Science
  • Identifier: http://hdl.handle.net/10353/11707 , vital:39099
  • Description: The aim of this study was to characterise and cryopreserve semen of the indigenous Namaqua Afrikaner breed, and to compare it to that of Dorper and Dohne Merino sheep, whose semen is commercially frozen on a large scale. The study was conducted between January and August 2015. September 2013-born Namaqua Afrikaner (12), Dohne Merino (12) and Dorper (9) rams were used in the study. The rams were kept under kraal conditions with adequate shade, and they received a high protein, high energy diet. Originally it was envisaged to collect semen samples using the artificial vagina (AV) method, which proved to be problematic with the Namaqua Afrikaner rams. Semen samples were subsequently collected twice a week by either AV (Dohne Merino and Dorper) or electro-ejaculation (EE; all three breeds). Macroscopic sperm traits were assessed and sperm concentration determined immediately after collection. Each semen sample was diluted with Triladyl® (1:3) and subsequently frozen in liquid nitrogen vapour in straws. Frozen straws were thawed and evaluated at 7, 30 and 90 days after cryopreservation. A droplet (0.5 ml) from each thawed sample was assessed microscopically for post-thaw motility and percentage live sperm. Nigrosin-Eosin smears were prepared of fresh, diluted and frozen-thawed semen samples for determination of percentage live sperm. Data of all the traits were analysed with the GLM and CHI-SQUARE procedures of the SAS statistical package. Breed had a significant effect on ejaculate volume of fresh semen collected either via electro-ejaculation or artificial vagina. Dorper rams (1.37 ± 0.08 ml) and Dohne Merino rams (1.20 ± 0.08 ml) produced ejaculates with higher (P <0.05) semen volume than Namaqua Afrikaner rams (1.09 ± 0.08 ml) when using the EE. With the AV method, Dohne Merino rams (1.46 ± 0.08 ml) produced a higher (P <0.05) ejaculate volume than Dorper rams (1.22 ± 0.08 ml). Motility of the frozen-thawed semen samples was lower than that of the fresh and diluted samples for all breeds and collection methods. Furthermore, motility 3 hours after thawing was also lower than motility assessed immediately after thawing for all breeds and collection methods. Motility of frozen-thawed semen collected with an AV and evaluated at 7, 30 and 90 days after freezing was significantly higher than that collected via EE. Dorper rams had the lowest sperm concentration (1.10 ± 5.29x109 sperm/ml) and the Namaqua rams the highest sperm concentration (1.22 ± 5.20x109 sperm/ml) (P ˂0.05). The AV samples had a higher (P >0.05) sperm concentration (1.20 ± 3.68x109 sperm/ml) than the EE samples (1.11 ± 3.51x109 sperm/ml). The percentage live sperm in the fresh semen samples did not differ among Namaqua Afrikaner (67.76 ± 1.94percent), Dohne Merino (68.59 ± 1.94percent) and Dorper (72.82 ± 1.98percent) rams. The percentage live sperm for all three breeds dropped considerably after freezing to 17.76 ± 2.03percent, 17.86 ± 2.03percent and 22.72 ± 2.07percent respectively. It remained constant for all the breeds from 7 until 90 days after freezing, indicating that length of storage should not have an effect on percentage live sperm for semen collected via AV or EE. Percentage live sperm of the frozen-thawed semen of the Namaqua rams was lower than that of the Dorper rams, indicating that the Namaqua semen collected via EE did not freeze as well as that of the Dorper semen. In conclusion, neither fresh nor frozen-thawed Dorper and Dohne Merino semen collected via EE did differ significantly. Furthermore, except for semen volume, Dorper and Dohne Merino semen collected via AV did not differ significantly whether evaluated as fresh or frozen-thawed semen. However, both Dorper and Dohne Merino rams produced semen with higher motility and a higher percentage live sperm post-thaw when the semen samples were collected via an AV than via EE. From these results it can therefore be postulated that if Namaqua semen were collected via AV it could have a higher post-thaw percentage live sperm than if semen was collected via EE. Advanced further studies are necessary to investigate the reason for the lower post-thaw survival rate of sperm of the Namaqua Afrikaner rams. This is necessary as semen stored in a cryobank for breeding and conservation purposes for this endangered breed has to be of high quality. Such resources as cryobanks are expensive and funds cannot be wasted on preserving inferior samples that could not fertilize an ovum when needed. The low percentage of live sperm obtained with the frozen-thawed samples in this, as well as other studies on indigenous breeds, is an indication that further research is needed into more suitable freezing protocols. It can be concluded that Namaqua Afrikaner semen cannot be frozen successfully for the purpose of storage in a cryobank, when using a freezing protocol based on Triladyl® as extender. Furthermore, any increase in post-thaw survival rate of sperm will be beneficial and it is therefore suggested that all efforts be made to solve the problem of the Namaqua Afrikaner rams that do not want to ejaculate into an artificial vagina.
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  • Date Issued: 2017

Characterisation and cryopreservation of semen from indigenous Namaqua Afrikaner sheep breed, in comparison with Dorper and Dohne Merino breeds

  • Authors: Letsoalo, Phutiane Thomas
  • Date: 2017
  • Subjects: Cryopreservation of organs, tissues, etc Merino sheep Dorper sheep
  • Language: English
  • Type: Thesis , Masters , Degree
  • Identifier: http://hdl.handle.net/10353/4759 , vital:28510
  • Description: The aim of this study was to characterise and cryopreserve semen of the indigenous Namaqua Afrikaner breed, and to compare it to that of Dorper and Dohne Merino sheep, whose semen is commercially frozen on a large scale. The study was conducted between January and August 2015. September 2013-born Namaqua Afrikaner (12), Dohne Merino (12) and Dorper (9) rams were used in the study. The rams were kept under kraal conditions with adequate shade, and they received a high protein, high energy diet. Originally it was envisaged to collect semen samples using the artificial vagina (AV) method, which proved to be problematic with the Namaqua Afrikaner rams. Semen samples were subsequently collected twice a week by either AV (Dohne Merino and Dorper) or electro-ejaculation (EE; all three breeds). Macroscopic sperm traits were assessed and sperm concentration determined immediately after collection. Each semen sample was diluted with Triladyl® (1:3) and subsequently frozen in liquid nitrogen vapour in straws. Frozen straws were thawed and evaluated at 7, 30 and 90 days after cryopreservation. A droplet (0.5 ml) from each thawed sample was assessed microscopically for post-thaw motility and percentage live sperm..
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  • Date Issued: 2017

Characterisation of antibacterial compounds produced by Pseudomonas spp. isolated from Hogsback wetlands, Eastern Cape, South Africa

  • Authors: Obi, Akudo Odochi
  • Date: 2017
  • Subjects: Bacteriology -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10353/15688 , vital:40507
  • Description: With microbial pathogens developing resistance against currently existing antimicrobials, there is an earnest need to discover and develop new therapeutic compounds with unique and/or precise modes of action. Natural products have provided the inspiration for most of the active ingredients in medicines and thus are regarded as a potential screening resource lead for discovery of new drugs. Pseudomonads are ubiquitous, Gram-negative, motile bacteria that flourish and inhabit a diversity of environments. Literature has vastly revealed that some members of the genus Pseudomonas are capable of producing a plethora of biologically active metabolites and thus are regarded as “attractive” bacteria for testing as potential sources for new therapeutic compounds. In this regard, this study was undertaken with an aim to isolate and characterize antibacterial compounds produced by Pseudomonas species isolated from aquatic milieu of the Hogsback wetlands, Eastern Cape, South Africa. A total of 12 water samples were aseptically collected from Hogsback wetlands. To ascertain antimicrobial potential of the isolates, 9 test bacterial (sensitive) strains, namely Escherichia coli ATCC 3695, Vibrio fluvialis, Salmonella typhimurium, Salmonella enteritidis, Pseudomonas aeruginosa ATCC 27853, Escherichia coli (2), Listeria ivanovii, Listeria monocytogenes and Enterococcus faecalis ATCC 19433 were used for antimicrobial screening. A total of 500 presumptive Pseudomonas spp. were isolated and screened for the production of antibacterial compound through the Agar-well diffusion method. About 8percent of the presumptive Pseudomonas spp. produced compound with activity against the test bacteria and based on the levels of activity shown, three isolates coded as A53, Y55 and Y138 were selected and identified by 16S rDNA sequence analysis and The Basic Local Alignment Search Tool analysis revealed that the three isolates (A53, Y55 and Y138) belonged to the Pseudomonas genus. Using MEGA6 software, a molecular phylogenetic tree was constructed by Maximum Likelihood Method. The phylogenetic analysis by this method showed that all three isolate codes (A53, Y55 and Y138) formed the same clade with Pseudomonas viridiflava strain P3 (Accession number: AY972186) and Pseudomonas plecoglossicida strain P9 (Accession number: AY972231) at a high bootstrap value of 100percent. Isolate code A53 and Y55 also grouped together at a bootstrap value of 96percent. Factors affecting antibacterial compound production by the three isolates were elucidated. The effect of pH on the three isolates revealed that isolate code A53 and Y55 could produce antibacterial compounds over all pH ranges (pH 4-9), however, antibacterial production was produced optimally at acidic conditions (pH 4) and a less acidic-neutral condition (pH 6) respectively. Isolate Y138 showed optimal production at pH 5. The effect of temperature on all three isolates was studied at different temperatures ranging between 25°C-40°C. Study on effect of temperature variations on antibacterial production revealed that all three isolates are capable of growing and producing antibacterial compounds over all the different temperature ranges, however, maximum/optimum production was observed at temperature of 30°C. In order to establish the role of plasmids in antibacterial production, two curing agents; Sodium dodecyl sulfate (SDS) and Ethidium bromide under different sub-lethal concentrations (1 mg/ml -11mg/ml and 2.5 μg/ml- 125 μg/ml respectively) were used to cure the selected isolates. Plasmid DNA samples of A53, Y55 and Y138, were separated by electrophoresis on a 0.7percent (w/v) agarose. Agarose gel electrophoresis revealed that not all the concentrations used were effective in curing the plasmid. A Quick Load 1 kb Extend DNA ladder marker was used for determining the size of the plasmids. Isolate code A53 and Y138 had a plasmid size of 48.5 kb while isolate Y55 had a plasmid size of approximately 20 kb. Antibacterial activity by agar-well diffusion method after the curing process revealed that antibacterial production was not lost or prevented, but rather increased. Thus, it is suggested that the genes responsible for antibiotic production in this study were chromosomal-encoded and not plasmid-encoded. This study revealed that Hogsback wetlands may represent a previously unexplored environment/source of discovering novel and potent antibacterial compounds.
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  • Date Issued: 2017

Characterisation, antimalarial and biological activities of secondary metabolites from leaves of anonidium mannii

  • Authors: Makoni, Pfungwa Gervase
  • Date: 2017
  • Subjects: Anonidium mannii -- Therapeutic use , Botanical chemistry , Annonaceae -- Therapeutic use , Apocynaceae -- Therapeutic use , Malaria -- Chemotherapy , Tuberculosis -- Chemotherapy , Bacterial diseases -- Chemotherapy , Cancer -- Chemotherapy
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/4797 , vital:20725
  • Description: Anonidium mannii is a plant of the Annonaceae genus which is used traditionally in Africa for the treatment of gonorrhoea, malaria, cancer, skin inflammation and dysentery. In this study we will evaluate antimalarial, antifungal, anti - tuberculosis, antibacterial activities and cytotoxicity of different fractions in order to provide a scientific rationale for the traditional use of Anonidium mannii as well as provide possible novel drugs in the treatment of multi drug resistant strains of parasites and bacteria. Extracts from dried leaves were obtained by using solvent extraction and different fractions obtained using column chromatography eluted with solvents of varying polarities to obtain a wide range of metabolites. The antimalarial activity of the various fractions and some pure compounds was evaluated using plasmodium lactate dehydrogenase (pLDH) assay. Cytotoxicity was evaluated using HeLa cells while anti – tuberculosis assay was evaluated using the green fluorescent protein. Antibacterial activity of the extracts was evaluated using micro-dilution assay against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria and Gram-negative (Escherichia coli and Salmonella typhi) bacteria. Antifungal activity was evaluated against Candida albicans. The antimalarial assays yielded some fractions with promising IC50 values. The selected fractions yielded activities ranging between 0.73 μg/mL and 20.23 μg/mL. The fraction with the best activity was obtained from a hexane/ethyl acetate fraction. AM1C, a cholestane, showed the best activity from the pure metabolites that were screened. AM3C, stigmasterol, a pure compound gave the best antifungal activity with an MIC of 0.063 μg/mL. AM9C another pure compound (sterol) showed the best activity against S. typhi with a value of 0.031 μg/mL. AM2C a pure compound showed an activity of 0.063 μg/mL against E. faecalis. The best cytotoxicity was demonstrated by the fraction C2AM3P with a cell viability of 7.1 ± 0.2 % while AM1C had a viability of 20.2 ± 1.2 %. Several pure metabolites were isolated and four of these were positively identified as steroids. Of these steroids the structure of three novel metabolites from A. mannii was deduced. The study showed promising antibacterial, antifungal, anti – tuberculosis, antimalarial and anticancer activity of A. mannii. These results validate the use of A. manni against cancer, skin inflammation which is caused by fungus, malaria and bacterial diseases.
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  • Date Issued: 2017

Characterization of a glycated gelatin model to explore the therapeutic properties of macrofungi in diabetic wound healing: an in vitro study

  • Authors: Pringle, Nadine Alex
  • Date: 2017
  • Subjects: Diabetes -- Animal models Chronic diseases -- Age factors
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/11992 , vital:27017
  • Description: Diabetic wounds frequently undergo impaired and prolonged wound healing due to a multitude of factors including hypoxia, impaired angiogenesis, hyperglycaemia, formation of ROS and AGEs, and infection - all of which may lead to cellular dysfunction. To date, however, treatment options for individuals suffering from impaired diabetic wound healing are limited, non-specific, and generally unsuccessful. The search for new and effective treatment strategies is severely hampered by the availability of adequately characterized screening models which comprehensively mimic the complexity of the diabetic wound healing process. In order to explore natural products as potential therapeutics to treat diabetic wounds and to encourage more research on this topic, this study sought out to develop and characterize a more convenient and cost effective in vitro screening assay which mimics the effects of protein glycation on the healing process of diabetic wounds. As proof of principal, this model was subsequently used to screen the potential of five wild mushroom species (P. tinctorius, R. capensis, B. badius, P. ostreatus and G. lucidum) as suitable diabetic wound healing therapies. The glycated gelatin model developed during this study was found to suitably mimic the diabetic state as it successfully simulated the major cellular dysfunctions in macrophages (NO production, phagocytosis, macrophage polarization, NF-ĸB translocation and COX-2 expression) and fibroblasts (proliferation and migration) documented during diabetic wound healing. Together these findings provide confidence that the model may serve as a valuable tool to study the poorly understood mechanisms which characterize cellular dysfunction in response to AGE accumulation and also to aid the identification of novel therapeutic agents to treat this pathology. Screening a number of mushroom extracts revealed that the ethanol extracts of R. capensis and P. ostreatus had the greatest potential for attenuating chronic inflammation due to their ability to promote macrophage phagocytosis, increased M2 activation (R. capensis) and decreased M1 activation (P. ostreatus) as well as reduced COX-2 expression while the water extract of G. lucidum proved to be the most promising candidate for stimulating fibroplasia as it was the most successful at promoting both fibroblast proliferation and migration. Different mushroom species were thus shown to promote different stages of the wound healing process providing sufficient evidence to support further studies related to the use of macrofungi as therapeutic agents in the search for more cost-effective and efficient treatment strategies for impaired diabetic wound healing.
  • Full Text:
  • Date Issued: 2017

Characterization of livestock manures biochar and their effect on soil chemical properties and crop growth under glasshouse conditions

  • Authors: Dzvene, Admire Rukudzo
  • Date: 2017
  • Subjects: Biochar Soil fertility
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10353/9863 , vital:35091
  • Description: Biochar is being promoted as an amendment to improve soil properties, crop productivity, and carbon sequestration. In Africa, biochar adoption is hindered by production systems which include technology and feedstocks availability. However, little research has been published on the influence of biochar incorporation on soil chemical properties and early crop establishment. The aim of this study was to characterize biochar from cattle, goat, sheep and poultry kraal manures and their effect on soil properties and crop growth. This was guided by the following specific objectives, (i) to explore the mixed-farming system of Raymond Mhlaba Municipality on availability and utilization of livestock kraal manures (ii) to characterize biochar samples produced from cattle, goat, sheep and poultry kraal manures (iii) to determine the nutrient release patterns of biochars amended in a degraded soil (iv) to determine the effectiveness of converting manure to biochar and cattle manure on maize early development and, (v) to determine the effects of biochar type and application rate on early maize development. The farming system was surveyed to identify quantities of livestock manure, its availability and utilization for soil fertility amendment in cropping in the Raymond Mhlaba Municipality. The emerging results across all the villages revealed that, the mean livestock numbers were, 9.24±8.21 sheep, 9.37±8.15 goats, 7.95±7.66 cattle and 9.02±9.47 chickens. The findings revealed that 94 (82.4percent) of the respondents had access to cropland allocations in the form of outfields and homegardens. However, only 55 (48.2percent) of the respondents were currently cropping their fields. Maize was the most common crop grown followed by butternuts and potatoes. The application of manure by the respondents currently cropping their lands was only 40 (35.1percent) and the quantities used ranged from 210-1450 kg ha-1. The results further showed that the estimated total manure production was 2.9 t year-1, 0.82 t year-1, 0.04 t year-1, and 0.8 t year-1 from cattle, goats, chicken, and sheeps respectively. Drum retort method of slow pyrolysis at a temperature of 400°C was used to produce biochar from cattle, goat, sheep and poultry manure feedstocks. The biochar yields were 63percent, 72percent, 61percent and 83percent on a weight basis for the different feedstocks. The chemical properties of the biochar were significantly different from those of the manure from which they were made. Biochars that were high in Ca and K such as poultry manure biochar and sheep manure biochar indicated higher pH and electrical conductivity values. For instance, sheep manure biochar was (8.1 mS cm-1) and poultry manure biochar was (9.2 mS cm-1). The scanning electron microscopy (SEM) revealed that, the biochars had porous structures ranging from 1.23um to 5.23um in diameter which are important for water conductance and holding capacity. The target soil carbon level to determine the effects of biochar soil incorporation was 2percent and the soil had 0.7percent. Therefore, it was treated with four livestock manure biochars at application rates of 0; 53.2 t ha-1 (CMB); 48.1 t ha-1 (GMB); 50.7 t ha-1 (SMB); and 40.2 t ha-1 (PMB) based on their carbon content to supplement the soil carbon difference. The effect on soil pH was such that SMB increased to 6.44, PMB (6.45), CMB (6.54), and GMB (6.53) relative to the control which did not show any changes. An increase was also observed on Olsen P concentrations (mg P kg-1) which varied with biochar treatments: PMB (6.22), GMB (6.37), SMB (6.44) and CMB (6.44) and were significantly higher than the control. Ammonium-N(NH4+) concentrations (mg NH4+-N) were increased in biochar treatments but, no significant differences were obtained with sampling time. SMB released 7.95 mg kg-1, CMB 7.50 mg kg- 1, PMB 7.46 mg kg-1 and GMB 7.05 mg kg-1, compared to the control 3.23 mg kg-1. Maize growth in soil sampled from farmers fields in cultivation and abandoned treated with biochar without application of inorganic fertilizer did not differ with control (soil only) treatments. However, maize growth in soil treated with biochar and inorganic fertilizer was comparative to manure treatments. This resulted in a follow up study to elucidate the effects of biochar alone and was carried out with cattle, goat, sheep and poultry biochars at five application rates (0, 100, 200, 300, and 400 kg C ha-1) applied to a sandy loam and a clayey loam soil of the Oakleaf and Tukulu soil forms respectively. Post-harvest soil pH, electrical conductivity and Olsen P showed improvements in biochar treatments relative to the control. Improvements in the chemical parameters and plant growth increased simultaneously with biochar application rate. Maize growth was not affected by biochar application at different rates.
  • Full Text:
  • Date Issued: 2017

Characterization of maize biochars, their effects on soils, early maize growth and effectiveness of fertilizers

  • Authors: Pinkson, Sibusisiwe
  • Date: 2017
  • Subjects: Soil fertility Crops and soils Biochar
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10353/9974 , vital:35211
  • Description: The use of maize biochar in smallholder cropping systems of the Eastern Cape (EC) Province could be a strategy that helps mitigate a common challenge such as poor soil fertility in maize productivity. The current study investigated the following: a) comparison of maize biochars derived from the drum and pit kiln pyrolytic systems as soil amendments; b) effects of maize biochars on soil acidity and extractable nutrients of three arable soil types of the EC Province; c) effects of maize biochars on early maize growth and nutrient uptake; d) effect of maize biochars on the effectiveness of organic and inorganic fertilizers for improved soil quality and maize growth. Maize biochars were produced from two pyrolytic systems namely the pit and drum kiln, each maize biochar type was analyzed with respect to its chemical and physical characteristics to investigate its potential as a soil amendment. Both pyrolytic systems were monitored to identify optimum pyrolytic temperatures reached by each process. Observed peak pyrolytic temperature were 300 °C and 500 °C for the pit and drum pyrolytic systems respectively. Both maize biochar types were alkaline in nature with pH values of 8.36 (H2O) and 7.45 (KCl) and 8.95 (H2O) and 7.82 (KCl) for pit and drum biochar respectively. Electrical conductivity (Ec) of drum biochar was 199 mS /m and that of pit biochar 186 mS /m. Generally, there were no differences in the chemical compositions of the two biochar types. However, in most analysis drum biochar gave higher values in nutrient composition compared to the pit biochar. Moreover, according to SEM analysis both biochar materials consisted of an increase in pore size distribution compared to the original feedstock material. In addition, an increase in nutrient composition in the two biochar types compared to the original feedstock was also observed. In an incubation experiment, potential effects of the two maize biochar types derived from the pit and drum kiln pyrolytic systems on soil acidity and nutrients were investigated on three arable soil types of the EC Province. Three soil types investigated were obtained from the University of Fort Hare (UFH), Phandulwazi (PND) and Msobomvu (MSV). The UFH soil was a sandy loam of the Oakleaf form or Eutric Cambisol, the PND soil was a sandy loam over sandy clay a Haplic Luvisol, while the MSV soil was a clay loam of Westleigh form a Ferric luvisol. Both maize biochar types significantly (p< 0.05) increased soil pH of the three soil types in the incubation study from an average of 4.68- 7.5. Soil pH improvement was in the following order pit biochar> drum biochar> control. Also, the two maize biochar types significantly (p< 0.05) increased the release of cations namely Ca, Mg and Na however, some decrease in nutrient concentrations were observed due to increase in pH levels at the later stage of the study. Biochar incorporation increased extractable P release from 30- 40 mg P/kg to an average range of between 120- 160 mg P/kg across all soil types. A glasshouse study was also conducted investigating the effect of different biochar rates of the two maize biochar types used in the previous studies on early maize growth and nutrient uptake, same soil types were used as those in the incubation study. Biochar was applied at application rates of 0, 100, 200 and 300 kg C/ha of biochar. The glasshouse experiment consisted of two cycles, each with a six week period of monitoring maize seedling growth development. Generally, a significant increase in maize growth parameters such as plant height, stem girth, number of leaves and leaf area increased after biochar additions compared to the control. Both biochars significantly improved maize seedling growth at an application rate of 200 kg C/haHowever, the two biochar types displayed varying impacts on maize growth due to influence of soil type and biochar application rates. Nutrient- uptake of Ca, P, Na and Mg showed to improve at an application rate of 200 kg C/ha for both biochar types showing a 50 percent increase compared to the control. Nutrient- uptake patterns for P, Ca, Mg and Na differed across all soil types, mainly due to changes in pH and Na levels which were influenced by increased biochar concentrations resulting in nutrient deficiency. Another glasshouse experiment aimed at investigating the effects on the two maize biochar types on influencing the effectiveness of both organic and inorganic fertilizers for improved early maize growth and soil productivity. Biochar was applied at an application rate of 400 kg C/ha of biochar, fertilizer was applied at application rates of 0, 10, 20, 30 and 40 kg N/ha and manure at 0, 10, 20, 30 and 40 t/ha respectively. The glasshouse experiment consisted of two cycles, each with a six week period of monitoring maize seedling growth development. In the 1st cycle, manure rate of 40 t/ha resulted in the highest plant height of maize seedlings grown in the glasshouse, biochar type also showed to influence plant height. After the 1st harvest Mg, K and P levels improved at 30 t/ha, Na at 20 t/ha and Ca 40 t/ha of manure. Plant height and stem girth improved at 30 kg N/ha of fertilizer, however, nutrient levels for Ca, K and Mg decreased after the 1st harvest, while Na levels increased. Nutrient uptake was the highest for Mg and Na at 40 kg N/ha while for Ca at 30 kg N/ha of fertilizer. During the 2nd cycle plant height was the highest at 30 t/ha of manure, and effect of manure rate was significant (p<0.05) for number of leaves, plant height and biomass. Whereas, manure rate and biochar type effect were insignificant (p>0.05) for pH, Ec and nutrient uptake changes. Maize seedling showed significant response to fertilizer 40 kg N/ha for most of the growth parameters measured (P<0.05), except for germination percentage. All treatments investigated had no effect on germination percentage. The two biochar types showed significant (p<0.05) effects on soil pH and Ec. Drum biochar was slightly better performing than pit biochar. Results obtained from the various studies suggests that maize biochars derived from the pit and drum pyrolytic systems are potential soil amendments in correcting soil acidity and nutrient deficiency in the EC Province. Both biochar types have shown abilities to improve early maize growth and effectiveness of fertilizers in maize based systems of the EC Province. However, some variations in soil fertility and early maize growth were observed as a result of the soil type response towards the two biochar applications. This could also have risen as a result of a number of factors such as the nutritional composition of biochar material, initial soil type chemical composition, biochar and fertilizer application rates and time taken or period to complete each study. Therefore, further experiments should be conducted to validate these results, preferable having longer periods of study, moreover, field experiments. In addition, investigations on potential feedstock materials such as animal wastes used as biochar in the EC Province can be conducted.
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  • Date Issued: 2017

Characterization of Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA) in selected recreational marine waters and beach sand in the Eastern Cape Province, South Africa

  • Authors: Ankabi, Olufemi Emmanuel
  • Date: 2017
  • Subjects: Marine microbiology -- South Africa -- Eastern Cape Staphylococcus aureus infections -- South Africa -- Eastern Cape Pathogenic microorganisms
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10353/4992 , vital:28915
  • Description: Staphylococcus aureus is a Gram-positive bacterium predominantly found on human skin and in nasal passages with 20 to 40 percent of the population carrying this organism. Although S. aureus is an unspectacular, non-motile coccoid bacterium, it is a perilous human pathogen associated with both nosocomial and community-acquired infections and it is increasingly becoming virulent and resistant to most antibiotics. It is responsible for several infections such as osteomyelitis, toxin-mediated diseases and bacteraemia, with severe infections arising from strains harbouring antibiotic resistance genes together with virulence genes. S. aureus has been largely confined to hospitals and long-term care facilities, but it is now emerging in the community in places such as recreational beach waters, and occurring in healthy individuals with no associated risk factors. This organism has been reported to be released by swimmers in beaches, suggesting that recreational waters are a potential source of community-acquired S. aureus infections. It is possibly the pathogen of greatest concern due to its intrinsic virulence, its capacity to cause various life-threatening infections, and its ability to adapt to varying environmental conditions. This study was aimed at characterizing S. aureus and methicillin-resistant S. aureus (MRSA) in Port Elizabeth, Port Alfred, Kenton-on-sea and East London beaches of the Eastern Cape Province of South Africa. This was done by investigating the occurrence, antibiotic susceptibilities, antibiotic-resistant genes and virulence genes profiles of S. aureus in the selected beaches. To achieve this aim, 249 beach sand and water samples were obtained from the beaches during the period of April 2015 to April 2016. Physico-chemical parameters of beach water was investigated on site using a multi-parameter ion specific meter during sample collection. Samples were filtered and inoculated on m-Endo agar, m-FC agar and bile aesculin azide agar for total and faecal coliform as well as Enterococci respectively. For isolation of S. aureus and MRSA, samples were cultured on Mannitol salt agar and Staph 24 agar. S. aureus was identified using morphological, Gram staining and molecular (PCR) methods. The isolates were further characterized by determining their antimicrobial resistance profiles, antibiotic resistant genes (mecA, rpoB, blaZ, ermB and tetK genes) and detection of virulent genes encoding intracellular adhesion (icaA), enterotoxin (seaA) and cytolytic toxins (PVL). The majority of study sites passed the directives of physico-chemical standards levels set by WHO during the study period. A total of 143 presumptive isolates were obtained of which 30 (30 percent) were confirmed as S. aureus with 22 (73.3 percent) of these confirmed isolates from marine water and 8 (26.7 percent) from marine sand. Upon culturing on MRSA 2 agar, 15 (50 percent) of isolates showed phonotypic resistance to methicillin. Based on Antimicrobial susceptibility tests, (22/30) 73.3 percent of the isolates showed phonotypic resistance to oxacillin. Out of the 30 isolates, 16 (53.3 percent) were mecA positive and were considered methicillin-resistant S. aureus. S. aureus showed high susceptibility to gentamycin, cefoxithin, levofloxacin, ciprofloxacin, imipenem, and chloramphenicol. A large proportion (36.67 percent to 96.7 percent) of the S. aureus isolates was resistant to penicillin G, ampicillin, oxacillin, tetracycline, clindamycin, rifampicin, vancomycin, sulfamethoxazole-Trimethoprim and erythromycin. Multiple antibiotic resistance (MAR) phenotypes were generated from 7 S. aureus isolates showing resistance to three or more antibiotics. The mecA, rpoB, blaZ, ermB and tetM genes coding for methicillin, rifampicin, βeta-lactam, erythromycin and tetracycline antibiotics resistance was detected in 5 (22.7 percent), 11 (45.8 percent), 16 (55.2 percent), 15 (71.4 percent) and 8 (72.7 percent) respectively. The PVL, icaA and seaA genes coding for virulent determinants were detected in 50, 20 and 13.3 percent of the confirmed isolates respectively. Physico-chemical and faecal indicator bacteria results obtained from this study can assist municipal authorities in developing appropriate management strategies for beaches in the study area. The findings of this study showed that the investigated beaches were contaminated with toxigenic and multi-drug resistant S. aureus strains. This emphasizes the need for the implementation of better control measures to reduce the occurrence of antibiotic resistant S. aureus and of virulent S. aureus strains in recreational waters. In our study it was established that the potential of recreational waters to be reservoirs of S. aureus should not be taken for granted, and it is important that beach goers be educated about this organism as well as other related pathogens that could affect human health, especially immuno-compromised individuals. The community should be educated on antibiotic stewardship and the detrimental effects of antibiotics abuse.
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  • Date Issued: 2017

Characterization of the distribution of platinum group elements in sulphide ores within the Merensky Reef at Modikwa and Two Rivers Platinum Mines, Eastern Bushveld Complex, South Africa

  • Authors: Zilibokwe, Nosibulelo Julie
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/7938 , vital:21326
  • Description: The distribution of the platinum group element (PGE), in the Merensky Reef was characterized by, first determining the occurrence of the platinum group minerals (PGM), then by establishing the PGE concentration in the base metal sulphides (BMS) associated with the PGE mineralization in the Merensky Reef from selected borehole intersections, at the Two Rivers (TRP) and Modikwa Platinum Mines in the Eastern Bushveld Complex. A mineral liberation analyser (MLA) was then used to identify the PGM phases; their silicate and base metal associations; and their grain size distribution. Electron microprobe quantitative analysis and mapping were then used to determine the compositional variation of the PGM and the PGE elemental distribution in the BMS, respectively. The study showed that the BMS including pyrrhotite, pentlandite, and chalcopyrite were the principal sulphides, where pyrrhotite was most prominent with minor quantities of pyrite. Orthopyroxene, clinopyroxene and plagioclase were the most abundant primary silicate minerals identified, while secondary silicates identified included talc, serpentine and amphibole. Platinum group minerals showed three distinct groups with respect to the mineralogical association with the PGE; (i) BMS association; (ii) chromite association; and (iii) silicate association. Of the BMS, chalcopyrite showed the most dominant association with the PGMs. All samples from both mines exhibited a wide range of PGMs, including maslovite, braggite, cooperate, laurite and PGE alloys such as ferroplatinum as well as other unidentified platinum and palladium sulphides, arsenides and bismuthides, while gold was present as electrum. The PGMs ranged in size from less than a micron to about 125 microns with an average of 20 microns. The close association of PGM with BMS along the margins of sulphides indicates that the PGMs were derived from the sulphide melt. PGE distribution in the sulphides at Modikwa showed pentlandite contained the highest concentrations of palladium (up to 379 ppm) and chalcopyrite hosting the highest rhodium concentrations (up to 793 ppm). Samples from Two Rivers revealed pentlandite as the principal host to both palladium and rhodium, with concentrations reaching up to 695 and 930 ppm, respectively. Magnetite at both Modikwa and Two Rivers showed significant rhodium content, reaching up to 982 and 930 ppm, respectively. The pyrrhotite compared to other sulphides contained all the elements found in the platinum group (PPGE), namely, platinum, palladium and rhodium, with all the platinum identified found in the pyrrhotite. The concentrations for the iridium group (IPGE) namely, iridium, osmium, and ruthenium were below the detection limit. The PGE mineralization in the stratigraphy varied within each mine. The mineralization revealed top loading in the central sector (Modikwa) and bottom loading in the southern sector (Two Rivers). The sequence of the Merensky Reef at the two sectors of the Eastern Bushveld Complex showed a remarkable similarity in their mineralogy suggesting that these two sectors were formed from the same liquid or formed simultaneously within a single magma chamber; however the PGE distribution within the stratigraphy may have been controlled by the presence of cumulate sulphides.
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  • Date Issued: 2017

Characterization of the Mitochondrial Plasmodium falciparum heat shock protein 70

  • Authors: Nyakundi, David Onchong’a
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/44449 , vital:25408 , https://doi.org/10.21504/10962/44448
  • Description: Malaria remains a global health problem and accounts for many deaths and illnesses in subSaharan Africa. Plasmodium falciparum, the causative agent of the most fatal form of malaria, expresses a repertoire of heat shock proteins for cytoprotection, survival and pathogenesis. The parasite genome encodes six Hsp70 proteins found in various cell compartments. However, the putative parasite mitochondrial Hsp70 (PfHsp70-3) has not been investigated. The J-proteins, Pfj1 and PFF1415c, were proposed to function as co-chaperones of PfHsp70-3. The biochemical characterization of PfHsp70-3 was initially complicated by the fact that the protein was insoluble when expressed in E. coli cells. Various approaches to solubilize it resulted in inactive protein. A general characteristic of eukaryotic mitochondrial Hsp70s is their insolubility and their reliance on an Hsp70 escort protein (Hep) for solubility and ultimate functions. In this study, a putative Hep protein was identified in the genome of P. falciparum that is referred to as PfHep1. Coexpression of PfHep1 with PfHsp70-3 resulted in soluble and biochemically active PfHsp70-3. Size exclusion chromatography was employed to separate PfHsp70-3 from PfHep1 after coexpression. PfHep1 suppressed thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were also found to be essential for maintaining the functions of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Furthermore, PfHep1 did not stimulate the basal ATPase or increase refoldase activities of PfHsp70-3 hence displaying no co-chaperone roles. The full-length putative mitochondrial type I J protein, Pfj1, could not be produced in E.coli but a truncated protein containing the J-domain was produced which stimulated both the ATPase and refoldase activities of PfHsp70-3. Further, this study demonstrated that both PfHep1 and PfHsp70-3 localized to the mitochondrion in the erythrocytic stage of P. falciparum development thus confirming in silico predictions of their localization. Besides, PfHsp70-3 was expressed during all stages of the intraerythrocytic cycle of parasite development and was heat inducible. Generally, the data obtained in this study will enhance the existing knowledge on the biology of the parasite mitochondrial chaperone functions and open the possible avenue of drug targeting considering the specificity of PfHsp70- 3 and PfHep1 partnerships.
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  • Date Issued: 2017

Chemical composition of leaf essential oils of Lantana camara varieties in South Africa and their effect on the behavioural preference of Falconia intermedia

  • Authors: Ngxande-Koza, Samella W
  • Date: 2017
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/4877 , vital:20739
  • Description: Lantana camara L. (Verbenaceae) is one the most problematic invaders in South Africa invading forest edges, sand dunes, and shorelines by forming impenetrable thickets. Lantana camara invasions degrade natural biodiversity, reduce the value of land and consequently it has been a target for biological control, over the last 50 years in South Africa. Studies that have reported on chemical profile of Lantana camara have been conducted around the world but not in South Africa. Hence, the first aim of the current study was to identify the chemical baseline of L. camara varieties in the Eastern Cape, South Africa. Recent studies have shown that feeding by one of the agents released against L. camara, Falconia intermedia (Distant) (Hemiptera: Miridae), induces anti-herbivory response through increased leaf toughness and trichome density. A preliminary study conducted also reported the production of volatile chemicals by one variety, Whitney Farm, due to feeding by the mirids. Therefore, the second aim was to determine the induced changes in chemical compounds of L. camara varieties after feeding by F. intermedia. A third aim was to determine the effect these chemical compounds have on the behaviour of F. intermedia. To identify the chemical baseline of L. camara varieties, the essential oils of four L. camara varieties (East London, Port Alfred, Whitney Farm and Heather Glen) were analysed using gas chromatography mass spectrometry (GC-MS) and that resulted to the identification of 163 constitutive and 75 induced chemicals across the varieties tested. Lantana camara varieties showed different chemical classes but were highly dominated by terpenes. A great variation in the number of constitutive chemical compounds was found in all the varieties. There were 56 constitutive chemical compounds in the Whitney Farm variety, 41 in the East London variety, 36 in the Heather Glen variety and 30 in the Port Alfred variety. The Whitney Farm variety had the highest number (22) of unique constitutive chemicals identified when compared with other varieties. This indicates the chemical distinctiveness of the Whitney Farm variety from the other varieties. In the varieties tested, there were common chemical compounds identified in constitutive and induced (discussed below) states of the plants such as caryophyllene, hexane, naphthalene, copaene and a-caryophyllene. Besides naphthalene, the majority of chemical compounds in South African L. camara varieties were similar to compounds that have been identified across the world, suggesting that they are closely related. The expression of naphthalene in these varieties may be due to changes in the chemicals expressed over evolutionary time as predicted by the Novel Weapons Hypothesis. Amongst the varieties, a great variation in chemical compounds and their concentrations was shown in the induced states of the plants. The concentration of constitutive caryophyllene ranged from (3.13 - 15.7) %, to (4.02 - 11.10) % after feeding. The concentration of constitutive hexane ranged from (6.13 - 71.19) %, to (33.3 - 75.8) % after feeding. The concentration of constitutive naphthalene ranged from (0.21 - 4.79) %, to (0.92 - 2.11) % after feeding. The concentration of constitutive copaene ranged from (0.57 - 1.57) %, to (1.20 - 2.72) %. Lastly, the concentration of constitutive a-caryophyllene ranged from (1.18 - 9.03) %, to (0.78 - 5.48) % after feeding. The changes in chemical concentrations in lantana varieties indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. To determine the effect of the identified compounds on the behaviour of F. intermedia adults, olfactometer bioassays were conducted using a Y-tube technique. A significantly higher proportion of F. intermedia were attracted to undamaged leaves over damaged leaves and purified air. Undamaged leaves attracted 52 % of F. intermedia from the East London variety, 62.5 % from the Port Alfred variety, 56 % from the Whitney Farm variety, 58 % from the Lyndhurst variety and 54.5 % from the Heather Glen variety in dual choice trials versus damaged leaves. Furthermore, a significantly higher proportion of F. intermedia were attracted to damaged leaves over purified air. Damaged leaves attracted 67 % of F. intermedia from the East London variety, 67 % from the Port Alfred variety, 65.9 % from the Whitney Farm variety, 65.3 % from the Heather Glen variety and 64.5 % from the Lyndhurst variety. Olfactometer bioassays were also conducted using purified standard compounds of four chemical compounds identified from essential oils, hexane was used as a positive control as it is reported to be an insect attractant in literature. Hexane was highly attractive to the mirids compared to three standard compounds caryophyllene, caryophyllene oxide and naphthalene at the rate of 80 %, 73 % and 80 %, respectively. The standard compounds tested against F. intermedia are major compounds contained by L. camara varieties and they have proven to have a repellent effect. This may indicate that after feeding by F. intermedia, the major compounds expressed by the plant varieties repel F. intermedia contributing to the invasiveness of this weed. The increased expression of hexane and caryophyllene after feeding may also indicate increased attraction to some insects, opening up the potential for third trophic level interactions in varieties where this is the case. This is the first study on the chemical composition of essential oils of L. camara in South Africa. Therefore, we recommend that where appropriate chemical profile studies of the invasive alien plants should be considered during host specificity testing, and the vital role of chemical compounds on agent-weed interactions must be taken into consideration with other factors before and after the biological control agents are released.
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  • Date Issued: 2017

Choice of market channels by smallholder vegetable farmers in King Sabata Dalindyebo Municipality in the Eastern Cape province of South Africa

  • Authors: Yokwana, Aphelele Lucia
  • Date: 2017
  • Subjects: Vegetables -- Marketing Farms, Small -- South Africa -- Eastern Cape Vegetable trade -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MAgric
  • Identifier: http://hdl.handle.net/10353/11906 , vital:39117
  • Description: The study investigates the choice of market channels by smallholder vegetable farmers in King Sabatha Dalindyebo Municipality, in the Eastern Cape Province of South Africa. Vegetables as a group of horticultural crops are important for their contribution as an income support to a large proportion of the rural households. However, enhancing vegetable farmers to reach markets and actively engage in the markets is a key challenge influencing vegetable production in South Africa. The perishable nature of vegetables demands effective marketing channels. The main objective of the study was to investigate factors affecting vegetable farmers’ choice of market channels in King Sabata Dalindyebo Municipality in the Eastern Cape Province. The study adopted a multistage stratified sampling method. Multi-stage sampling was done in which the first stage involved selecting respondents from the different wards in the King Sabata Dalindyebo Municipality. This was done through stratification by separating vegetable smallholder farmers and homesteads within that area (different villages within the area). This was followed by employing quota sampling through the different households and smallholder farmers within those areas in order to determine households and smallholder farmers that are able to provide the needed information concerning the choice of market channels. By stratified random sampling based on village, project membership and smallholder farmers, a sample of 110 heads of households was chosen for the study in eight different wards of KSD. The sampling for this study was based on a large sampling technique of n ≥ 30 as there is no information regarding the population of the total number of homesteads and smallholder farmers that are under each traditional leader (chief) in these study sites. This sample comprises homesteads and smallholder farmers that took part in vegetable production. A structured questionnaire together with field observations and measurements were adopted for obtaining information from household respondents. Descriptive statistics (percentages, means, frequency tables and figures) and a Multinomial logistic regression model have been used to analyze the data. From the Multinomial logistic regression results, farming experience is positively related to choice of farm gate market channel at 1percent level of significance. The age of vegetable farmers was positively related to the choice of direct to consumer market channel at 5percent significance level. The level of education of the vegetable farmers was positively related to the choice of direct to consumer market channel at 5percent significance level. Moreover, the results also showed that the inputs used are positively related to the choice of farm-gate as well as direct to consumer market channels at 5percent significance level. Similarly, means of transportation used and choice of marketing channel of the vegetable farmers are positively related at 1percent significance level at the direct to consumer choice of market channel. Furthermore, access to extension services indicated a positive relationship to the choice of market channel amongst the smallholder vegetable farmers for the direct to consumer at 5percent level of significance which is insignificant for that of the farm-gate. There is therefore, need for strong extension support in assisting the farmers to diversify their production, provide market information thereby enhancing production and opening up channels for market accessibility. This is seen to enhance rural households’ livelihood outcomes in agricultural production thereby improving the choice of market channels by smallholder vegetable farmers and alleviating poverty and improving food security. More so, the government and research institutes need to organize workshops and extension programs in famer’ training for more efficiency in their vegetable production and marketing.
  • Full Text:
  • Date Issued: 2017

Climate change mitigation and resilience by four major supermarkets in East London, South Africa

  • Authors: Sibanda, Patience
  • Date: 2017
  • Subjects: Climatic changes -- Economic aspects -- South Africa -- Eastern Cape Climate change mitigation -- South Africa -- Eastern Cape Agriculture -- Environmental aspects
  • Language: English
  • Type: Thesis , Masters , MSoc
  • Identifier: http://hdl.handle.net/10353/5406 , vital:29231
  • Description: Climate change is a human development challenge. Its negative impacts have the potential to reverse the human development gains made in Africa. South Africa, just like many other countries in the Global South, is being negatively affected by climate change. The country`s economy is largely dependent on agriculture, extractive industries and manufacturing, all of which are vulnerable to climate change in different ways. This vulnerability means different public and private stakeholders must institute sustainable climate change mitigation and adaptation measures so as to ameliorate climate change impacts. Gradually transforming to an environmentally friendly ‘green economy’ and the reduction of greenhouse gas emissions are some of South Africa’s climate change mitigation priorities. Just like the public sector, the private sector has a major role to play in this transition to a low carbon economy through minimising its carbon emissions in their operations. Against this background, this qualitative research examines the role played by four major supermarkets (Shoprite, Spar, Pick n Pay and Woolworths), in climate change mitigation and resilience building. It does so through an appraisal of their mitigation and resilience programs. The four supermarkets were purposively selected in East London, Eastern Cape. Data collection combined heavy reliance on desktop discourse analysis with field interviews in the form of purposively sampled key informant interviews. The results show that the four major supermarkets are implementing a variety of climate change mitigation and resilience strategies. These include reduction of greenhouse gas emissions, prioritisation of renewable energy, recycling and environmentally friendly packaging, promotion of sustainable ways of farming and improved fuel efficiency in their transport systems. In terms of policy improvement, the study recommends that there is need for supermarkets to learn from each other’s’ climate change mitigation initiatives so as to advance South Africa’s ‘green economy’ agenda.
  • Full Text:
  • Date Issued: 2017
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