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Assessment of anti-urease and consequential inhibitory potential of South African honey extracts on the multiplication of drug-resistant, vacA and cagA positive helicobacter pylori strains under acidic conditions

  • Authors: Dube, Callote
  • Date: 2017
  • Subjects: Helicobacter pylori Drug resistance in microorganisms Honey -- Therapeutic use
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10353/7787 , vital:30764
  • Description: Helicobacter pylori, a neutralophile chronically infects the gastric stomach of more than half of the world’s population. Infection with the organism is associated with acute or chronic duodenal/gastric ulcer disease, gastritis, gastric adenocarcinoma, mucosa-associated tissue lymphoma (MALT) and primary B-cell gastric lymphoma and has been grouped as a class one carcinogen by the World Health Organisation (WHO). Prevalence of this organism is very high in developing countries especially in Africa, including South Africa. H. pylori treatment using the common first and second line regimens, triple therapy with two antibiotics and a proton pump inhibitor (PPI) is showing inefficiency due to increasing drug resistance. However, newly developed treatment regimens seem to be more expensive and are accompanied by more side effects. Honey contains phytochemicals which are a wealthy source of biologically active compounds some of which have been put into good use in the pharmaceutical industry. Pathogenesis of H. pylori infection in the human stomach relies on several virulence factors which include the urease enzyme, cagA and vacA. The urease enzyme actively hydrolyses urea to produce ammonia an important by-product involved in pH regulation favouring the survival of the organism in the acidic human stomach. This study therefore focuses on screening for anti-urease solvent extracts of South African honey, and evaluate whether inhibition of urease offsets the growth of H. pylori under acidic conditions. Locally produced natural honeys; Bush honey, Raw honey, Gold Crest honey, Q Bee honey, Little Bee honey, Fleures honey-radurised, Siyakholwa pure honey and Manuka honey; an import from New Zealand were purchased and the method by Syazana et al. (2010) was used for the extraction of compounds in honey. A standard strain ATCC 43526 (American Type Culture Collection, Manassas, VA, USA) and 48 pure cultures obtained from clinical isolates cultured from gastric corpus biopsy specimen of patients with gastric morbidities who were ix visiting the endoscopy unit in Livingstone Hospital, Port Elizabeth between June 2008 to December 2008 were initially used as source of urease enzyme as per extraction method done by Amin et al. (2013), but with modifications. Prior to urease extraction, H. pylori strains were identified by biochemical tests (urease, catalase, oxidase, Gram stain), confirmed by PCR targeting the glmM gene (140 bp) and drug resistance profiling was done on all the 48 strains according to Seanego et al. (2012). The screening for anti-urease active compounds was done according to Kaltwasser et al. (1966), a method relying on the reduction of NADH in a coupled urease dehydrogenase (GDH) system. Acetohydroxamic acid was used as a standard inhibitor. Prevalence of cytotoxin-associated gene A (cagA) gene and vacuolating cytotoxin gene A (vacA) gene was determined among all 48 clinical samples. The standard strains of H. pylori, X47 (cagA positive), J99 (vacA s1m1) and Tx30a (s2m2) were used as positive controls. H. pylori’s growth was then monitored under acidic pH in a cocktail spiked with anti-urease compounds (test samples) and in a cocktail without anti-urease compounds (negative control). Acetohydroxamic acid was used as a standard urease inhibitor. H. pylori multiplication was monitored in Brain Heart Infusion Broth (BHIB) adjusted to pH of 2, 3, 4, 5, 6 and 7. The strain MP01 was used as a standard urease negative strain while X47 and J99 were used as positive standards for cagA and vacA s1m1 respectively. The compounds that had anti-urease activity and were successful towards suppressing the multiplication of H. pylori under acidic environment, all other factors optimised, were subjected to gas chromatograph mass spectrometry (GC-MS) and liquid chromatograph spectrometry (LCMS) to determine volatile compounds and drugs in honey extracts respectively. The findings of this study revealed that at a concentration of 50 mg/mL, urease inhibition by petroleum ether extracts of Gold Crest and Fleures honey, hexane extracts of Little Bee and Manuka honey, and chloroform extracts of Bush honey and Q Bee honey had a range above or equal to 50 percent and there was no significance difference in urease inhibition percentage (I percent) of urease from different sources including that extracted from drug resistant H. pylori (p >0.05). Virulence factors are important for the pathogenesis of H. pylori. All the 48 clinical isolates were glmM (140 bp) positive and cagA was detected in 97.9 percent of the test isolates. The vacA gene was detected in all isolates but with different subtypes. The vacA allelic combination s1m1 was detected in 75 percent of the test isolates and s1m2 allelic combination was detected in 16.7 percent of the test isolates while the combination s2m2 was detected in 8.3 percent of the test isolates. None of the test isolates possessed the allelic combination s2m1. When H. pylori multiplication was monitored under acidic conditions in the presence of anti-urease active compounds, it was revealed that anti-urease active compounds in honey are capable of inhibiting the normal multiplication of H. pylori strains that are cagA positive, vacA positive and drug resistant. The GC-MS analysis showed that Fleures honey (urease I percent = 67.8 – 68.5 percent) and Gold Crest honey (urease I percent = 50.9 percent – 53.3 percent), all petroleum ether extracts had 27 and 26 volatile compounds. The hexane extract of Manuka honey (urease I percent = 50.0 – 53.2) had 43 compounds detected. The chloroform extract of Q Bee (urease I percent = 64.2 – 66.2 percent) had 13 volatile compounds detected. All the volatile compounds considered as representative samples of GC-MS analysis had a spectral matching ≥ 90 percent with the NIST11 library. However, the majority of compounds that were detected by LC-MS in representative honey extracts include vardenafil, urapidil, hydrocortisone, e.t.c which are drugs commonly used in the treatment of different ailments or infections that affect human beings. In addition, two xi drugs, sulfaquinoxaline and hydroxyquinoline which are used in veterinary medicine and antiseptic, disinfectant and pesticide applications in agricultural activities were detected in Little Bee honey. We therefore conclude that inhibition of urease has a bactericidal effect on drug resistant, cagA positive and vacA positive H. pylori strains growing under acidic environment.
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  • Date Issued: 2017

A goal-setting intervention with motocross racers : a case study investigating the effects of an intervention on perceived motivation, confidence, and self-efficacy

  • Authors: Fleming, Tracey Laura
  • Date: 2014
  • Subjects: Motocross -- Psychological aspects -- Research , Motorcyclists -- Psychological aspects -- Research , Goal (Psychology) -- Research , Competition (Psychology) -- Research , Motivation (Psychology) -- Case studies , Confidence -- Case studies , Self-efficacy -- Case studies , Sports -- Psychological aspects
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3224 , http://hdl.handle.net/10962/d1012996
  • Description: This study aimed to investigate the effects that a specifically tailored goal-setting program would have on two motocross racers in terms of their self-efficacy and motivation, as well as the process of designing this intervention. This case-study approach involved a mixed methods approach, consisting of pre-intervention and post-intervention assessments, interviews, and performance profiles. The tools used include Vealey’s (1986) Competitive Orientation Inventory (COI), Gill and Deeter’s (1988) Sport Orientation Questionnaire (SOQ), performance profiles, and semi-structured interviews. The goal-setting intervention lasted a total of five weeks. The results from the preintervention and post-intervention assessments were compared to determine whether any changes in motivation or self-efficacy occurred during the intervention. For the first participant, significant changes in both motivation and self-efficacy were present in addition to significant changes in competitive orientation. For the second participant, there were no significant changes in either motivation or self-efficacy. However, for the second participant there was also no change in competitive orientation. Findings suggest that the focus and competitive orientation of an athlete have a significant influence on the types of goals set, and consequently on positive changes in motivation, confidence, and self-efficacy. The influence of the competitive orientation in athletes also highlighted the importance of attaining a balance between performance and outcome goal-related activities. It was also discovered through qualitative assessment that this program is suitable for particular groups of athletes such as those who are injured, display an external locus of causality or are otherwise not performing at their prime.
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  • Date Issued: 2014

The extent of accessibility of public buildings to persons with disabilities in Kenya

  • Authors: Maigua, Mwaura Isaac
  • Date: 2012
  • Subjects: Buildings -- Barrier-free design -- Kenya , People with disabilities -- Kenya , Barrier-free design -- Kenya
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:9124 , http://hdl.handle.net/10948/d1017098
  • Description: Many countries in the world have in recent years developed measures to increase accessibility to the built environment for persons with disabilities. Of particular concern are facilities such as roads, railways and public premises. The United Nations Convention on the Rights of Persons With Disabilities (CRPD) confers accessibility as a right and gives responsibility to state parties to ensure to persons with disabilities (PWDs) a barrier free environment. The Constitution of Kenya (2010) states that PWDs have a right to facilities including educational that integrate their needs. The Person With Disabilities Act (2003) provides for mechanisms through which such enforcements can be enacted. The body responsible for implementing the Act has developed minimum accessibility guidelines to inform this endeavor as part of Kenya‟s dream of becoming a middle income economy by the year 2030. This research report/treatise details the findings of a pilot baseline survey study conducted in Nairobi, Kisumu and Mombasa Cities.
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  • Date Issued: 2012

International trade and environmental disputes : an analysis of Article XX of the General Agreement on Tariffs and Trade (1994) and environmental policies of the developing and developed world

  • Authors: Manjoro, Faith Tendayi
  • Date: 2007
  • Subjects: World Trade Organization General Agreement on Tariffs and Trade (Organization) Environmental protection Environmental degradation Free trade -- Environmental aspects Foreign trade regulation International trade
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: vital:3713 , http://hdl.handle.net/10962/d1007444
  • Description: A major problem emanating from the trade/environment conflict is the use of trade measures, such as restrictions and sanctions, as tools for environmental protection. Proponents of free trade argue that the use of these measures is tantamount to abuse of environmental standards for protectionist ends. This is particularly so if the imposition of the standard amounts to a unilateral act which blocks the entry of a specified product into the market of another member state for reasons other than environmental protection. Environmentalists at the same time argue that free trade will lead to environmental degradation and therefore advocate for the use of trade-restrictive measures to safeguard against the destruction of the environment. The GATT has proved problematic when it comes to the resolution of trade/environment conflicts. The GATT aims at trade liberalisation yet most environmental policies are enforced through trade-restrictive devices like quotas and licences. Article XX of the GATT is anomalous: it does not explicitly mention the environment, yet member states rely on it as an environmental protection clause. This thesis discusses the various issues emanating from the trade/environmental debate. The history of Article XX is reviewed and the issues that arise in the adjudication of Articles XX (b) and (g) in a trade/environment context are analysed in light of the decisions by the GATTIWTO dispute settlement bodies. The role played by Multilateral Environmental Agreements (MEAs) in protecting the environment is discussed. However, the relationship between MEAs and the WTO is also scrutinised as these rule-making bodies often come into conflict: firstly, because they serve two differing interests - on the one hand, MEAs allow for the use of trade restrictive measures in environmental agreements and on the other, the WTO calls for unrestricted trade unless exceptional circumstances exist; and secondly, member states that are party to both the WTO and MEAs are often forced to subscribe to international trade rules that are incompatible with those in environmental agreements. The trade/environmental debate is important to both the developed and developing worlds. The developed world is in favour of environmental policies which protect the environment from degradation. On the other hand, the developing world is in desperate need of the benefits of trade liberalisation so as to cater for high unemployment rates and poor economic growth. The question thus arises as to whether, when environmental issues are promoted, developing countries will not suffer at the expense of developed nations which may engage in protectionist measures under the pretext of environmental conservation. The divide between developed and developing countries is illustrated in Chapter 5 through case studies on coal mining in the USA and South Africa. The conclusion reached is that total co-operation is essential between developed and developing states for success in safeguarding the environment from degradation. Accordingly, the trade/environmental debate cannot be isolated from the conflicting approaches in developed and developing countries. The conclusions in the final chapter seek to strike a balance between trade liberalisation and environmental protection. Recommendations are made on how the trade/environmental challenges could be dealt with and the regulation of trade restrictive devices to exclude, or at least limit, protectionism.
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  • Date Issued: 2007

The biology and systematics of South African pipefishes of the genus Syngnathus

  • Authors: Mwale, Monica
  • Date: 2007
  • Subjects: Pipefishes -- South Africa Syngnathus -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5237 , http://hdl.handle.net/10962/d1005080
  • Description: Syngnathus the most speciose genus in the family Syngnathidae is widely in the Atlantic and Eastern Pacific oceans. However, it is poorly represented in the Indian Ocean with the only two species, Syngnathus temminckii and S. watermeyeri occurring in Southern African estuaries and coastal areas. Syngnathus temminckii the most common South African pipefish has been synonymised with S. acus, as the morphological and genetic divergence between these two populations has not been documented. There is also uncertainty in the taxonomic status of S. watermeyeri, an endemic estuarine pipefish that is restricted to two Eastern Cape estuaries. The purpose of this study was therefore to compare biological, morphological and genetic variation of South African Syngnathus species among different populations/locations, and with European populations of S. acus. Sixteen meristic and ten morphometric characteristics were quantified from specimens obtained from field as well as various international natural history museum collections. Univariate (ANOVA) and multivariate (principal component analysis and discriminant analyses) analyses were used to assess morphological differences among the species. Morphometric variables were adjusted as ratios of the standard length and using an allometric procedure. ANCOVA analysis indicated significant differences between S. acus and S. temminckii for the relationships of the standard length (SL) and all morphological characters. There was no significant correlation between SL and snout length, snout depth, inter-orbital width and trunk depth for S. watermeyeri. The analyses provided evidence for distinct populations of S. acus, S. temminckii and S. watermeyeri although morphological character differentiation was greater between S. watermeyeri and the other two larger species. Although, significant differences were observed for meristic characters, pairwise comparisons did not reflect a clear pattern of variability. Most of the measured morphological characters contributed more than 70% to the morphological variation between the populations. Plot of the canonical scores for the variables resulted in the specimens clustering according to species groups and locations of S. temminckii. Sequences of 750 base pairs of the mitochondrial cytochrome gene from 11 localities were compared with published sequences of other species of Syngnathus. Phylogenetic analysis was performed using parsimony, maximum likelihood (ML) and Bayesian inference (BI). The South African species were revealed to be sister-taxa with about 6 % divergence, while S. temminckii and S. acus had about 11% sequence divergence. 20 haplotypes among 46 total specimens from the three species. Gene flow was estimated at approximately 3 migrants per generation between the two South African populations and about 1 per generation between S. temminckii and S. acus. Such strong stock structuring among presumably recently established post-Pliocene (< 2 Million years ago) populations suggests that these species are reproductively isolated. Morphological and genetic variation observed in this study combined with current knowledge of life history attributes of the South African pipefishes indicate that conservative management decisions are necessary until the patterns and extent of differentiation among populations species-wide can be investigated further. It is thus being proposed that the name of the South African population of S. acus be changed to Syngnathus temminckii (Kaup, 1856).
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  • Date Issued: 2007

An investigation of the development and adoption of educational metadata standards for the widespread use of learning objects

  • Authors: Krull, Greig Emil
  • Date: 2005
  • Subjects: Metadata , Internet in education , Web databases , Education -- Standards , Educational technology , Computer-assisted instruction
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:1142 , http://hdl.handle.net/10962/d1002771 , Metadata , Internet in education , Web databases , Education -- Standards , Educational technology , Computer-assisted instruction
  • Description: This research investigates the development and adoption of educational metadata standards for the widespread use of learning objects. Learning objects, metadata, the related IEEE standard and the various application profiles derived from the standard are discussed. A number of standards and specifications for educational metadata used to describe learning objects are explored, namely the Dublin Core, IMS, SCORM, ARIADNE, CanCore and the UK LOM Core. Three metadata editors and the experience with using one of them, RELOAD, is described. These educational metadata specifications are used in a practical metadata implementation scenario and the experiences are extrapolated to derive a localised instance of the generic IEEE standard. A new application profile is proposed, “RU LOM Core”, for the South African higher education context. Some existing results are confirmed about the complexity of using the IEEE standard and it is demonstrated that it is possible to instantiate the standard for South African conditions. The results are largely qualitative and based on practical experience. However, the results concur with results from related research. Although the development of an application profile is certainly not new, the development of RU LOM Core illustrates that the IEEE standard, developed largely within the northern hemisphere, can be adapted to work in the South African scenario. RU LOM Core has been developed for the South African higher education environment and takes linguistic and cultural diversity and the low rate of technological literacy into consideration. The lessons learned and the proposed LOM core can be built upon in further research and collaboration to use and support the use of such standards within South Africa.
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  • Date Issued: 2005

Phylogeography and comparative ecophysiology of Chrysanthemoides Turn. Ex Medik. (Tribe Calenduleae)

  • Authors: Howis, Seranne
  • Date: 2005
  • Subjects: Chrysanthemoides , Phylogeny , Ecophysiology , DNA , Plant genetics
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4256 , http://hdl.handle.net/10962/d1008189
  • Description: Chrysanthem Oides is a common Southern African shrub that grows in a variety of habitats. From coastal shrubland and fynbos to mountainous areas as far north as Kenya. The genus has two species and 8 subspecies. The diagnoses and delimitation of which have been based almost exclusively on morphological characteristics. This project aims to investigate, with the use of phylogenetic species concepts. The validity of these subspecies. Unlike biological species concepts that rely on reproductive isolation as a defining character of a species. Phylogenetic species concepts (PSC) are concerned with delimiting evolutionary significant units (ESUs). ESUs are evolutionarily isolated lineages, and under the PSC a species is an aggregation of organisms consistently diagnosable by a fixed character or combination of characters. This project therefore searched for genetic and physiological characters by which to delimit ESUs within the Cill), samhemoides genus. DNA sequencing was used to investigate the genetic characters, while gas exchange studies were used to investigate the ecophysiological characters. DNA sequence analysis indicated that the ESUs can be diagnosed by genetic means and that one species may be of hybrid origin. Field studies of three disparate genetically identifiable ESUs from three disparate climates found that there are noticeable differences in ecophysiological responses of these ESUs in the field. Plants from each ESU were transferred to a greenhouse and grown under identical conditions for several months and compared to determine if these traits are inherent, or elastic in relation to environmental conditions. Under simulated high rainfall conditions. There does not appear to be a significant difference in the photosynthetic traits.
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  • Date Issued: 2005

Towards the development of a protocol for the selection of probiotics in marine fish larviculture

  • Authors: Vine, Niall Gordon
  • Date: 2005
  • Subjects: Marine fishes -- Larvae Bacteria Fishes -- Microbiology Fish culture
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5329 , http://hdl.handle.net/10962/d1005175
  • Description: Manipulation or control of the microbiological aquaculture environment has been identified as an important focus area for future hatchery development. Subsequently, alternatives to obtain control of the microbiological environment are being sought of which the field of probiotics appears highly promising. Probiotics are usually selected based on various in vitro characteristics, however, the methods used differ and are sometimes unsuccessful due to poor experimentation. The aim of this work is to contribute towards the development of a protocol for the in vitro screening of bacterial candidate probiotics for marine fish larviculture. To reduce the number of candidate probiotics to be tested in vivo, various in vitro experiments need to be conducted, each screening for a particular mode of action – antagonism towards pathogen through production of antimicrobial compounds, growth and attachment to fish intestinal mucus, and the production of other beneficial compounds such as vitamins, fatty-acids and digestive enzymes. A total of 108 bacteria species were isolated from the digestive tract of the adult common clownfish, Amphiprion percula to screen for potential probiotics to be used in clownfish larval rearing. The antagonistic compounds assay identified twelve isolates which showed antagonism towards two or more aquatic pathogens. This was followed by an in vitro test that involved growing the organisms in fish intestinal mucus and modeling their growth parameters. A ranking index (RI) was developed using the lag period (λ) and doubling time (td) of the organism, where (1over λ x td) x 100. Five candidate probionts (AP1-AP5) with varied growth parameters were used for further in vitro experiments. The attachment to mucus assay introduced a novel tool for quantifying competition for attachment sites between candidate probionts and pathogens on mucus. Candidate probiont Pseudoalteromonas AP5 reduced the attachment ability of Vibrio alginolyticus when added before the pathogen and partially out-competed the pathogen for attachment sites when added second. In vitro screening for the production of beneficial compounds tested the candidate probiotics’ ability to produce digestive enzymes - trypsin, lipase and alkaline phosphatase as well as carotenoids and vitamin C. Candidate probiont Pseudoalteromonas AP5 produced high levels of the enzymes (98.2, 34.1 and 91.3 mU product liberated.ml⁻¹, respectively) and contained carotenoids while Kocuria AP4 contained carotenoids but produced low quantities of enzymes (7.8, 0 and 59 mU product liberated.ml⁻¹, respectively). None of the candidate probiotics produced vitamin C. To eliminate potential pathogenic or toxic candidate probionts, Artemia nauplii were exposed to each candidate probiont and the percentage Artemia mortality after 24-hours was determined. Candidate probiont AP2 caused high mortality of Artemia nauplii (98.4%) and was excluded from further studies. Identification of candidate probionts AP3-AP5 was performed using 16S-rDNA molecular techniques and the bacteria were assigned the names Bacillus AP3, Kocuria AP4 and Pseudoalteromonas AP5, respectively. Two methods of larval probiont delivery were tested – attachment to Artemia, and in-water delivery. Attachment to Artemia was high for both Kocuria AP4 and Pseudoalteromonas AP5 (7.2 x10³ and 2.7x10⁴ bacteria.nauplius⁻¹, respectively) while the in-water viability experiment showed that Kocuria AP4 comprised 23.9% of the total culturable water microflora after 24 hours while Pseudoalteromonas AP5 contributed 100%. To validate the findings from the in vitro experiments, in vivo trials using clownfish larvae were performed. Of the four candidate probiotics tested, only Kocuria AP4 showed potential to increase larval survival. In vitro tests produced a better understanding of the possible mode of action and strategies of competition between bacteria, however, the number of criteria in which a candidate probiont is successful in vitro may not be the best predictor for its effectiveness in vivo. Commercial studies that reduce between-treatment variation are required to test predictions about the most suitable probiont or combinations thereof.
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  • Date Issued: 2005

Genetic variation within two pulmonate limpet species, Siphonaria capensis and S. serrata along the South African coast

  • Authors: Seaman, Jennifer Ann
  • Date: 2003
  • Subjects: Limpets -- South Africa Pulmonata Siphonaria Limpets -- Genetics
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5800 , http://hdl.handle.net/10962/d1006155
  • Description: Dispersal rates are known to play a fundamental role in establishing the genetic structure found within a species. Dispersal in marine benthic invertebrates is largely dependent on life history strategy. The presence of pelagic larvae will potentially result in high dispersal within a species, while direct development limits dispersal. This study used two intertidal pulmonate limpet species to investigate the relationship between dispersal potential and genetic structure of populations. Siphonaria capensis produces benthic egg masses, which release pelagic larvae. These float in ocean currents before settling and metamorphosing into adults. S. serrata reproduces by direct development. The larvae hatch as completely metamorphosed juveniles after developing in an egg case not far from the parent. The high dispersal capacity of S. capensis pelagic larvae should result in high levels of within-population variation since individuals within a particular population may originate from several different populations. This should lead to high levels of gene flow along the coast and to low genetic differentiation among populations. On the other hand, the low dispersal potential of S. serrata should cause low levels of genetic variation within populations, as relatives will remain close to one another. Low levels of gene flow and high genetic differentiation among populations are expected in this species. In dealing with the relationship between life history strategy and population genetic structure in these two species, a series of indirect techniques was utilised. Multivariate analyses of the morphological variation within each species showed that variation in size was similar between the two species and largely governed by environmental factors. Variation in shell shape was largely under genetic control and supported the predictions made for each species. Variation in total proteins was relatively uninformative in terms of examining the differences between the two species. Allozyme analysis and mtDNA sequencing clearly showed differences between the species in terms of their population genetic structure. High levels of gene flow were found within S. capensis. This was strongly influenced by ocean currents, with the close inshore Agulhas current along the Transkei coast contributing to high levels of dispersal and hence gene flow. Low levels of gene flow occurred within S. serrata, resulting in low within-population variation and high among-population differentiation.
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  • Date Issued: 2003

Intercohort cannibalism and parturition-associated behaviour of captive-bred swordtail, Xiphophorus helleri (Pisces: Poeciliidae)

  • Authors: Jones, Clifford Louis Wilshire
  • Date: 2003
  • Subjects: Poeciliidae -- Behavior Xiphophorus helleri Fish culture
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5351 , http://hdl.handle.net/10962/d1007812
  • Description: Adult fish that belong to the family Poeciliidae cannibalise juveniles, both in the wild and under captive conditions, but this behaviour has only been partly investigated in the Poeciliidae in some of the commercially valuable species. The objective of the research is to develop an understanding of intercohort cannibalism and parturition-associated behaviour in captive-bred swordtail (Xiphophorus helleri), with applications to industry and future research of other poeciliids. Experiments investigating the effect of adult stocking density and sex ratio on the production of juveniles were used to determine if cannibalism occurs under culture conditions. The average rate of intercohort cannibalism ranged from (5.5 to 53.9%), and was positively density dependent and independent of sex ratio, indicating that males and females were probably equally cannibalistic. The highest number of juveniles (1725.7±141.4) produced per tank over 70 days was obtained from two males and eight females. To develop a better understanding of adult and juvenile behaviour during parturition, fish were observed under controlled laboratory conditions using video and behaviours such as attack (burst of speed by an adult in the direction of a juvenile), escape (avoidance of cannibalism after attack) and cannibalism (predation of a live juvenile by an adult), for example, were identified. Under laboratory conditions most young escaped in downward direction after attack (49%) and most utilised the refuge made that was made available. Furthermore, most attacks (62-65%) and cannibalism (57-84%) occurred at the bottom. Since the presence of refuge significantly increased the rate of juvenile survival under culture conditions, it was hypothesised that the rate of cannibalism could be reduced under farming conditions if juveniles were protected when they escaped downwards. This hypothesis was accepted as it was found that refuge at the bottom of the water column or the inclusion of a false-bottom reduced the rate of cannibalism by 49% and 72%, respectively. Similarly, the hypothesise that the rate of cannibalism could be reduced if juveniles where given protection when escaping sideways (32% of juveniles escaped sideways in the laboratory) was also accepted when tested under farm-scale conditions because a false-side reduced the rate of cannibalism by an average of 45%. Since males and females were equally responsible for cannibalising juveniles in the laboratory, it was hypothesised that the rate of cannibalism would decrease proportionately with the removal of males (Le. 20% of the cannibals) from the population; the removal of males under farming conditions resulted in a 19.5% reduction in the rate of cannibalism. Since older juveniles were better able to escape cannibalism than neonates and since adults habituate to stimuli that previously resulted in attack behaviour, it was hypothesised that the rate of cannibalism would remain unaffected by the length of time that juveniles were exposed to adults in the breeding tanks. This hypothesis was also accepted when tested under farm conditions. However, some hypotheses based on laboratory observations were not accepted. For example, a constant low light intensity did not appear to decrease the rate of cannibalism under farm conditions; also, the occurrence of dead and deformed juveniles went unnoticed in the laboratory, and under farm conditions, where adults did not have access to the bottom of the tank, 10% of the harvest consisted of dead and deformed juveniles. It is concluded that technologies, such as bottom-refuge or a false-side, that increase the size of the liveharvest and allow for the removal of potentially less viable offspring are recommended for the commercial production of poeciliids. The overall similarity of X. helleri behaviour between the laboratory experiments and the farm-scale trials suggests that the post-partum behaviour of X. helleri remains consistent under these different conditions; thus, behaviour under one set of conditions may be used to predict behaviour under other conditions. The application and significance of extrapolations to industry and future research of X. helleri and possibly other poeciliids were discussed and the most applicable laboratory observations with the highest extrapolation capacity were proposed. Furthermore, techniques were developed to aid industry and future researchers in making predictions relating to behaviour of X. helleri under different conditions based on laboratory observations. The results were used to develop a model indicating that selection pressures against cannibalism are not likely to exist at the rate of cannibalism observed here since the potential genetic gain through kin survival and inclusive fitness was shown to be greater than any potential genetiC loss experienced by a victim of cannibalism. The model was successfully tested under a range of social conditions. Other possible explanations for cannibalism in poeciliids, such as parental manipulation, nutritional advantages, opportunistic predation and the recovery of energy are discussed. It is suggested that the most likely proximate cause of cannibalism under captive conditions is opportunistic predation. The theory that cannibalism ensures that only viable genes of the victim are expressed, through inclusive fitness, is a possible ultimate cause of cannibalism, which may have been inherited from feral ancestors of captive-bred X. helleri.
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  • Date Issued: 2003

Building brand loyalty within selected segments of the South African fast moving consumer goods market

  • Authors: Terblanche, Etienne
  • Date: 2002
  • Language: English
  • Type: Thesis , Masters , MTech (Marketing)
  • Identifier: vital:10774 , http://hdl.handle.net/10948/d1002108
  • Description: The rapidly increasing competitiveness within the fast-moving consumer goods (FMCG) market compels an organisation within this market to not only entice consumers to purchase the organisation’s brand, but also to keep these consumers purchasing the brand. It is therefore essential that an organisation creates and maintains loyalty among consumers towards its brand. The objective of the research was to find out what strategies an organisation could implement to achieve and sustain loyalty from current and prospective consumers towards its brand in a highly competitive, FMCG market. The main areas of focus were as follows: Establishing the basis on which consumers differentiate between homogenous products. Determining what strategies an organisation could utilise to ensure that consumers will differentiate its brand from those of competitors. Obtaining relevant information to find out what variables motivate consumers to be brand loyal within the FMCG market. Ascertaining how an organisation could build a brand. Determining how an organisation could maintain brand loyalty from its existing consumers. The research included a study of relevant literature and an empirical study. The aim of the literature study was to obtain a solid base of information and opinions regarding the concepts of brands and building brand loyalty. Making use of structured questionnaires and through performing personal interviews, the empirical study consisted of two aspects. The one aspect was a brand loyalty survey conducted among 303 respondents, and the second aspect was a brand loyalty survey conducted with nine owners or marketers of leading brands. The following were the major findings of the research: Relying on being a leader in price and quality is not enough to ensure that a consumer would continue purchasing an organisation’s brand. A brand is an experience and in order for a consumer to become loyal towards a brand, the consumer should have a host of positive thoughts regarding past experience with the brand. It is essential that organisations within the FMCG market proactively develop and implement strategies aimed at creating and maintaining loyalty towards their brands.
  • Full Text:
  • Date Issued: 2002

An investigation into the present state of school guidance in Ciskeian secondary schools in the Keiskammahoek area

  • Authors: Lombo, Mzimkhulu Solomon
  • Date: 1994
  • Subjects: Educational counseling -- Keiskammahoek
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1613 , http://hdl.handle.net/10962/d1003495
  • Description: Although school guidance and counselling services were established in Ciskeian Secondary Schools in the early 1980's, little appears to be taking place. One is continually hearing the plea for an improvement in the system, but once again little is happening. Before such improvement can take place, however, it needs to be known what exactly is and isn't taking place. Furthermore, the problems preventing the services from operating successfully need to be clarified. This research aims at describing the state of guidance in a group of five secondary schools in the Keiskammahoek area of the Ciskei, and elucidating the problems experienced by practitioners in the field. An open-ended questionnaire was administered to 98 pupils and 18 guidance teachers, and the five principals of these schools were interviewed. The findings, which are discussed in detail, confirm the suspicions of the researcher that little guidance indeed is taking place. Many reasons for this state of affairs are given. Finally, suggestions are made as to how this unsatisfactory situation may be improved.
  • Full Text:
  • Date Issued: 1994

The role of the industrial social worker in corporate community relations

  • Authors: Harnett, Claire F
  • Date: 1993
  • Language: English
  • Type: Thesis , Masters , MSocSc
  • Identifier: vital:21091 , http://hdl.handle.net/10962/6342
  • Description: This research study is a qualitative investigation of the role of the industrial social worker in corporate community relations. The research study was undertaken by means of mailed questionnaires. Two different populations were utilized, namely corporations known to practice corporate social responsibility and corporations employing industrial social workers. As a background to the research, relations is defined and its Furthermore, the contribution of relations in the realization of a corporate development community traced. corporate community government-business partnership to address community social problems, is discussed. Lastly, in an attempt to demonstrate that the social worker can indeed play a role in corporate community relations, the extent to which corporate community relations goals and approaches correspond with the community organization model of social work practice, is examined. The purpose of the empirical part of the research study was to determine what form community relations has taken in South Africa and the role that the industrial social worker assumes in this regard. From the findings it appears that there is a focus on philanthropic activities and less direct corporate involvement in creating new resources. Industrial social workers involvement in this function was limited. They primarily assumed the roles of consultant and expert. Although these social workers' have laid the ground work for expansion of the industrial social worker's role, it appears that development has been more serendipitous than rationally planned. It appears from the findings that the potential does exist for industrial social workers to assist the corporation to expand its social responsibility programme, and in so doing expand their practice to include macro level intervention strategies. Based on these assumptions, it is suggested that further in-depth research is carried out to establish what strategies are being employed by industrial social workers to expand their roles, it appears that there is a need to assist the industrial social worker to adopt a rationally planned approach in order to assume a greater role in the corporation's social responsibility activities internally and externally.
  • Full Text:
  • Date Issued: 1993

The relationship of general retention ability to new South African group test non-verbal/verbal IQ discrepancies and their academic correlates

  • Authors: Watson, Peter James
  • Date: 1992
  • Subjects: Intellect Intelligence tests -- South Africa Academic achievement -- South Africa
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1725 , http://hdl.handle.net/10962/d1003608
  • Description: Both experimental research (Robbertse,1952)and clinical observation (Kruger, 1972; van der Merwe,1978) have indicated that pupils with a Verbal IQ score 10 or more points lower than their non-Verbal IQ (termed a 'Type 1' discrepancy in the present research) on the New South African Group Test (NSAGT) show poorer academic achievement than their peers of similar ability. The present research investigates the relationship of general retention ability, as defined by Hakstian and Cattell (1978), to Type 1 discrepancies as well as to their academic correlates. One hundred and thirty-nine standard seven English-speaking boys were tested on the NSAGT and the Junior Aptitude Test (JAT) (of which tests 8 and 9 give an indication of general retention ability) and divided into a group with Type 1 discrepancies and two control groups. All three groups were matched on full-scale IQ. Comparison of these three groups, using the analysis of variance technique, showed that there was no significant difference between them in level of general retention ability or in academic performance (measured by average percentage in the final standard seven examination). While no significant difference was found between the three groups regarding the relationship of general retention ability to academic performance, in the Type 1 discrepancy group the relationship of rote memory (JAT test 8) to academic performance differed markedly from that of associative memory (JAT test 9) to academic performance. In the Type 1 discrepancy group rote memory was highly associated with academic performance, possibly indicating a compensatory strategy for the lower Verbal ability in this group, enabling it to achieve academically on par with the control groups, contrary to what would be expected on the basis of Robbertse's (1962) findings. In terms of Jensen's (1982) Level 1/Level 11 theory of intelligence, it appears from the present research that rote memory ability (JAT test 8) varies between being a Level 11 ability (in the Type 1 discrepancy group) to acting as a Level 1 ability in the two control groups. The present research questions Verwey and Wolmarans's (1980) description of both JAT tests 8 and 9 as simple measures of retention Test 9, in particular, appears to function consistently as a Level 11 ability.
  • Full Text:
  • Date Issued: 1992
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