The relationship between organisational leadership and job satisfaction of three generational age groups in a school context
- Haasbroek, Juan Gert Diedericks
- Authors: Haasbroek, Juan Gert Diedericks
- Date: 2021
- Subjects: Educational leadership -- South Africa , High Schools -- Administration -- South Africa -- Western Cape , Management , High school teachers -- South Africa -- Western Cape -- Case studies , High school teachers -- South Africa -- Western Cape -- Job satisfaction , High school teachers -- South Africa -- Western Cape -- Attitudes
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/170802 , vital:41961
- Description: With multiple generations in education, there are different leadership styles preferred by schoolteachers that affect their job satisfaction (Cufaude and Riemersma, 1999:1-3). Schools should ensure that leadership works toward satisfied teachers to reach sustainable organisational performance. The resource-based view argues that organisations should look within the organisation, particularly human resources, to find sources that lead to improved organisational performance (Jurevicius, 2013:1). Therefore, organisations should equip themselves with the required leadership style(s) to meet employee expectations. Furthermore, it is imperative to look at different generations within the school’s context, as it will strengthen or weaken the relationship between organisational leadership and job satisfaction. The study adopted a quantitative approach, using the Multiple Leadership Questionnaire and the Minnesota Satisfaction Questionnaire as instruments for collecting primary data. The population consists of high school teachers in the Eden District, Western Cape that work at affluent schools, which are declared as quantile 4 and 5 model schools. There is a total of 13 high schools that fall within this specification with a total population of 220 teachers. In total, 111 questionnaires were distributed, of which 73 were returned. Sixty-eight were considered usable. Both sample parameters specified by the research instruments were met. The primary purpose of the study was to investigate the relationship between leadership within the organisation (referring to transformational, transactional, and passive-avoidant organisational leadership styles) and employee job satisfaction of high school teachers in the Eden District. Different generations, from the age group perspective, is composed as a moderating variable in the relationship between organisational leadership and job satisfaction. The empirical study established that the independent variables, the leadership styles employed by the organisation, are directly related to employee job satisfaction. Of the three independent variables, transformational leadership and, to a lesser extent, transactional leadership proved to have a positive association with job satisfaction. In contrast, passive-avoidant leadership has a negative relationship with job satisfaction. It is also established that the relationship is stronger or weaker based on generations, positioning generations from the age group perspective as satisfactory moderator. It was found that Millennials prefer the transactional leadership style as this will strengthen the relationship between organisational leadership and job satisfaction. Baby Boomers prefer transformational leadership for the greatest positivity. To a lesser extent, transactional leadership will also contribute to the relationship’s strength between organisational leadership and job satisfaction. Generation X is indifferent to transactional or transformational leadership.
- Full Text:
- Date Issued: 2021
- Authors: Haasbroek, Juan Gert Diedericks
- Date: 2021
- Subjects: Educational leadership -- South Africa , High Schools -- Administration -- South Africa -- Western Cape , Management , High school teachers -- South Africa -- Western Cape -- Case studies , High school teachers -- South Africa -- Western Cape -- Job satisfaction , High school teachers -- South Africa -- Western Cape -- Attitudes
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/170802 , vital:41961
- Description: With multiple generations in education, there are different leadership styles preferred by schoolteachers that affect their job satisfaction (Cufaude and Riemersma, 1999:1-3). Schools should ensure that leadership works toward satisfied teachers to reach sustainable organisational performance. The resource-based view argues that organisations should look within the organisation, particularly human resources, to find sources that lead to improved organisational performance (Jurevicius, 2013:1). Therefore, organisations should equip themselves with the required leadership style(s) to meet employee expectations. Furthermore, it is imperative to look at different generations within the school’s context, as it will strengthen or weaken the relationship between organisational leadership and job satisfaction. The study adopted a quantitative approach, using the Multiple Leadership Questionnaire and the Minnesota Satisfaction Questionnaire as instruments for collecting primary data. The population consists of high school teachers in the Eden District, Western Cape that work at affluent schools, which are declared as quantile 4 and 5 model schools. There is a total of 13 high schools that fall within this specification with a total population of 220 teachers. In total, 111 questionnaires were distributed, of which 73 were returned. Sixty-eight were considered usable. Both sample parameters specified by the research instruments were met. The primary purpose of the study was to investigate the relationship between leadership within the organisation (referring to transformational, transactional, and passive-avoidant organisational leadership styles) and employee job satisfaction of high school teachers in the Eden District. Different generations, from the age group perspective, is composed as a moderating variable in the relationship between organisational leadership and job satisfaction. The empirical study established that the independent variables, the leadership styles employed by the organisation, are directly related to employee job satisfaction. Of the three independent variables, transformational leadership and, to a lesser extent, transactional leadership proved to have a positive association with job satisfaction. In contrast, passive-avoidant leadership has a negative relationship with job satisfaction. It is also established that the relationship is stronger or weaker based on generations, positioning generations from the age group perspective as satisfactory moderator. It was found that Millennials prefer the transactional leadership style as this will strengthen the relationship between organisational leadership and job satisfaction. Baby Boomers prefer transformational leadership for the greatest positivity. To a lesser extent, transactional leadership will also contribute to the relationship’s strength between organisational leadership and job satisfaction. Generation X is indifferent to transactional or transformational leadership.
- Full Text:
- Date Issued: 2021
Satire in J.J. R. Jolobe's literary works : a critique in relation to contemporary South Africa
- Authors: Benayo, Xolela
- Date: 2020
- Subjects: Jolobe, James J. R. , Xhosa literature -- History and criticism , Xhosa poetry -- History and criticism , Humor in literature , Xhosa literature -- Humor , Xhosa language
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/161762 , vital:40667
- Description: J.J.R. Jolobe is regarded as one of the individuals who made a valuable contribution to the development of isiXhosa literature through his works, notably in his poetry (Ilitha, Umyezo; Jolobe 1936). His poetry ranges from abstract subjects to more philosophical matters. This study is aimed at decoding the manner in which he employs satire to conscientise African people of the then horrible situation that they were facing. With that said, poetry will not be the only work that this thesis analyses in the process of evaluating Jolobe’s satire; his essays will also be examined (Amavo; Jolobe 1940). Based on the writings of various authors specialising in the subject, satire has been deemed to be a style of literary writing, one which involves invective satire. For the researcher, that statement will be rebutted, as it will be argued that the mode of satire need not be wholly invective. Jolobe’s light-hearted satire not only showcases the amusing side of his writings, but also indicates the seriousness with which they were intended. Themes covered in Jolobe’s satire have inspired the researcher to evaluate these literary texts in relation to modern contexts, especially when it comes to the relationship between the lines of the author’s experience and the public. With that said, the social role of satire is something that one cannot deny. One could therefore say that there is an urgent need for African satirists to face the existing social and economic reality as authentically as possible. The voice of a satirist should also echo the voice of their society as a whole. Satirical study in post-colonial Africa, in South Africa in particular, is useful due to the idea that the works of the likes of Jolobe may diminish in significance due to neo-colonialism. In fact, this is the point which is considered in this study of Jolobe’s satire. This study also examines stages afforded to the development of satire in Africa, especially in the post-colonial era. The purpose is to identify the effects of satire that are related to socio-political as well as religious factors. These factors are often seen as those that play a vital role is one’s personal morals, and those that are meant to shape the whole community. Jolobe addresses imperialism and the class struggle, which speaks to the society’s loyalties regarding the mobilization toward realizing the dream of being independent. This speaks to the works analysed, revealing protests against oppression and exploitation by imperialists; such works show how inhumane people could be against those who they deem to be beneath their standards. Researchers like Mahlasela (1973), Sirayi (1985), Kwetana (2000) and Khumalo (2015) are amongst those who have made it a point to study Jolobe to ensure that these works are kept alive, along with their significance. Other prospective researchers can follow suite in researching the great Jolobe. In ensuring that the aims of this study come to light, the researcher will be using socialist realism as a way of seeing that the works of Jolobe are realistic in nature. With that said, there will be an exploration of allegoric satire. Satiric allegory will be evaluated with regard to the view that it represents a unique slant on satire, whereby it deems satire to be more than just a supportive method of literary criticism. This allows the researcher to hold the view that satire should not be a restrictive framework when dealing with African literature. Satire as a modern form of criticism can be viewed as having an element of humanism, which would result in the satirist doing all he can to make sure that what is satirized is not isolated from the struggle of the community. It is for the above-mentioned reasons that we see a big challenge in the future development of satiric discourse in African literature.
- Full Text:
- Date Issued: 2020
- Authors: Benayo, Xolela
- Date: 2020
- Subjects: Jolobe, James J. R. , Xhosa literature -- History and criticism , Xhosa poetry -- History and criticism , Humor in literature , Xhosa literature -- Humor , Xhosa language
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/161762 , vital:40667
- Description: J.J.R. Jolobe is regarded as one of the individuals who made a valuable contribution to the development of isiXhosa literature through his works, notably in his poetry (Ilitha, Umyezo; Jolobe 1936). His poetry ranges from abstract subjects to more philosophical matters. This study is aimed at decoding the manner in which he employs satire to conscientise African people of the then horrible situation that they were facing. With that said, poetry will not be the only work that this thesis analyses in the process of evaluating Jolobe’s satire; his essays will also be examined (Amavo; Jolobe 1940). Based on the writings of various authors specialising in the subject, satire has been deemed to be a style of literary writing, one which involves invective satire. For the researcher, that statement will be rebutted, as it will be argued that the mode of satire need not be wholly invective. Jolobe’s light-hearted satire not only showcases the amusing side of his writings, but also indicates the seriousness with which they were intended. Themes covered in Jolobe’s satire have inspired the researcher to evaluate these literary texts in relation to modern contexts, especially when it comes to the relationship between the lines of the author’s experience and the public. With that said, the social role of satire is something that one cannot deny. One could therefore say that there is an urgent need for African satirists to face the existing social and economic reality as authentically as possible. The voice of a satirist should also echo the voice of their society as a whole. Satirical study in post-colonial Africa, in South Africa in particular, is useful due to the idea that the works of the likes of Jolobe may diminish in significance due to neo-colonialism. In fact, this is the point which is considered in this study of Jolobe’s satire. This study also examines stages afforded to the development of satire in Africa, especially in the post-colonial era. The purpose is to identify the effects of satire that are related to socio-political as well as religious factors. These factors are often seen as those that play a vital role is one’s personal morals, and those that are meant to shape the whole community. Jolobe addresses imperialism and the class struggle, which speaks to the society’s loyalties regarding the mobilization toward realizing the dream of being independent. This speaks to the works analysed, revealing protests against oppression and exploitation by imperialists; such works show how inhumane people could be against those who they deem to be beneath their standards. Researchers like Mahlasela (1973), Sirayi (1985), Kwetana (2000) and Khumalo (2015) are amongst those who have made it a point to study Jolobe to ensure that these works are kept alive, along with their significance. Other prospective researchers can follow suite in researching the great Jolobe. In ensuring that the aims of this study come to light, the researcher will be using socialist realism as a way of seeing that the works of Jolobe are realistic in nature. With that said, there will be an exploration of allegoric satire. Satiric allegory will be evaluated with regard to the view that it represents a unique slant on satire, whereby it deems satire to be more than just a supportive method of literary criticism. This allows the researcher to hold the view that satire should not be a restrictive framework when dealing with African literature. Satire as a modern form of criticism can be viewed as having an element of humanism, which would result in the satirist doing all he can to make sure that what is satirized is not isolated from the struggle of the community. It is for the above-mentioned reasons that we see a big challenge in the future development of satiric discourse in African literature.
- Full Text:
- Date Issued: 2020
Towards understanding how exploitation influences the wild energetic response of marine fish to temperature variability
- Authors: Skeeles, Michael Richard
- Date: 2020
- Subjects: Chrysoblepus laticeps -- Climatic factors , Sparidae -- Genetics , Sparidae -- South Africa -- Climatic factors
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145133 , vital:38411
- Description: Exploitation of fish populations can exacerbate the effects of climate change, yet our understanding of their synergistic effects remains limited. As fish are increasingly exposed to temperatures on the edges of their optimal thermal performance window, their physiological response is expected to shape their future performance. It is therefore concerning that exploitation can select for specific physiological phenotypes, as this may affect fished populations’ physiological response to temperature change. A recent laboratory study revealed fewer high-performance metabolic-scope phenotypes in an exploited population of the marine Sparid Chrysoblepus laticeps across a range of experimental temperatures in comparison to an unexploited population. This suggested that individuals in exploited populations may have less available energy for aerobic performance at thermal extremes, which may reduce the resilience of the population to changes in temperature. However, since laboratory experiments exclude numerous other variables that fish encounter in the wild, it was necessary to test this finding in a natural setting. This thesis aimed to further develop the laboratory study by assessing whether exploitation effects the wild energetic response of C. laticeps to thermal variability. To achieve this, the field metabolic rate of C. laticeps, a resident and endemic South African fish, from a near-pristine population (Tsitsikamma National Park) and a heavily exploited population (Port Elizabeth) was compared using acoustic accelerometry. A laboratory-based study using a swim-tunnel respirometer and accelerometer transmitters was conducted to develop a model to predict metabolic rate from acceleration data at temperatures from 10 to 22⁰C. Acceleration, temperature, mass and population (exploited/unexploited) were found to be the best predictors of the metabolic rate of C. laticeps and were incorporated into the model to estimate the field metabolic rate of fish tagged with acoustic accelerometers in the wild. To examine the combined effects of temperature and exploitation on the field metabolic rate of C. laticeps in their natural state, two fine-scale telemetry arrays with temperature loggers were used to assess the acceleration of the fish across different temperatures in the wild for three months during a period of high thermal variability. Ten fish from the exploited and unexploited populations were caught, surgically implanted with accelerometer transmitters and released back into the wild. Close to 500 000 and 400 000 acceleration estimates were recorded from wild exploited and unexploited fish, respectively. The field metabolic rate of both populations was estimated by combining the field acceleration and temperature data with the laboratory calibration model. The field metabolic rate of C. laticeps from the exploited population was constrained near cold and warm extremes compared to no constraints observed in the unexploited population. This was attributed to reduced inter-individual variability in the field metabolic rate-temperature relationship within the exploited population. There appeared to be a greater proportion of individuals that maintained a high field metabolic rate at extreme temperatures in the unexploited population. In contrast, all but one fish from the exploited population did not maintain a high field metabolic rate at extreme temperatures. These findings aligned with the laboratory-based metabolic-scope study on both populations of C. laticeps and demonstrate that passive-fishing may be removing thermally tolerant individuals and rendering exploited populations less resilient to thermal change. These findings are discussed in the context of fisheries management and particularly on the role that marine protected areas could play in maintaining physiological diversity, and therefore the resilience of fish in the Anthropocene. This study highlights the importance of applied conservation physiology in understanding the consequences of fisheries-induced evolution in an increasingly variable climate.
- Full Text:
- Date Issued: 2020
- Authors: Skeeles, Michael Richard
- Date: 2020
- Subjects: Chrysoblepus laticeps -- Climatic factors , Sparidae -- Genetics , Sparidae -- South Africa -- Climatic factors
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145133 , vital:38411
- Description: Exploitation of fish populations can exacerbate the effects of climate change, yet our understanding of their synergistic effects remains limited. As fish are increasingly exposed to temperatures on the edges of their optimal thermal performance window, their physiological response is expected to shape their future performance. It is therefore concerning that exploitation can select for specific physiological phenotypes, as this may affect fished populations’ physiological response to temperature change. A recent laboratory study revealed fewer high-performance metabolic-scope phenotypes in an exploited population of the marine Sparid Chrysoblepus laticeps across a range of experimental temperatures in comparison to an unexploited population. This suggested that individuals in exploited populations may have less available energy for aerobic performance at thermal extremes, which may reduce the resilience of the population to changes in temperature. However, since laboratory experiments exclude numerous other variables that fish encounter in the wild, it was necessary to test this finding in a natural setting. This thesis aimed to further develop the laboratory study by assessing whether exploitation effects the wild energetic response of C. laticeps to thermal variability. To achieve this, the field metabolic rate of C. laticeps, a resident and endemic South African fish, from a near-pristine population (Tsitsikamma National Park) and a heavily exploited population (Port Elizabeth) was compared using acoustic accelerometry. A laboratory-based study using a swim-tunnel respirometer and accelerometer transmitters was conducted to develop a model to predict metabolic rate from acceleration data at temperatures from 10 to 22⁰C. Acceleration, temperature, mass and population (exploited/unexploited) were found to be the best predictors of the metabolic rate of C. laticeps and were incorporated into the model to estimate the field metabolic rate of fish tagged with acoustic accelerometers in the wild. To examine the combined effects of temperature and exploitation on the field metabolic rate of C. laticeps in their natural state, two fine-scale telemetry arrays with temperature loggers were used to assess the acceleration of the fish across different temperatures in the wild for three months during a period of high thermal variability. Ten fish from the exploited and unexploited populations were caught, surgically implanted with accelerometer transmitters and released back into the wild. Close to 500 000 and 400 000 acceleration estimates were recorded from wild exploited and unexploited fish, respectively. The field metabolic rate of both populations was estimated by combining the field acceleration and temperature data with the laboratory calibration model. The field metabolic rate of C. laticeps from the exploited population was constrained near cold and warm extremes compared to no constraints observed in the unexploited population. This was attributed to reduced inter-individual variability in the field metabolic rate-temperature relationship within the exploited population. There appeared to be a greater proportion of individuals that maintained a high field metabolic rate at extreme temperatures in the unexploited population. In contrast, all but one fish from the exploited population did not maintain a high field metabolic rate at extreme temperatures. These findings aligned with the laboratory-based metabolic-scope study on both populations of C. laticeps and demonstrate that passive-fishing may be removing thermally tolerant individuals and rendering exploited populations less resilient to thermal change. These findings are discussed in the context of fisheries management and particularly on the role that marine protected areas could play in maintaining physiological diversity, and therefore the resilience of fish in the Anthropocene. This study highlights the importance of applied conservation physiology in understanding the consequences of fisheries-induced evolution in an increasingly variable climate.
- Full Text:
- Date Issued: 2020
Chitin hydrolysis with chitinolytic enzymes for the production of chitooligomers with antimicrobial properties
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
Investigating assay formats for screening malaria Hsp90-Hop interaction inhibitors
- Authors: Derry, Leigh-Anne Tracy Kim
- Date: 2019
- Subjects: Antimalarials , Heat shock proteins , Drug interactions , Drug resistance , Plasmodium falciparum , High throughput screening (Drug development) , Bioluminescence resonance energy transfer (BRET) , Fluorescence resonance energy transfer (FRET)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63345 , vital:28395
- Description: Although significant gains have been made in the combat against malaria in the last decade, the persistent threat of drug and insecticide resistance continues to motivate the search for new classes of antimalarial drug compounds and targets. Due to their predominance in cellular reactions, protein-protein interactions (P-PIs) are emerging as a promising general target class for therapeutic development. The P-PI which is the focus of this project is the interaction between the chaperone heat shock protein 90 (Hsp90) and its co-chaperone Hsp70/Hsp90 organising protein (Hop). Hop binds to Hsp70 and Hsp90 and facilitates the transfer of client proteins (proteins undergoing folding) from the former to the latter and also regulates nucleotide exchange on Hsp90. Due to its role in correcting protein misfolding during cell stress, Hsp90 is being pursued as a cancer drug target and compounds that inhibit its ATPase activity have entered clinical trials. However, it has been proposed that inhibiting the interaction between Hsp90 and Hop may be alternative approach for inhibiting Hsp90 function for cancer therapy. The malaria parasite Plasmodium falciparum experiences temperature fluctuations during vector-host transitions and febrile episodes and cell stress due to rapid growth and immune responses. Hence, it also depends on chaperones, including PfHsp90, to maintain protein functionality and pathogenesis, demonstrated inter alia by the sensitivity of parasites to Hsp90 inhibitors. In addition, PfHsp90 exists as a complex with the malarial Hop homologue, PfHop, in parasite lysates. Consequently, the purpose of this study was to explore P-PI assay formats that can confirm the interaction of PfHsp90 and PfHop and can be used to identify inhibitors of the interaction, preferably in a medium- to high-throughput screening mode. As a first approach, cell-based bioluminescence and fluorescence resonance energy transfer (BRET and FRET) assays were performed in HeLa cells. To facilitate this, expression plasmid constructs containing coding sequences of P. falciparum and mammalian Hsp90 and Hop and their interacting domains (Hsp90 C-domain and Hop TPR2A domain) fused to the BRET and FRET reporter proteins – yellow fluorescent protein (YFP), cyan fluorescent protein (CFP) and Renilla luciferase (Rluc) - were prepared and used for HeLa cell transient transfections. The FRET assay produced positive interaction signals for the full-length P. falciparum and mammalian Hsp90-Hop interactions. However, C-domain-TPR2A domain interactions were not detected, no interactions could be demonstrated with the BRET assay and western blotting experiments failed to detect expression of all the interaction partners in transiently transfected HeLa cells. Consequently, an alternative in vitro FRET assay format using recombinant proteins was investigated. Expression constructs for the P. falciparum and mammalian C-domains and TPR2A domains fused respectively to YFP and CFP were prepared and the corresponding fusion proteins expressed and purified from E. coli. No interaction was found with the mammalian interaction partners, but interaction of the P. falciparum C-domain and TPR2A domain was consistently detected with a robust Z’ factor value of 0.54. A peptide corresponding to the PfTPR2A domain sequence primarily responsible for Hsp90 binding (based on a human TPR2A peptide described by Horibe et al., 2011) was designed and showed dose-dependent inhibition of the interaction, with 53.7% inhibition at 100 μM. The components of the assay are limited to the purified recombinant proteins, requires minimal liquid steps and may thus be a useful primary screening format for identifying inhibitors of P. falciparum Hsp90-Hop interaction.
- Full Text:
- Date Issued: 2019
- Authors: Derry, Leigh-Anne Tracy Kim
- Date: 2019
- Subjects: Antimalarials , Heat shock proteins , Drug interactions , Drug resistance , Plasmodium falciparum , High throughput screening (Drug development) , Bioluminescence resonance energy transfer (BRET) , Fluorescence resonance energy transfer (FRET)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63345 , vital:28395
- Description: Although significant gains have been made in the combat against malaria in the last decade, the persistent threat of drug and insecticide resistance continues to motivate the search for new classes of antimalarial drug compounds and targets. Due to their predominance in cellular reactions, protein-protein interactions (P-PIs) are emerging as a promising general target class for therapeutic development. The P-PI which is the focus of this project is the interaction between the chaperone heat shock protein 90 (Hsp90) and its co-chaperone Hsp70/Hsp90 organising protein (Hop). Hop binds to Hsp70 and Hsp90 and facilitates the transfer of client proteins (proteins undergoing folding) from the former to the latter and also regulates nucleotide exchange on Hsp90. Due to its role in correcting protein misfolding during cell stress, Hsp90 is being pursued as a cancer drug target and compounds that inhibit its ATPase activity have entered clinical trials. However, it has been proposed that inhibiting the interaction between Hsp90 and Hop may be alternative approach for inhibiting Hsp90 function for cancer therapy. The malaria parasite Plasmodium falciparum experiences temperature fluctuations during vector-host transitions and febrile episodes and cell stress due to rapid growth and immune responses. Hence, it also depends on chaperones, including PfHsp90, to maintain protein functionality and pathogenesis, demonstrated inter alia by the sensitivity of parasites to Hsp90 inhibitors. In addition, PfHsp90 exists as a complex with the malarial Hop homologue, PfHop, in parasite lysates. Consequently, the purpose of this study was to explore P-PI assay formats that can confirm the interaction of PfHsp90 and PfHop and can be used to identify inhibitors of the interaction, preferably in a medium- to high-throughput screening mode. As a first approach, cell-based bioluminescence and fluorescence resonance energy transfer (BRET and FRET) assays were performed in HeLa cells. To facilitate this, expression plasmid constructs containing coding sequences of P. falciparum and mammalian Hsp90 and Hop and their interacting domains (Hsp90 C-domain and Hop TPR2A domain) fused to the BRET and FRET reporter proteins – yellow fluorescent protein (YFP), cyan fluorescent protein (CFP) and Renilla luciferase (Rluc) - were prepared and used for HeLa cell transient transfections. The FRET assay produced positive interaction signals for the full-length P. falciparum and mammalian Hsp90-Hop interactions. However, C-domain-TPR2A domain interactions were not detected, no interactions could be demonstrated with the BRET assay and western blotting experiments failed to detect expression of all the interaction partners in transiently transfected HeLa cells. Consequently, an alternative in vitro FRET assay format using recombinant proteins was investigated. Expression constructs for the P. falciparum and mammalian C-domains and TPR2A domains fused respectively to YFP and CFP were prepared and the corresponding fusion proteins expressed and purified from E. coli. No interaction was found with the mammalian interaction partners, but interaction of the P. falciparum C-domain and TPR2A domain was consistently detected with a robust Z’ factor value of 0.54. A peptide corresponding to the PfTPR2A domain sequence primarily responsible for Hsp90 binding (based on a human TPR2A peptide described by Horibe et al., 2011) was designed and showed dose-dependent inhibition of the interaction, with 53.7% inhibition at 100 μM. The components of the assay are limited to the purified recombinant proteins, requires minimal liquid steps and may thus be a useful primary screening format for identifying inhibitors of P. falciparum Hsp90-Hop interaction.
- Full Text:
- Date Issued: 2019
Chasing shadow and make believe
- Authors: Mofokeng, Reikanne
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Science fiction, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63626 , vital:28449
- Description: My thesis is a science fiction novella. It follows the story of an adolescent boy, Shadow, and a little girl, Makebelieve, in an ahistorical future. The world that they traverse is earth, after being nursed back to health, by technologically advanced Southern African societies. A series of inexplicable astronomical events leads to their being hunted down. Through the travels of Shadow and Makebelieve I show how the world and the societies around them operate. I am inspired by Samuel R Delaney’s Aye, Gomorrah and Derrick Bell’s The Space Traders, because of their prowess in world building and exploration of complex and innovative ideas.
- Full Text:
- Date Issued: 2018
- Authors: Mofokeng, Reikanne
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Science fiction, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63626 , vital:28449
- Description: My thesis is a science fiction novella. It follows the story of an adolescent boy, Shadow, and a little girl, Makebelieve, in an ahistorical future. The world that they traverse is earth, after being nursed back to health, by technologically advanced Southern African societies. A series of inexplicable astronomical events leads to their being hunted down. Through the travels of Shadow and Makebelieve I show how the world and the societies around them operate. I am inspired by Samuel R Delaney’s Aye, Gomorrah and Derrick Bell’s The Space Traders, because of their prowess in world building and exploration of complex and innovative ideas.
- Full Text:
- Date Issued: 2018
Antimalarial secondary metabolites from Morinda lucida
- Authors: Chithambo, Bertha
- Date: 2017
- Subjects: Botanical chemistry , Anthraquinones , Antimalarials , Rubiaceae -- Therapeutic use , Malaria -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45730 , vital:25535
- Description: Antimalarial activities of secondary metabolites from Morinda lucida (Rubiaceae), were investigated. Even though M. lucida is traditionally used to treat malaria, diabetes, jaundice, hypertension, dysentery and many other diseases, the compounds in this plant have not yet been fully investigated and characterised. Most of the studies that have been done on this plant focused on the medicinal properties of the crude extracts but have not gone further to isolate and characterise the compounds. In this study, the methanol - dichloromethane crude extract from the bark of M. lucida was fractionated into fractions 1-8. Fractions 2-5 were purified in order to isolate active secondary metabolites. The isolated pure compounds were characterised and identified. An in vitro antimalarial assay was carried out on the crude extract, fractions, pure compounds and solutions made from different combinations of pure compounds using the parasite lactate dehydrogenase (pLDH) assay. An IC50 done on the methanolic crude extract gave a value of 25 µg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Each of the pure compounds tested had very little activity. Their activities were increased when samples from the different compounds were mixed. One of these mixtures reduced malaria viability to about 22 % at 20 µM and gave an IC50 value of 17 µM. Antibacterial assays were also carried out on the crude extract and fractions. Fractions 2 and 3 were relatively active (MIC values ranging between 125-1000 µg/mL) against M. cattarhalis and E. faecalis. Fraction 2 was also the most active on S. typhimurium and S. aureus (MIC value of 1000 µg/mL) compared with the other fractions. This same fraction also showed some activity against M. tuberculosis with MIC90 and MIC99 values of 40.9 and 46.3 µg/mL respectively in an anti-tuberculosis assay.The following compounds, comprising of iridoids (asperuloside and asperulosidic acid), terpenoids (stigmasterol, P-sitosterol, campesterol, lanosterol and cycloartenol) and anthraquinones [5,15-O-dimethylmorindol, 1,7-dihydroxy-2-methoxy-5-(methoxymethyl) anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone], were isolated. All these compounds have been isolated from different plants before with the exception of 1,7-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone which were tentatively assigned the structures due to insufficient data. To the best of our knowledge, this is the first report on the identification of all of the mentioned compounds, with the exception of ß-sitosterol and stigmasterol, from M. lucida. Molecular docking was performed on one of the isolated anthraquinones (5,15-O- dimethylmorindol) to check if it can bind to cytochrome bci, a known target for atovaquone. This compound interacted with the same amino acids that atovaquone, a well known antimalarial agent, interacted with on cytochrome bc1 indicating a possible similar mode of action.
- Full Text:
- Date Issued: 2017
- Authors: Chithambo, Bertha
- Date: 2017
- Subjects: Botanical chemistry , Anthraquinones , Antimalarials , Rubiaceae -- Therapeutic use , Malaria -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45730 , vital:25535
- Description: Antimalarial activities of secondary metabolites from Morinda lucida (Rubiaceae), were investigated. Even though M. lucida is traditionally used to treat malaria, diabetes, jaundice, hypertension, dysentery and many other diseases, the compounds in this plant have not yet been fully investigated and characterised. Most of the studies that have been done on this plant focused on the medicinal properties of the crude extracts but have not gone further to isolate and characterise the compounds. In this study, the methanol - dichloromethane crude extract from the bark of M. lucida was fractionated into fractions 1-8. Fractions 2-5 were purified in order to isolate active secondary metabolites. The isolated pure compounds were characterised and identified. An in vitro antimalarial assay was carried out on the crude extract, fractions, pure compounds and solutions made from different combinations of pure compounds using the parasite lactate dehydrogenase (pLDH) assay. An IC50 done on the methanolic crude extract gave a value of 25 µg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Each of the pure compounds tested had very little activity. Their activities were increased when samples from the different compounds were mixed. One of these mixtures reduced malaria viability to about 22 % at 20 µM and gave an IC50 value of 17 µM. Antibacterial assays were also carried out on the crude extract and fractions. Fractions 2 and 3 were relatively active (MIC values ranging between 125-1000 µg/mL) against M. cattarhalis and E. faecalis. Fraction 2 was also the most active on S. typhimurium and S. aureus (MIC value of 1000 µg/mL) compared with the other fractions. This same fraction also showed some activity against M. tuberculosis with MIC90 and MIC99 values of 40.9 and 46.3 µg/mL respectively in an anti-tuberculosis assay.The following compounds, comprising of iridoids (asperuloside and asperulosidic acid), terpenoids (stigmasterol, P-sitosterol, campesterol, lanosterol and cycloartenol) and anthraquinones [5,15-O-dimethylmorindol, 1,7-dihydroxy-2-methoxy-5-(methoxymethyl) anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone], were isolated. All these compounds have been isolated from different plants before with the exception of 1,7-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone which were tentatively assigned the structures due to insufficient data. To the best of our knowledge, this is the first report on the identification of all of the mentioned compounds, with the exception of ß-sitosterol and stigmasterol, from M. lucida. Molecular docking was performed on one of the isolated anthraquinones (5,15-O- dimethylmorindol) to check if it can bind to cytochrome bci, a known target for atovaquone. This compound interacted with the same amino acids that atovaquone, a well known antimalarial agent, interacted with on cytochrome bc1 indicating a possible similar mode of action.
- Full Text:
- Date Issued: 2017
Interactions between two biological control agents released on Pereskia aculeata Miller (Cactaceae), in South Africa
- Authors: Mnqeta, Zezethu
- Date: 2017
- Subjects: Pereskia aculeata -- Biological control , Cactus -- Biological control -- South Africa , Alien plants -- Biological control -- South Africa , Flea beetles -- South Africa , Coreidae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7949 , vital:21327
- Description: Pereskia aculeata Miller (Cactaceae) is an alien invasive plant introduced into South Africa from Brazil, which has negative impacts on native biodiversity in South Africa. Phenrica guerini Bechyne (Chrysomelidae) and Catorhintha schaffneri Brailovsky & Garcia (Coreidae) are two biological control agents released against P. aculeata in South Africa. Phenrica guerini was first released against P. aculeata, in 1991, followed by C. schaffneri in 2014. The overall aim of this study was to improve the biological control programme against P. aculeata in order to decrease its density to a level where it does not threaten the native biodiversity of South Africa. The first part of this study evaluated the efficacy of P. guerini on P. aculeata at Port Alfred (Eastern Cape) to better understand the role of P. guerini in the biological control of P. aculeata. An insecticide exclusion experiment was conducted over 100 days. Plots with P. guerini had a mean of 187 (SE ± 62) fewer leaves/m2 than plots without P. guerini. The agent reduced percentage cover in plots with P. guerini, with a mean of 19.42% (SE ± 3.15) lower cover than plots without P. guerini. Although P. guerini had an impact on P. aculeata at Port Alfred previous studies have indicated that a reduction to below 50% cover is required for native biodiversity to recover and the agent only reduced cover to 62% at Port Alfred. Phenrica guerini has therefore not reduced percentage cover sufficiently to completely control the weed. The data collected from Port Alfred was compared to the performance of the agent nationwide. Although P. guerini was found at far more sites than previously recorded, there were very few sites with comparable levels of damage to Port Alfred. This evidence suggests that P. guerini is not sufficiently damaging to reduce P. aculeata to acceptable levels and other biological control agents should be considered.Interactions between two biological control agents can have complex and unexpected impacts for a biological control programme. The second part of this study was to investigate interactions between C. schaffneri and P. guerini under laboratory conditions to test whether the two agents, individually or jointly, enhanced or reduced their impact on P. aculeata. Potted P. aculeata plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species in combination. Four stocking densities, ranging from 2 to 12 insects per plant were used. Catorhintha schaffneri alone at high densities was more damaging than all other treatments with a significantly greater reduction in the mean number of leaves, 11.7 (SE ± 1.29), and shoot lengths, 2.17cm (SE ± O. 75). Even at lower density treatments, the combination of the two agents was not significantly more damaging than C. schaffneri alone and C. schaffneri was always more damaging than P. guerini alone. Mortality of P. guerini was significantly higher than C. schaffneri at the highest stocking density when in combination. Phenrica guerini contributes towards the biological control of P. aculeata at some sites in South Africa but not enough to completely control the weed. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. Catorhintha schaffneri should be released at sites were P. guerini is not present and evaluations of the success of this agent in the field should be conducted. Extrapolation of laboratory-based studies into the field is often challenging so mass-rearing of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2017
- Authors: Mnqeta, Zezethu
- Date: 2017
- Subjects: Pereskia aculeata -- Biological control , Cactus -- Biological control -- South Africa , Alien plants -- Biological control -- South Africa , Flea beetles -- South Africa , Coreidae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7949 , vital:21327
- Description: Pereskia aculeata Miller (Cactaceae) is an alien invasive plant introduced into South Africa from Brazil, which has negative impacts on native biodiversity in South Africa. Phenrica guerini Bechyne (Chrysomelidae) and Catorhintha schaffneri Brailovsky & Garcia (Coreidae) are two biological control agents released against P. aculeata in South Africa. Phenrica guerini was first released against P. aculeata, in 1991, followed by C. schaffneri in 2014. The overall aim of this study was to improve the biological control programme against P. aculeata in order to decrease its density to a level where it does not threaten the native biodiversity of South Africa. The first part of this study evaluated the efficacy of P. guerini on P. aculeata at Port Alfred (Eastern Cape) to better understand the role of P. guerini in the biological control of P. aculeata. An insecticide exclusion experiment was conducted over 100 days. Plots with P. guerini had a mean of 187 (SE ± 62) fewer leaves/m2 than plots without P. guerini. The agent reduced percentage cover in plots with P. guerini, with a mean of 19.42% (SE ± 3.15) lower cover than plots without P. guerini. Although P. guerini had an impact on P. aculeata at Port Alfred previous studies have indicated that a reduction to below 50% cover is required for native biodiversity to recover and the agent only reduced cover to 62% at Port Alfred. Phenrica guerini has therefore not reduced percentage cover sufficiently to completely control the weed. The data collected from Port Alfred was compared to the performance of the agent nationwide. Although P. guerini was found at far more sites than previously recorded, there were very few sites with comparable levels of damage to Port Alfred. This evidence suggests that P. guerini is not sufficiently damaging to reduce P. aculeata to acceptable levels and other biological control agents should be considered.Interactions between two biological control agents can have complex and unexpected impacts for a biological control programme. The second part of this study was to investigate interactions between C. schaffneri and P. guerini under laboratory conditions to test whether the two agents, individually or jointly, enhanced or reduced their impact on P. aculeata. Potted P. aculeata plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species in combination. Four stocking densities, ranging from 2 to 12 insects per plant were used. Catorhintha schaffneri alone at high densities was more damaging than all other treatments with a significantly greater reduction in the mean number of leaves, 11.7 (SE ± 1.29), and shoot lengths, 2.17cm (SE ± O. 75). Even at lower density treatments, the combination of the two agents was not significantly more damaging than C. schaffneri alone and C. schaffneri was always more damaging than P. guerini alone. Mortality of P. guerini was significantly higher than C. schaffneri at the highest stocking density when in combination. Phenrica guerini contributes towards the biological control of P. aculeata at some sites in South Africa but not enough to completely control the weed. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. Catorhintha schaffneri should be released at sites were P. guerini is not present and evaluations of the success of this agent in the field should be conducted. Extrapolation of laboratory-based studies into the field is often challenging so mass-rearing of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2017
Release success of captive bred Cape Vultures (Gyps coprotheres) in the Magaliesberg Mountains, South Africa
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text:
- Date Issued: 2017
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text:
- Date Issued: 2017
Study South Africa
- International Education Association of South Africa (IEASA), Quinlan, Orla
- Authors: International Education Association of South Africa (IEASA) , Quinlan, Orla
- Date: 2017
- Subjects: Education, Higher -- South Africa , Education and globalization -- South Africa Student mobility -- Africa International education -- South Africa Education, Higher -- International cooperation , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/64853 , vital:28620 , ISBN 9780620769662
- Description: [Editor's Letter]: Welcome to the seventeenth Study SA, compiled as IEASA celebrates its twentieth anniversary. Study SA is the South African publication that provides an overview of South African Higher Education issues and developments. This edition has a special Commemorative section, celebrating 20 years of IEASA, as well as the standard sections found in every issue of Study SA, consisting of Higher Education in Context, Features and Medical Aid and the updated profiles of the 26 public Higher Education Institutions. Universities South Africa, USAF, kindly provided partial funding for this edition of Study SA and we are delighted to include a message from the current CEO Dr Ahmed Bawa, a consistent supporter of internationalisation in Higher Education. We also have a message from the former Minister of Higher Education, Dr Blade Nzimande (2009-2017). A voluntary organisation supported by a small secretariat, IEASA is testament to a group of people who saw the need for an organisation to support the South African Higher Education’s re-entry and engagement with the rest of the world, once it became a democracy in 1994. This edition includes articles by two of the founding members: lEASA’s first President, Dr Roshun Kishun and its first Treasurer, Dr Derek Swemmer. Our sincere thanks to all the committed individuals in South African Higher education, who have kept IEASA going from strength to strength. Thilor Manikam, lEASA’s longest serving staffing member and the Office Manager has provided continuity and institutional memory over the best part of the twenty years. Guided by lEASA’s Constitution, Thilor has ensured that regardless of the change in the Management Council over the years, IEASA operations are impeccably managed and that IEASA has received an unqualified audit every year since its inception. In its history, IEASA has had seven Presidents: Dr Roshun Kishan, Ms Fazela Hanif, Mr David Ferrai, Ms Merle Hodges, Mr Lavern Samuels, Dr Nico Jooste and the current President Leolyn Jackson, whose term will run until the end of 2018, when the current President Elect, Ms Orla Quinlan will serve a two-year term from 2019-2020. IEASA has facilitated the development of a close knit community of practice in South Africa with members drawing on each other’s strengths and skills; inviting each other to our respective institutions to share knowledge, skills and ideas on appropriate internationalisation, within the South African context. More than that, we have become friends and have developed a collective responsibility to present and represent South African Higher Education to the rest of the world. Sadly, we lost three of our very dear colleagues and friends in recent years: Mr Len Mkhize, Mr Jimmy Ellis and Professor Stan Ridge. We pay tribute to the energy and joy they brought to IEASA in all their endeavours. They are missed. Others who have supported IEASA over the years include PWC, who have provided free audit services up to 2017, as a contribution to South Africa’s Higher Education; ABSA and the Medical Aid companies, who have provided sponsorship to IEASA. Finally, its volunteer Management Council, members of which serve two-year terms, with the possibility of being re-elected, and each one of our members who participate in and support IEASA activities and events. IEASA continued its work with the Department of Home Affairs (DHA) to clarify the visa application procedures, communicate the processes and to request interventions when visa processing is unduly delayed or if there are extenuating circumstances, which require intervention. IEASA and DHA have held one joint workshop with universities in 2016; a second was held following the IEASA 20th conference in August 2017 and an initial meeting called by USAF was held with DHA, HR Directors from universities and IEASA in late 2017. Visa Facilitation Services (VFS) have introduced a new mobile biometric service for campuses who do not have a VFS office in their locality. IEASA will continue to work on behalf of the international students and the rest of the international Higher Education community to improve the clarity of immigration requirements and to help overcome any difficulties faced. An article providing an update on progress is included in this edition. The international landscape has shifted enormously in recent years, where previously unquestioned democratic principles are being contested in some of the world’s most established democracies. lEASA’s 20th Anniversary Conference theme was “Advancing internationalisation: overcoming hostilities and building communities”. While in reflective and celebratory mode about the achievements of the last twenty years during the the Colloquium, the conference attendees switched mode and engaged in robust debates, about the current challenges in Higher Education including economic and financial challenges, xenophobia, the lack of equity in existing partnerships, institutional strategies, opportunities for engaging with partners interested in South African Higher Education. IEASA is cognisant of its responsibility to build capacity for the upcoming professionals in the sector and workshops on themes pertinent to the professionals in International Offices included immigration, partnerships and developing internationalisation strategy. , 17th Edition
- Full Text:
- Date Issued: 2017
- Authors: International Education Association of South Africa (IEASA) , Quinlan, Orla
- Date: 2017
- Subjects: Education, Higher -- South Africa , Education and globalization -- South Africa Student mobility -- Africa International education -- South Africa Education, Higher -- International cooperation , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/64853 , vital:28620 , ISBN 9780620769662
- Description: [Editor's Letter]: Welcome to the seventeenth Study SA, compiled as IEASA celebrates its twentieth anniversary. Study SA is the South African publication that provides an overview of South African Higher Education issues and developments. This edition has a special Commemorative section, celebrating 20 years of IEASA, as well as the standard sections found in every issue of Study SA, consisting of Higher Education in Context, Features and Medical Aid and the updated profiles of the 26 public Higher Education Institutions. Universities South Africa, USAF, kindly provided partial funding for this edition of Study SA and we are delighted to include a message from the current CEO Dr Ahmed Bawa, a consistent supporter of internationalisation in Higher Education. We also have a message from the former Minister of Higher Education, Dr Blade Nzimande (2009-2017). A voluntary organisation supported by a small secretariat, IEASA is testament to a group of people who saw the need for an organisation to support the South African Higher Education’s re-entry and engagement with the rest of the world, once it became a democracy in 1994. This edition includes articles by two of the founding members: lEASA’s first President, Dr Roshun Kishun and its first Treasurer, Dr Derek Swemmer. Our sincere thanks to all the committed individuals in South African Higher education, who have kept IEASA going from strength to strength. Thilor Manikam, lEASA’s longest serving staffing member and the Office Manager has provided continuity and institutional memory over the best part of the twenty years. Guided by lEASA’s Constitution, Thilor has ensured that regardless of the change in the Management Council over the years, IEASA operations are impeccably managed and that IEASA has received an unqualified audit every year since its inception. In its history, IEASA has had seven Presidents: Dr Roshun Kishan, Ms Fazela Hanif, Mr David Ferrai, Ms Merle Hodges, Mr Lavern Samuels, Dr Nico Jooste and the current President Leolyn Jackson, whose term will run until the end of 2018, when the current President Elect, Ms Orla Quinlan will serve a two-year term from 2019-2020. IEASA has facilitated the development of a close knit community of practice in South Africa with members drawing on each other’s strengths and skills; inviting each other to our respective institutions to share knowledge, skills and ideas on appropriate internationalisation, within the South African context. More than that, we have become friends and have developed a collective responsibility to present and represent South African Higher Education to the rest of the world. Sadly, we lost three of our very dear colleagues and friends in recent years: Mr Len Mkhize, Mr Jimmy Ellis and Professor Stan Ridge. We pay tribute to the energy and joy they brought to IEASA in all their endeavours. They are missed. Others who have supported IEASA over the years include PWC, who have provided free audit services up to 2017, as a contribution to South Africa’s Higher Education; ABSA and the Medical Aid companies, who have provided sponsorship to IEASA. Finally, its volunteer Management Council, members of which serve two-year terms, with the possibility of being re-elected, and each one of our members who participate in and support IEASA activities and events. IEASA continued its work with the Department of Home Affairs (DHA) to clarify the visa application procedures, communicate the processes and to request interventions when visa processing is unduly delayed or if there are extenuating circumstances, which require intervention. IEASA and DHA have held one joint workshop with universities in 2016; a second was held following the IEASA 20th conference in August 2017 and an initial meeting called by USAF was held with DHA, HR Directors from universities and IEASA in late 2017. Visa Facilitation Services (VFS) have introduced a new mobile biometric service for campuses who do not have a VFS office in their locality. IEASA will continue to work on behalf of the international students and the rest of the international Higher Education community to improve the clarity of immigration requirements and to help overcome any difficulties faced. An article providing an update on progress is included in this edition. The international landscape has shifted enormously in recent years, where previously unquestioned democratic principles are being contested in some of the world’s most established democracies. lEASA’s 20th Anniversary Conference theme was “Advancing internationalisation: overcoming hostilities and building communities”. While in reflective and celebratory mode about the achievements of the last twenty years during the the Colloquium, the conference attendees switched mode and engaged in robust debates, about the current challenges in Higher Education including economic and financial challenges, xenophobia, the lack of equity in existing partnerships, institutional strategies, opportunities for engaging with partners interested in South African Higher Education. IEASA is cognisant of its responsibility to build capacity for the upcoming professionals in the sector and workshops on themes pertinent to the professionals in International Offices included immigration, partnerships and developing internationalisation strategy. , 17th Edition
- Full Text:
- Date Issued: 2017
Trade and the environmental Kuznets curve: is Southern Africa a pollution haven?
- Nahman, Anton, Antrobus, Geoffrey G
- Authors: Nahman, Anton , Antrobus, Geoffrey G
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143202 , vital:38210 , DOI: 10.1111/j.1813-6982.2005.00055.x
- Description: Evidence that the environmental Kuznets curve (EKC) may be explained by trade patterns casts doubt on the oft‐stated conclusion that economic growth automatically leads to environmental improvement. Trends in net exports as a proportion of consumption for both USA and UK trade with SACU were examined for various dirty industries. Some evidence of pollution haven effects is found, although a similar trend for clean industries suggests that this effect is weak. However, even a general shift in manufacturing industries from North to South (as opposed to a shift in specifically dirty industries) may explain the EKC to some extent.
- Full Text:
- Date Issued: 2006
- Authors: Nahman, Anton , Antrobus, Geoffrey G
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143202 , vital:38210 , DOI: 10.1111/j.1813-6982.2005.00055.x
- Description: Evidence that the environmental Kuznets curve (EKC) may be explained by trade patterns casts doubt on the oft‐stated conclusion that economic growth automatically leads to environmental improvement. Trends in net exports as a proportion of consumption for both USA and UK trade with SACU were examined for various dirty industries. Some evidence of pollution haven effects is found, although a similar trend for clean industries suggests that this effect is weak. However, even a general shift in manufacturing industries from North to South (as opposed to a shift in specifically dirty industries) may explain the EKC to some extent.
- Full Text:
- Date Issued: 2006
South Africa within SADC : hegemon or partner?
- Authors: Molefi, Tebogo Shadrack
- Date: 2003
- Subjects: Southern African Development Community , Political stability -- Africa, Southern , South Africa -- Economic conditions , South Africa -- Foreign relations -- Africa , South Africa -- Economic policy
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2866 , http://hdl.handle.net/10962/d1007674 , Southern African Development Community , Political stability -- Africa, Southern , South Africa -- Economic conditions , South Africa -- Foreign relations -- Africa , South Africa -- Economic policy
- Description: This study attempts to make a contribution to the debate on the role of South Africa within Southern African Development Community. An attempt is made to analyse this role within the context of regional integration debate. This role has been conceptualised within the dichotomies of hegemon versus partner. The study argues that South Africa is a hegemon in the region of SADC, and that given its overarching economic dominance and it has the potential of establishing its hegemony in the region. It maintains that there are several factors, which could facilitate South Africa's hegemonic dominance such as in military, technology and manufacturing sector. It concludes by arguing that given the changing geopolitical factors both within the region and the globe impedes South Africa from firmly expressing this hegemonic dominance. Furthermore, South Africa's pioneering role in the struggle to change the status quo globally in favour of the Southern states is another crucial factor, which imposes limitations on its hegemonic intentions regionally.
- Full Text:
- Date Issued: 2003
- Authors: Molefi, Tebogo Shadrack
- Date: 2003
- Subjects: Southern African Development Community , Political stability -- Africa, Southern , South Africa -- Economic conditions , South Africa -- Foreign relations -- Africa , South Africa -- Economic policy
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2866 , http://hdl.handle.net/10962/d1007674 , Southern African Development Community , Political stability -- Africa, Southern , South Africa -- Economic conditions , South Africa -- Foreign relations -- Africa , South Africa -- Economic policy
- Description: This study attempts to make a contribution to the debate on the role of South Africa within Southern African Development Community. An attempt is made to analyse this role within the context of regional integration debate. This role has been conceptualised within the dichotomies of hegemon versus partner. The study argues that South Africa is a hegemon in the region of SADC, and that given its overarching economic dominance and it has the potential of establishing its hegemony in the region. It maintains that there are several factors, which could facilitate South Africa's hegemonic dominance such as in military, technology and manufacturing sector. It concludes by arguing that given the changing geopolitical factors both within the region and the globe impedes South Africa from firmly expressing this hegemonic dominance. Furthermore, South Africa's pioneering role in the struggle to change the status quo globally in favour of the Southern states is another crucial factor, which imposes limitations on its hegemonic intentions regionally.
- Full Text:
- Date Issued: 2003
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