An investigation of the experiences of psychotherapists regarding Ubuntu in their psychotherapy practice: an interpretative phenomenological analysis
- Authors: Qangule, Lumka Sybil
- Date: 2020
- Subjects: Ubuntu (Philosophy) , Psychotherapy -- Cross-cultural studies , Psychoanalysis and culture -- South Africa , Xhosa (African people) -- Psychology , Xhosa (African people) -- Mental health , Black people -- South Africa -- Psychology , Black people -- South Africa -- Mental health , Psychotherapists -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146923 , vital:38577
- Description: Psychotherapy is a Eurocentric concept and practice that has migrated to South Africa with technology, as part of the general transfer of knowledge (Mkhize, 2003). It has embedded Eurocentric principles that sometimes do not easily accommodate working with Africans. It has been practised by psychotherapists of African origin with clients of African origin, but is based upon Eurocentric ideas and guidelines for practice. Many African people consider their core values to be uBuntu, rooted in a principle ‘umntu ngumntu ngabantu’ (translated as ‘a human being is a human being because of other human beings’). Some important features of uBuntu are interdependence, respect, spirituality and the primacy of communality as an approach to life. Some of the ways in which these impact on daily functioning are not foregrounded by adherence to Western principles. The use of only Eurocentric principles when working with clients of African origin may thus not lead to the desired outcomes in psychotherapy. However, these Eurocentric principles are recognised and enforced by the authoritative bodies in the field of psychology, such as the Health Professions Council of South Africa. A distinction will be made between the more inflexible ethical principles of psychology and the ideas of therapy frames. Therapy frames are not seen as being as rigid as ethical codes and they could be augmented, to be appropriate for the context, particularly in the commonly multicultural settings that are found here. Psychotherapists of African origin are torn between abiding by the ethical principles that they have been taught and practising in the way that they, together with their clients, have been socialised. Abiding by the principles as described in the codes is safe because it does not pose any threat of being sanctioned by the regulator of practice, but clients may be let down and there may be limited success with certain clients. This clash of ideas of ways of practice poses dissonance and many dilemmas among psychotherapists of African origin. Due to the nature of this study, Interpretative Phenomenological Analysis (IPA) was adopted as a suitable methodology, where eight practising amaXhosa psychotherapists were interviewed about their experiences of incorporating uBuntu in their psychotherapy practice. The raw data from initial interviews were analysed and the findings concluded that although psychotherapists were trained in Western ways of practice, they included some practices of uBuntu in their practice as well as upholding some Eurocentric principles that seemed to be helpful for their clientele. Subsequently a summary of the findings were discussed with participants in a focus group setting, where participants endorsed and expanded upon their original responses. With the above in mind, a psychotherapy model called uBuntu-Centred Psychotherapy was created, which reflects the principles and therapy frames that have been found to be useful in treating clients of African origin. This modality is more congruent with the worldviews and style of living of many South Africans, in the post-apartheid era. It embraces some Eurocentric principles that are relevant for Africans, while it is embedded in the phenomena and way of life reflected in uBuntu, a predominant mode of functioning for the group that was the focus of this study, the amaXhosa. The study ends by making recommendations for practice, as well as highlighting the need for further and more extensive research to contribute to the project of Africanising psychotherapy.
- Full Text:
- Authors: Qangule, Lumka Sybil
- Date: 2020
- Subjects: Ubuntu (Philosophy) , Psychotherapy -- Cross-cultural studies , Psychoanalysis and culture -- South Africa , Xhosa (African people) -- Psychology , Xhosa (African people) -- Mental health , Black people -- South Africa -- Psychology , Black people -- South Africa -- Mental health , Psychotherapists -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146923 , vital:38577
- Description: Psychotherapy is a Eurocentric concept and practice that has migrated to South Africa with technology, as part of the general transfer of knowledge (Mkhize, 2003). It has embedded Eurocentric principles that sometimes do not easily accommodate working with Africans. It has been practised by psychotherapists of African origin with clients of African origin, but is based upon Eurocentric ideas and guidelines for practice. Many African people consider their core values to be uBuntu, rooted in a principle ‘umntu ngumntu ngabantu’ (translated as ‘a human being is a human being because of other human beings’). Some important features of uBuntu are interdependence, respect, spirituality and the primacy of communality as an approach to life. Some of the ways in which these impact on daily functioning are not foregrounded by adherence to Western principles. The use of only Eurocentric principles when working with clients of African origin may thus not lead to the desired outcomes in psychotherapy. However, these Eurocentric principles are recognised and enforced by the authoritative bodies in the field of psychology, such as the Health Professions Council of South Africa. A distinction will be made between the more inflexible ethical principles of psychology and the ideas of therapy frames. Therapy frames are not seen as being as rigid as ethical codes and they could be augmented, to be appropriate for the context, particularly in the commonly multicultural settings that are found here. Psychotherapists of African origin are torn between abiding by the ethical principles that they have been taught and practising in the way that they, together with their clients, have been socialised. Abiding by the principles as described in the codes is safe because it does not pose any threat of being sanctioned by the regulator of practice, but clients may be let down and there may be limited success with certain clients. This clash of ideas of ways of practice poses dissonance and many dilemmas among psychotherapists of African origin. Due to the nature of this study, Interpretative Phenomenological Analysis (IPA) was adopted as a suitable methodology, where eight practising amaXhosa psychotherapists were interviewed about their experiences of incorporating uBuntu in their psychotherapy practice. The raw data from initial interviews were analysed and the findings concluded that although psychotherapists were trained in Western ways of practice, they included some practices of uBuntu in their practice as well as upholding some Eurocentric principles that seemed to be helpful for their clientele. Subsequently a summary of the findings were discussed with participants in a focus group setting, where participants endorsed and expanded upon their original responses. With the above in mind, a psychotherapy model called uBuntu-Centred Psychotherapy was created, which reflects the principles and therapy frames that have been found to be useful in treating clients of African origin. This modality is more congruent with the worldviews and style of living of many South Africans, in the post-apartheid era. It embraces some Eurocentric principles that are relevant for Africans, while it is embedded in the phenomena and way of life reflected in uBuntu, a predominant mode of functioning for the group that was the focus of this study, the amaXhosa. The study ends by making recommendations for practice, as well as highlighting the need for further and more extensive research to contribute to the project of Africanising psychotherapy.
- Full Text:
An investigation of the influence of knowledge-production and learning processes on complex practices in a community-driven citizen science initiative: A nature conservation case study
- Authors: Alexander, Jaclyn
- Date: 2020
- Subjects: Science -- Citizen participation , Western Leopard Toad Conservation Committee , Environmental education , Frogs -- South Africa
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/138173 , vital:37603
- Description: Community-driven citizen science initiatives have become an increasingly popular tool for combating social-ecological challenges that arise within communities. Scientific protocols have been designed to strengthen and support the accuracy and reliability of data collection and information sharing; however, little is understood of the dynamic social processes that reinforce and co-ordinate such community-driven action. This qualitative case study was undertaken to identify and understand complex organisational, political and socio-cultural processes (in particular knowledge-production and learning processes) that have guided, sustained and informed complex practices in a community driven citizen science initiative. The study aimed to inform the development of a social protocol that might be transferable to other citizen science contexts. The study drew on the theory of ‘Landscapes of Practice’, which highlights how multiple communities of practice overlap, interrelate, share knowledge and cross boundaries to create potential learning across a landscape. Additionally, ideas and typologies in recent citizen science literature offered perspective on the community-driven citizen science practices. This qualitative case study focused on the bounded case of the Western Leopard Toad Conservation Committee. Specific data generation tools (interviews, observations, document analysis and diagrams) were used from multiple perspectives over time to provide rigor and depth to the data. The study demonstrated how multiple ‘nexes of practice’ co-engaged in collective knowledge creation practices, which helped to enhance ‘knowledgeability’ across the landscape. This coordinated effort, however, was sporadic and inconsistent. Recommendations are made for the development of social protocols that could assist collaborators in citizen science initiatives to scrutinise and rethink their practices and to examine both their successes and shortfalls towards their shared interest.
- Full Text:
- Authors: Alexander, Jaclyn
- Date: 2020
- Subjects: Science -- Citizen participation , Western Leopard Toad Conservation Committee , Environmental education , Frogs -- South Africa
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/138173 , vital:37603
- Description: Community-driven citizen science initiatives have become an increasingly popular tool for combating social-ecological challenges that arise within communities. Scientific protocols have been designed to strengthen and support the accuracy and reliability of data collection and information sharing; however, little is understood of the dynamic social processes that reinforce and co-ordinate such community-driven action. This qualitative case study was undertaken to identify and understand complex organisational, political and socio-cultural processes (in particular knowledge-production and learning processes) that have guided, sustained and informed complex practices in a community driven citizen science initiative. The study aimed to inform the development of a social protocol that might be transferable to other citizen science contexts. The study drew on the theory of ‘Landscapes of Practice’, which highlights how multiple communities of practice overlap, interrelate, share knowledge and cross boundaries to create potential learning across a landscape. Additionally, ideas and typologies in recent citizen science literature offered perspective on the community-driven citizen science practices. This qualitative case study focused on the bounded case of the Western Leopard Toad Conservation Committee. Specific data generation tools (interviews, observations, document analysis and diagrams) were used from multiple perspectives over time to provide rigor and depth to the data. The study demonstrated how multiple ‘nexes of practice’ co-engaged in collective knowledge creation practices, which helped to enhance ‘knowledgeability’ across the landscape. This coordinated effort, however, was sporadic and inconsistent. Recommendations are made for the development of social protocols that could assist collaborators in citizen science initiatives to scrutinise and rethink their practices and to examine both their successes and shortfalls towards their shared interest.
- Full Text:
An investigation of the internal challenges that hinder sustainability of the Furntech Nyanga incubates
- Authors: Sakuba, Siyasanga
- Date: 2020
- Subjects: Business incubators -- South Africa -- Cape Town , Business incubators -- Training of -- South Africa -- Cape Town , Entrepreneurship -- South Africa – Cape Town , Unemployment -- South Africa , Rate of return -- South Africa , Economic development -- South Africa , Training needs -- South Africa -- Cape Town , Furntech (Nyanga)
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/142830 , vital:38121
- Description: The South African unemployment rate is currently at 27.6 per cent (Statistics South Africa, 2019). In an effort to combat unemployment, the South African government has implemented various mechanisms to provide opportunities to the people and combat unemployment. One of these mechanisms is to invest in the establishment of entrepreneurship incubators while the Furntech incubator is one of the incubators established for this purpose. It is imperative that the government spending on these mechanisms is justified by a return on investment which, in this case, should be to reduce unemployment and increase the overall entrepreneurial activity. In view of Furntech, with specific reference to the Nyanga incubation centre, there is a high failure rate with very little output of sustainable enterprises from the two-year incubation period. This study seeks to investigate the internal challenges that hinder the sustainability of these entrepreneurs to either drop out before the end of the two-year incubation period or to furnish the two years without becoming sustainable entrepreneurs. This study seeks to investigate this matter by using a semi -structured interview schedule that was geared towards investigating the research problem from the view of the incubates. The findings of the study showed that Furntech can be commended in respect of the transfer of technical skills. Furntech, however, failed to support the entrepreneurs with the other business support services that are part of their services, namely the business advisory, financial support and business skills. These findings provide a guideline of where Furntech needs to improve its service offering to gain a higher output of sustainable entrepreneurs. It is important to note that even though Furntech has representation in three provinces with two incubators in the Western Cape (Cape Town and Nyanga), however, this study was limited to the Furntech Nyanga incubates.
- Full Text:
- Authors: Sakuba, Siyasanga
- Date: 2020
- Subjects: Business incubators -- South Africa -- Cape Town , Business incubators -- Training of -- South Africa -- Cape Town , Entrepreneurship -- South Africa – Cape Town , Unemployment -- South Africa , Rate of return -- South Africa , Economic development -- South Africa , Training needs -- South Africa -- Cape Town , Furntech (Nyanga)
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/142830 , vital:38121
- Description: The South African unemployment rate is currently at 27.6 per cent (Statistics South Africa, 2019). In an effort to combat unemployment, the South African government has implemented various mechanisms to provide opportunities to the people and combat unemployment. One of these mechanisms is to invest in the establishment of entrepreneurship incubators while the Furntech incubator is one of the incubators established for this purpose. It is imperative that the government spending on these mechanisms is justified by a return on investment which, in this case, should be to reduce unemployment and increase the overall entrepreneurial activity. In view of Furntech, with specific reference to the Nyanga incubation centre, there is a high failure rate with very little output of sustainable enterprises from the two-year incubation period. This study seeks to investigate the internal challenges that hinder the sustainability of these entrepreneurs to either drop out before the end of the two-year incubation period or to furnish the two years without becoming sustainable entrepreneurs. This study seeks to investigate this matter by using a semi -structured interview schedule that was geared towards investigating the research problem from the view of the incubates. The findings of the study showed that Furntech can be commended in respect of the transfer of technical skills. Furntech, however, failed to support the entrepreneurs with the other business support services that are part of their services, namely the business advisory, financial support and business skills. These findings provide a guideline of where Furntech needs to improve its service offering to gain a higher output of sustainable entrepreneurs. It is important to note that even though Furntech has representation in three provinces with two incubators in the Western Cape (Cape Town and Nyanga), however, this study was limited to the Furntech Nyanga incubates.
- Full Text:
An octabrominated Sn (iv) tetraisopropylporphyrin as a photosensitizer dye for singlet oxygen biomedical applications
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
An unsung dialogue: music, society and the history of The Flames
- Authors: Park, Duncan Keith
- Date: 2020
- Subjects: The Flames (Musical group) , Fataar, Steve , Durban (South Africa) -- History , Durban (South Africa) -- Race relations , Musical groups -- South Africa , Music -- Social aspects -- South Africa , Music -- Social aspects -- South Africa -- Durban , South Africa -- Politics and government -- 1961-1978
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/169632 , vital:41780
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid . The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames 1963–1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. South Africa during apartheid, with its racialised legislation provides an ideal context to scrutinize the effects (both potential and real) of music on social conditions. The Flames provide a particularly relevant case point; being a collective of “mixed-race” individuals classified as Coloured performing for a multi-racial fan- base. This means that at their concerts, audience members would have frequently been from a variety of different racial backgrounds. This would have been in direct contravention to the National Party‟s (NP) Separate Amenities Act as well as the policy of “separate development”, the cornerstone of apartheid. The thesis will firstly contextualise the research within the broader, global historical context, as well as in the existing theoretical literature which focuses on the relationship between music, politics and society. Firstly, this will entail a brief historical account of popular music around the world during the twentieth century. Through this we will observe both the ways in which the development and popularisation of various forms of popular music came to be shaped in a particular way, as well as the ways in which the public received this music. This will include an examination of positive responses to certain kinds of popular music which resonated and became popular with various sectors of society. Conversely, it will also closely examine the backlashes against these musical forms, and attempt to identify why certain sectors of the public were deeply opposed to particular kinds of popular music which may have been perceived to embody certain values and meanings. This will be conducted by studying various forms of popular music from the turn of the twentieth century into the early 1970s with a cross-cultural, global perspective, examining particular historical instances and existing theories relating to these instances. Chapter one will then shift from a global perspective and will situate the research within the South African musical context specifically. This will include an account of the development of South African popular music through the twentieth century in relation to the country's politics. Through examining this relationship, the dialogue between historical case studies and theoretical literature will continue, in which existing theories relating to the relationship between music, politics and society will be discussed. This theoretical literature will be made use of in the final section of the paper in order to make sense of The Flames and their role in South African history. The second section of this thesis will focus on the socio-historical context of the city of Durban under apartheid. The author will contextualise the research through a narrative historical retelling of Durban‟s social history, focusing on both political and social public mobilisation and the role of cultural spaces and practices within these his torical moments and their relevant structures. Attention will be paid to the development of segregation and apartheid within Durban specifically, while racial relations will also be fo cused upon. This will provide the reader with the necessary background required in order to meaningfully understand how the band The Flames came into existence, became popular, and whether or not they had any meaningful effect on their historical context. The section on Durban's history will be followed by a brief account of Durban's Coloured community's history, as well as a discussion around Coloured identity more broadly within the South African context. This will be vital to the research due to the fact that the musicians of The Flames were classified as Coloured under apartheid, and such an historical background will be critical to understanding the social, political and economic context of the band. Finally, the thesis will end with the written history of The Flame . This final section will provide an account of The Flames' history in which the band will be made sense of within the context of Durban during apartheid, as well as within the context of South African music, and the globalised context of popular music. By situating the band within these three contexts, we can truly assess both how they were shaped by their contexts, and whether they had any effect on these contexts of which they were a part. In this section those existing theories around the relationship between music, politics and society will be discussed and assessed in order to determine how useful a framework they may be for understanding popular music in certain historical contexts. In this way, the research aims to make a meaningful contribution to the study of music and its socio-political role throughout history, as well as to the broader understanding of Durban's history. Specifically, the role of music in Durban's history is being examined, and the researcher hopes that this work can begin to open up new discussions around the importance of studying music in Durban, and South Africa's history. Additionally, this thesis will open up a new area of research into a band which, until this point, has not been engaged with in the field of music history whatsoever. .
- Full Text:
- Authors: Park, Duncan Keith
- Date: 2020
- Subjects: The Flames (Musical group) , Fataar, Steve , Durban (South Africa) -- History , Durban (South Africa) -- Race relations , Musical groups -- South Africa , Music -- Social aspects -- South Africa , Music -- Social aspects -- South Africa -- Durban , South Africa -- Politics and government -- 1961-1978
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/169632 , vital:41780
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid . The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames 1963–1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. South Africa during apartheid, with its racialised legislation provides an ideal context to scrutinize the effects (both potential and real) of music on social conditions. The Flames provide a particularly relevant case point; being a collective of “mixed-race” individuals classified as Coloured performing for a multi-racial fan- base. This means that at their concerts, audience members would have frequently been from a variety of different racial backgrounds. This would have been in direct contravention to the National Party‟s (NP) Separate Amenities Act as well as the policy of “separate development”, the cornerstone of apartheid. The thesis will firstly contextualise the research within the broader, global historical context, as well as in the existing theoretical literature which focuses on the relationship between music, politics and society. Firstly, this will entail a brief historical account of popular music around the world during the twentieth century. Through this we will observe both the ways in which the development and popularisation of various forms of popular music came to be shaped in a particular way, as well as the ways in which the public received this music. This will include an examination of positive responses to certain kinds of popular music which resonated and became popular with various sectors of society. Conversely, it will also closely examine the backlashes against these musical forms, and attempt to identify why certain sectors of the public were deeply opposed to particular kinds of popular music which may have been perceived to embody certain values and meanings. This will be conducted by studying various forms of popular music from the turn of the twentieth century into the early 1970s with a cross-cultural, global perspective, examining particular historical instances and existing theories relating to these instances. Chapter one will then shift from a global perspective and will situate the research within the South African musical context specifically. This will include an account of the development of South African popular music through the twentieth century in relation to the country's politics. Through examining this relationship, the dialogue between historical case studies and theoretical literature will continue, in which existing theories relating to the relationship between music, politics and society will be discussed. This theoretical literature will be made use of in the final section of the paper in order to make sense of The Flames and their role in South African history. The second section of this thesis will focus on the socio-historical context of the city of Durban under apartheid. The author will contextualise the research through a narrative historical retelling of Durban‟s social history, focusing on both political and social public mobilisation and the role of cultural spaces and practices within these his torical moments and their relevant structures. Attention will be paid to the development of segregation and apartheid within Durban specifically, while racial relations will also be fo cused upon. This will provide the reader with the necessary background required in order to meaningfully understand how the band The Flames came into existence, became popular, and whether or not they had any meaningful effect on their historical context. The section on Durban's history will be followed by a brief account of Durban's Coloured community's history, as well as a discussion around Coloured identity more broadly within the South African context. This will be vital to the research due to the fact that the musicians of The Flames were classified as Coloured under apartheid, and such an historical background will be critical to understanding the social, political and economic context of the band. Finally, the thesis will end with the written history of The Flame . This final section will provide an account of The Flames' history in which the band will be made sense of within the context of Durban during apartheid, as well as within the context of South African music, and the globalised context of popular music. By situating the band within these three contexts, we can truly assess both how they were shaped by their contexts, and whether they had any effect on these contexts of which they were a part. In this section those existing theories around the relationship between music, politics and society will be discussed and assessed in order to determine how useful a framework they may be for understanding popular music in certain historical contexts. In this way, the research aims to make a meaningful contribution to the study of music and its socio-political role throughout history, as well as to the broader understanding of Durban's history. Specifically, the role of music in Durban's history is being examined, and the researcher hopes that this work can begin to open up new discussions around the importance of studying music in Durban, and South Africa's history. Additionally, this thesis will open up a new area of research into a band which, until this point, has not been engaged with in the field of music history whatsoever. .
- Full Text:
An update on the indigenous vascular flora of sub-Antarctic Marion Island: taxonomic changes, sequences for DNA barcode loci, and genome size data
- Chau, John H, Mtsi, Nasipi I S, Münbergová, Zuzana, Greve, Michelle, le Roux, Peter C, Mairal, Mario, Le Roux, Johannes J, Dorrington, Rosemary A, van Vuuren, Bettine
- Authors: Chau, John H , Mtsi, Nasipi I S , Münbergová, Zuzana , Greve, Michelle , le Roux, Peter C , Mairal, Mario , Le Roux, Johannes J , Dorrington, Rosemary A , van Vuuren, Bettine
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160344 , vital:40437 , https://0-doi.org.wam.seals.ac.za/10.1007/s00300-020-02747-7
- Description: The flora of sub-Antarctic Marion Island forms part of the unique South Indian Ocean Biogeographic Province, and is under threat from climate change and invasive species. Current information on the flora is necessary to rapidly identify and manage future changes. We conducted a literature search on the taxonomy of indigenous vascular plant species on Marion Island and found nomenclatural changes following taxonomic revisions for Austroblechnum penna-marina (Poir.) Gasper and V.A.O.Dittrich, Carex dikei (Nelmes) K.L.Wilson, Leptinella plumosa Hook.f., Notogrammitis crassior (Kirk) Parris, Phlegmariurus saururus (Lam.) B.Øllg., and Polypogon magellanicus (Lam.) Finot. Additionally, Ranunculus moseleyi Hook.f. was removed from our species checklist due to its long absence in floristic surveys, leaving 21 species in the indigenous vascular plant flora present on Marion Island. We also amplified and sequenced the universal plant barcoding loci rbcL and matK for 19 and 13 species, respectively, and found that ample interspecific genetic distance and minimal intraspecific genetic distance allowed for easy discrimination between species.
- Full Text:
- Authors: Chau, John H , Mtsi, Nasipi I S , Münbergová, Zuzana , Greve, Michelle , le Roux, Peter C , Mairal, Mario , Le Roux, Johannes J , Dorrington, Rosemary A , van Vuuren, Bettine
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160344 , vital:40437 , https://0-doi.org.wam.seals.ac.za/10.1007/s00300-020-02747-7
- Description: The flora of sub-Antarctic Marion Island forms part of the unique South Indian Ocean Biogeographic Province, and is under threat from climate change and invasive species. Current information on the flora is necessary to rapidly identify and manage future changes. We conducted a literature search on the taxonomy of indigenous vascular plant species on Marion Island and found nomenclatural changes following taxonomic revisions for Austroblechnum penna-marina (Poir.) Gasper and V.A.O.Dittrich, Carex dikei (Nelmes) K.L.Wilson, Leptinella plumosa Hook.f., Notogrammitis crassior (Kirk) Parris, Phlegmariurus saururus (Lam.) B.Øllg., and Polypogon magellanicus (Lam.) Finot. Additionally, Ranunculus moseleyi Hook.f. was removed from our species checklist due to its long absence in floristic surveys, leaving 21 species in the indigenous vascular plant flora present on Marion Island. We also amplified and sequenced the universal plant barcoding loci rbcL and matK for 19 and 13 species, respectively, and found that ample interspecific genetic distance and minimal intraspecific genetic distance allowed for easy discrimination between species.
- Full Text:
Analysing emergent time within an isolated Universe through the application of interactions in the conditional probability approach
- Authors: Bryan, Kate Louise Halse
- Date: 2020
- Subjects: Space and time , Quantum gravity , Quantum theory , Relativity (Physics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146676 , vital:38547
- Description: Time remains a frequently discussed issue in physics and philosophy. One interpretation of growing popularity is the ‘timeless’ view which states that our experience of time is only an illusion. The isolated Universe model, provided by the Wheeler-DeWitt equation, supports this interpretation by describing time using clocks in the conditional probability interpretation (CPI). However, the CPI customarily dismisses interaction effects as negligible creating a potential blind spot which overlooks the potential influence of interaction effects. Accounting for interactions opens up a new avenue of analysis and a potential challenge to the interpretation of time. In aid of our assessment of the impact interaction effects have on the CPI, we present rudimentary definitions of time and its associated concepts. Defined in a minimalist manner, time is argued to require a postulate of causality as a means of accounting for temporal ordering in physical theories. Several of these theories are discussed here in terms of their respective approaches to time and, despite their differences, there are indications that the accounts of time are unified in a more fundamental theory. An analytic analysis of the CPI, incorporating two different clock choices, and a qualitative analysis both confirm that interactions have a necessary role within the CPI. The consequence of removing interactions is a maximised uncertainty in any measurement of the clock and a restriction to a two-state system, as indicated by the results of the toy models and qualitative argument respectively. The philosophical implication is that we are not restricted to the timeless view since including interactions as agents of causal interventions between systems provides an account of time as a real phenomenon. This result highlights the reliance on a postulate of causality which forms a pressing problem in explaining our experience of time.
- Full Text:
- Authors: Bryan, Kate Louise Halse
- Date: 2020
- Subjects: Space and time , Quantum gravity , Quantum theory , Relativity (Physics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146676 , vital:38547
- Description: Time remains a frequently discussed issue in physics and philosophy. One interpretation of growing popularity is the ‘timeless’ view which states that our experience of time is only an illusion. The isolated Universe model, provided by the Wheeler-DeWitt equation, supports this interpretation by describing time using clocks in the conditional probability interpretation (CPI). However, the CPI customarily dismisses interaction effects as negligible creating a potential blind spot which overlooks the potential influence of interaction effects. Accounting for interactions opens up a new avenue of analysis and a potential challenge to the interpretation of time. In aid of our assessment of the impact interaction effects have on the CPI, we present rudimentary definitions of time and its associated concepts. Defined in a minimalist manner, time is argued to require a postulate of causality as a means of accounting for temporal ordering in physical theories. Several of these theories are discussed here in terms of their respective approaches to time and, despite their differences, there are indications that the accounts of time are unified in a more fundamental theory. An analytic analysis of the CPI, incorporating two different clock choices, and a qualitative analysis both confirm that interactions have a necessary role within the CPI. The consequence of removing interactions is a maximised uncertainty in any measurement of the clock and a restriction to a two-state system, as indicated by the results of the toy models and qualitative argument respectively. The philosophical implication is that we are not restricted to the timeless view since including interactions as agents of causal interventions between systems provides an account of time as a real phenomenon. This result highlights the reliance on a postulate of causality which forms a pressing problem in explaining our experience of time.
- Full Text:
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
Analysis of the regulation of HSP90α expression upon differentiation of C2C12 cells
- Authors: Holm, Nathan Christopher
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163318 , vital:41028
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Authors: Holm, Nathan Christopher
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163318 , vital:41028
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
Analysis of the relationship between changes in macroeconomic variables and various sector price indices of JSE
- Mapanda, Tungamirai Chisvuvo
- Authors: Mapanda, Tungamirai Chisvuvo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stock price indexes -- South Africa , Interest rates -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/147445 , vital:38637
- Description: Purpose- The purpose of this paper is to analyse the relationship between changes in domestic macroeconomic variables and various indices of the JSE during the full time period, June 1995 to December 2018 and the sub-periods, June 1995 to June 2007 and July 2007 to December 2018. Design/ methodology/ approach- The paper employs the Autoregressive Distributed Lag (ARDL) model approach to cointegration using monthly data from June 1995 to December 2018. Findings- In terms of the long run, the results show that the coincident indicator measure of domestic economic activity is positively and significantly related to the various JSE indices for all study periods. In terms of inflation, the results show no relationship between inflation rate and the various indices for both whole period and June 1995 to June 2007 sub period. However for the July 2007 to December 2018 sub period, JSE All Share Index and JSE Top 40 Index are negatively related. For the real effective exchange rate, only the Consumer Services Index is positively related to the exchange rate in terms of June 1995 to June 2007 sub period. However, JSE All Share Index and JSE Top 40 Index are negatively related to the exchange rate in all study periods. In terms of the short term interest rate, for the whole period, JSE All Share Index, JSE Top 40 Index, Health Care Index and Telecommunications Index are negatively related to interest rate. In terms of the June 1995 to June 2007 sub period, JSE All Share Index and Industrials Index are negatively related to the short term interest rate. For the July 2007 to December 2018 sub period, Telecommunications Index and Technology Index are negatively related. In terms of the short run, the coincident indicator is positively and significantly related to the various JSE indices for all study periods. Inflation is not significantly related to any index in the whole period. In terms of the June 1995 to June 2007 sub period, Industrials Index and Financials Index are positively related to inflation and in the July 2007 to December 2018 sub period, Consumer Goods Index, Health Index and Consumer Services Index are negatively related to the inflation rate. The real effective exchange rate is positively and significantly related to the various JSE indices in the different study periods. In terms of the short term interest rate, for the whole period and the June 1995 to June 2007 sub period only the Technology Index is not significantly and negatively related to the short term interest rate, but for the July 2007 to December 2018 sub period, Top 40 Index, Telecommunications Index and Technology Index are positively related to the interest rate. Only the Financial Index is negatively related to short term interest rates during this sub period. Research Limitations- Not a lot literature was found on the relationship between macroeconomic variables and the various sector indices of the JSE. Most previous work, in the South African context focused just on the JSE All Share Index. Practical Implications- The findings can help investors diversify their portfolios into indices that benefit from expected changes in macroeconomic variables, such as recessions, rising interest rates, rising inflation or a weakening exchange rate. Alternatively, they can hedge themselves against the negative implications of such macroeconomic changes on portfolio performance. In addition, the findings are important for the monetary authorities to better understand the implications of their policy changes on financial markets.
- Full Text:
- Authors: Mapanda, Tungamirai Chisvuvo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stock price indexes -- South Africa , Interest rates -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/147445 , vital:38637
- Description: Purpose- The purpose of this paper is to analyse the relationship between changes in domestic macroeconomic variables and various indices of the JSE during the full time period, June 1995 to December 2018 and the sub-periods, June 1995 to June 2007 and July 2007 to December 2018. Design/ methodology/ approach- The paper employs the Autoregressive Distributed Lag (ARDL) model approach to cointegration using monthly data from June 1995 to December 2018. Findings- In terms of the long run, the results show that the coincident indicator measure of domestic economic activity is positively and significantly related to the various JSE indices for all study periods. In terms of inflation, the results show no relationship between inflation rate and the various indices for both whole period and June 1995 to June 2007 sub period. However for the July 2007 to December 2018 sub period, JSE All Share Index and JSE Top 40 Index are negatively related. For the real effective exchange rate, only the Consumer Services Index is positively related to the exchange rate in terms of June 1995 to June 2007 sub period. However, JSE All Share Index and JSE Top 40 Index are negatively related to the exchange rate in all study periods. In terms of the short term interest rate, for the whole period, JSE All Share Index, JSE Top 40 Index, Health Care Index and Telecommunications Index are negatively related to interest rate. In terms of the June 1995 to June 2007 sub period, JSE All Share Index and Industrials Index are negatively related to the short term interest rate. For the July 2007 to December 2018 sub period, Telecommunications Index and Technology Index are negatively related. In terms of the short run, the coincident indicator is positively and significantly related to the various JSE indices for all study periods. Inflation is not significantly related to any index in the whole period. In terms of the June 1995 to June 2007 sub period, Industrials Index and Financials Index are positively related to inflation and in the July 2007 to December 2018 sub period, Consumer Goods Index, Health Index and Consumer Services Index are negatively related to the inflation rate. The real effective exchange rate is positively and significantly related to the various JSE indices in the different study periods. In terms of the short term interest rate, for the whole period and the June 1995 to June 2007 sub period only the Technology Index is not significantly and negatively related to the short term interest rate, but for the July 2007 to December 2018 sub period, Top 40 Index, Telecommunications Index and Technology Index are positively related to the interest rate. Only the Financial Index is negatively related to short term interest rates during this sub period. Research Limitations- Not a lot literature was found on the relationship between macroeconomic variables and the various sector indices of the JSE. Most previous work, in the South African context focused just on the JSE All Share Index. Practical Implications- The findings can help investors diversify their portfolios into indices that benefit from expected changes in macroeconomic variables, such as recessions, rising interest rates, rising inflation or a weakening exchange rate. Alternatively, they can hedge themselves against the negative implications of such macroeconomic changes on portfolio performance. In addition, the findings are important for the monetary authorities to better understand the implications of their policy changes on financial markets.
- Full Text:
Analytical Detection and Electrocatalysis of Paracetamol in Aqueous Media Using Rare‐Earth Double‐Decker Phthalocyaninato Chelates as Electrochemically Active Materials
- Sekhosana, Kutloano E, Nkhahle, Reitumetse, Nyokong, Tebello
- Authors: Sekhosana, Kutloano E , Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190840 , vital:45033 , xlink:href="https://doi.org/10.1002/slct.202002268"
- Description: Paracetamol (PA), being an analgesic and antipyretic medicine, can cause fatal hepatotoxicity and nephrotoxicity when overdosed. It is therefore important to develop electrochemical sensors that can monitor and quantify it in aquatic environments. In this study, rare-earth sandwich-type phthalocyaninato chelates based on neodymium (1 a) and samarium (1 b) were employed as electrocatalysts to modify glassy carbon electrodes (GCE) for the first time. It was found that 1 a-modified GCE (herein referred to as 1 a-GCE) is less conductive than 1 b-modified counterpart (1 b-GCE). A larger rate constant was also obtained for 1 b-GCE. It was established that a faster oxidation rate efficiency was responsible for lower limit of detection value obtained for 1 b-GCE as compared to 1 a-GCE.
- Full Text:
- Authors: Sekhosana, Kutloano E , Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190840 , vital:45033 , xlink:href="https://doi.org/10.1002/slct.202002268"
- Description: Paracetamol (PA), being an analgesic and antipyretic medicine, can cause fatal hepatotoxicity and nephrotoxicity when overdosed. It is therefore important to develop electrochemical sensors that can monitor and quantify it in aquatic environments. In this study, rare-earth sandwich-type phthalocyaninato chelates based on neodymium (1 a) and samarium (1 b) were employed as electrocatalysts to modify glassy carbon electrodes (GCE) for the first time. It was found that 1 a-modified GCE (herein referred to as 1 a-GCE) is less conductive than 1 b-modified counterpart (1 b-GCE). A larger rate constant was also obtained for 1 b-GCE. It was established that a faster oxidation rate efficiency was responsible for lower limit of detection value obtained for 1 b-GCE as compared to 1 a-GCE.
- Full Text:
Anger, Pain and the Body in the Public Sphere:
- Authors: Garman, Anthea
- Date: 2020
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/158459 , vital:40188 , ISBN 9781776145898
- Description: In this timely, original and sophisticated collection, writers from the Global South demonstrate that forms of publicness are multiple, mobile and varied. The notion that societies mediate issues through certain kinds of engagement is at the heart of imaginings of democracy and often centers on the ideal of the public sphere. But this imagined foundation of how we live collectively appears to have suffered a dramatic collapse across the world, with many democracies apparently unable to solve problems through talk – or even to agree on who speaks, in what ways and where. In the 10 essays in this timely, original and sophisticated collection, writers from southern Africa combine theoretical analysis with the examination of historical cases and contemporary developments to demonstrate that forms of publicness are multiple, mobile and varied. They propose new concepts and methodologies to analyse how public engagements work in society.
- Full Text:
- Authors: Garman, Anthea
- Date: 2020
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/158459 , vital:40188 , ISBN 9781776145898
- Description: In this timely, original and sophisticated collection, writers from the Global South demonstrate that forms of publicness are multiple, mobile and varied. The notion that societies mediate issues through certain kinds of engagement is at the heart of imaginings of democracy and often centers on the ideal of the public sphere. But this imagined foundation of how we live collectively appears to have suffered a dramatic collapse across the world, with many democracies apparently unable to solve problems through talk – or even to agree on who speaks, in what ways and where. In the 10 essays in this timely, original and sophisticated collection, writers from southern Africa combine theoretical analysis with the examination of historical cases and contemporary developments to demonstrate that forms of publicness are multiple, mobile and varied. They propose new concepts and methodologies to analyse how public engagements work in society.
- Full Text:
Anti-cancer and anti-trypanosomal properties of alkaloids from the root bark of Zanthoxylum leprieurii Guill and Perr
- Eze, Fabian I, Siwe-Noundou, Xavier, Isaacs, Michelle, Patala, Srivinas, Osadebe, Patience O, Krause, Rui W M
- Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Isaacs, Michelle , Patala, Srivinas , Osadebe, Patience O , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193352 , vital:45324 , xlink:href="http://dx.doi.org/10.4314/tjpr.v19i11.19"
- Description: Purpose: To isolate the anti-cancer and anti-trypanosomal principles of Zanthoxylum leprieurii, a medicinally versatile wild tropical plant used for managing tumours, African trypanosomiasis, and inflammation in southeastern Nigeria. Methods: The pure compounds were isolated using chromatographic methods. The structural elucidation of the pure compounds was based on their NMR (1D and 2D) and mass spectral data as well as chemical test results. Structure-activity relationships were based on the structural differences among the compounds. The cytotoxicity of the extracts and compounds (1, 2, 3, and 4) was evaluated in HeLa (human cervix adenocarcinoma) cell line while the trypanocidal activities were evaluated on Trypanosoma brucei brucei. Results: Two acridone alkaloids, 1-hydroxy-3-methoxy-10-methylacridin-9 (10H)-one, named fabiocinine (1), and 1-hydroxy-2,3-dimethoxy-10-methylacridin-9 (10H)-one (arborinine, 2), together with a furoquinoline alkaloid, skimmianine (3), and a chelerythrine derivative, 6-acetonyl-5,6-dihydrochelerythrine (4) were isolated from the root bark of Zanthoxylum leprieurii. Skimmianine (3) exhibited cytotoxicity and anti-trypanosomal IC50 of 12.8 and 13.2 µg/mL respectively (p less than 0.05). Compound (1) and arborinine (2) were selectively cytotoxic to HeLa cells with cytotoxicity IC50 of 28.49 and 62.71 µg/mL, respectively, while (4) did not show significant activity (p less than 0.05). Conclusion: Zanthoxylum leprieurii root bark contains cytotoxic and trypanocidal compounds, and is thus a potential source of anti-cancer and anti-trypanosomal leads.
- Full Text:
- Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Isaacs, Michelle , Patala, Srivinas , Osadebe, Patience O , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193352 , vital:45324 , xlink:href="http://dx.doi.org/10.4314/tjpr.v19i11.19"
- Description: Purpose: To isolate the anti-cancer and anti-trypanosomal principles of Zanthoxylum leprieurii, a medicinally versatile wild tropical plant used for managing tumours, African trypanosomiasis, and inflammation in southeastern Nigeria. Methods: The pure compounds were isolated using chromatographic methods. The structural elucidation of the pure compounds was based on their NMR (1D and 2D) and mass spectral data as well as chemical test results. Structure-activity relationships were based on the structural differences among the compounds. The cytotoxicity of the extracts and compounds (1, 2, 3, and 4) was evaluated in HeLa (human cervix adenocarcinoma) cell line while the trypanocidal activities were evaluated on Trypanosoma brucei brucei. Results: Two acridone alkaloids, 1-hydroxy-3-methoxy-10-methylacridin-9 (10H)-one, named fabiocinine (1), and 1-hydroxy-2,3-dimethoxy-10-methylacridin-9 (10H)-one (arborinine, 2), together with a furoquinoline alkaloid, skimmianine (3), and a chelerythrine derivative, 6-acetonyl-5,6-dihydrochelerythrine (4) were isolated from the root bark of Zanthoxylum leprieurii. Skimmianine (3) exhibited cytotoxicity and anti-trypanosomal IC50 of 12.8 and 13.2 µg/mL respectively (p less than 0.05). Compound (1) and arborinine (2) were selectively cytotoxic to HeLa cells with cytotoxicity IC50 of 28.49 and 62.71 µg/mL, respectively, while (4) did not show significant activity (p less than 0.05). Conclusion: Zanthoxylum leprieurii root bark contains cytotoxic and trypanocidal compounds, and is thus a potential source of anti-cancer and anti-trypanosomal leads.
- Full Text:
Antiparasitic Constituents of Beilschmiedia louisii and Beilschmiedia obscura and Some Semisynthetic Derivatives
- Waleguele, Christine C, Mba'ning, Brice M, Awantu, Angelbert F, Bankeu, Jean J, Fongang, Yannick S F, Ngouela, Augustin S, Tsamo, Etienne, Sewald, Norbert, Lenta, Bruno N, Krause, Rui W M
- Authors: Waleguele, Christine C , Mba'ning, Brice M , Awantu, Angelbert F , Bankeu, Jean J , Fongang, Yannick S F , Ngouela, Augustin S , Tsamo, Etienne , Sewald, Norbert , Lenta, Bruno N , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193364 , vital:45325 , xlink:href="https://doi.org/10.3390/molecules25122862"
- Description: The MeOH/CH2Cl2 (1:1) extracts of the roots and leaves of Beilschmiedia louisii and B. obscura showed potent antitrypanosomal activity during preliminary screening on Trypanosoma brucei brucei. Phytochemical investigation of these extracts led to the isolation of a mixture of two new endiandric acid derivatives beilschmiedol B (1) and beilschmiedol C (2), and one new phenylalkene obscurene A (3) together with twelve known compounds (4–15). In addition, four new derivatives (11a–11d) were synthesized from compound 11. Their structures were elucidated based on their NMR and MS data. Compounds 5, 6, and 7 were isolated for the first time from the Beilschmiedia genus. Additionally, the NMR data of compound 4 are given here for the first time. The isolates were evaluated for their antitrypanosomal and antimalarial activities against Tb brucei and the Plasmodium falciparum chloroquine-resistant strain Pf3D7 in vitro, respectively. From the tested compounds, the mixture of new compounds 1 and 2 exhibited the most potent antitrypanosomal activity in vitro with IC50 value of 4.91 μM.
- Full Text:
- Authors: Waleguele, Christine C , Mba'ning, Brice M , Awantu, Angelbert F , Bankeu, Jean J , Fongang, Yannick S F , Ngouela, Augustin S , Tsamo, Etienne , Sewald, Norbert , Lenta, Bruno N , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193364 , vital:45325 , xlink:href="https://doi.org/10.3390/molecules25122862"
- Description: The MeOH/CH2Cl2 (1:1) extracts of the roots and leaves of Beilschmiedia louisii and B. obscura showed potent antitrypanosomal activity during preliminary screening on Trypanosoma brucei brucei. Phytochemical investigation of these extracts led to the isolation of a mixture of two new endiandric acid derivatives beilschmiedol B (1) and beilschmiedol C (2), and one new phenylalkene obscurene A (3) together with twelve known compounds (4–15). In addition, four new derivatives (11a–11d) were synthesized from compound 11. Their structures were elucidated based on their NMR and MS data. Compounds 5, 6, and 7 were isolated for the first time from the Beilschmiedia genus. Additionally, the NMR data of compound 4 are given here for the first time. The isolates were evaluated for their antitrypanosomal and antimalarial activities against Tb brucei and the Plasmodium falciparum chloroquine-resistant strain Pf3D7 in vitro, respectively. From the tested compounds, the mixture of new compounds 1 and 2 exhibited the most potent antitrypanosomal activity in vitro with IC50 value of 4.91 μM.
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Application of In Vitro Release Testing (IVRT) and a dermatopharmacokinetic approach (tape stripping) for the assessment of Metronidazole topical formulations
- Rath, Seeprarani Prabirkumar
- Authors: Rath, Seeprarani Prabirkumar
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164617 , vital:41148 , doi:10.21504/10962/164617
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
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- Authors: Rath, Seeprarani Prabirkumar
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164617 , vital:41148 , doi:10.21504/10962/164617
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
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Application of machine learning, molecular modelling and structural data mining against antiretroviral drug resistance in HIV-1
- Sheik Amamuddy, Olivier Serge André
- Authors: Sheik Amamuddy, Olivier Serge André
- Date: 2020
- Subjects: Machine learning , Molecules -- Models , Data mining , Neural networks (Computer science) , Antiretroviral agents , Protease inhibitors , Drug resistance , Multidrug resistance , Molecular dynamics , Renin-angiotensin system , HIV (Viruses) -- South Africa , HIV (Viruses) -- Social aspects -- South Africa , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115964 , vital:34282
- Description: Millions are affected with the Human Immunodeficiency Virus (HIV) world wide, even though the death toll is on the decline. Antiretrovirals (ARVs), more specifically protease inhibitors have shown tremendous success since their introduction into therapy since the mid 1990’s by slowing down progression to the Acquired Immune Deficiency Syndrome (AIDS). However, Drug Resistance Mutations (DRMs) are constantly selected for due to viral adaptation, making drugs less effective over time. The current challenge is to manage the infection optimally with a limited set of drugs, with differing associated levels of toxicities in the face of a virus that (1) exists as a quasispecies, (2) may transmit acquired DRMs to drug-naive individuals and (3) that can manifest class-wide resistance due to similarities in design. The presence of latent reservoirs, unawareness of infection status, education and various socio-economic factors make the problem even more complex. Adequate timing and choice of drug prescription together with treatment adherence are very important as drug toxicities, drug failure and sub-optimal treatment regimens leave room for further development of drug resistance. While CD4 cell count and the determination of viral load from patients in resource-limited settings are very helpful to track how well a patient’s immune system is able to keep the virus in check, they can be lengthy in determining whether an ARV is effective. Phenosense assay kits answer this problem using viruses engineered to contain the patient sequences and evaluating their growth in the presence of different ARVs, but this can be expensive and too involved for routine checks. As a cheaper and faster alternative, genotypic assays provide similar information from HIV pol sequences obtained from blood samples, inferring ARV efficacy on the basis of drug resistance mutation patterns. However, these are inherently complex and the various methods of in silico prediction, such as Geno2pheno, REGA and Stanford HIVdb do not always agree in every case, even though this gap decreases as the list of resistance mutations is updated. A major gap in HIV treatment is that the information used for predicting drug resistance is mainly computed from data containing an overwhelming majority of B subtype HIV, when these only comprise about 12% of the worldwide HIV infections. In addition to growing evidence that drug resistance is subtype-related, it is intuitive to hypothesize that as subtyping is a phylogenetic classification, the more divergent a subtype is from the strains used in training prediction models, the less their resistance profiles would correlate. For the aforementioned reasons, we used a multi-faceted approach to attack the virus in multiple ways. This research aimed to (1) improve resistance prediction methods by focusing solely on the available subtype, (2) mine structural information pertaining to resistance in order to find any exploitable weak points and increase knowledge of the mechanistic processes of drug resistance in HIV protease. Finally, (3) we screen for protease inhibitors amongst a database of natural compounds [the South African natural compound database (SANCDB)] to find molecules or molecular properties usable to come up with improved inhibition against the drug target. In this work, structural information was mined using the Anisotropic Network Model, Dynamics Cross-Correlation, Perturbation Response Scanning, residue contact network analysis and the radius of gyration. These methods failed to give any resistance-associated patterns in terms of natural movement, internal correlated motions, residue perturbation response, relational behaviour and global compaction respectively. Applications of drug docking, homology-modelling and energy minimization for generating features suitable for machine-learning were not very promising, and rather suggest that the value of binding energies by themselves from Vina may not be very reliable quantitatively. All these failures lead to a refinement that resulted in a highly sensitive statistically-guided network construction and analysis, which leads to key findings in the early dynamics associated with resistance across all PI drugs. The latter experiment unravelled a conserved lateral expansion motion occurring at the flap elbows, and an associated contraction that drives the base of the dimerization domain towards the catalytic site’s floor in the case of drug resistance. Interestingly, we found that despite the conserved movement, bond angles were degenerate. Alongside, 16 Artificial Neural Network models were optimised for HIV proteases and reverse transcriptase inhibitors, with performances on par with Stanford HIVdb. Finally, we prioritised 9 compounds with potential protease inhibitory activity using virtual screening and molecular dynamics (MD) to additionally suggest a promising modification to one of the compounds. This yielded another molecule inhibiting equally well both opened and closed receptor target conformations, whereby each of the compounds had been selected against an array of multi-drug-resistant receptor variants. While a main hurdle was a lack of non-B subtype data, our findings, especially from the statistically-guided network analysis, may extrapolate to a certain extent to them as the level of conservation was very high within subtype B, despite all the present variations. This network construction method lays down a sensitive approach for analysing a pair of alternate phenotypes for which complex patterns prevail, given a sufficient number of experimental units. During the course of research a weighted contact mapping tool was developed to compare renin-angiotensinogen variants and packaged as part of the MD-TASK tool suite. Finally the functionality, compatibility and performance of the MODE-TASK tool were evaluated and confirmed for both Python2.7.x and Python3.x, for the analysis of normals modes from single protein structures and essential modes from MD trajectories. These techniques and tools collectively add onto the conventional means of MD analysis.
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- Authors: Sheik Amamuddy, Olivier Serge André
- Date: 2020
- Subjects: Machine learning , Molecules -- Models , Data mining , Neural networks (Computer science) , Antiretroviral agents , Protease inhibitors , Drug resistance , Multidrug resistance , Molecular dynamics , Renin-angiotensin system , HIV (Viruses) -- South Africa , HIV (Viruses) -- Social aspects -- South Africa , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115964 , vital:34282
- Description: Millions are affected with the Human Immunodeficiency Virus (HIV) world wide, even though the death toll is on the decline. Antiretrovirals (ARVs), more specifically protease inhibitors have shown tremendous success since their introduction into therapy since the mid 1990’s by slowing down progression to the Acquired Immune Deficiency Syndrome (AIDS). However, Drug Resistance Mutations (DRMs) are constantly selected for due to viral adaptation, making drugs less effective over time. The current challenge is to manage the infection optimally with a limited set of drugs, with differing associated levels of toxicities in the face of a virus that (1) exists as a quasispecies, (2) may transmit acquired DRMs to drug-naive individuals and (3) that can manifest class-wide resistance due to similarities in design. The presence of latent reservoirs, unawareness of infection status, education and various socio-economic factors make the problem even more complex. Adequate timing and choice of drug prescription together with treatment adherence are very important as drug toxicities, drug failure and sub-optimal treatment regimens leave room for further development of drug resistance. While CD4 cell count and the determination of viral load from patients in resource-limited settings are very helpful to track how well a patient’s immune system is able to keep the virus in check, they can be lengthy in determining whether an ARV is effective. Phenosense assay kits answer this problem using viruses engineered to contain the patient sequences and evaluating their growth in the presence of different ARVs, but this can be expensive and too involved for routine checks. As a cheaper and faster alternative, genotypic assays provide similar information from HIV pol sequences obtained from blood samples, inferring ARV efficacy on the basis of drug resistance mutation patterns. However, these are inherently complex and the various methods of in silico prediction, such as Geno2pheno, REGA and Stanford HIVdb do not always agree in every case, even though this gap decreases as the list of resistance mutations is updated. A major gap in HIV treatment is that the information used for predicting drug resistance is mainly computed from data containing an overwhelming majority of B subtype HIV, when these only comprise about 12% of the worldwide HIV infections. In addition to growing evidence that drug resistance is subtype-related, it is intuitive to hypothesize that as subtyping is a phylogenetic classification, the more divergent a subtype is from the strains used in training prediction models, the less their resistance profiles would correlate. For the aforementioned reasons, we used a multi-faceted approach to attack the virus in multiple ways. This research aimed to (1) improve resistance prediction methods by focusing solely on the available subtype, (2) mine structural information pertaining to resistance in order to find any exploitable weak points and increase knowledge of the mechanistic processes of drug resistance in HIV protease. Finally, (3) we screen for protease inhibitors amongst a database of natural compounds [the South African natural compound database (SANCDB)] to find molecules or molecular properties usable to come up with improved inhibition against the drug target. In this work, structural information was mined using the Anisotropic Network Model, Dynamics Cross-Correlation, Perturbation Response Scanning, residue contact network analysis and the radius of gyration. These methods failed to give any resistance-associated patterns in terms of natural movement, internal correlated motions, residue perturbation response, relational behaviour and global compaction respectively. Applications of drug docking, homology-modelling and energy minimization for generating features suitable for machine-learning were not very promising, and rather suggest that the value of binding energies by themselves from Vina may not be very reliable quantitatively. All these failures lead to a refinement that resulted in a highly sensitive statistically-guided network construction and analysis, which leads to key findings in the early dynamics associated with resistance across all PI drugs. The latter experiment unravelled a conserved lateral expansion motion occurring at the flap elbows, and an associated contraction that drives the base of the dimerization domain towards the catalytic site’s floor in the case of drug resistance. Interestingly, we found that despite the conserved movement, bond angles were degenerate. Alongside, 16 Artificial Neural Network models were optimised for HIV proteases and reverse transcriptase inhibitors, with performances on par with Stanford HIVdb. Finally, we prioritised 9 compounds with potential protease inhibitory activity using virtual screening and molecular dynamics (MD) to additionally suggest a promising modification to one of the compounds. This yielded another molecule inhibiting equally well both opened and closed receptor target conformations, whereby each of the compounds had been selected against an array of multi-drug-resistant receptor variants. While a main hurdle was a lack of non-B subtype data, our findings, especially from the statistically-guided network analysis, may extrapolate to a certain extent to them as the level of conservation was very high within subtype B, despite all the present variations. This network construction method lays down a sensitive approach for analysing a pair of alternate phenotypes for which complex patterns prevail, given a sufficient number of experimental units. During the course of research a weighted contact mapping tool was developed to compare renin-angiotensinogen variants and packaged as part of the MD-TASK tool suite. Finally the functionality, compatibility and performance of the MODE-TASK tool were evaluated and confirmed for both Python2.7.x and Python3.x, for the analysis of normals modes from single protein structures and essential modes from MD trajectories. These techniques and tools collectively add onto the conventional means of MD analysis.
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Application of quality by design principles for optimizing process variables of Extrusion and Spheronization of a Captopril Pellet Formulation:
- Veerubhotla, Krishna, Walker, Roderick B
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
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- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
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Arid-adapted paradiaptomid copepods contribute to mosquito regulation
- Cuthbert, Ross N, Wasserman, Ryan J, Dalu, Tatenda
- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443260 , vital:74103 , https://hdl.handle.net/10520/ejc-afzoo-v55-n3-a1
- Description: We are writing to describe the predatory potential of calanoid copepods for the regulation of mosquito larval populations in aquatic environments. Mosquito-borne diseases continue to drive unparalleled human morbidity and mortality (Ferguson 2018), and directly threaten other wildlife (George et al. 2015). This disease burden is most concentrated in Sub-Saharan Africa, where aquatic habitats exploited by mosquitoes are often temporary and, under natural conditions, characterised by arid-adapted ecological communities. These communities can be predator rich, contributing to the regulation of aquatic larval mosquito populations and therefore the adult vectors of the diseases at the landscape scale. A newly described southern African copepod species, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 (Paradiaptominae) (Figure 1), has been identified as an efficacious predatory agent for the natural regulation of medically important mosquito populations in temporary aquatic environments (Cuthbert et al. 2018).
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- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443260 , vital:74103 , https://hdl.handle.net/10520/ejc-afzoo-v55-n3-a1
- Description: We are writing to describe the predatory potential of calanoid copepods for the regulation of mosquito larval populations in aquatic environments. Mosquito-borne diseases continue to drive unparalleled human morbidity and mortality (Ferguson 2018), and directly threaten other wildlife (George et al. 2015). This disease burden is most concentrated in Sub-Saharan Africa, where aquatic habitats exploited by mosquitoes are often temporary and, under natural conditions, characterised by arid-adapted ecological communities. These communities can be predator rich, contributing to the regulation of aquatic larval mosquito populations and therefore the adult vectors of the diseases at the landscape scale. A newly described southern African copepod species, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 (Paradiaptominae) (Figure 1), has been identified as an efficacious predatory agent for the natural regulation of medically important mosquito populations in temporary aquatic environments (Cuthbert et al. 2018).
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Assessing community structure and trophic interrelationships in three differently impacted headwater streams in the AmatholeWinterberg freshwater ecoregion, South Africa
- Authors: Matomela, Nonjabulo Happy
- Date: 2020
- Subjects: Stream ecology -- South Africa -- Eastern Cape , Freshwater animals -- Ecology -- South Africa -- Eastern Cape , Kat River (South Africa) -- , Lushington River (South Africa) , Elands River (South Africa) , Eyre River (South Africa) , Food chains (Ecology) -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/147653 , vital:38658
- Description: Afromontane regions represent some of the highly threatened ecosystems on the planet as they harbour endemic and often relic freshwater fauna. These ecologically sensitive ecosystems have been altered by multiple impacts, including invasion by non-native fishes, replacement of diverse indigenous vegetation with monoculture plantations, agricultural and mining activities, hydrological modifications, and degradation of instream habitats, with potential detrimental effects on aquatic community structures and food web dynamics. The aim of the present study was to compare spatio-temporal patterns of macroinvertebrate and fish communities as well as food web dynamics in three differently impacted headwater tributaries of the Kat River in the Amathole-Winterberg freshwater ecoregion in the Eastern Cape Province of South Africa. The upper Kat River catchment was the ideal model for purposes of the present study as it contains streams with varying degrees of human impact. The streams considered in the present study were (i) the Eyre River which was considered to closely represent near-natural conditions as it is the least impacted stream in this catchment, with the riparian zone dominated by relatively intact and diverse native woody vegetation, (ii) the Elands River whose catchment has been altered by agricultural activities, and (iii) the Lushington River, whose riparian zone has been heavily invaded by black wattle. The three headwater streams were generally distinguished based on the physical-chemical variables. The Elands River was characterised by high conductivity and total dissolved solids (TDS). In addition, the Elands River was more alkaline and relatively warmer than the other two rivers. This suggested the negative influence of agriculture activities on the water quality in the Elands River. In general, the Lushington and Eyre rivers had comparable physical and chemical variables. However, the Lushington River was generally characterised by low streamflow, likely as a consequent of black wattle which is known for altering hydrological regimes of streams .The Eyre River and Lushington River were comparable in terms of macroinvertebrate richness and diversity, whereas the Elands River was characterised by low macroinvertebrate diversity and richness. Redundancy analysis indicated that the macroinvertebrate communities were mostly influenced by seasonality, with land-use accounting for a small but significant difference in community composition. In comparison, the generalised linear mixed-effects models (GLMMs) showed that chubbyhead barb abundance was significantly influenced by land-use patterns. Evaluation of food web dynamics using stable isotope analysis revealed that the food web structure in the three rivers differed substantially as a result of land-use. Specifically, the Eyre River was characterised by less variation in stable isotope values of basal food sources and consequently, the consumer groups had a narrow isotopic breadth. In contrast, the Elands River was characterised by a wide variation in basal food sources and therefore, a wider isotopic breadth for consumers. The Lushington River was spatially variable in terms of basal sources and isotopic breadth for consumers. The study concluded that food webs and trophic interrelationships were a more informative indicator of land-use than community structure was in evaluating the impact of land-use patterns on aquatic communities. In addition, future studies should seek to investigate food webs interrelationships in addition to community structure to infer a more conclusive river assessment.
- Full Text:
- Authors: Matomela, Nonjabulo Happy
- Date: 2020
- Subjects: Stream ecology -- South Africa -- Eastern Cape , Freshwater animals -- Ecology -- South Africa -- Eastern Cape , Kat River (South Africa) -- , Lushington River (South Africa) , Elands River (South Africa) , Eyre River (South Africa) , Food chains (Ecology) -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/147653 , vital:38658
- Description: Afromontane regions represent some of the highly threatened ecosystems on the planet as they harbour endemic and often relic freshwater fauna. These ecologically sensitive ecosystems have been altered by multiple impacts, including invasion by non-native fishes, replacement of diverse indigenous vegetation with monoculture plantations, agricultural and mining activities, hydrological modifications, and degradation of instream habitats, with potential detrimental effects on aquatic community structures and food web dynamics. The aim of the present study was to compare spatio-temporal patterns of macroinvertebrate and fish communities as well as food web dynamics in three differently impacted headwater tributaries of the Kat River in the Amathole-Winterberg freshwater ecoregion in the Eastern Cape Province of South Africa. The upper Kat River catchment was the ideal model for purposes of the present study as it contains streams with varying degrees of human impact. The streams considered in the present study were (i) the Eyre River which was considered to closely represent near-natural conditions as it is the least impacted stream in this catchment, with the riparian zone dominated by relatively intact and diverse native woody vegetation, (ii) the Elands River whose catchment has been altered by agricultural activities, and (iii) the Lushington River, whose riparian zone has been heavily invaded by black wattle. The three headwater streams were generally distinguished based on the physical-chemical variables. The Elands River was characterised by high conductivity and total dissolved solids (TDS). In addition, the Elands River was more alkaline and relatively warmer than the other two rivers. This suggested the negative influence of agriculture activities on the water quality in the Elands River. In general, the Lushington and Eyre rivers had comparable physical and chemical variables. However, the Lushington River was generally characterised by low streamflow, likely as a consequent of black wattle which is known for altering hydrological regimes of streams .The Eyre River and Lushington River were comparable in terms of macroinvertebrate richness and diversity, whereas the Elands River was characterised by low macroinvertebrate diversity and richness. Redundancy analysis indicated that the macroinvertebrate communities were mostly influenced by seasonality, with land-use accounting for a small but significant difference in community composition. In comparison, the generalised linear mixed-effects models (GLMMs) showed that chubbyhead barb abundance was significantly influenced by land-use patterns. Evaluation of food web dynamics using stable isotope analysis revealed that the food web structure in the three rivers differed substantially as a result of land-use. Specifically, the Eyre River was characterised by less variation in stable isotope values of basal food sources and consequently, the consumer groups had a narrow isotopic breadth. In contrast, the Elands River was characterised by a wide variation in basal food sources and therefore, a wider isotopic breadth for consumers. The Lushington River was spatially variable in terms of basal sources and isotopic breadth for consumers. The study concluded that food webs and trophic interrelationships were a more informative indicator of land-use than community structure was in evaluating the impact of land-use patterns on aquatic communities. In addition, future studies should seek to investigate food webs interrelationships in addition to community structure to infer a more conclusive river assessment.
- Full Text: