Production of Cydia pomonella granulovirus (CpGV) in a heteralogous host, Thaumatotibia Leucotreta (Meyrick) (False codling moth)
- Authors: Chambers, Craig Brian
- Date: 2015
- Subjects: Cryptophlebia leucotreta -- South Africa , Codling moth -- South Africa , Apples -- Diseases and pests -- South Africa , Codling moth -- Biological control -- South Africa , Insect pests -- Biological control -- South Africa , Biological pest control agents -- South Africa , Baculoviruses -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5935 , http://hdl.handle.net/10962/d1017906
- Description: Cydia pomonella (Linnaeus) (Family: Tortricidae), the codling moth, is considered one of the most significant pests of apples and pears worldwide, causing up to 80% crop loss in orchards if no control measures are applied. Cydia pomonella is oligophagous feeding on a number of alternate hosts including quince, walnuts, apricots, peaches, plums and nectarines. Historically the control of this pest has been achieved with the use of various chemical control strategies which have maintained pest levels below the economic threshold at a relatively low cost to the grower. However, there are serious concerns surrounding the use of chemical insecticides including the development of resistance in insect populations, the banning of various insecticides, regulations for lowering of the maximum residue level and employee and consumer safety. For this reason, alternate measures of control are slowly being adopted by growers such as mating disruption, cultural methods and the use of baculovirus biopesticides as part of integrated pest management programmes. The reluctance of growers to accept baculovirus or other biological control products in the past has been due to questionable product quality and inconsistencies in their field performance. Moreover, the development and application of biological control products is more costly than the use of chemical alternatives. Baculoviruses are arthropod specific viruses that are highly virulent to a number of lepidopteran species. Due to the virulence and host specificity of baculoviruses, Cydia pomonella granulovirus has been extensively and successfully used as part of integrated pest management systems for the control of C. pomonella in Europe and around the world, including South Africa. Commercial formulations have been typically based on the Mexican strain of CpGV. However due to long-term multiple applications of CpGV and the reliance on CpGV in organic farming practices in Europe, resistance to the CpGV-M strain has developed in a number of field populations of C. pomonella. This study aimed to identify and characterize novel isolates of CpGV in South Africa and compare their virulence with the commercial standard CpGV-M. Secondly, since C. pomonella is difficult to culture on a large scale, an alternate method of CpGV production was investigated in order to determine if CpGV could be produced more efficiently and at a reduced cost without negatively impacting the quality of the product. Several isolates of CpGV were recovered either from field collected larvae or from a laboratory-reared C. pomonella colony. Characterisation of DNA profiles using a variety of restriction enzymes revealed that only a single isolate, CpGV-SA, was genetically different from the Mexican strain of the virus used in the commercially available CpGV based products in South Africa. In dose-response bioassays using CpGV-SA, LC₅₀ and LC₉₀ values for neonate C. pomonella larvae were 3.18 x 10³ OBs/ml and 7.33 x 10⁴ respectively. A comparison of these values with those of CpGV-M indicated no significant difference in the virulence of the two isolates under laboratory conditions. This is a first report of a genetically distinct CpGV isolate in South Africa. The biological activity and novelty of CpGV-SA makes this isolate a potentially important tool for CpGV resistance management in South Africa. In order to justify production of CpGV in an alternative host, studies on the comparative biological performance of C. pomonella and T. leucotreta based on oviposition, time to hatch, larval developmental times and rearing efficiency as well as production costs were performed. Thaumatotibia leucotreta was found to be more fecund and to have significantly shorter egg and larval developmental times. In addition, larval production per unit of artificial diet was significantly higher than for C. pomonella. This resulted in T. leucotreta being more cost effective to produce with implications for reduced insectary space, sanitation practices as well as the labour component of production. Virus yield data generated by inoculation both C. pomonella and T. leucotreta with nine concentrations of CpGV resulted in comparable virus yields, justifying the continuation of the research into production of CpGV in T. leucotreta. It was important to determine the LC and LT values required for mass production of CpGV in late instar T. leucotreta larvae. Dose- and time-response bioassays with CpGV-M were conducted on artificial diet to determine these values. Fourth instar LC₅₀ and LC₉₀ values were 5.96 x 10³ OBs/ml and 1.64 x 10⁵ OBs/ml respectively. LT50 and LT90 values were 81.10 hours and 88.58 hours respectively. Fifth instar LC₅₀ and LC₉₀ values were 6.88 x 10⁴ OBs/ml and 9.78 x 10⁶ OBs/ml respectively. LT₅₀ and LT₉₀ values were 111.56 hours and 137.57 hours respectively. Virus produced in fourth instar T. leucotreta larvae was bioassayed against C. pomonella neonate larvae and compared to CpGV-M to establish if production in the heterologous host negatively affected the virulence of the isolate. No significant difference in virulence was observed between virus produced in T. leucotreta and that produced in C. pomonella. The data generated in the bioassays was used in CpGV mass production trials to evaluate production. All production methods tested produced acceptable virus yields. To examine the quality of the virus product, genomic DNA was extracted from larval cadavers and subjected to REN analysis with HindIII. The resulting DNA profiles indicated that the virus product was contaminated with the homologous virus, CrleGV. Based on the above results, the use of T. leucotreta as an alternate host for the in vivo production of CpGV on a commercial basis is not at this stage viable and requires further investigation before this production methodology can be reliable used to produce CpGV. However, this study has shown that CpGV can be produced in a homologous host, T. leucotreta and significant strides have been made towards developing a set of quality control standards that are essential for further development of successful production methodology. Finally a novel isolate of CpGV has been identified with comparable virulence to the CpGV-M. This is an important finding as it has broad reaching implications for resistance management of CpGV products in South Africa.
- Full Text:
- Date Issued: 2015
- Authors: Chambers, Craig Brian
- Date: 2015
- Subjects: Cryptophlebia leucotreta -- South Africa , Codling moth -- South Africa , Apples -- Diseases and pests -- South Africa , Codling moth -- Biological control -- South Africa , Insect pests -- Biological control -- South Africa , Biological pest control agents -- South Africa , Baculoviruses -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5935 , http://hdl.handle.net/10962/d1017906
- Description: Cydia pomonella (Linnaeus) (Family: Tortricidae), the codling moth, is considered one of the most significant pests of apples and pears worldwide, causing up to 80% crop loss in orchards if no control measures are applied. Cydia pomonella is oligophagous feeding on a number of alternate hosts including quince, walnuts, apricots, peaches, plums and nectarines. Historically the control of this pest has been achieved with the use of various chemical control strategies which have maintained pest levels below the economic threshold at a relatively low cost to the grower. However, there are serious concerns surrounding the use of chemical insecticides including the development of resistance in insect populations, the banning of various insecticides, regulations for lowering of the maximum residue level and employee and consumer safety. For this reason, alternate measures of control are slowly being adopted by growers such as mating disruption, cultural methods and the use of baculovirus biopesticides as part of integrated pest management programmes. The reluctance of growers to accept baculovirus or other biological control products in the past has been due to questionable product quality and inconsistencies in their field performance. Moreover, the development and application of biological control products is more costly than the use of chemical alternatives. Baculoviruses are arthropod specific viruses that are highly virulent to a number of lepidopteran species. Due to the virulence and host specificity of baculoviruses, Cydia pomonella granulovirus has been extensively and successfully used as part of integrated pest management systems for the control of C. pomonella in Europe and around the world, including South Africa. Commercial formulations have been typically based on the Mexican strain of CpGV. However due to long-term multiple applications of CpGV and the reliance on CpGV in organic farming practices in Europe, resistance to the CpGV-M strain has developed in a number of field populations of C. pomonella. This study aimed to identify and characterize novel isolates of CpGV in South Africa and compare their virulence with the commercial standard CpGV-M. Secondly, since C. pomonella is difficult to culture on a large scale, an alternate method of CpGV production was investigated in order to determine if CpGV could be produced more efficiently and at a reduced cost without negatively impacting the quality of the product. Several isolates of CpGV were recovered either from field collected larvae or from a laboratory-reared C. pomonella colony. Characterisation of DNA profiles using a variety of restriction enzymes revealed that only a single isolate, CpGV-SA, was genetically different from the Mexican strain of the virus used in the commercially available CpGV based products in South Africa. In dose-response bioassays using CpGV-SA, LC₅₀ and LC₉₀ values for neonate C. pomonella larvae were 3.18 x 10³ OBs/ml and 7.33 x 10⁴ respectively. A comparison of these values with those of CpGV-M indicated no significant difference in the virulence of the two isolates under laboratory conditions. This is a first report of a genetically distinct CpGV isolate in South Africa. The biological activity and novelty of CpGV-SA makes this isolate a potentially important tool for CpGV resistance management in South Africa. In order to justify production of CpGV in an alternative host, studies on the comparative biological performance of C. pomonella and T. leucotreta based on oviposition, time to hatch, larval developmental times and rearing efficiency as well as production costs were performed. Thaumatotibia leucotreta was found to be more fecund and to have significantly shorter egg and larval developmental times. In addition, larval production per unit of artificial diet was significantly higher than for C. pomonella. This resulted in T. leucotreta being more cost effective to produce with implications for reduced insectary space, sanitation practices as well as the labour component of production. Virus yield data generated by inoculation both C. pomonella and T. leucotreta with nine concentrations of CpGV resulted in comparable virus yields, justifying the continuation of the research into production of CpGV in T. leucotreta. It was important to determine the LC and LT values required for mass production of CpGV in late instar T. leucotreta larvae. Dose- and time-response bioassays with CpGV-M were conducted on artificial diet to determine these values. Fourth instar LC₅₀ and LC₉₀ values were 5.96 x 10³ OBs/ml and 1.64 x 10⁵ OBs/ml respectively. LT50 and LT90 values were 81.10 hours and 88.58 hours respectively. Fifth instar LC₅₀ and LC₉₀ values were 6.88 x 10⁴ OBs/ml and 9.78 x 10⁶ OBs/ml respectively. LT₅₀ and LT₉₀ values were 111.56 hours and 137.57 hours respectively. Virus produced in fourth instar T. leucotreta larvae was bioassayed against C. pomonella neonate larvae and compared to CpGV-M to establish if production in the heterologous host negatively affected the virulence of the isolate. No significant difference in virulence was observed between virus produced in T. leucotreta and that produced in C. pomonella. The data generated in the bioassays was used in CpGV mass production trials to evaluate production. All production methods tested produced acceptable virus yields. To examine the quality of the virus product, genomic DNA was extracted from larval cadavers and subjected to REN analysis with HindIII. The resulting DNA profiles indicated that the virus product was contaminated with the homologous virus, CrleGV. Based on the above results, the use of T. leucotreta as an alternate host for the in vivo production of CpGV on a commercial basis is not at this stage viable and requires further investigation before this production methodology can be reliable used to produce CpGV. However, this study has shown that CpGV can be produced in a homologous host, T. leucotreta and significant strides have been made towards developing a set of quality control standards that are essential for further development of successful production methodology. Finally a novel isolate of CpGV has been identified with comparable virulence to the CpGV-M. This is an important finding as it has broad reaching implications for resistance management of CpGV products in South Africa.
- Full Text:
- Date Issued: 2015
Re-imagining the nation
- Mngomezulu, Nosipho Sthabiso Thandiwe
- Authors: Mngomezulu, Nosipho Sthabiso Thandiwe
- Date: 2015
- Subjects: Mauritius -- Truth and Justice Commission , Nationalism -- Mauritius , National characteristics, Mauritian , Social justice -- Mauritius , Youth -- Mauritius -- Social conditions , Youth -- Mauritius -- Attitudes , Mauritius -- Politics and government -- 1992- , Ethnicity -- Mauritius
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2124 , http://hdl.handle.net/10962/d1019999
- Description: This thesis examines young people’s constructions of nationhood in Mauritius. In 2008, the Mauritian government instituted a Truth and Justice Commission (TJC), set up to investigate the consequences of slavery and indentured labour. Through the Truth and Justice Commission, the Mauritian government indicated its desire to achieve social justice and national unity. Drawing on developments in studies of national identification practices in the 21st Century, this thesis addresses the question of young Mauritian’s locally and globally informed identification practices and asks how their unofficial narratives of nationhood challenge, or divert, or relate to official state narratives of nationhood. The basis of the study emerges from data collected from 132 participants during fieldwork in multiple fieldsites from May to September 2010 as well as research on Mauritian youth on-line from 2011-2014. The advent of the TJC offers an ideal moment to evaluate the dynamics of post-colonial nation-building and nationhood in a selfstyled multi-cultural state. Nationhood, does not exist apriori to the constructions of narratives of the nation, thus the stories told about the nation, imagine the nation into being. By situating the Truth and Justice Commission and other official state narratives alongside young people’s narratives, I argue that contemporary narratives of nationhood in Mauritius represent an intergenerational struggle to define the meaning of the past in the present and consequently outline the future. Reflecting on the ideas and socio-economic and political processes that induce national consciousness, I argue that young people’s narratives of everyday lived experiences are vital for an interpretation of how nationhood is produced in everyday life. The cultural projects of young people – often rendered as liminal or marginal – offer a critical vantage point from where to read constructions of nationhood. Far from being growing pains or childish games, young people’s identity making practices are what Sherry B. Ortner has called “serious games.” This research suggests that official state government narratives of multicultural nationhood in Mauritius narrowly define national identification along communal loyalties, overlooking the dynamism of interculturality and transnationalism in daily practice on the island. Although communalism and rigid colonial interpretations of ethnicity attempt to police and limit the possibilities of alternative modes of being in Mauritius, young people’s identification practices question, challenge, and threaten to disrupt official discourses of ethnic identification in Mauritius Scholarly investigations of young peoples’ lived experiences of nationhood extend theoretical and methodological frames for the study of nationalized subjects and deepen the understanding of the construction of national consciousness. The construction of nationhood always involves narratives of some sort – scholarship on this area has usually focused on official state narratives from social theorists, state governments, and state elites. I argue for the importance of considering subjectivity and lived experience in conceptions of nationhood. In contemporary post-colonial societies, young people are the numerical majority, however, their voices are seldom represented in theories and narratives of nationhood. Whilst young people may appear in state policies (especially education) and official narratives about the future of the nation, their creative imagining and reimagining of narratives of selfhood is often ignored. I examine how young people increasingly are aware of their transnational connections, through participation in transnational youth cultures, and they are consequently increasingly multi-lingual and multicultural. Fixed notions of ethnic identification and discourses of trauma are not at the forefront of young people’s identification of selfhood, rather their ability to take advantage of their multiply situated identification processes allows them new means to evade and transform these narratives. Their identification of selfhood is characterised by a greater degree of dynamism than previous generations had access to, and thus they do not only identify themselves through officially sanctioned national forms of identification. Loyalty to nationhood is thus less predictable, and young people represent a potential threat to the continuation of older forms of nationhood. While official narratives of nationhood may manipulate ethnic and racial cleavages to secure old loyalties, not all young people are persuaded by these notions
- Full Text:
- Date Issued: 2015
- Authors: Mngomezulu, Nosipho Sthabiso Thandiwe
- Date: 2015
- Subjects: Mauritius -- Truth and Justice Commission , Nationalism -- Mauritius , National characteristics, Mauritian , Social justice -- Mauritius , Youth -- Mauritius -- Social conditions , Youth -- Mauritius -- Attitudes , Mauritius -- Politics and government -- 1992- , Ethnicity -- Mauritius
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2124 , http://hdl.handle.net/10962/d1019999
- Description: This thesis examines young people’s constructions of nationhood in Mauritius. In 2008, the Mauritian government instituted a Truth and Justice Commission (TJC), set up to investigate the consequences of slavery and indentured labour. Through the Truth and Justice Commission, the Mauritian government indicated its desire to achieve social justice and national unity. Drawing on developments in studies of national identification practices in the 21st Century, this thesis addresses the question of young Mauritian’s locally and globally informed identification practices and asks how their unofficial narratives of nationhood challenge, or divert, or relate to official state narratives of nationhood. The basis of the study emerges from data collected from 132 participants during fieldwork in multiple fieldsites from May to September 2010 as well as research on Mauritian youth on-line from 2011-2014. The advent of the TJC offers an ideal moment to evaluate the dynamics of post-colonial nation-building and nationhood in a selfstyled multi-cultural state. Nationhood, does not exist apriori to the constructions of narratives of the nation, thus the stories told about the nation, imagine the nation into being. By situating the Truth and Justice Commission and other official state narratives alongside young people’s narratives, I argue that contemporary narratives of nationhood in Mauritius represent an intergenerational struggle to define the meaning of the past in the present and consequently outline the future. Reflecting on the ideas and socio-economic and political processes that induce national consciousness, I argue that young people’s narratives of everyday lived experiences are vital for an interpretation of how nationhood is produced in everyday life. The cultural projects of young people – often rendered as liminal or marginal – offer a critical vantage point from where to read constructions of nationhood. Far from being growing pains or childish games, young people’s identity making practices are what Sherry B. Ortner has called “serious games.” This research suggests that official state government narratives of multicultural nationhood in Mauritius narrowly define national identification along communal loyalties, overlooking the dynamism of interculturality and transnationalism in daily practice on the island. Although communalism and rigid colonial interpretations of ethnicity attempt to police and limit the possibilities of alternative modes of being in Mauritius, young people’s identification practices question, challenge, and threaten to disrupt official discourses of ethnic identification in Mauritius Scholarly investigations of young peoples’ lived experiences of nationhood extend theoretical and methodological frames for the study of nationalized subjects and deepen the understanding of the construction of national consciousness. The construction of nationhood always involves narratives of some sort – scholarship on this area has usually focused on official state narratives from social theorists, state governments, and state elites. I argue for the importance of considering subjectivity and lived experience in conceptions of nationhood. In contemporary post-colonial societies, young people are the numerical majority, however, their voices are seldom represented in theories and narratives of nationhood. Whilst young people may appear in state policies (especially education) and official narratives about the future of the nation, their creative imagining and reimagining of narratives of selfhood is often ignored. I examine how young people increasingly are aware of their transnational connections, through participation in transnational youth cultures, and they are consequently increasingly multi-lingual and multicultural. Fixed notions of ethnic identification and discourses of trauma are not at the forefront of young people’s identification of selfhood, rather their ability to take advantage of their multiply situated identification processes allows them new means to evade and transform these narratives. Their identification of selfhood is characterised by a greater degree of dynamism than previous generations had access to, and thus they do not only identify themselves through officially sanctioned national forms of identification. Loyalty to nationhood is thus less predictable, and young people represent a potential threat to the continuation of older forms of nationhood. While official narratives of nationhood may manipulate ethnic and racial cleavages to secure old loyalties, not all young people are persuaded by these notions
- Full Text:
- Date Issued: 2015
Reading identities: a case study of grade 8 learners' interactions in a reading club
- Scheckle, Eileen Margaret Agnes
- Authors: Scheckle, Eileen Margaret Agnes
- Date: 2015
- Subjects: Group reading -- South Africa , Reading (Middle school) -- South Africa , Literacy programs -- South Africa , Identity (Psychology) in adolescence , Identity (Psychology) in adolescence -- South Africa , Discourse analysis -- Social aspects , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1329 , http://hdl.handle.net/10962/d1017766
- Description: This study offers an account of reading clubs as a literacy intervention in a grade 8 English class at a former ‘Coloured’ high school in South Africa. Using Margaret Archer’s social realist methodology, it examines different practices of ‘reading’ used by learners in talking and writing about text. Archer’s analytical dualism and morphogenetic model provided an explanatory framework for this study. Analytical dualism allows for the separation of the parts (structural and cultural elements) from the people (the grade 8 learners) so as to analyse the interplay between structure and culture. The morphogenetic model recognises that antecedent structures predate this, and any study but that through the exercise of agency, morphogenesis, in the form of structural elaboration or morphostasis in the form of continuity, may occur. This study used a New Literacies perspective based on an ideological model of literacy which recognises many different literacies, in addition to dominant school literacies. Learners’ talk about books as well as personal journal writing provided an insight into what cultural mechanisms and powers children bring to the reading of novels. Understandings of discourses as well as of Gee’s (1990; 2008) construct of Discourse provided a framework for examining learners’ identities and shifts as readers. The data in this study, which is presented through a series of vignettes, found that grade 8 learners use many different experiences and draw on different discourses when making sense of texts. Through the separation of the structural and cultural components, this research could explore how reading clubs as structures enabled learners to access different discourses from the domain of culture. Through the process and engagement in the reading clubs, following Gee (2000b), learners were attributed affinity, discoursal and institutional identities as readers. It was found, in the course of the study, that providing a safe space, scaffolding, multiple opportunities to practice and a variety of reading material, helped learners to access and appropriate dominant literacies. In addition, learners need a repertoire of literacy practices to draw from as successful reading needs flexibility and adaptability. Reading and writing inform each other and through gradual induction into literary writing, learners began to appropriate and approximate dominant literacy practices. Following others who have contributed to the field of New Literacy Studies (Heath, 1983; Street, 1984; Gee 1990; Prinsloo & Breier, 1996), this study would suggest that literacies of traditionally underserved communities should not be considered in deficit terms. Instead these need to be understood as resources for negotiating meaning making and as tools or mechanisms to access dominant discourse practices. In addition the resilience and competition from Discourses of popular culture need to be recognised and developed as tools to access school literacies.
- Full Text:
- Date Issued: 2015
- Authors: Scheckle, Eileen Margaret Agnes
- Date: 2015
- Subjects: Group reading -- South Africa , Reading (Middle school) -- South Africa , Literacy programs -- South Africa , Identity (Psychology) in adolescence , Identity (Psychology) in adolescence -- South Africa , Discourse analysis -- Social aspects , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1329 , http://hdl.handle.net/10962/d1017766
- Description: This study offers an account of reading clubs as a literacy intervention in a grade 8 English class at a former ‘Coloured’ high school in South Africa. Using Margaret Archer’s social realist methodology, it examines different practices of ‘reading’ used by learners in talking and writing about text. Archer’s analytical dualism and morphogenetic model provided an explanatory framework for this study. Analytical dualism allows for the separation of the parts (structural and cultural elements) from the people (the grade 8 learners) so as to analyse the interplay between structure and culture. The morphogenetic model recognises that antecedent structures predate this, and any study but that through the exercise of agency, morphogenesis, in the form of structural elaboration or morphostasis in the form of continuity, may occur. This study used a New Literacies perspective based on an ideological model of literacy which recognises many different literacies, in addition to dominant school literacies. Learners’ talk about books as well as personal journal writing provided an insight into what cultural mechanisms and powers children bring to the reading of novels. Understandings of discourses as well as of Gee’s (1990; 2008) construct of Discourse provided a framework for examining learners’ identities and shifts as readers. The data in this study, which is presented through a series of vignettes, found that grade 8 learners use many different experiences and draw on different discourses when making sense of texts. Through the separation of the structural and cultural components, this research could explore how reading clubs as structures enabled learners to access different discourses from the domain of culture. Through the process and engagement in the reading clubs, following Gee (2000b), learners were attributed affinity, discoursal and institutional identities as readers. It was found, in the course of the study, that providing a safe space, scaffolding, multiple opportunities to practice and a variety of reading material, helped learners to access and appropriate dominant literacies. In addition, learners need a repertoire of literacy practices to draw from as successful reading needs flexibility and adaptability. Reading and writing inform each other and through gradual induction into literary writing, learners began to appropriate and approximate dominant literacy practices. Following others who have contributed to the field of New Literacy Studies (Heath, 1983; Street, 1984; Gee 1990; Prinsloo & Breier, 1996), this study would suggest that literacies of traditionally underserved communities should not be considered in deficit terms. Instead these need to be understood as resources for negotiating meaning making and as tools or mechanisms to access dominant discourse practices. In addition the resilience and competition from Discourses of popular culture need to be recognised and developed as tools to access school literacies.
- Full Text:
- Date Issued: 2015
Rethinking care and support of 'vulnerable' learners in the age of HIV and AIDS : an arts-based approach
- Authors: Khanare, Fumane Portia
- Date: 2015
- Subjects: School children -- Care , AIDS (Disease) in children -- Prevention , Rural schools
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9573 , http://hdl.handle.net/10948/d1017612
- Description: This study explores secondary school children’s constructions of care and support provided for ‘vulnerable’ schoolchildren in the age of HIV and AIDS. The study attempts to respond to the following two research questions: What are secondary school children’s constructions of care and support in a rural school context in the age of HIV and AIDS? How can the use of participatory arts-based research enable agency in the lives of ‘vulnerable’ secondary school children in a rural school context in the age of HIV and AIDS? The provision of care and support for ‘vulnerable’ school children is of key concern in South African schools since the number of ‘vulnerable’ children is rising because of the increase in the prevalence of HIV and AIDS, which renders many school children ‘vulnerable’. Schools are mandated by departmental policy to provide care and support to ‘vulnerable’ school children, but they are challenged in their implementation of this policy, which leaves ‘vulnerable’ school children inadequately cared for and supported. The input from school children is often not drawn upon, and this hampers the effectiveness of the provision of care and support. This qualitative study is positioned within a critical paradigm, and employs a participatory arts-based research methodology in its intention to take an approach based on the notion of research as intervention. Twenty Grade 11 male and female school children aged 16 to 21, from two secondary schools in the rural Vulindlela district in KwaZulu-Natal, were purposively selected, using inclusion criteria. The Life Orientation teachers assisted in identifying participants from the school register of ‘vulnerable’ schoolchildren. This did not mean that they were living with HIV or AIDS, but that they were ‘vulnerable’, and at risk of dropping out of school. The study made use of a multimodal approach of data generation with the school children, in which several visual methods, such as drawing, photovoice, and collage, as well as reflective free writing, were used in a participatory way as modes of inquiry, representation, and dissemination. The ethics of research with ‘vulnerable’ school children made the dictum, “do the most good” through the research important, and hence the use of the strategy of research as intervention. The data analysis involved two levels – that of the school children’s own analysis of their visual artifacts, and my overarching thematic analysis, using Tesch’s (1990) open coding. Informed by the theoretical frameworks of Bronfenbrenner’s (1979) bio-ecological systems theory and Giddens’s (1984) structuration theory, the findings show that care and support in schools is constructed as a reciprocal relationship, and they point to the importance of school children’s own agency in the provision of care and support. The findings show that school children construct themselves as both visible and invisible in relation to care and support in school, in that they receive care and support but are overlooked in terms of being able to offer input on how care and support should be provided. Furthermore, the findings indicate that school children perceive the school to be an environment that enables but also constrains the provision of care and support: the infrastructure, the safety and security, and the instructional spaces in the school do provide the basics for care and support, but the overt and covert discrimination by school children and teachers, the challenge of putting policies into practice, and the overall fragmented provision of care and support in the school are constraining. Another emerging finding from this study is that secondary school children construct themselves as being included in the strengthening of care and support in rural schools. The use of visual arts-based methods enabled the exploration of how ‘vulnerable’ school children construct care and support in a rural school; the findings also indicated how the use of visual arts-based research contributed to making a difference in the lives of ‘vulnerable’ school children: it was a joyful experience; it leveraged multiple literacies; it contributed to cooperation, collaboration, and collective construction of knowledge; and, in encouraging thought about the issue, it raised critical awareness of, and solutions to, providing care and support in the school. The findings also pointed out how the visual artifacts could be disseminated in the school, and how this could influence the well-being of the community. The findings have implications for how schools provide care and support for ‘vulnerable’ school children. The findings could be engaged with by schools and the Department of Basic Education as a tool to accomplish strengthening the provision of care and support in rural schools, so that care and support are socially and culturally embedded, and to inform policy making through an approach that can be described as being from the ground up.
- Full Text:
- Date Issued: 2015
- Authors: Khanare, Fumane Portia
- Date: 2015
- Subjects: School children -- Care , AIDS (Disease) in children -- Prevention , Rural schools
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9573 , http://hdl.handle.net/10948/d1017612
- Description: This study explores secondary school children’s constructions of care and support provided for ‘vulnerable’ schoolchildren in the age of HIV and AIDS. The study attempts to respond to the following two research questions: What are secondary school children’s constructions of care and support in a rural school context in the age of HIV and AIDS? How can the use of participatory arts-based research enable agency in the lives of ‘vulnerable’ secondary school children in a rural school context in the age of HIV and AIDS? The provision of care and support for ‘vulnerable’ school children is of key concern in South African schools since the number of ‘vulnerable’ children is rising because of the increase in the prevalence of HIV and AIDS, which renders many school children ‘vulnerable’. Schools are mandated by departmental policy to provide care and support to ‘vulnerable’ school children, but they are challenged in their implementation of this policy, which leaves ‘vulnerable’ school children inadequately cared for and supported. The input from school children is often not drawn upon, and this hampers the effectiveness of the provision of care and support. This qualitative study is positioned within a critical paradigm, and employs a participatory arts-based research methodology in its intention to take an approach based on the notion of research as intervention. Twenty Grade 11 male and female school children aged 16 to 21, from two secondary schools in the rural Vulindlela district in KwaZulu-Natal, were purposively selected, using inclusion criteria. The Life Orientation teachers assisted in identifying participants from the school register of ‘vulnerable’ schoolchildren. This did not mean that they were living with HIV or AIDS, but that they were ‘vulnerable’, and at risk of dropping out of school. The study made use of a multimodal approach of data generation with the school children, in which several visual methods, such as drawing, photovoice, and collage, as well as reflective free writing, were used in a participatory way as modes of inquiry, representation, and dissemination. The ethics of research with ‘vulnerable’ school children made the dictum, “do the most good” through the research important, and hence the use of the strategy of research as intervention. The data analysis involved two levels – that of the school children’s own analysis of their visual artifacts, and my overarching thematic analysis, using Tesch’s (1990) open coding. Informed by the theoretical frameworks of Bronfenbrenner’s (1979) bio-ecological systems theory and Giddens’s (1984) structuration theory, the findings show that care and support in schools is constructed as a reciprocal relationship, and they point to the importance of school children’s own agency in the provision of care and support. The findings show that school children construct themselves as both visible and invisible in relation to care and support in school, in that they receive care and support but are overlooked in terms of being able to offer input on how care and support should be provided. Furthermore, the findings indicate that school children perceive the school to be an environment that enables but also constrains the provision of care and support: the infrastructure, the safety and security, and the instructional spaces in the school do provide the basics for care and support, but the overt and covert discrimination by school children and teachers, the challenge of putting policies into practice, and the overall fragmented provision of care and support in the school are constraining. Another emerging finding from this study is that secondary school children construct themselves as being included in the strengthening of care and support in rural schools. The use of visual arts-based methods enabled the exploration of how ‘vulnerable’ school children construct care and support in a rural school; the findings also indicated how the use of visual arts-based research contributed to making a difference in the lives of ‘vulnerable’ school children: it was a joyful experience; it leveraged multiple literacies; it contributed to cooperation, collaboration, and collective construction of knowledge; and, in encouraging thought about the issue, it raised critical awareness of, and solutions to, providing care and support in the school. The findings also pointed out how the visual artifacts could be disseminated in the school, and how this could influence the well-being of the community. The findings have implications for how schools provide care and support for ‘vulnerable’ school children. The findings could be engaged with by schools and the Department of Basic Education as a tool to accomplish strengthening the provision of care and support in rural schools, so that care and support are socially and culturally embedded, and to inform policy making through an approach that can be described as being from the ground up.
- Full Text:
- Date Issued: 2015
Saving the Sowetan : the public interest and commercial imperatives in journalism practice
- Authors: Cowling, Lesley
- Date: 2015
- Subjects: Sowetan (Johannesburg, South Africa) , Journalism -- Economic aspects -- South Africa -- Soweto , Journalism -- Political aspects -- South Africa -- Soweto , Black newspapers -- South Africa -- Soweto , Public interest -- South Africa -- Soweto , Corporate culture -- South Africa -- Soweto , Journalistic ethics -- South Africa -- Soweto , Journalism -- Objectivity -- South Africa -- Soweto
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3540 , http://hdl.handle.net/10962/d1017781
- Description: This thesis examines the complex ways in which notions of the public interest and commercial imperatives intertwine in journalism practice. It does this through a study of the 2004 takeover and relaunch of the Sowetan newspaper, the highest circulation daily in South Africa throughout the 1990s and an institution of black public life. The ‘public interest’ and ‘the commercial’ are recurring ideas in journalism scholarship and practice, and the relaunch appeared to be a challenge to reconcile the Sowetan’s commercial challenges with its historical responsibility to a ‘nation-building’ public. However, the research shows that the public/commercial aspects of journalism were inextricably entangled with Sowetan’s organisational culture, which was the matrix through which its journalism practice was expressed. Conflict in the organisation over the changes was not simply a contest between commercial realities and the public interest, with journalists defending a responsibility to the public and managers pushing commercial solutions, but a conflict between the culture of Sowetan “insiders”, steeped in the legacy of the newspaper, and “outsiders”, employed by the new owners to effect change. Another conclusion of the research is that commercial “realities” – often conceptualised as counter to the public interest – are highly mutable. Basic conditions, such as a dependence on advertising, exist. However, media managers must choose from a range of strategies to be commercially viable, which requires risk-taking, innovation and, often, guesswork. In such situations, the ‘wall’ between media managers and senior editors is porous, as all executives must manage the relationship between business and editorial imperatives. Executives tend to overlook culture as a factor in changing organisations, but I argue that journalism could benefit from engaging with management theory and organisational psychology, which offer ways to understand the specific dynamics of the organisation. Finally, I argue that the case of the Sowetan throws into question the idea that there may be a broadly universal journalism culture. The attachment of Sowetan journalists to their particular values and practice suggests that forms of journalism evolve in certain contexts to diverge from the ‘professional’ Anglo-American modes. These ‘journalisms’ use similar terms – such as the ‘public interest’ – but operationalise them quite differently. The responsibility to the public is imagined in very different ways, but remains a significant attachment for journalists.
- Full Text:
- Date Issued: 2015
- Authors: Cowling, Lesley
- Date: 2015
- Subjects: Sowetan (Johannesburg, South Africa) , Journalism -- Economic aspects -- South Africa -- Soweto , Journalism -- Political aspects -- South Africa -- Soweto , Black newspapers -- South Africa -- Soweto , Public interest -- South Africa -- Soweto , Corporate culture -- South Africa -- Soweto , Journalistic ethics -- South Africa -- Soweto , Journalism -- Objectivity -- South Africa -- Soweto
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3540 , http://hdl.handle.net/10962/d1017781
- Description: This thesis examines the complex ways in which notions of the public interest and commercial imperatives intertwine in journalism practice. It does this through a study of the 2004 takeover and relaunch of the Sowetan newspaper, the highest circulation daily in South Africa throughout the 1990s and an institution of black public life. The ‘public interest’ and ‘the commercial’ are recurring ideas in journalism scholarship and practice, and the relaunch appeared to be a challenge to reconcile the Sowetan’s commercial challenges with its historical responsibility to a ‘nation-building’ public. However, the research shows that the public/commercial aspects of journalism were inextricably entangled with Sowetan’s organisational culture, which was the matrix through which its journalism practice was expressed. Conflict in the organisation over the changes was not simply a contest between commercial realities and the public interest, with journalists defending a responsibility to the public and managers pushing commercial solutions, but a conflict between the culture of Sowetan “insiders”, steeped in the legacy of the newspaper, and “outsiders”, employed by the new owners to effect change. Another conclusion of the research is that commercial “realities” – often conceptualised as counter to the public interest – are highly mutable. Basic conditions, such as a dependence on advertising, exist. However, media managers must choose from a range of strategies to be commercially viable, which requires risk-taking, innovation and, often, guesswork. In such situations, the ‘wall’ between media managers and senior editors is porous, as all executives must manage the relationship between business and editorial imperatives. Executives tend to overlook culture as a factor in changing organisations, but I argue that journalism could benefit from engaging with management theory and organisational psychology, which offer ways to understand the specific dynamics of the organisation. Finally, I argue that the case of the Sowetan throws into question the idea that there may be a broadly universal journalism culture. The attachment of Sowetan journalists to their particular values and practice suggests that forms of journalism evolve in certain contexts to diverge from the ‘professional’ Anglo-American modes. These ‘journalisms’ use similar terms – such as the ‘public interest’ – but operationalise them quite differently. The responsibility to the public is imagined in very different ways, but remains a significant attachment for journalists.
- Full Text:
- Date Issued: 2015
Sediment connectivity in the upper Thina Catchment, Eastern Cape, South Africa
- Van der Waal, Benjamin Cornelis Wentsel
- Authors: Van der Waal, Benjamin Cornelis Wentsel
- Date: 2015
- Subjects: Soil erosion -- South Africa -- Eastern Cape , Sedimentation and deposition -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Arroyos -- South Africa -- Eastern Cape , Sediment transport -- South Africa -- Eastern Cape , Soil conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4892 , http://hdl.handle.net/10962/d1019754
- Description: [Portion of abstract]: Sediment dynamics are influenced by transformed landscape connectivity in catchments worldwide. The upper Thina catchment, an important high rainfall resource in the northern Eastern Cape, South Africa, is an example of where ongoing subsistence farming on communal land has led to overgrazing and trampling that has initiated large erosive features (e.g. gullies) and river incision. The formation of gullies led to increased hillslope-channel connectivity and the resultant river incision decreased the channel-valley fill connectivity. These two changes in connectivity led to increased sediment export from the catchment that has various down-stream ecological and socio-economic impacts. This study investigates how the change in hillslope-channel and channel-valley fill connectivity has altered the sediment dynamics in the Vuvu catchment, a headwater tributary of the Thina River. A combination of methods were used to assess the changes in hillslope-channel and channel-valley fill connectivity. High resolution aerial images were used to map source features, such as fields, gullies, sheet erosion, landslides, roads and livestock tracks. Topographic and geological characteristics of the source features were extracted using a Geographic Information System. Furthermore, hillslope-channel pathways, such as the natural drainage network, continuous gullies, discontinuous gullies, roads and livestock tracks were mapped and analysed in terms of topographic and geological characteristics. Historic aerial images were assessed to calculate the date the larger gullies began forming. Recent aerial photos and cross sectional surveys of the valley fill were combined to map the various sediment sinks. Particle size and organic content were analysed for flood bench cores and terrace samples. The chronology of the flood benches was determined using unsupported Pb-210 and Cs-137 dating, and determined for the terraces using Optically Stimulated Luminescence dating. Quantitative and qualitative sediment tracing approaches, using mineral magnetic properties, were used to trace the origin of suspended sediment (collected during flood events), sediment stored in the flood benches and sediment stored in the terraces. Hydrological monitoring was used to assess the potential to store sediment on flood benches along the valley fill through flood bench inundation frequency. Hydrological and hydraulic modelling extended the measured inundation frequencies to a 73 year period and other cross sections along the valley fill. Furthermore, a future scenario of an increased vegetation cover and reduced hillslope-channel connectivity was assessed in terms of channel-valley fill inundation frequency.
- Full Text:
- Date Issued: 2015
- Authors: Van der Waal, Benjamin Cornelis Wentsel
- Date: 2015
- Subjects: Soil erosion -- South Africa -- Eastern Cape , Sedimentation and deposition -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Arroyos -- South Africa -- Eastern Cape , Sediment transport -- South Africa -- Eastern Cape , Soil conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4892 , http://hdl.handle.net/10962/d1019754
- Description: [Portion of abstract]: Sediment dynamics are influenced by transformed landscape connectivity in catchments worldwide. The upper Thina catchment, an important high rainfall resource in the northern Eastern Cape, South Africa, is an example of where ongoing subsistence farming on communal land has led to overgrazing and trampling that has initiated large erosive features (e.g. gullies) and river incision. The formation of gullies led to increased hillslope-channel connectivity and the resultant river incision decreased the channel-valley fill connectivity. These two changes in connectivity led to increased sediment export from the catchment that has various down-stream ecological and socio-economic impacts. This study investigates how the change in hillslope-channel and channel-valley fill connectivity has altered the sediment dynamics in the Vuvu catchment, a headwater tributary of the Thina River. A combination of methods were used to assess the changes in hillslope-channel and channel-valley fill connectivity. High resolution aerial images were used to map source features, such as fields, gullies, sheet erosion, landslides, roads and livestock tracks. Topographic and geological characteristics of the source features were extracted using a Geographic Information System. Furthermore, hillslope-channel pathways, such as the natural drainage network, continuous gullies, discontinuous gullies, roads and livestock tracks were mapped and analysed in terms of topographic and geological characteristics. Historic aerial images were assessed to calculate the date the larger gullies began forming. Recent aerial photos and cross sectional surveys of the valley fill were combined to map the various sediment sinks. Particle size and organic content were analysed for flood bench cores and terrace samples. The chronology of the flood benches was determined using unsupported Pb-210 and Cs-137 dating, and determined for the terraces using Optically Stimulated Luminescence dating. Quantitative and qualitative sediment tracing approaches, using mineral magnetic properties, were used to trace the origin of suspended sediment (collected during flood events), sediment stored in the flood benches and sediment stored in the terraces. Hydrological monitoring was used to assess the potential to store sediment on flood benches along the valley fill through flood bench inundation frequency. Hydrological and hydraulic modelling extended the measured inundation frequencies to a 73 year period and other cross sections along the valley fill. Furthermore, a future scenario of an increased vegetation cover and reduced hillslope-channel connectivity was assessed in terms of channel-valley fill inundation frequency.
- Full Text:
- Date Issued: 2015
Social-ecological resilience for well-being : a critical realist case study of Boksburg Lake, South Africa
- Authors: Fox, Helen Elizabeth
- Date: 2015
- Subjects: Boksburg Lake and Wetland project , Reservoirs -- South Africa -- Boksburg , Water -- Pollution -- South Africa -- Boksburg , Human ecology -- South Africa -- Boksburg , Social learning -- South Africa -- Boksburg , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6048 , http://hdl.handle.net/10962/d1017872
- Description: This thesis is based on a case study of the degraded Boksburg Lake social-ecological system and an environmental education initiative that aimed to support its transformation. This initiative aimed to involve local people in reclaiming the lake’s social and ecological value, through a process of collectively reimagining possibilities, shaping identities, gaining knowledge and developing local human agency. The focus was on social learning processes in schools and churches to explore opportunities for co-engaged reflexivity that might produce transformation. Schools and Christian churches, two institutions that reflect modern, western socialecological worldviews also have the potential to bring about change. Critical Realism was chosen as my philosophical framework as it provided the tools to explore deeper mechanisms beyond empirical reality, both influencing the degrading trajectory as well as providing possibilities for transformation. It also legitimised case study research as a means to understand more generalised processes characterising modern social-ecological systems. The choice of Critical Realism informed the scope of my primary research question: What generative mechanisms constrain and enable the development of social-ecological resilience for well-being, in the modern social-ecological system of Boksburg Lake? The following three goals were formulated to address this primary question. Goal 1: Based on a multitheoretical perspective of social-ecological literature, develop conceptual tools that have explanatory power to probe generative mechanisms operating in the Boksburg Lake social-ecological system. Goal 2: Identify generative mechanisms driving the current degradation of the Boksburg Lake social-ecological system. Goal 3: Identify learning mechanisms that support transformation for greater social-ecological resilience of the Boksburg Lake social-ecological system. By addressing the primary question and research goals I aimed to gain insights into modern global socialecological systems, the mechanisms that drive high social-ecological risk and the requirements for and possibilities of global systemic change. Drawing on a broad reading of social-ecological literature from different vantage points, tools with explanatory power were developed to probe for generative mechanisms in the Boksburg Lake social-ecological system (goal 1). The human capacity for symbolic representation is identified as an emergent property of coevolving human-ecological systems. These symbolic representations become expressed in culture and worldviews, and influence patterns of identifying, types of knowledge and forms of agency. The nature of these will determine the degree that cultural systems are embedded within ecological reality and the extent of cultural-ecological coupling. A cultural system closely coupled with ecological realities is likely to value ecological systems and manage them for their health, while less coupled cultural-ecological systems are likely to lead to the opposite. Because of their integrated nature, the extent of ecological health and value will affect the decline or sustainability of cultural-ecological systems. There are numerous examples of the learning that can take place when cultural-ecological systems are facing decline. This learning can enhance or reduce biophyllic instincts that become encoded in patterns of identifying, types of knowledge and forms of agency. This in turn affects the strength of cultural-ecological coupling and the extent that human societies co-evolve with ecological systems. , Normalising ideologies is a concept coined in the thesis to refer to symbolic representations of reality that have become integral to a social fabric and determine meaning, while maintaining the domination of the powerful. These ideologies determine patterns of identifying, knowledge and agency and are recognised as having a fundamental influence on the resilience of social-ecological systems. Four normalising ideologies are identified that promote apparent human progress at the expense of ecological integrity and social equality and thus alienation with each other and the ecological world. These are human-ecological dualism, anthropocentrism, nature is mechanised and nature is to be controlled. There are also a number of ideologies promoting connectedness with the ecological world that, if they became normalised, would support greater social-ecological resilience for well-being. Generative mechanisms driving the current degradation of the Boksburg Lake socialecological system were identified (goal 2). Drawing on critical methodology, the main method adopted was document analysis of the Boksburg Advertiser archives, Boksburg’s local newspaper. Four generative mechanisms are recognised as most influential. Two of these have been named hegemonic symbolic systems. The primary symbolic system consists of the four normalising ideologies, mentioned above, that promote human progress at the expense of ecological health. The secondary, more explicit symbolic system, built on this, consists of the following normative ideologies: economic growth is imperative, unrestrained development is promoted, competition is the necessary means and consumerism is the good life. These two symbolic systems have had causal influence on the systematic erosion of ecological processes and biological diversity that has occurred in Boksburg, with the consequent undermining of social-ecological resilience for well-being. The third mechanism that constrains resilience is the power dynamics that have shaped Boksburg’s economic history and social-ecological system. This has resulted in a society built on inequality and injustice with all its associated social and environmental ills, expressed as externalities. The fourth mechanism resides in Boksburg’s political and municipal dynamics. These structures are not designed to tackle complex social-ecological problems and they hold considerable agential power, yet seem dysfunctional at present. Learning mechanisms that support transformation for greater social-ecological resilience of the Boksburg Lake social-ecological system were identified (goal 3). By adopting the role of a reflexive practitioner, supported by action research, case study and interpretivist methodologies, data on the empirical manifestations of the environmental educational initiative were collected. Methods included semistructured interviews, focus groups, document analysis and participant observation. Findings indicate that schools and churches are important institutions that can positively influence patterns of identifying, knowledge about and agency for Boksburg Lake and can thus play a role in transforming hegemonic normalising ideologies. Important learning mechanisms identified included: Learning reflexively together within communities of practice that provide opportunities for active rather than passive learning; involving the youth as they are a group of people with notable enthusiasm, vision, energy and motivation; learning through information acquisition, investigation, action and deliberation; learning about abstract concepts and theoretical knowledge but embedding this in local realities; and learning that provides reference markers for how things can be different.
- Full Text:
- Date Issued: 2015
- Authors: Fox, Helen Elizabeth
- Date: 2015
- Subjects: Boksburg Lake and Wetland project , Reservoirs -- South Africa -- Boksburg , Water -- Pollution -- South Africa -- Boksburg , Human ecology -- South Africa -- Boksburg , Social learning -- South Africa -- Boksburg , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6048 , http://hdl.handle.net/10962/d1017872
- Description: This thesis is based on a case study of the degraded Boksburg Lake social-ecological system and an environmental education initiative that aimed to support its transformation. This initiative aimed to involve local people in reclaiming the lake’s social and ecological value, through a process of collectively reimagining possibilities, shaping identities, gaining knowledge and developing local human agency. The focus was on social learning processes in schools and churches to explore opportunities for co-engaged reflexivity that might produce transformation. Schools and Christian churches, two institutions that reflect modern, western socialecological worldviews also have the potential to bring about change. Critical Realism was chosen as my philosophical framework as it provided the tools to explore deeper mechanisms beyond empirical reality, both influencing the degrading trajectory as well as providing possibilities for transformation. It also legitimised case study research as a means to understand more generalised processes characterising modern social-ecological systems. The choice of Critical Realism informed the scope of my primary research question: What generative mechanisms constrain and enable the development of social-ecological resilience for well-being, in the modern social-ecological system of Boksburg Lake? The following three goals were formulated to address this primary question. Goal 1: Based on a multitheoretical perspective of social-ecological literature, develop conceptual tools that have explanatory power to probe generative mechanisms operating in the Boksburg Lake social-ecological system. Goal 2: Identify generative mechanisms driving the current degradation of the Boksburg Lake social-ecological system. Goal 3: Identify learning mechanisms that support transformation for greater social-ecological resilience of the Boksburg Lake social-ecological system. By addressing the primary question and research goals I aimed to gain insights into modern global socialecological systems, the mechanisms that drive high social-ecological risk and the requirements for and possibilities of global systemic change. Drawing on a broad reading of social-ecological literature from different vantage points, tools with explanatory power were developed to probe for generative mechanisms in the Boksburg Lake social-ecological system (goal 1). The human capacity for symbolic representation is identified as an emergent property of coevolving human-ecological systems. These symbolic representations become expressed in culture and worldviews, and influence patterns of identifying, types of knowledge and forms of agency. The nature of these will determine the degree that cultural systems are embedded within ecological reality and the extent of cultural-ecological coupling. A cultural system closely coupled with ecological realities is likely to value ecological systems and manage them for their health, while less coupled cultural-ecological systems are likely to lead to the opposite. Because of their integrated nature, the extent of ecological health and value will affect the decline or sustainability of cultural-ecological systems. There are numerous examples of the learning that can take place when cultural-ecological systems are facing decline. This learning can enhance or reduce biophyllic instincts that become encoded in patterns of identifying, types of knowledge and forms of agency. This in turn affects the strength of cultural-ecological coupling and the extent that human societies co-evolve with ecological systems. , Normalising ideologies is a concept coined in the thesis to refer to symbolic representations of reality that have become integral to a social fabric and determine meaning, while maintaining the domination of the powerful. These ideologies determine patterns of identifying, knowledge and agency and are recognised as having a fundamental influence on the resilience of social-ecological systems. Four normalising ideologies are identified that promote apparent human progress at the expense of ecological integrity and social equality and thus alienation with each other and the ecological world. These are human-ecological dualism, anthropocentrism, nature is mechanised and nature is to be controlled. There are also a number of ideologies promoting connectedness with the ecological world that, if they became normalised, would support greater social-ecological resilience for well-being. Generative mechanisms driving the current degradation of the Boksburg Lake socialecological system were identified (goal 2). Drawing on critical methodology, the main method adopted was document analysis of the Boksburg Advertiser archives, Boksburg’s local newspaper. Four generative mechanisms are recognised as most influential. Two of these have been named hegemonic symbolic systems. The primary symbolic system consists of the four normalising ideologies, mentioned above, that promote human progress at the expense of ecological health. The secondary, more explicit symbolic system, built on this, consists of the following normative ideologies: economic growth is imperative, unrestrained development is promoted, competition is the necessary means and consumerism is the good life. These two symbolic systems have had causal influence on the systematic erosion of ecological processes and biological diversity that has occurred in Boksburg, with the consequent undermining of social-ecological resilience for well-being. The third mechanism that constrains resilience is the power dynamics that have shaped Boksburg’s economic history and social-ecological system. This has resulted in a society built on inequality and injustice with all its associated social and environmental ills, expressed as externalities. The fourth mechanism resides in Boksburg’s political and municipal dynamics. These structures are not designed to tackle complex social-ecological problems and they hold considerable agential power, yet seem dysfunctional at present. Learning mechanisms that support transformation for greater social-ecological resilience of the Boksburg Lake social-ecological system were identified (goal 3). By adopting the role of a reflexive practitioner, supported by action research, case study and interpretivist methodologies, data on the empirical manifestations of the environmental educational initiative were collected. Methods included semistructured interviews, focus groups, document analysis and participant observation. Findings indicate that schools and churches are important institutions that can positively influence patterns of identifying, knowledge about and agency for Boksburg Lake and can thus play a role in transforming hegemonic normalising ideologies. Important learning mechanisms identified included: Learning reflexively together within communities of practice that provide opportunities for active rather than passive learning; involving the youth as they are a group of people with notable enthusiasm, vision, energy and motivation; learning through information acquisition, investigation, action and deliberation; learning about abstract concepts and theoretical knowledge but embedding this in local realities; and learning that provides reference markers for how things can be different.
- Full Text:
- Date Issued: 2015
Spatial and temporal variations in trophic connectivity within an estuarine environment : benthic-pelagic and terrestrial-aquatic linkages via invertebrates and fishes
- Authors: Bergamino Roman, Leandro
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Marine invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5921 , http://hdl.handle.net/10962/d1017799
- Description: Estuarine ecosystems are among the most biologically productive areas and they provide important ecosystem services such as erosion control, habitat and refugia for several species. These environments are characterized by the presence of a variety of organic matter sources due to their transitional position between rivers and the sea. The biotic compositions can undergo spatial and seasonal changes along the estuary due to the spatial and temporal fluctuations of environmental factors such as salinity, temperature and seston loads. Therefore, the different combinations of biotic and abiotic factors make each estuary a unique ecosystem. Because of this spatial and temporal complexity, the understanding of estuarine food web structure and which factors affect the trophic relationships within the ecosystem through space and time represent challenging tasks. Furthermore, estuaries are under an increasing number of anthropogenic perturbations because of the growing concentration of human populations in coastal areas. Knowledge of ecosystem structure and functioning is essential for effective conservation and management planning of coastal areas.In this dissertation, I combine the utilization of biological tracers to examine spatial and temporal variability in the food web structure within a small temperate and microtidal estuary located in South Africa. To this end, fatty acid profiles and stable isotope signatures were measured in several primary organic matter sources and consumers (including zooplankton, fishes and benthic invertebrates) during four consecutive seasons and in three different estuarine regions: upper, middle, and lower reaches. The three reaches had distinct habitat features of vegetation type and morphology, and in particular the lower reaches were colonized by the marsh grass Spartina maritima. Isotopic mixing models were used to estimate the relative contribution of each food source to the diets of invertebrates and fishes within the estuarine food web. The isotopic and fatty acid data showed similar results. In general, the lower reaches of the estuary were characterized by a higher deposition and assimilation by brachyuran crabs of carbon derived from marsh grass detritus, whiletowards the upper reaches a mixture of microphytobenthos and particulate organic matter (phytoplankton and detritus) was deposited and sustained the pelagic and benthic fauna. The highest deposition and assimilation of marsh grass detritus in the lower reaches of the estuary occurred during periods of low freshwater discharge (autumn and winter). In the upper reaches, microphytobenthos and suspended particulate organic matter were dominant basal food resources for the food web during all seasons. These results indicated that benthic consumers incorporated mainly local carbon sources from their local habitat.To clarify isotopic and fatty acid patterns I examined the trophic behaviour of the sesarmid crab Sesarma catenata through laboratory feeding experiments. Results from these experiments validated that decomposed leaves of riparian trees and the salt marsh plant S. maritima were the preferred food of the sesarmid crabs, potentially due to high bacterial loads. The remaining leaf material not assimilated by crabs, together with faecal material, are likely important subsidies for adjacent environments, hence representing an important energy pathway involving the microbial food chain. Furthermore, this dissertation showed the importance of mobile top predators as vectors energetically connecting distinct food chains within the estuary (i.e. littoral, benthic and pelagic). I concluded that a combination of physical (i.e. patterns of freshwater discharge and estuary morphology) and biological factors (i.e. organism feeding behaviour, mobility, primary productivity, the local vegetation type) influence the pattern of dominant primary organic matter sources, and therefore the food web structure along the estuarine environment. In particular, marsh grass detritus contributed substantially to the diets of estuarine fauna during periods of low freshwater discharge. Given the importance of the salt marsh habitat in providing trophic resources, it is important to preserve this environment to sustain the natural biota and ecosystem functioning.
- Full Text:
- Date Issued: 2015
- Authors: Bergamino Roman, Leandro
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Marine invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5921 , http://hdl.handle.net/10962/d1017799
- Description: Estuarine ecosystems are among the most biologically productive areas and they provide important ecosystem services such as erosion control, habitat and refugia for several species. These environments are characterized by the presence of a variety of organic matter sources due to their transitional position between rivers and the sea. The biotic compositions can undergo spatial and seasonal changes along the estuary due to the spatial and temporal fluctuations of environmental factors such as salinity, temperature and seston loads. Therefore, the different combinations of biotic and abiotic factors make each estuary a unique ecosystem. Because of this spatial and temporal complexity, the understanding of estuarine food web structure and which factors affect the trophic relationships within the ecosystem through space and time represent challenging tasks. Furthermore, estuaries are under an increasing number of anthropogenic perturbations because of the growing concentration of human populations in coastal areas. Knowledge of ecosystem structure and functioning is essential for effective conservation and management planning of coastal areas.In this dissertation, I combine the utilization of biological tracers to examine spatial and temporal variability in the food web structure within a small temperate and microtidal estuary located in South Africa. To this end, fatty acid profiles and stable isotope signatures were measured in several primary organic matter sources and consumers (including zooplankton, fishes and benthic invertebrates) during four consecutive seasons and in three different estuarine regions: upper, middle, and lower reaches. The three reaches had distinct habitat features of vegetation type and morphology, and in particular the lower reaches were colonized by the marsh grass Spartina maritima. Isotopic mixing models were used to estimate the relative contribution of each food source to the diets of invertebrates and fishes within the estuarine food web. The isotopic and fatty acid data showed similar results. In general, the lower reaches of the estuary were characterized by a higher deposition and assimilation by brachyuran crabs of carbon derived from marsh grass detritus, whiletowards the upper reaches a mixture of microphytobenthos and particulate organic matter (phytoplankton and detritus) was deposited and sustained the pelagic and benthic fauna. The highest deposition and assimilation of marsh grass detritus in the lower reaches of the estuary occurred during periods of low freshwater discharge (autumn and winter). In the upper reaches, microphytobenthos and suspended particulate organic matter were dominant basal food resources for the food web during all seasons. These results indicated that benthic consumers incorporated mainly local carbon sources from their local habitat.To clarify isotopic and fatty acid patterns I examined the trophic behaviour of the sesarmid crab Sesarma catenata through laboratory feeding experiments. Results from these experiments validated that decomposed leaves of riparian trees and the salt marsh plant S. maritima were the preferred food of the sesarmid crabs, potentially due to high bacterial loads. The remaining leaf material not assimilated by crabs, together with faecal material, are likely important subsidies for adjacent environments, hence representing an important energy pathway involving the microbial food chain. Furthermore, this dissertation showed the importance of mobile top predators as vectors energetically connecting distinct food chains within the estuary (i.e. littoral, benthic and pelagic). I concluded that a combination of physical (i.e. patterns of freshwater discharge and estuary morphology) and biological factors (i.e. organism feeding behaviour, mobility, primary productivity, the local vegetation type) influence the pattern of dominant primary organic matter sources, and therefore the food web structure along the estuarine environment. In particular, marsh grass detritus contributed substantially to the diets of estuarine fauna during periods of low freshwater discharge. Given the importance of the salt marsh habitat in providing trophic resources, it is important to preserve this environment to sustain the natural biota and ecosystem functioning.
- Full Text:
- Date Issued: 2015
Spatio-temporal variation in the phytobenthos and phytoplankton community structure and composition of particulate matter along a river-estuary continuum assessed using microscopic and stable isotope analyses
- Authors: Dalu, Tatenda
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54416 , vital:26563
- Description: Phytoplankton and phytobenthos communities play an important role in lotic systems as primary producers providing essential biomolecules to higher trophic oganisms and are important indicators for environmental or ecological change. In this thesis, field studies (observational and experimental) along a river–estuary continuum were conducted to assess the spatio-temporal variation and development of phytobenthos and phytoplankton communities using a combination of stable isotope and community analyses in a temperate southern African system across four study periods: September (early spring) and November/December (late spring) 2012, and February (summer) and May/June (winter) 2013. Additionally, the sources and composition of the particulate organic matter were also analysed using stable isotope (δ15N and δ13C) analysis. The effects of substrate type and flood occurrence were assessed through experimental studies at an up- and downstream site of the river after a major flood event that occurred between October and November 2012. Common household tiles were used as artificial substrates to study the development/succession of phytobenthos communities after the flood disturbance. Distinct diatom communities were observed between upstream and downstream sites and at each site, community structure changed with time indicating succession. In addition to recording diatom characteristics on three natural substrates, namely; macrophytes, rocks and sediment, artificial substrates observations were also made on three different types of artificial substrates, namely; brick, brown clay and grey clay tiles. The natural (species richness 78) and artificial substrates (sp. richness 93) had different communities with the latter having greater species richness. Common phytobenthos taxa were not restricted to a single substrate but preference was generally high for the artificial substrates, especially brown tiles (mean sp. richness 47). Results of the redundancy analysis (RDA) analysis indicated that ammonium, conductivity, total dissolved solids, salinity, pH, oxygen reduction potential, phosphate and water depth were the major determinants of the phytobenthos composition at the two sites. The spatio–temporal variation of phytoplankton and phytobenthos communities and allochthonous organic matter along the river–estuary continuum was assessed at 8 sites using a combination of community and stable isotope analyses. A total of 178 species belonging to 78 genera were recorded with diatoms being predominant, accounting for 81.9 % of the total abundance. The total chl-a concentration along the river-estuary continuum increased from spring to a high in summer before decreasing to a low in winter. Periphyton communities were observed to be significantly different across sites (p < 0.05) in terms of species richness, abundances and isotopically The high periphytic δ15N values (range 7.9–15.2 ‰) recorded at the downstream sites compared to the pristine upstream sites (δ15N values range 4–7 ‰) suggest nutrient enrichment most likely derived from anthropogenic sources. Overall, our results reveal general patterns of periphyton communities and stable isotopes and provide improved information in the use of periphyton δ15N as an excellent indicator of anthropogenic nitrogen pollution. Ecologists are interested in the factors that control, and the variability in, the contributions of different sources to mixed organic materials traveling through lotic systems. We hypothesized that the source matter fuelling mixed organic pools in a river-estuary continuum varies over space and time, with the upper reaches of a system characterized by allochthonous-dominated material and autochthonous contributions becoming more important in the lower reaches. Samples of the mixed organic pools and allochthonous and autochthonous source materials were collected during the four study periods. The C:N ratios of suspended particulate matter (SPM) collected during summer and winter indicated that the lower reaches of the system had similar organic matter contributions from the freshwater and terrestrial sources. Stable isotope analysis in R revealed that the contributions of autochthonous organic matter were high in SPM along the entire continuum, and aquatic macrophytes were significant contributors to SPM specifically in the upper reaches. The terrestrial leaves made major contributions to the SPM in the middle regions of the system (i.e. downstream sites of the river, particularly in early and late spring). Bulk detritus had large allochthonous matter components in the lower reaches (estuary), and the contributions of aquatic macrophytes and benthic algae to bulk detritus were high (> 50 %) in the upper to middle reaches (river), but low (< 20 %) in the lower reaches (estuary). The current investigation represents the first attempt to assess the validity of the River Continuum Concept (RCC) in a southern African temperate river. The phytoplankton and phytobenthos communities, and chl-a concentration followed a trend similar to that proposed for the river continuum concept (RCC). The middle reaches based on the phytobenthos or phytoplankton communities and chl-a concentrations which were employed as proxies for primary production, were the most productive, while the upper reaches were the least primary productive. The evaluation of organic matter contributions to the SPM and detritus along the river–estuary continuum provided a baseline assessment of the nature and sources of potential food for consumers inhabiting different locations during different times of the year. Incorporating such spatio-temporal variations in SPM and detritus into food web studies will improve our understanding of the flow of carbon through aquatic systems.
- Full Text:
- Date Issued: 2015
- Authors: Dalu, Tatenda
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54416 , vital:26563
- Description: Phytoplankton and phytobenthos communities play an important role in lotic systems as primary producers providing essential biomolecules to higher trophic oganisms and are important indicators for environmental or ecological change. In this thesis, field studies (observational and experimental) along a river–estuary continuum were conducted to assess the spatio-temporal variation and development of phytobenthos and phytoplankton communities using a combination of stable isotope and community analyses in a temperate southern African system across four study periods: September (early spring) and November/December (late spring) 2012, and February (summer) and May/June (winter) 2013. Additionally, the sources and composition of the particulate organic matter were also analysed using stable isotope (δ15N and δ13C) analysis. The effects of substrate type and flood occurrence were assessed through experimental studies at an up- and downstream site of the river after a major flood event that occurred between October and November 2012. Common household tiles were used as artificial substrates to study the development/succession of phytobenthos communities after the flood disturbance. Distinct diatom communities were observed between upstream and downstream sites and at each site, community structure changed with time indicating succession. In addition to recording diatom characteristics on three natural substrates, namely; macrophytes, rocks and sediment, artificial substrates observations were also made on three different types of artificial substrates, namely; brick, brown clay and grey clay tiles. The natural (species richness 78) and artificial substrates (sp. richness 93) had different communities with the latter having greater species richness. Common phytobenthos taxa were not restricted to a single substrate but preference was generally high for the artificial substrates, especially brown tiles (mean sp. richness 47). Results of the redundancy analysis (RDA) analysis indicated that ammonium, conductivity, total dissolved solids, salinity, pH, oxygen reduction potential, phosphate and water depth were the major determinants of the phytobenthos composition at the two sites. The spatio–temporal variation of phytoplankton and phytobenthos communities and allochthonous organic matter along the river–estuary continuum was assessed at 8 sites using a combination of community and stable isotope analyses. A total of 178 species belonging to 78 genera were recorded with diatoms being predominant, accounting for 81.9 % of the total abundance. The total chl-a concentration along the river-estuary continuum increased from spring to a high in summer before decreasing to a low in winter. Periphyton communities were observed to be significantly different across sites (p < 0.05) in terms of species richness, abundances and isotopically The high periphytic δ15N values (range 7.9–15.2 ‰) recorded at the downstream sites compared to the pristine upstream sites (δ15N values range 4–7 ‰) suggest nutrient enrichment most likely derived from anthropogenic sources. Overall, our results reveal general patterns of periphyton communities and stable isotopes and provide improved information in the use of periphyton δ15N as an excellent indicator of anthropogenic nitrogen pollution. Ecologists are interested in the factors that control, and the variability in, the contributions of different sources to mixed organic materials traveling through lotic systems. We hypothesized that the source matter fuelling mixed organic pools in a river-estuary continuum varies over space and time, with the upper reaches of a system characterized by allochthonous-dominated material and autochthonous contributions becoming more important in the lower reaches. Samples of the mixed organic pools and allochthonous and autochthonous source materials were collected during the four study periods. The C:N ratios of suspended particulate matter (SPM) collected during summer and winter indicated that the lower reaches of the system had similar organic matter contributions from the freshwater and terrestrial sources. Stable isotope analysis in R revealed that the contributions of autochthonous organic matter were high in SPM along the entire continuum, and aquatic macrophytes were significant contributors to SPM specifically in the upper reaches. The terrestrial leaves made major contributions to the SPM in the middle regions of the system (i.e. downstream sites of the river, particularly in early and late spring). Bulk detritus had large allochthonous matter components in the lower reaches (estuary), and the contributions of aquatic macrophytes and benthic algae to bulk detritus were high (> 50 %) in the upper to middle reaches (river), but low (< 20 %) in the lower reaches (estuary). The current investigation represents the first attempt to assess the validity of the River Continuum Concept (RCC) in a southern African temperate river. The phytoplankton and phytobenthos communities, and chl-a concentration followed a trend similar to that proposed for the river continuum concept (RCC). The middle reaches based on the phytobenthos or phytoplankton communities and chl-a concentrations which were employed as proxies for primary production, were the most productive, while the upper reaches were the least primary productive. The evaluation of organic matter contributions to the SPM and detritus along the river–estuary continuum provided a baseline assessment of the nature and sources of potential food for consumers inhabiting different locations during different times of the year. Incorporating such spatio-temporal variations in SPM and detritus into food web studies will improve our understanding of the flow of carbon through aquatic systems.
- Full Text:
- Date Issued: 2015
Supporting the implementation of alternatives to corporal punishment in the Eastern Cape secondary schools : towards a framework for school management teams and teachers
- Authors: Kalipa, Velelo Clifton
- Date: 2015
- Subjects: School discipline -- South Africa -- Eastern Cape Corporal punishment of children -- South Africa -- Eastern Cape Rewards and punishments in education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/5664 , vital:29359
- Description: Alternative to corporal punishment in schools is a worldwide practice. Most countries have banned the use of corporal punishment in schools and have promulgated laws and adopted policies aiming to enforce the practice of alternative to corporal punishment. South Africa is one of the countries that have introduced policy on alternatives to corporal punishment. However, this policy does not provide details on how School Management Teams (SMTs) and teachers should support the implementation of alternatives to corporal punishment; as a result, schools end up having different approaches in as far as implementing alternatives to corporal punishment is concerned. There is also a serious problem of indiscipline in schools and this has since attracted growing attention of researchers in South Africa and the whole world. There are serious offences by learners in schools which range from serious criminal ones such as drug abuse, assaults, theft, murders and rapes to less serious ones such as truancy, incomplete projects, absenteeism and lateness, dodging and bunking of classes in schools. This study therefore sought to investigate how SMT and teachers support the implementation of alternatives to corporal punishment in schools. This was a multi case study of four secondary schools in the King Williams Town Education District which was conducted through qualitative research approach. Interviews and documentary analysis were used to collect data and a total of 16 participants (four principals, four SMT members and eight teachers) were selected. From the data, it emerged that some teachers were fixed in using corporal punishment to discipline learners in schools. The data also showed that the alternatives to corporal punishment (ATCP) policies were inconsistently applied as schools had different approaches in as far as how ATCP is implemented and that some schools had no ATCP policies at all. It also emerged from the data that school leadership was a problem in as far as supporting the implementation of ATCP in schools as in some schools the issues of disciplining learners was centralised in the principal’s office. It also became clear that the majority of participants did not understand the national policy on ATCP. There were no indications of parental involvement in the implementation of ATCP in schools. It can be concluded that the channels of communication among principals, SMTs, teachers with regards to the implementation of ATCP was problematic as there were no clear roles as to how each of these officials should implement ATCP. Some teachers still perceived the ATCP as unsuitable for maintaining discipline in rural schools and their discipline strategies were still characterized by punitive measures which border on corporal punishment. School discipline was not seen as a societal matter where other relevant stakeholders could play a pivotal role in learner discipline. This had a negative impact on the school discipline. Learners had no responsibility on maintenance of positive school atmosphere as they were not in any way part taking in the maintenance of discipline in schools. This study therefore recommends a comprehensive framework for the implementation of ATCP that will give details on the roles of SMTs and teachers in the implementation of ATCP in schools. It is recommended that this framework be inclusive of parents and other community stakeholders who would give different perspectives on the implementation of ATCP in schools as education is a societal matter. It is also recommended that more research be conducted that will deal with urban schools and on the involvement of parents and other stakeholders in the implementation of ATCP.
- Full Text:
- Date Issued: 2015
- Authors: Kalipa, Velelo Clifton
- Date: 2015
- Subjects: School discipline -- South Africa -- Eastern Cape Corporal punishment of children -- South Africa -- Eastern Cape Rewards and punishments in education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/5664 , vital:29359
- Description: Alternative to corporal punishment in schools is a worldwide practice. Most countries have banned the use of corporal punishment in schools and have promulgated laws and adopted policies aiming to enforce the practice of alternative to corporal punishment. South Africa is one of the countries that have introduced policy on alternatives to corporal punishment. However, this policy does not provide details on how School Management Teams (SMTs) and teachers should support the implementation of alternatives to corporal punishment; as a result, schools end up having different approaches in as far as implementing alternatives to corporal punishment is concerned. There is also a serious problem of indiscipline in schools and this has since attracted growing attention of researchers in South Africa and the whole world. There are serious offences by learners in schools which range from serious criminal ones such as drug abuse, assaults, theft, murders and rapes to less serious ones such as truancy, incomplete projects, absenteeism and lateness, dodging and bunking of classes in schools. This study therefore sought to investigate how SMT and teachers support the implementation of alternatives to corporal punishment in schools. This was a multi case study of four secondary schools in the King Williams Town Education District which was conducted through qualitative research approach. Interviews and documentary analysis were used to collect data and a total of 16 participants (four principals, four SMT members and eight teachers) were selected. From the data, it emerged that some teachers were fixed in using corporal punishment to discipline learners in schools. The data also showed that the alternatives to corporal punishment (ATCP) policies were inconsistently applied as schools had different approaches in as far as how ATCP is implemented and that some schools had no ATCP policies at all. It also emerged from the data that school leadership was a problem in as far as supporting the implementation of ATCP in schools as in some schools the issues of disciplining learners was centralised in the principal’s office. It also became clear that the majority of participants did not understand the national policy on ATCP. There were no indications of parental involvement in the implementation of ATCP in schools. It can be concluded that the channels of communication among principals, SMTs, teachers with regards to the implementation of ATCP was problematic as there were no clear roles as to how each of these officials should implement ATCP. Some teachers still perceived the ATCP as unsuitable for maintaining discipline in rural schools and their discipline strategies were still characterized by punitive measures which border on corporal punishment. School discipline was not seen as a societal matter where other relevant stakeholders could play a pivotal role in learner discipline. This had a negative impact on the school discipline. Learners had no responsibility on maintenance of positive school atmosphere as they were not in any way part taking in the maintenance of discipline in schools. This study therefore recommends a comprehensive framework for the implementation of ATCP that will give details on the roles of SMTs and teachers in the implementation of ATCP in schools. It is recommended that this framework be inclusive of parents and other community stakeholders who would give different perspectives on the implementation of ATCP in schools as education is a societal matter. It is also recommended that more research be conducted that will deal with urban schools and on the involvement of parents and other stakeholders in the implementation of ATCP.
- Full Text:
- Date Issued: 2015
Supportive strategies for teachers and parents dealing with learners experiencing mild intellectual barriers to learning
- Authors: Swartz, Deon Jude
- Date: 2015
- Subjects: Learning disabilities , Inclusive education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5065 , vital:20799
- Description: Education support provision underwent a complete metamorphosis with the adoption of Education White Paper 6: Building an Inclusive Education and Training System in 2001. Within this new paradigm, learners who experience Mild intellectual barriers to learning are understood from a culture of inclusion and accommodation within mainstream education, alongside their non disabled peers. Another important development within Inclusive Education is the recognition of parents as important role-players in their children’s education. This bold transformation implies that teachers and parents need the necessary support from health professionals and support staff at District Based Support Teams (DBSTs) attached to the local Education Support Centres, in order for them to support their children who experience Mild intellectual barriers to learning. As a result of the radical overhaul of the education system to accommodate learners who experience Mild intellectual barriers to learning in mainstream schools, the main aim of the study is to establish the implications for teachers and parents who deal with such learners. The researcher employed a qualitative research design within an interpretive paradigm from a phenomenological perspective, in order to capture the organic richness of the participants’ perceived experiences with regards to the phenomenon under investigation. The researcher made use of a combination of convenience, judgement and purposive sampling. The sample group included teachers and parents from two primary schools who deal with learners who experience Mild intellectual barriers to learning. The learners had previously been assessed psychometrically by Educational Psychologists and identified as fulfilling the criteria for Mild intellectual barriers to learning. Data were collected by means of semi-structured interviews and separate interview schedules were drafted for teachers and parents. Data was analysed using Tesch’s eight step data analysis procedure to identify common themes which emerged from the participants’ responses. The findings of the research indicated teachers and parents had different perceptions about their roles in regards to the children whose learning they support. It also indicated that teachers experience challenges in their attempts to support their learners who experience Mild intellectual barriers in their classes, and with understanding the philosophy of Inclusive education. Furthermore, both parents and teachers experience a lack of support from health professionals and Inclusive Education specialists at the DBSTs within Bronfenbrenner’s eco-systemic framework, which formed the theoretical foundation for this study. Consequently, strategies to support teachers and parents to address these challenges were proposed.
- Full Text:
- Date Issued: 2015
- Authors: Swartz, Deon Jude
- Date: 2015
- Subjects: Learning disabilities , Inclusive education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5065 , vital:20799
- Description: Education support provision underwent a complete metamorphosis with the adoption of Education White Paper 6: Building an Inclusive Education and Training System in 2001. Within this new paradigm, learners who experience Mild intellectual barriers to learning are understood from a culture of inclusion and accommodation within mainstream education, alongside their non disabled peers. Another important development within Inclusive Education is the recognition of parents as important role-players in their children’s education. This bold transformation implies that teachers and parents need the necessary support from health professionals and support staff at District Based Support Teams (DBSTs) attached to the local Education Support Centres, in order for them to support their children who experience Mild intellectual barriers to learning. As a result of the radical overhaul of the education system to accommodate learners who experience Mild intellectual barriers to learning in mainstream schools, the main aim of the study is to establish the implications for teachers and parents who deal with such learners. The researcher employed a qualitative research design within an interpretive paradigm from a phenomenological perspective, in order to capture the organic richness of the participants’ perceived experiences with regards to the phenomenon under investigation. The researcher made use of a combination of convenience, judgement and purposive sampling. The sample group included teachers and parents from two primary schools who deal with learners who experience Mild intellectual barriers to learning. The learners had previously been assessed psychometrically by Educational Psychologists and identified as fulfilling the criteria for Mild intellectual barriers to learning. Data were collected by means of semi-structured interviews and separate interview schedules were drafted for teachers and parents. Data was analysed using Tesch’s eight step data analysis procedure to identify common themes which emerged from the participants’ responses. The findings of the research indicated teachers and parents had different perceptions about their roles in regards to the children whose learning they support. It also indicated that teachers experience challenges in their attempts to support their learners who experience Mild intellectual barriers in their classes, and with understanding the philosophy of Inclusive education. Furthermore, both parents and teachers experience a lack of support from health professionals and Inclusive Education specialists at the DBSTs within Bronfenbrenner’s eco-systemic framework, which formed the theoretical foundation for this study. Consequently, strategies to support teachers and parents to address these challenges were proposed.
- Full Text:
- Date Issued: 2015
Synthesis and biological evaluation of truncated sarganaphthoquinoic acid derivatives as Hsp90 inhibitors
- Authors: Chiwakata, Maynard T
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64708 , vital:28594
- Description: Hsp90 inhibition has been at the centre of attention in current research due to the possibility of “cracking down” on the entire process leading to the development of malignant cancers. Small underlying principles common in all types of cancers have been determined that govern the transformation of normal human cells into cancerous cells, with all relying on the ATPase activity of Hsp90 protein. Hsp90 protein is therefore an attractive drug target that if successfully inhibited can result in the remission of cancer tumours by one form of treatment. To date, no Hsp90 inhibitor has been sanctioned for cancer treatment as most are still in clinical development. Our research was therefore inspired by reports that indicated the potential of quinones / naphthoquinones to act as Hsp90 inhibitors. Preliminary results of a few selected marine natural product quinone systems i.e. sargaquinoic acid (SQA) (2.47) and lapachol (3.6) showed moderate cytotoxicity and weak interactions with the Hsp90 molecular chaperone, and evidence suggested C-terminal binding of these molecules. No correlation has been determined yet between cytotoxicity and Hsp90 inhibition, hence we aimed to develop natural product inspired molecules that exhibit both cytotoxic and Hsp90 inhibition properties. Due to limited amounts of the natural product that can be acquired from natural sources, synthetic analogues were opted for. Isolation of a few selected quinones was conducted to have material that could be used in biological assays. For structural modifications, a series of truncated naphthoquinone systems were prepared adopting the sarganaphthoquinoic acid (3.5) scaffold. The naphthoquinones were prepared via Diels-Alder reactions of relevant benzoquinones with myrcene, followed by aromatization reactions using MnO2. Various alkyl and aryl amines were then coupled to the C-2/3 position of the naphthoquinone using Michael’s addition reactions. Tricyclic naphthoquinones were also synthesized from reactions with hypotaurine and citral. Design of the analogues incorporated functionalities from known Hsp90 inhibitors e.g. geldanamycin (2.28) and its analogues. Preliminary results obtained showed that coupling of naphthoquinones with aryl-amines resulted in the most cytotoxic compounds (4.14-4.19) with IC50 values as low as 0.3 μM against Hs578T breast cancer carcinoma (triple negative). Most of the alkyl amines (4.20-4.25) had IC50 values greater than 50 μM except for 4.20 and 4.21 that showed IC50 values of 7.6 μM and 2.6 μM respectively. Tricyclic naphthoquinones (4.28-4.29) showed moderate cytotoxic activity of approximately 10 μM. Hsp90 inhibition was assessed by client protein degradation assays, of which SQA (2.47), showed the best Hsp90 inhibition properties, followed by compound 4.20. The most cytotoxic arylamino-naphthoquinone (4.16) and tricyclic naphthoquinones (4.28-4.29) showed only moderate inhibition. None of the compounds led to Hsp70 induction, suggesting possible binding to the C-terminus of Hsp90. Interactions at the binding site were assessed by molecular docking studies and saturation transfer difference (STD) NMR. Docking studies were conducted on the N-terminus of Hsp90 and better binding was observed for arylamino naphthoquinones (4.14-4.19) than for other series of compounds. Unfortunately, the co-crystal structure for the C-terminus of Hsp90 is unavailable, hence docking study comparisons on both domains could not be conducted. However, STD NMR offered a platform to assess binding interactions between the naphthoquinones and the N- or C-terminal domains of Hsp90. However no interactions were observed at both the N- and C- termini of Hsp90 due to either weak binding of ligands to the protein or poor water solubility of the ligands. From these preliminary results, naphthoquinones bind to Hsp90 protein but conclusive remarks to which terminal domain they bind to could not be made. The best candidate from amongst the series of naphthoquinones prepared that showed moderate cytotoxicity and promising Hsp90 inhibition was compound 4.20. We therefore succeeded in developing a new series of naphthoquinones that possess moderate cytotoxicity and show Hsp90 inhibition.
- Full Text:
- Date Issued: 2015
- Authors: Chiwakata, Maynard T
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64708 , vital:28594
- Description: Hsp90 inhibition has been at the centre of attention in current research due to the possibility of “cracking down” on the entire process leading to the development of malignant cancers. Small underlying principles common in all types of cancers have been determined that govern the transformation of normal human cells into cancerous cells, with all relying on the ATPase activity of Hsp90 protein. Hsp90 protein is therefore an attractive drug target that if successfully inhibited can result in the remission of cancer tumours by one form of treatment. To date, no Hsp90 inhibitor has been sanctioned for cancer treatment as most are still in clinical development. Our research was therefore inspired by reports that indicated the potential of quinones / naphthoquinones to act as Hsp90 inhibitors. Preliminary results of a few selected marine natural product quinone systems i.e. sargaquinoic acid (SQA) (2.47) and lapachol (3.6) showed moderate cytotoxicity and weak interactions with the Hsp90 molecular chaperone, and evidence suggested C-terminal binding of these molecules. No correlation has been determined yet between cytotoxicity and Hsp90 inhibition, hence we aimed to develop natural product inspired molecules that exhibit both cytotoxic and Hsp90 inhibition properties. Due to limited amounts of the natural product that can be acquired from natural sources, synthetic analogues were opted for. Isolation of a few selected quinones was conducted to have material that could be used in biological assays. For structural modifications, a series of truncated naphthoquinone systems were prepared adopting the sarganaphthoquinoic acid (3.5) scaffold. The naphthoquinones were prepared via Diels-Alder reactions of relevant benzoquinones with myrcene, followed by aromatization reactions using MnO2. Various alkyl and aryl amines were then coupled to the C-2/3 position of the naphthoquinone using Michael’s addition reactions. Tricyclic naphthoquinones were also synthesized from reactions with hypotaurine and citral. Design of the analogues incorporated functionalities from known Hsp90 inhibitors e.g. geldanamycin (2.28) and its analogues. Preliminary results obtained showed that coupling of naphthoquinones with aryl-amines resulted in the most cytotoxic compounds (4.14-4.19) with IC50 values as low as 0.3 μM against Hs578T breast cancer carcinoma (triple negative). Most of the alkyl amines (4.20-4.25) had IC50 values greater than 50 μM except for 4.20 and 4.21 that showed IC50 values of 7.6 μM and 2.6 μM respectively. Tricyclic naphthoquinones (4.28-4.29) showed moderate cytotoxic activity of approximately 10 μM. Hsp90 inhibition was assessed by client protein degradation assays, of which SQA (2.47), showed the best Hsp90 inhibition properties, followed by compound 4.20. The most cytotoxic arylamino-naphthoquinone (4.16) and tricyclic naphthoquinones (4.28-4.29) showed only moderate inhibition. None of the compounds led to Hsp70 induction, suggesting possible binding to the C-terminus of Hsp90. Interactions at the binding site were assessed by molecular docking studies and saturation transfer difference (STD) NMR. Docking studies were conducted on the N-terminus of Hsp90 and better binding was observed for arylamino naphthoquinones (4.14-4.19) than for other series of compounds. Unfortunately, the co-crystal structure for the C-terminus of Hsp90 is unavailable, hence docking study comparisons on both domains could not be conducted. However, STD NMR offered a platform to assess binding interactions between the naphthoquinones and the N- or C-terminal domains of Hsp90. However no interactions were observed at both the N- and C- termini of Hsp90 due to either weak binding of ligands to the protein or poor water solubility of the ligands. From these preliminary results, naphthoquinones bind to Hsp90 protein but conclusive remarks to which terminal domain they bind to could not be made. The best candidate from amongst the series of naphthoquinones prepared that showed moderate cytotoxicity and promising Hsp90 inhibition was compound 4.20. We therefore succeeded in developing a new series of naphthoquinones that possess moderate cytotoxicity and show Hsp90 inhibition.
- Full Text:
- Date Issued: 2015
The antifungal activity of an aqueous Tulbaghia violacea plant extract against Aspergillus flavus
- Authors: Belewa, Xoliswa Vuyokazi
- Date: 2015
- Subjects: Medicinal plants , Antifungal agents , Fungi -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5858 , vital:21001
- Description: Phytochemical analysis of both HEA1 and the crude plant extract showed the presence of phenolics, tannins and saponins. Saponins were the predominant secondary metabolites and were mostly abundant in the plant extract and to a lesser extent in the active compound. Steroidal saponins, tannins and phenolics were also detected in the plant extract, but only the phenolics were detected in the active compound. The results of the phytochemical analysis showed that those compounds that were not present in the active compound could be removed from the crude extract during the TLC purification process. Investigation on the mechanism of action of the crude plant extract on the sterol production by A. flavus showed that the plant extract affected ergosterol biosynthesis by causing an accumulation of oxidosqualene in the ergosterol biosynthetic pathway resulting in a decline in ergosterol production. An oscillatory response in lanosterol production was observed in the presence of the plant extract, which may be an adaptation mechanism of A. flavus to unfavourable conditions and compensation for the loss of enzyme activity which may have occurred as a result of the accumulation of oxidosqualene. The antifungal activity of the plant extract on ergosterol production by A. flavus may also be due to saponins which target the cell membrane and ergosterol production in fungi. The effect of the plant extract on the fungal cell wall of A. flavus also showed that the plant extract caused a decline in β-(1, 3) glucan production by inhibiting β-glucan synthase. The plant extract also affected the chitin synthesis pathway of A. flavus, by causing a decline in chitin production, which was due to the inhibition of chitin synthase. Investigation of chitinase production using 4MU substrates showed that the plant extract caused an accumulation of chitobioses, by activating chitobiosidases and endochitinases. A decline in N-acetylglucosaminidase activity in the presence of the plant extract was observed and this prevented the formation of N-acetylglucosamine. The accumulation of chitobiosidase and endochitinase may be as a result of autolysis that may be triggered by A. flavus as a survival mechanism in the presence of the plant extract and as a compensatory mechanism for the loss of β-glucans and chitin. The antifungal effect of the plant extract on various components of the cell wall of A. flavus, makes T. violacea aqueous plant extract an ideal chemotherapeutic agent against both human and plant pathogens of Aspergillus. The broad spectrum of antifungal activity of T. violacea against A. flavus also eliminates any chances of the fungus developing resistance towards it and would make it a candidate for use as a potential antifungal agent. Further identification and possible chemical synthesis is needed to shed light on the safety and efficacy of the active compound for further development as a chemotherapeutic agent.
- Full Text:
- Date Issued: 2015
- Authors: Belewa, Xoliswa Vuyokazi
- Date: 2015
- Subjects: Medicinal plants , Antifungal agents , Fungi -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5858 , vital:21001
- Description: Phytochemical analysis of both HEA1 and the crude plant extract showed the presence of phenolics, tannins and saponins. Saponins were the predominant secondary metabolites and were mostly abundant in the plant extract and to a lesser extent in the active compound. Steroidal saponins, tannins and phenolics were also detected in the plant extract, but only the phenolics were detected in the active compound. The results of the phytochemical analysis showed that those compounds that were not present in the active compound could be removed from the crude extract during the TLC purification process. Investigation on the mechanism of action of the crude plant extract on the sterol production by A. flavus showed that the plant extract affected ergosterol biosynthesis by causing an accumulation of oxidosqualene in the ergosterol biosynthetic pathway resulting in a decline in ergosterol production. An oscillatory response in lanosterol production was observed in the presence of the plant extract, which may be an adaptation mechanism of A. flavus to unfavourable conditions and compensation for the loss of enzyme activity which may have occurred as a result of the accumulation of oxidosqualene. The antifungal activity of the plant extract on ergosterol production by A. flavus may also be due to saponins which target the cell membrane and ergosterol production in fungi. The effect of the plant extract on the fungal cell wall of A. flavus also showed that the plant extract caused a decline in β-(1, 3) glucan production by inhibiting β-glucan synthase. The plant extract also affected the chitin synthesis pathway of A. flavus, by causing a decline in chitin production, which was due to the inhibition of chitin synthase. Investigation of chitinase production using 4MU substrates showed that the plant extract caused an accumulation of chitobioses, by activating chitobiosidases and endochitinases. A decline in N-acetylglucosaminidase activity in the presence of the plant extract was observed and this prevented the formation of N-acetylglucosamine. The accumulation of chitobiosidase and endochitinase may be as a result of autolysis that may be triggered by A. flavus as a survival mechanism in the presence of the plant extract and as a compensatory mechanism for the loss of β-glucans and chitin. The antifungal effect of the plant extract on various components of the cell wall of A. flavus, makes T. violacea aqueous plant extract an ideal chemotherapeutic agent against both human and plant pathogens of Aspergillus. The broad spectrum of antifungal activity of T. violacea against A. flavus also eliminates any chances of the fungus developing resistance towards it and would make it a candidate for use as a potential antifungal agent. Further identification and possible chemical synthesis is needed to shed light on the safety and efficacy of the active compound for further development as a chemotherapeutic agent.
- Full Text:
- Date Issued: 2015
The associative behaviour of silky sharks, Carcharhinus falciformis, with floating objects in the open ocean
- Authors: Filmalter, John David
- Date: 2015
- Subjects: Silky shark , Silky shark -- Behavior , Silky shark -- Marking , Silky shark -- Food , Tuna fisheries -- Bycatches , Fish aggregation devices , Underwater acoustic telemetry , Fish tagging
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5381 , http://hdl.handle.net/10962/d1018177
- Description: The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population.
- Full Text:
- Date Issued: 2015
- Authors: Filmalter, John David
- Date: 2015
- Subjects: Silky shark , Silky shark -- Behavior , Silky shark -- Marking , Silky shark -- Food , Tuna fisheries -- Bycatches , Fish aggregation devices , Underwater acoustic telemetry , Fish tagging
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5381 , http://hdl.handle.net/10962/d1018177
- Description: The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population.
- Full Text:
- Date Issued: 2015
The call centre labour process : a study of work and workers’ experiences at Joburg Connect, South Africa
- Authors: Magoqwana, Babalwa Mirianda
- Date: 2015
- Subjects: Johannesburg (South Africa) -- Joburg Connect , Call center agents -- South Africa -- Johannesburg -- Case studies , Work environment -- South Africa -- Johannesburg -- Case studies , Customer services -- South Africa -- Johannesburg -- Case studies , Personnel management -- South Africa -- Johannesburg -- Case studies , Employee morale -- South Africa -- Johannesburg -- Case studies , Employees -- Attitudes -- Case studies , Municipal services -- South Africa -- Johannesburg -- Case studies , South Africa -- Economic conditions -- 1991- , South Africa -- Politics and government -- 1994- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3400 , http://hdl.handle.net/10962/d1018569 , Johannesburg (South Africa) -- Joburg Connect , Call center agents -- South Africa -- Johannesburg -- Case studies , Work environment -- South Africa -- Johannesburg -- Case studies , Customer services -- South Africa -- Johannesburg -- Case studies , Personnel management -- South Africa -- Johannesburg -- Case studies , Employee morale -- South Africa -- Johannesburg -- Case studies , Employees -- Attitudes -- Case studies , Municipal services -- South Africa -- Johannesburg -- Case studies , South Africa -- Economic conditions -- 1991- , South Africa -- Politics and government -- 1994-
- Description: This thesis is an investigation of the call centre labour process focusing on both the way work is organised and experienced by the operators and the management of employee relations inside a local government workplace – The City of Johannesburg (COJ) Call Centre. The City of Johannesburg is used to understand labour process dynamics in local government. Johannesburg was recently named the ‘World’s Second Most Inspiring City’ (by Global City Index, 2014) possessing economic and political influence within and around South Africa. Johannesburg is the economic hub of the country, contributing nine per cent to the South African GDP. But it needs to be emphasised that the focus of this thesis is on the labour process rather than the City of Johannesburg. The nature of work in the COJ local government call centre involves answering calls about water, electricity, refuse removal, accounts and other general municipal services. The government’s objective was to have a more customer centred service delivery plan in compliance with the Batho Pele (People first) framework (RSA, 1997, White Paper on Local Government). This resulted in a shift in the government ‘mantra’ and philosophy from viewing Johannesburg residents as customers rather than citizens. This shift from public administration to New Public Management (NPM) has meant the introduction of private sector business principles into public services. This seeks to improve organisational and individual performance to enhance service delivery within South African municipalities. This is also meant to promote responsive and performance management culture. The study uses Labour Process Theory set out in Labour and Monopoly Capital (LMC-1974) by Harry Braverman to argue for the need to contextualise the labour process debate within the socio-political understanding of work in South Africa. In developing the argument about the narrow analysis of public sector call centres based on economic lines I have reviewed literature on call centres which is influenced by Michel Foucault and Harry Braverman to understand the public sector call centre labour process. Inspired by Adesina (2002) and Mafeje (1981) this study uses a ‘complementarity’ approach to knowledge. This means the local context tends to complement the global trends though not without contradictions within the local context. The case study approach was used for in-depth analysis of the local context through different methods (semi-structured interviews, focus group discussions, observations and survey questionnaires) to collect data from different stakeholders within the City of Johannesburg between 2010 and 2013. The concept of a ‘(dis)connecting city’ is fitting for the COJ as this city connects the rest of Sub-Saharan Africa and South Africa to the world through its commerce and political influence. Based on the challenges experienced in this local government call centre I attempt to show the the politicised nature of the public sector call centre labour process. I use the differential power relations in the frontline between customer and Joburg connect workers to illustrate this point. The lack of emphasis on the politicised nature of public sector call centres within literature is informed by the de-contextualised nature of these call centres. In the end, I argue that public sector call centre labour process is multilayered, contradictory and complicated because of these workers’ role as citizens, customers, community members and service providers from a politicised community environment.
- Full Text:
- Date Issued: 2015
- Authors: Magoqwana, Babalwa Mirianda
- Date: 2015
- Subjects: Johannesburg (South Africa) -- Joburg Connect , Call center agents -- South Africa -- Johannesburg -- Case studies , Work environment -- South Africa -- Johannesburg -- Case studies , Customer services -- South Africa -- Johannesburg -- Case studies , Personnel management -- South Africa -- Johannesburg -- Case studies , Employee morale -- South Africa -- Johannesburg -- Case studies , Employees -- Attitudes -- Case studies , Municipal services -- South Africa -- Johannesburg -- Case studies , South Africa -- Economic conditions -- 1991- , South Africa -- Politics and government -- 1994- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3400 , http://hdl.handle.net/10962/d1018569 , Johannesburg (South Africa) -- Joburg Connect , Call center agents -- South Africa -- Johannesburg -- Case studies , Work environment -- South Africa -- Johannesburg -- Case studies , Customer services -- South Africa -- Johannesburg -- Case studies , Personnel management -- South Africa -- Johannesburg -- Case studies , Employee morale -- South Africa -- Johannesburg -- Case studies , Employees -- Attitudes -- Case studies , Municipal services -- South Africa -- Johannesburg -- Case studies , South Africa -- Economic conditions -- 1991- , South Africa -- Politics and government -- 1994-
- Description: This thesis is an investigation of the call centre labour process focusing on both the way work is organised and experienced by the operators and the management of employee relations inside a local government workplace – The City of Johannesburg (COJ) Call Centre. The City of Johannesburg is used to understand labour process dynamics in local government. Johannesburg was recently named the ‘World’s Second Most Inspiring City’ (by Global City Index, 2014) possessing economic and political influence within and around South Africa. Johannesburg is the economic hub of the country, contributing nine per cent to the South African GDP. But it needs to be emphasised that the focus of this thesis is on the labour process rather than the City of Johannesburg. The nature of work in the COJ local government call centre involves answering calls about water, electricity, refuse removal, accounts and other general municipal services. The government’s objective was to have a more customer centred service delivery plan in compliance with the Batho Pele (People first) framework (RSA, 1997, White Paper on Local Government). This resulted in a shift in the government ‘mantra’ and philosophy from viewing Johannesburg residents as customers rather than citizens. This shift from public administration to New Public Management (NPM) has meant the introduction of private sector business principles into public services. This seeks to improve organisational and individual performance to enhance service delivery within South African municipalities. This is also meant to promote responsive and performance management culture. The study uses Labour Process Theory set out in Labour and Monopoly Capital (LMC-1974) by Harry Braverman to argue for the need to contextualise the labour process debate within the socio-political understanding of work in South Africa. In developing the argument about the narrow analysis of public sector call centres based on economic lines I have reviewed literature on call centres which is influenced by Michel Foucault and Harry Braverman to understand the public sector call centre labour process. Inspired by Adesina (2002) and Mafeje (1981) this study uses a ‘complementarity’ approach to knowledge. This means the local context tends to complement the global trends though not without contradictions within the local context. The case study approach was used for in-depth analysis of the local context through different methods (semi-structured interviews, focus group discussions, observations and survey questionnaires) to collect data from different stakeholders within the City of Johannesburg between 2010 and 2013. The concept of a ‘(dis)connecting city’ is fitting for the COJ as this city connects the rest of Sub-Saharan Africa and South Africa to the world through its commerce and political influence. Based on the challenges experienced in this local government call centre I attempt to show the the politicised nature of the public sector call centre labour process. I use the differential power relations in the frontline between customer and Joburg connect workers to illustrate this point. The lack of emphasis on the politicised nature of public sector call centres within literature is informed by the de-contextualised nature of these call centres. In the end, I argue that public sector call centre labour process is multilayered, contradictory and complicated because of these workers’ role as citizens, customers, community members and service providers from a politicised community environment.
- Full Text:
- Date Issued: 2015
The detection of glyphosate and glyphosate-based herbicides in water, using nanotechnology
- De Almeida, Louise Kashiyavala Sophia
- Authors: De Almeida, Louise Kashiyavala Sophia
- Date: 2015
- Subjects: Water -- Glyphosate content , Aquatic herbicides -- South Africa , Aquatic herbicides -- Physiological effect , Nanotechnology , Invasive plants -- South Africa , Genetic toxicology , Thiazoles , Tetrazolium , Immunotoxicology , Colorimetry , Nanofibers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4163 , http://hdl.handle.net/10962/d1019755
- Description: Glyphosate (N-phosphonomethylglycine) is an organophosphate compound which was developed by the Monsanto Company in 1971 and is the active ingredient found in several herbicide formulations. The use of glyphosate-based herbicides in South Africa for the control of alien invasive plants and weeds is well established, extensive and currently unregulated, which vastly increases the likelihood of glyphosate contamination in environmental water systems. Although the use of glyphosate-based herbicides is required for economic enhancement in industries such as agriculture, the presence of this compound in natural water systems presents a potential risk to human health. Glyphosate and glyphosate formulations were previously considered safe, however their toxicity has become a major focal point of research over recent years. The lack of monitoring protocols for pesticides in South Africa is primarily due to limited financial capacity and the lack of analytical techniques.
- Full Text:
- Date Issued: 2015
- Authors: De Almeida, Louise Kashiyavala Sophia
- Date: 2015
- Subjects: Water -- Glyphosate content , Aquatic herbicides -- South Africa , Aquatic herbicides -- Physiological effect , Nanotechnology , Invasive plants -- South Africa , Genetic toxicology , Thiazoles , Tetrazolium , Immunotoxicology , Colorimetry , Nanofibers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4163 , http://hdl.handle.net/10962/d1019755
- Description: Glyphosate (N-phosphonomethylglycine) is an organophosphate compound which was developed by the Monsanto Company in 1971 and is the active ingredient found in several herbicide formulations. The use of glyphosate-based herbicides in South Africa for the control of alien invasive plants and weeds is well established, extensive and currently unregulated, which vastly increases the likelihood of glyphosate contamination in environmental water systems. Although the use of glyphosate-based herbicides is required for economic enhancement in industries such as agriculture, the presence of this compound in natural water systems presents a potential risk to human health. Glyphosate and glyphosate formulations were previously considered safe, however their toxicity has become a major focal point of research over recent years. The lack of monitoring protocols for pesticides in South Africa is primarily due to limited financial capacity and the lack of analytical techniques.
- Full Text:
- Date Issued: 2015
The development of amine-based extractants for separation of base metals in a sulfate medium
- Authors: Magwa, Nomampondo Penelope
- Date: 2015
- Subjects: Extraction (Chemistry) , Sulfates , Ligands , Benzimidazoles , Infrared spectroscopy , Nuclear magnetic resonance spectroscopy , Metal ions , Metals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4559 , http://hdl.handle.net/10962/d1020010
- Description: Tridentate benzimidazole-based ligands, bis((1H-benzimidazol-2-yl)methyl)sulfide (BNSN) and bis((1H-benzimidazol-2-yl)methyl)amine (BNNN), along with dinonylnaphthalene sulfonic acid (DNNSA) as a synergist, were investigated as potential selective extractants for Ni2+ from base metals in a solvent extraction system using 2-octanol/Shellsol 2325 (8:2) as diluent and modifier. However, extraction studies show a lack of pH-metric separation of the later 3d metal ions with bis((1-octylbenzimidazol-2-yl)methyl)sulfide (BONSN) and bis((1- decylbenzimidazol-2-yl)methyl)amine (BDNNN) as extractants, but extractions occurred in the low pH range with an opportunity for back extraction. This investigation suggested that tridentate ligands (at least those of the nature investigated here) are not feasible extractants for separation of base metal ions due to their lack of stereochemical “tailor-making.”
- Full Text:
- Date Issued: 2015
- Authors: Magwa, Nomampondo Penelope
- Date: 2015
- Subjects: Extraction (Chemistry) , Sulfates , Ligands , Benzimidazoles , Infrared spectroscopy , Nuclear magnetic resonance spectroscopy , Metal ions , Metals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4559 , http://hdl.handle.net/10962/d1020010
- Description: Tridentate benzimidazole-based ligands, bis((1H-benzimidazol-2-yl)methyl)sulfide (BNSN) and bis((1H-benzimidazol-2-yl)methyl)amine (BNNN), along with dinonylnaphthalene sulfonic acid (DNNSA) as a synergist, were investigated as potential selective extractants for Ni2+ from base metals in a solvent extraction system using 2-octanol/Shellsol 2325 (8:2) as diluent and modifier. However, extraction studies show a lack of pH-metric separation of the later 3d metal ions with bis((1-octylbenzimidazol-2-yl)methyl)sulfide (BONSN) and bis((1- decylbenzimidazol-2-yl)methyl)amine (BDNNN) as extractants, but extractions occurred in the low pH range with an opportunity for back extraction. This investigation suggested that tridentate ligands (at least those of the nature investigated here) are not feasible extractants for separation of base metal ions due to their lack of stereochemical “tailor-making.”
- Full Text:
- Date Issued: 2015
The diversity of root fungi associated with Erica species occurring in the Albany Centre of Endemism
- Authors: Bizabani, Christine
- Date: 2015
- Subjects: Ericaceae , Ericas , Roots (Botany) -- Diseases and pests , Mycorrhizal fungi , Polymerase chain reaction , Fungi -- Classification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4160 , http://hdl.handle.net/10962/d1018575
- Description: South Africa has the highest species diversity of ericaceous plants belonging to the Erica genus. There are over 850 identified species in the Cape Floral Region. The Albany Centre of Endemism (ACOE) is located within this region and is a hotspot of diversity consisting of various plant genera. The success of Erica plants is ubiquitously attributed to mycorrhizal relationships they engage in with a diverse group of fungi. This symbiosis is known as the ericoid mycorrhizal (ERM) association. The overall aim of this study was to establish the diversity of root fungi associated with Erica plants using morphological, molecular and 454 pyrosequencing techniques. Six Erica species were identified using leaf and flower morphology according to taxonomic keys. The identified plants were Erica cerinthoides, Erica demissa, Erica chamissonis, Erica glumiflora, Erica caffra and Erica nemorosa. Roots from sampled plants were stained and examined microscopically to determine their mycorrhizal status. Ericoid mycorrhizal associations together with dark septate endophyte (DSE) structures and hyphae that did not form any specific structure were observed in all the roots. In addition arbuscular mycorrhizal (AM) structures in the form of vesicles were detected in E. glumiflora and E. cerinthoides. In order to identify the culturable fungi associated with the respective hosts, sterilised roots were placed on various culture media for cultivation. Thereafter isolated fungi were morphologically classified into 67 morphotypes. These were mostly sterile and darkly pigmented. Non-sporulating mycelia of variable colouration such as white, cream-yellowish, beige, green and brown were also observed. Further identification was carried out using molecular techniques. DNA was extracted separately from pure cultures and amplified using ITS1 and ITS4 primers in a polymerase chain reaction (PCR). Thereafter sequencing and Basic Local Alignment Search Tool (BLAST) were used to identify the isolates to generic level. The fungi were taxonomically classified into 54 operational taxonomic units and 94 percent were Ascomycetes and Helotiales was the dominant order. Unclassified Helotiales with affinities to fungi currently identified as Epacrid root fungus was common in all hosts. Other isolates that were identified included Oidiodendron, Meliniomyces, Phialocephala, Cadophora, Lachnum, Leohumicola Cryptosporiopsis, Chaetomium, Acremonium and Epicoccum species. Basidiomycetes were represented by two OTUs belonging to the genus Mycena. Four OTUs comprised fungi that had no significant alignments in the reference databases. Direct root DNA extraction together with 454 pyrosequencing was used to detect the diversity of culturable and unculturable fungi associated with the identified hosts. The ITS2 region was targeted for sequencing. Although Ascomycetes remained the dominant phyla, Basidiomycetes were also detected in all host plants. Glomeromycota was present in E. caffra and E. cerinthoides. Helotiales was dominant in all Erica plants with the exception of E. cerinthoides and E. chamissonis which were dominated by the order Chaetothyriales. The OTUs identified to genus level included Epacris pulchella root fungus, Oidiodendron cf. maius, Acremonium implicatum, Leohumicola, Lachnum, Capronia and Mycena species. Culture-based techniques and pyrosequencing detected similar fungal composition comprising Ascomycetes, while, pyrosequencing was able to detect Glomeromycetes and Basidiomycetes.
- Full Text:
- Date Issued: 2015
The diversity of root fungi associated with Erica species occurring in the Albany Centre of Endemism
- Authors: Bizabani, Christine
- Date: 2015
- Subjects: Ericaceae , Ericas , Roots (Botany) -- Diseases and pests , Mycorrhizal fungi , Polymerase chain reaction , Fungi -- Classification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4160 , http://hdl.handle.net/10962/d1018575
- Description: South Africa has the highest species diversity of ericaceous plants belonging to the Erica genus. There are over 850 identified species in the Cape Floral Region. The Albany Centre of Endemism (ACOE) is located within this region and is a hotspot of diversity consisting of various plant genera. The success of Erica plants is ubiquitously attributed to mycorrhizal relationships they engage in with a diverse group of fungi. This symbiosis is known as the ericoid mycorrhizal (ERM) association. The overall aim of this study was to establish the diversity of root fungi associated with Erica plants using morphological, molecular and 454 pyrosequencing techniques. Six Erica species were identified using leaf and flower morphology according to taxonomic keys. The identified plants were Erica cerinthoides, Erica demissa, Erica chamissonis, Erica glumiflora, Erica caffra and Erica nemorosa. Roots from sampled plants were stained and examined microscopically to determine their mycorrhizal status. Ericoid mycorrhizal associations together with dark septate endophyte (DSE) structures and hyphae that did not form any specific structure were observed in all the roots. In addition arbuscular mycorrhizal (AM) structures in the form of vesicles were detected in E. glumiflora and E. cerinthoides. In order to identify the culturable fungi associated with the respective hosts, sterilised roots were placed on various culture media for cultivation. Thereafter isolated fungi were morphologically classified into 67 morphotypes. These were mostly sterile and darkly pigmented. Non-sporulating mycelia of variable colouration such as white, cream-yellowish, beige, green and brown were also observed. Further identification was carried out using molecular techniques. DNA was extracted separately from pure cultures and amplified using ITS1 and ITS4 primers in a polymerase chain reaction (PCR). Thereafter sequencing and Basic Local Alignment Search Tool (BLAST) were used to identify the isolates to generic level. The fungi were taxonomically classified into 54 operational taxonomic units and 94 percent were Ascomycetes and Helotiales was the dominant order. Unclassified Helotiales with affinities to fungi currently identified as Epacrid root fungus was common in all hosts. Other isolates that were identified included Oidiodendron, Meliniomyces, Phialocephala, Cadophora, Lachnum, Leohumicola Cryptosporiopsis, Chaetomium, Acremonium and Epicoccum species. Basidiomycetes were represented by two OTUs belonging to the genus Mycena. Four OTUs comprised fungi that had no significant alignments in the reference databases. Direct root DNA extraction together with 454 pyrosequencing was used to detect the diversity of culturable and unculturable fungi associated with the identified hosts. The ITS2 region was targeted for sequencing. Although Ascomycetes remained the dominant phyla, Basidiomycetes were also detected in all host plants. Glomeromycota was present in E. caffra and E. cerinthoides. Helotiales was dominant in all Erica plants with the exception of E. cerinthoides and E. chamissonis which were dominated by the order Chaetothyriales. The OTUs identified to genus level included Epacris pulchella root fungus, Oidiodendron cf. maius, Acremonium implicatum, Leohumicola, Lachnum, Capronia and Mycena species. Culture-based techniques and pyrosequencing detected similar fungal composition comprising Ascomycetes, while, pyrosequencing was able to detect Glomeromycetes and Basidiomycetes.
- Full Text:
- Date Issued: 2015
The isolation, characterisation and chemotaxonomic significance of secondary metabolites from selected South African Laurencia spp. Rhodophyta
- Authors: Fakee, Jameel
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64696 , vital:28593
- Description: Bioprospection of marine organisms as a potential source for lead drugs is becoming increasingly popular. The secondary metabolome of these organisms consists of structurally diverse molecules possessing unprecedented carbon skeletons, the biosynthesis of which occurs via complex metabolomic pathways driven by specialist enzymes. This structural novelty is highly influential on the favourable bioactivity these compounds display. A prominent example of such a compound is trabectedin marketed as Yondelis®. Registered for the treatment of soft tissue sarcomas, this marine drug was developed from extracts of the tunicate Ecteinascidia turbinata. South Africa is renowned for possessing a highly diverse marine biota including several endemic species of marine red algae belonging to the Laurencia sensu stricto genus, which falls within the Laurencia complex. Despite having a good reputation for fascinating secondary metabolites, the taxonomy of Laurencia natural products is proving challenging for reasons including the presence of cryptic species, as well as individual species displaying morphological variability. The aim of this study was thus to isolate secondary metabolites from various South African Laurencia spp. and subsequently assess their chemotaxonomic significance by analysis of a parallel plastid rbcL phylogeny study of Laurencia spp. This study reports the first phycochemical investigation into Laurencia natalensis Kylin, Laurencia cf. corymbosa J.Agardh, Laurencia complanata (Suhr) Kützing, Laurencia sodwaniensis Francis, Bolton, Mattio and Anderson submitted, Laurencia multiclavata Francis, Bolton, Mattio and Anderson submitted, and a South African specimen of Laurenciella marilzae Gil-Rodríguez, Sentíes, Díaz-Larrea, Cassano and M.T. Fujii (basionym: Laurencia marilzae) originally described from Spain. Additionally, the chemical profiles of previously explored species Laurencia flexuosa Kützing and Laurencia glomerata Kützing were re-investigated. The organic extracts of the above species afforded 31 compounds belonging to a wide array of structural classes including halo-chamigranes, linear C15 acetogenins, indole alkaloids, cuparanes and cyclic bromo-ethers. A new tri-cyclic keto-cuparane (4.4) was isolated from L.cf. corymbosa alongside the new cuparanes 4.1 and 4.7. Algoane (5.9), a unique marker compound isolated from L. natalensis, was previously only reported from a sea-hare. Such marker compounds which are exclusive to an individual algal species increase the ease of their subsequent identification. The feasibility of chemotaxonomy as an additional tool to classify Laurencia spp. Was established as broad predictions of a specimen’s phylogeny, based on representatives of its secondary metabolome, proved viable. The study specimens were shown to possess similar chemical profiles to their sister species e.g. L. complanata, L. sodwaniensis and L. multiclavata produced similar metabolites to their sister species as inferred by an rbcL phylogeny tree. Finally, a 1H NMR profiling study on the crude organic extracts of various Laurencia spp. generated distinctive, reproducible spectra, exposing the value of NMR spectroscopy as a rudimentary species discernment tool.
- Full Text:
- Date Issued: 2015
- Authors: Fakee, Jameel
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64696 , vital:28593
- Description: Bioprospection of marine organisms as a potential source for lead drugs is becoming increasingly popular. The secondary metabolome of these organisms consists of structurally diverse molecules possessing unprecedented carbon skeletons, the biosynthesis of which occurs via complex metabolomic pathways driven by specialist enzymes. This structural novelty is highly influential on the favourable bioactivity these compounds display. A prominent example of such a compound is trabectedin marketed as Yondelis®. Registered for the treatment of soft tissue sarcomas, this marine drug was developed from extracts of the tunicate Ecteinascidia turbinata. South Africa is renowned for possessing a highly diverse marine biota including several endemic species of marine red algae belonging to the Laurencia sensu stricto genus, which falls within the Laurencia complex. Despite having a good reputation for fascinating secondary metabolites, the taxonomy of Laurencia natural products is proving challenging for reasons including the presence of cryptic species, as well as individual species displaying morphological variability. The aim of this study was thus to isolate secondary metabolites from various South African Laurencia spp. and subsequently assess their chemotaxonomic significance by analysis of a parallel plastid rbcL phylogeny study of Laurencia spp. This study reports the first phycochemical investigation into Laurencia natalensis Kylin, Laurencia cf. corymbosa J.Agardh, Laurencia complanata (Suhr) Kützing, Laurencia sodwaniensis Francis, Bolton, Mattio and Anderson submitted, Laurencia multiclavata Francis, Bolton, Mattio and Anderson submitted, and a South African specimen of Laurenciella marilzae Gil-Rodríguez, Sentíes, Díaz-Larrea, Cassano and M.T. Fujii (basionym: Laurencia marilzae) originally described from Spain. Additionally, the chemical profiles of previously explored species Laurencia flexuosa Kützing and Laurencia glomerata Kützing were re-investigated. The organic extracts of the above species afforded 31 compounds belonging to a wide array of structural classes including halo-chamigranes, linear C15 acetogenins, indole alkaloids, cuparanes and cyclic bromo-ethers. A new tri-cyclic keto-cuparane (4.4) was isolated from L.cf. corymbosa alongside the new cuparanes 4.1 and 4.7. Algoane (5.9), a unique marker compound isolated from L. natalensis, was previously only reported from a sea-hare. Such marker compounds which are exclusive to an individual algal species increase the ease of their subsequent identification. The feasibility of chemotaxonomy as an additional tool to classify Laurencia spp. Was established as broad predictions of a specimen’s phylogeny, based on representatives of its secondary metabolome, proved viable. The study specimens were shown to possess similar chemical profiles to their sister species e.g. L. complanata, L. sodwaniensis and L. multiclavata produced similar metabolites to their sister species as inferred by an rbcL phylogeny tree. Finally, a 1H NMR profiling study on the crude organic extracts of various Laurencia spp. generated distinctive, reproducible spectra, exposing the value of NMR spectroscopy as a rudimentary species discernment tool.
- Full Text:
- Date Issued: 2015
The metabolism and environmental fate of the cyanobacterial neurotoxin Beta-N-methylamino-L-alanine
- Authors: Downing, Simoné
- Date: 2015
- Subjects: Cyanobacteria , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4225 , vital:20569
- Description: The neurotoxic amino acid β-‐N-‐methylamino-Lalanine (BMAA)is present in environmentally ubiquitous cyanobacteria and bioaccumulates and biomagnifies within the environment. The implication of BMAA in the development of neurodegenerative disease has raised concerns over the potential risk of human exposure to this neurotoxin, and has focussed attention on identifying possible routes of exposure that include direct contact with cyanobacteria and the ingestion of BMAA-‐containing plant and animal products.
- Full Text:
- Date Issued: 2015
- Authors: Downing, Simoné
- Date: 2015
- Subjects: Cyanobacteria , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4225 , vital:20569
- Description: The neurotoxic amino acid β-‐N-‐methylamino-Lalanine (BMAA)is present in environmentally ubiquitous cyanobacteria and bioaccumulates and biomagnifies within the environment. The implication of BMAA in the development of neurodegenerative disease has raised concerns over the potential risk of human exposure to this neurotoxin, and has focussed attention on identifying possible routes of exposure that include direct contact with cyanobacteria and the ingestion of BMAA-‐containing plant and animal products.
- Full Text:
- Date Issued: 2015