Genetic and biological characterisation of a novel South African Plutella xylostella granulovirus (PlxyGV) isolate
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
Relative contribution of wild foods to individual and household food security in the context of increasing vulnerability due to HIV/AIDS and climate variability
- Abu-Basutu, Keitometsi Ngulube
- Authors: Abu-Basutu, Keitometsi Ngulube
- Date: 2014
- Subjects: Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4774 , http://hdl.handle.net/10962/d1010864 , Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Description: Wild foods are an integral component of the household food basket, yet their quantified contribution to food security relative to other sources in the context of HIV/AIDS, climate change and variability remains underexplored. This study was carried out in Willowvale and Lesseyton which are rural communities in the Eastern Cape province of South Africa. Willowvale is a relatively remote, medium-rainfall coastal community, while Lesseyton is a peri-urban low rainfall inland community. Qualitative and quantitative methods were used to collect data from 78 HIV/AIDS afflicted households with 329 individuals and 87 non-afflicted households with 365 individuals in the two study sites. Households were visited quarterly over 12 months to assess food acquisition methods, dietary intake and quality, and levels of food security, and to determine strategies employed by households to cope with droughts. The wild foods investigated were wild meat, wild birds, wild fish, wild mushrooms, wild leafy vegetables and wild fruits. Diets were moderately well-balanced and limited in variety, with cereal items contributing 52 % to total calorie intake. Mid-upper arm circumference measurements showed that all respondents were adequately nourished. The bulk of the food consumed by households was purchased, with supplementation from own production, wild vegetables and wild fruits. In Willowvale, wild vegetables comprised 46 % of overall vegetable consumption for afflicted households and 32 % for non-afflicted households, while own fruit production comprised 100 % of fruit consumption. In Lesseyton, wild vegetables comprised only 6 % and 4 % of vegetable consumption for afflicted and non-afflicted households, while wild fruit comprised 63 % and 41 % for afflicted and non-afflicted households. More than 80 % of respondents from both afflicted and non-afflicted households had sufficient daily kilocalories, although the majority of afflicted households felt they were food insecure and sometimes collected wild foods as one of their multiple coping strategies. Hunting and gathering of wild foods was associated with site, household affliction status, gender, age and season. More than 80 % of respondents ate wild vegetables and said they were more drought tolerant than conventional vegetables, making them the most consumed wild food and approximately 16 % of respondents ate wild birds, making them the least consumed wild food. Approximately 14 % of respondents from afflicted households in Willowvale sold wild fish, whilst 34 % of respondents from afflicted households and 7 % from non-afflicted households sold wild fruits in Lesseyton. Strategies adopted by households to cope with droughts were different between the two study sites, and households in Willowvale used a wider range of strategies. Given the devastating effects of HIV/AIDS coupled with the drawbacks of climate change and variability on food security, wild foods represent a free and easy way for vulnerable households to obtain food.
- Full Text:
- Authors: Abu-Basutu, Keitometsi Ngulube
- Date: 2014
- Subjects: Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4774 , http://hdl.handle.net/10962/d1010864 , Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Description: Wild foods are an integral component of the household food basket, yet their quantified contribution to food security relative to other sources in the context of HIV/AIDS, climate change and variability remains underexplored. This study was carried out in Willowvale and Lesseyton which are rural communities in the Eastern Cape province of South Africa. Willowvale is a relatively remote, medium-rainfall coastal community, while Lesseyton is a peri-urban low rainfall inland community. Qualitative and quantitative methods were used to collect data from 78 HIV/AIDS afflicted households with 329 individuals and 87 non-afflicted households with 365 individuals in the two study sites. Households were visited quarterly over 12 months to assess food acquisition methods, dietary intake and quality, and levels of food security, and to determine strategies employed by households to cope with droughts. The wild foods investigated were wild meat, wild birds, wild fish, wild mushrooms, wild leafy vegetables and wild fruits. Diets were moderately well-balanced and limited in variety, with cereal items contributing 52 % to total calorie intake. Mid-upper arm circumference measurements showed that all respondents were adequately nourished. The bulk of the food consumed by households was purchased, with supplementation from own production, wild vegetables and wild fruits. In Willowvale, wild vegetables comprised 46 % of overall vegetable consumption for afflicted households and 32 % for non-afflicted households, while own fruit production comprised 100 % of fruit consumption. In Lesseyton, wild vegetables comprised only 6 % and 4 % of vegetable consumption for afflicted and non-afflicted households, while wild fruit comprised 63 % and 41 % for afflicted and non-afflicted households. More than 80 % of respondents from both afflicted and non-afflicted households had sufficient daily kilocalories, although the majority of afflicted households felt they were food insecure and sometimes collected wild foods as one of their multiple coping strategies. Hunting and gathering of wild foods was associated with site, household affliction status, gender, age and season. More than 80 % of respondents ate wild vegetables and said they were more drought tolerant than conventional vegetables, making them the most consumed wild food and approximately 16 % of respondents ate wild birds, making them the least consumed wild food. Approximately 14 % of respondents from afflicted households in Willowvale sold wild fish, whilst 34 % of respondents from afflicted households and 7 % from non-afflicted households sold wild fruits in Lesseyton. Strategies adopted by households to cope with droughts were different between the two study sites, and households in Willowvale used a wider range of strategies. Given the devastating effects of HIV/AIDS coupled with the drawbacks of climate change and variability on food security, wild foods represent a free and easy way for vulnerable households to obtain food.
- Full Text:
Conjugation of mono-substituted phthalocyanine derivatives to CdSe@ ZnS quantum dots and their applications as fluorescent-based sensors
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189842 , vital:44936 , xlink:href="https://doi.org/10.1016/j.synthmet.2013.11.016"
- Description: Unsymmetrically substituted derivatives of aluminium amino phthalocyanines were synthesized for the first time, fully characterized and conjugated to CdSe@ZnS quantum dots (QDs). The conjugates were employed as fluorescence-based sensors for anion sensing. Among the anions that enhanced the fluorescence of the probe, fluoride ion was chosen as the test ion to test the efficacy of the probe. Förster resonance energy transfer from the QDs to the phthalocyanine was observed as an indication for the fluorescence quenching of the QDs upon binding to the phthalocyanine. The fluorescence of the linked QDs was progressively enhanced, and linearly proportional to increasing concentrations of fluoride ion. The type of substituent attached to the phthalocyanine ring influenced the efficiency of fluorescence enhancement. The proposed nanoprobe has been employed to detect fluoride ion in cell culture medium and tap water.
- Full Text:
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189842 , vital:44936 , xlink:href="https://doi.org/10.1016/j.synthmet.2013.11.016"
- Description: Unsymmetrically substituted derivatives of aluminium amino phthalocyanines were synthesized for the first time, fully characterized and conjugated to CdSe@ZnS quantum dots (QDs). The conjugates were employed as fluorescence-based sensors for anion sensing. Among the anions that enhanced the fluorescence of the probe, fluoride ion was chosen as the test ion to test the efficacy of the probe. Förster resonance energy transfer from the QDs to the phthalocyanine was observed as an indication for the fluorescence quenching of the QDs upon binding to the phthalocyanine. The fluorescence of the linked QDs was progressively enhanced, and linearly proportional to increasing concentrations of fluoride ion. The type of substituent attached to the phthalocyanine ring influenced the efficiency of fluorescence enhancement. The proposed nanoprobe has been employed to detect fluoride ion in cell culture medium and tap water.
- Full Text:
Effects of analytes on the fluorescence properties of CdTe@ ZnS quantum dots decorated with cobalt tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
Unsymmetrically substituted nickel triazatetra-benzcorrole and phthalocynanine complexes
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189818 , vital:44934 , xlink:href="https://doi.org/10.1007/s10895-013-1317-4"
- Description: We report on the design and application of fluorescent nanoprobes based on the covalent linking of L-glutathione-capped CdSe@ZnS quantum dots (QDs) to newly synthesized unsymmetrically substituted nickel mercaptosuccinic acid triazatetra-benzcorrole (3) and phthalocyanine (4) complexes. Fluorescence quenching of the QDs occurred on conjugation to complexes 3 or 4. The nanoprobes were selectively screened in the presence of different cations and Hg2+ showed excellent affinity in “turning ON” the fluorescence of the nanoprobes. Experimental results showed that the sensitivity of QDs-4 towards Hg2+ was much higher than that of QDs-3 nanoprobe. The mechanism of reaction has been elucidated based on the ability of Hg2+ to coordinate with the sulphur atom of the Ni complex ring and apparently “turn ON” the fluorescence of the linked QDs.
- Full Text:
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189818 , vital:44934 , xlink:href="https://doi.org/10.1007/s10895-013-1317-4"
- Description: We report on the design and application of fluorescent nanoprobes based on the covalent linking of L-glutathione-capped CdSe@ZnS quantum dots (QDs) to newly synthesized unsymmetrically substituted nickel mercaptosuccinic acid triazatetra-benzcorrole (3) and phthalocyanine (4) complexes. Fluorescence quenching of the QDs occurred on conjugation to complexes 3 or 4. The nanoprobes were selectively screened in the presence of different cations and Hg2+ showed excellent affinity in “turning ON” the fluorescence of the nanoprobes. Experimental results showed that the sensitivity of QDs-4 towards Hg2+ was much higher than that of QDs-3 nanoprobe. The mechanism of reaction has been elucidated based on the ability of Hg2+ to coordinate with the sulphur atom of the Ni complex ring and apparently “turn ON” the fluorescence of the linked QDs.
- Full Text:
The design of quantum dots and their conjugates as luminescent probes for analyte sensing
- Authors: Adegoke, Oluwasesan
- Date: 2014
- Subjects: Quantum dots Anolytes Luminescent probes Luminescence spectroscopy Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4457 , http://hdl.handle.net/10962/d1010866
- Description: The design and applications of quantum dots (QDs) as fluorescent probes for analyte sensing is presented. Cadmium based thiol-capped QDs were employed as probe for the detection of analytes. Comparative studies between core CdTe and core-shell CdTe@ZnS QDs showed that the overall sensitivity and selectivity of the sensor was dependent on the nature of the capping agent and the QDs employed, hence making CdTe@ZnS QDs a more superior sensor than the core. To explore the luminescent sensing of QDs based on the fluorescence “turn ON” mode, L-glutathione-capped CdTe QDs was conjugated to 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT) to form a QDs-4AT conjugate system. The QDs-4AT nanoprobe was highly selective and sensitive to the detection of bromide ion with a very low limit of detection. Subsequently, metallo-phthalocyanines (MPcs) were employed as host molecules on the surface of QDs based on the covalent linking of the QDs to the MPc. Elucidation of the reaction mechanism showed that the fluorescence “turn ON” effect of the QDs-MPc probe in the presence of the analyte was due to axial ligation of the analytes to the Pc ring. Studies showed that the type of substituent attached to the MPc ring influenced the overall sensitivity of the probe. Additionally, a comparative investigation using newly synthesized phthalocyanine and triaza-benzcorrole complexes was conducted when these complexes were conjugated to CdSe@ZnS QDs for analyte sensing. Results showed that the triaza-benzcorrole complex can be employed as a host-molecule sensor but displayed a lower sensitivity for analyte sensing in comparison to the phthalocyanine complex.
- Full Text:
- Authors: Adegoke, Oluwasesan
- Date: 2014
- Subjects: Quantum dots Anolytes Luminescent probes Luminescence spectroscopy Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4457 , http://hdl.handle.net/10962/d1010866
- Description: The design and applications of quantum dots (QDs) as fluorescent probes for analyte sensing is presented. Cadmium based thiol-capped QDs were employed as probe for the detection of analytes. Comparative studies between core CdTe and core-shell CdTe@ZnS QDs showed that the overall sensitivity and selectivity of the sensor was dependent on the nature of the capping agent and the QDs employed, hence making CdTe@ZnS QDs a more superior sensor than the core. To explore the luminescent sensing of QDs based on the fluorescence “turn ON” mode, L-glutathione-capped CdTe QDs was conjugated to 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT) to form a QDs-4AT conjugate system. The QDs-4AT nanoprobe was highly selective and sensitive to the detection of bromide ion with a very low limit of detection. Subsequently, metallo-phthalocyanines (MPcs) were employed as host molecules on the surface of QDs based on the covalent linking of the QDs to the MPc. Elucidation of the reaction mechanism showed that the fluorescence “turn ON” effect of the QDs-MPc probe in the presence of the analyte was due to axial ligation of the analytes to the Pc ring. Studies showed that the type of substituent attached to the MPc ring influenced the overall sensitivity of the probe. Additionally, a comparative investigation using newly synthesized phthalocyanine and triaza-benzcorrole complexes was conducted when these complexes were conjugated to CdSe@ZnS QDs for analyte sensing. Results showed that the triaza-benzcorrole complex can be employed as a host-molecule sensor but displayed a lower sensitivity for analyte sensing in comparison to the phthalocyanine complex.
- Full Text:
Structural bioinformatics analysis of the Hsp40 and Hsp70 molecular chaperones from humans
- Authors: Adeyemi, Samson Adebowale
- Date: 2014
- Subjects: Structural bioinformatics , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Biomolecules
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4171 , http://hdl.handle.net/10962/d1020962
- Description: HSP70 is one of the most important families of molecular chaperone that regulate the folding and transport of client proteins in an ATP dependent manner. The ATPase activity of HSP70 is stimulated through an interaction with its family of HSP40 co-chaperones. There is evidence to suggest that specific partnerships occur between the different HSP40 and HSP70 isoforms. While some of the residues involved in the interaction are known, many of the residues governing the specificity of HSP40-HSP70 partnerships are not precisely defined. It is not currently possible to predict which HSP40 and HSP70 isoforms will interact. We attempted to use bioinformatics to identify residues involved in the specificity of the interaction between the J domain from HSP40 and the ATPase domain from the HSP70 isoforms from humans. A total of 49 HSP40 and 13 HSP70 sequences from humans were retrieved and used for subsequent analyses. The HSP40 J domains and HSP70 ATPase domains were extracted using python scripts and classified according to the subcellular localization of the proteins using localization prediction programs. Motif analysis was carried out using the full length HSP40 proteins and Multiple Sequence Alignment (MSA) was performed to identify conserved residues that may contribute to the J domain – ATPase domain interactions. Phylogenetic inference of the proteins was also performed in order to study their evolutionary relationship. Homology models of the J domains and ATPase domains were generated. The corresponding models were docked using HADDOCK server in order to analyze possible putative interactions between the partner proteins using the Protein Interactions Calculator (PIC). The level of residue conservation was found to be higher in Type I and II HSP40 than in Type III J proteins. While highly conserved residues on helixes II and III could play critical roles in J domain interactions with corresponding HSP70s, conserved residues on helixes I and IV seemed to be significant in keeping the J domain in its right orientation for functional interactions with HSP70s. Our results also showed that helixes II and III formed the interaction interface for binding to HSP70 ATPase domain as well as the linker residues. Finally, data based docking procedures, such as applied in this study, could be an effective method to investigate protein-protein interactions complex of biomolecules.
- Full Text:
- Authors: Adeyemi, Samson Adebowale
- Date: 2014
- Subjects: Structural bioinformatics , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Biomolecules
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4171 , http://hdl.handle.net/10962/d1020962
- Description: HSP70 is one of the most important families of molecular chaperone that regulate the folding and transport of client proteins in an ATP dependent manner. The ATPase activity of HSP70 is stimulated through an interaction with its family of HSP40 co-chaperones. There is evidence to suggest that specific partnerships occur between the different HSP40 and HSP70 isoforms. While some of the residues involved in the interaction are known, many of the residues governing the specificity of HSP40-HSP70 partnerships are not precisely defined. It is not currently possible to predict which HSP40 and HSP70 isoforms will interact. We attempted to use bioinformatics to identify residues involved in the specificity of the interaction between the J domain from HSP40 and the ATPase domain from the HSP70 isoforms from humans. A total of 49 HSP40 and 13 HSP70 sequences from humans were retrieved and used for subsequent analyses. The HSP40 J domains and HSP70 ATPase domains were extracted using python scripts and classified according to the subcellular localization of the proteins using localization prediction programs. Motif analysis was carried out using the full length HSP40 proteins and Multiple Sequence Alignment (MSA) was performed to identify conserved residues that may contribute to the J domain – ATPase domain interactions. Phylogenetic inference of the proteins was also performed in order to study their evolutionary relationship. Homology models of the J domains and ATPase domains were generated. The corresponding models were docked using HADDOCK server in order to analyze possible putative interactions between the partner proteins using the Protein Interactions Calculator (PIC). The level of residue conservation was found to be higher in Type I and II HSP40 than in Type III J proteins. While highly conserved residues on helixes II and III could play critical roles in J domain interactions with corresponding HSP70s, conserved residues on helixes I and IV seemed to be significant in keeping the J domain in its right orientation for functional interactions with HSP70s. Our results also showed that helixes II and III formed the interaction interface for binding to HSP70 ATPase domain as well as the linker residues. Finally, data based docking procedures, such as applied in this study, could be an effective method to investigate protein-protein interactions complex of biomolecules.
- Full Text:
Teachers' perceptions of behavioural problems manifested by Grade 11 and 12 learners in three Namibian schools
- Authors: Akawa, Ester Anna Nelago
- Date: 2014
- Subjects: Education, Secondary -- Namibia School children -- Namibia -- Attitudes Learning disabilities -- Social aspects Behavior disorders in children -- Education (Secondary) -- Namibia Children with social disabilities -- Education (Secondary) -- Namibia Emotional problems of children -- Education (Secondary) -- Namibia Teachers -- Job stress -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1962 , http://hdl.handle.net/10962/d1010868
- Description: In Namibia today few learners with behavioural and learning problems are within special schools as most are placed within the mainstream school system. Placing these learners within the mainstream system is part of the policy of Inclusive Education (IE) because it argues that this would benefit these learners and also save resources. IE is concerned with addressing barriers to learning and behavioural problems are regarded as one of these barriers. IE argues for a series of new approaches to the diagnosis and response to learners with behavioural problems. This poses challenges for teachers in mainstream schools. Teachers are at the forefront of this situation as they are usually the first to observe and experience the behavioural problems in the schools and are expected to respond appropriately. They find this situation both challenging and problematic. This research explores a sample of teachers’ perceptions of learners’ behavioural problems. To collect in-depth information, this study followed a qualitative approach with a case study design. The data were collected through semi-structured interviews, supplemented with observation and document analysis. The study consisted of fifteen respondents: three principals, three teacher counsellors and nine teachers from the three selected schools. This study illuminates the types of behaviour that teachers encounter, the impact of these behaviours, the factors seen as contributing to these behaviours, and how teachers and the school system deal with these behaviours. In addition the study applies Bronfenbrenner’s bioecological model (1992) to explain how the behaviours manifested by Grade 11 and 12 learners, and identified as problematic by teachers, are part of an interconnected nested social system. The results from the study indicate the manifestation of behavioural problems to be common occurrences in secondary schools are evident, amongst others, through fighting, bullying, substance abuse, truancy, and disrespect of teachers and authority. The teachers pointed to the prevalence of these problems as well as the serious impact such problems have on these learners, their fellow learners, and on the teachers. The teachers identified a complex array of what they saw as contributing factors located within the school, peer groups, family and home circumstances, the local community, as well within the national education policy, the economy and society. The study points to some specific, as well as broader, lessons and opportunities for action both for those managing the education system at the national level and for schools and teachers.
- Full Text:
- Authors: Akawa, Ester Anna Nelago
- Date: 2014
- Subjects: Education, Secondary -- Namibia School children -- Namibia -- Attitudes Learning disabilities -- Social aspects Behavior disorders in children -- Education (Secondary) -- Namibia Children with social disabilities -- Education (Secondary) -- Namibia Emotional problems of children -- Education (Secondary) -- Namibia Teachers -- Job stress -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1962 , http://hdl.handle.net/10962/d1010868
- Description: In Namibia today few learners with behavioural and learning problems are within special schools as most are placed within the mainstream school system. Placing these learners within the mainstream system is part of the policy of Inclusive Education (IE) because it argues that this would benefit these learners and also save resources. IE is concerned with addressing barriers to learning and behavioural problems are regarded as one of these barriers. IE argues for a series of new approaches to the diagnosis and response to learners with behavioural problems. This poses challenges for teachers in mainstream schools. Teachers are at the forefront of this situation as they are usually the first to observe and experience the behavioural problems in the schools and are expected to respond appropriately. They find this situation both challenging and problematic. This research explores a sample of teachers’ perceptions of learners’ behavioural problems. To collect in-depth information, this study followed a qualitative approach with a case study design. The data were collected through semi-structured interviews, supplemented with observation and document analysis. The study consisted of fifteen respondents: three principals, three teacher counsellors and nine teachers from the three selected schools. This study illuminates the types of behaviour that teachers encounter, the impact of these behaviours, the factors seen as contributing to these behaviours, and how teachers and the school system deal with these behaviours. In addition the study applies Bronfenbrenner’s bioecological model (1992) to explain how the behaviours manifested by Grade 11 and 12 learners, and identified as problematic by teachers, are part of an interconnected nested social system. The results from the study indicate the manifestation of behavioural problems to be common occurrences in secondary schools are evident, amongst others, through fighting, bullying, substance abuse, truancy, and disrespect of teachers and authority. The teachers pointed to the prevalence of these problems as well as the serious impact such problems have on these learners, their fellow learners, and on the teachers. The teachers identified a complex array of what they saw as contributing factors located within the school, peer groups, family and home circumstances, the local community, as well within the national education policy, the economy and society. The study points to some specific, as well as broader, lessons and opportunities for action both for those managing the education system at the national level and for schools and teachers.
- Full Text:
Toward a culture of engagement: leveraging the enterprise social network
- Authors: Alistoun, Garth
- Date: 2014
- Subjects: Communication in organizations -- South Africa Business communication -- South Africa Social media -- South Africa -- Case studies Leadership -- South Africa -- Case studies Human capital -- Management Personnel management Organizational effectiveness
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1154 , http://hdl.handle.net/10962/d1010869
- Description: This research aims to provide a theory of enterprise social networking that generates and/or sustains a culture of employee engagement within a chosen South African private sector company. Based on an extensive review of interesting literature and the application of a grounded theory process in a chosen case, this research work provides a theory of enterprise social networking sustaining and growing employee engagement together with an explanatory theoretical framework that makes the theory more practical. Employee engagement is defined as “the harnessing of organisation member’s selves to their work roles; in engagement people employ and express themselves physically, cognitively, and emotionally during role performances.” This research regards employee engagement as a three part concept composed of a trait (personality/cognitive) aspect, a state (emotional) aspect, and a behavioural aspect. Research has shown that employee engagement has an unequivocal positive impact on business outcomes, such as profitability, business performance, employee retention and productivity. Employee engagement can be regarded as a culture if it is abundant within the organization’s employee population. Gatenby et al. (2009) propose that employee engagement is fostered by creating the desire and opportunity for employees to connect with colleagues, managers and the wider organisation. This standpoint is supported by Kular et al. (2008) who state that the “key drivers of employee engagement identified include communication, opportunities for employees to feed their views upward and thinking that their managers are committed to the organisation.” Further indicators of employee engagement include strong leadership (particularly in the form of servant leadership), accountability, a positive and open organisational culture, autonomy, and opportunities for development. One of the key facets of employee engagement is connection. A complementary definition of social media, an umbrella under which enterprise social networks fall, is that “(it) is more of a relationship channel, a connection channel. Each and every tweet, update, video, post, is a connection point to another human being. And it’s the other human being who will determine your worth to them.” Social media provides participants with access to a larger pool of resources and relationships than they would normally have access to. This enlarged relationship/resource pool is a result of expanding human and social capital enabled through social media tools. In order to produce a theory of enterprise social networking sustaining and growing a culture of employee engagement a rigorous grounded theory methodology coupled with a case study methodology was applied. The case study methodology was used to identify a suitable research site and interesting participants within the site while the grounded theory process was used to produce both qualitative and quantitative data sets in a suitability rigorous fashion. The corroborative data was then used to discover and define the emergent theory.
- Full Text:
- Authors: Alistoun, Garth
- Date: 2014
- Subjects: Communication in organizations -- South Africa Business communication -- South Africa Social media -- South Africa -- Case studies Leadership -- South Africa -- Case studies Human capital -- Management Personnel management Organizational effectiveness
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1154 , http://hdl.handle.net/10962/d1010869
- Description: This research aims to provide a theory of enterprise social networking that generates and/or sustains a culture of employee engagement within a chosen South African private sector company. Based on an extensive review of interesting literature and the application of a grounded theory process in a chosen case, this research work provides a theory of enterprise social networking sustaining and growing employee engagement together with an explanatory theoretical framework that makes the theory more practical. Employee engagement is defined as “the harnessing of organisation member’s selves to their work roles; in engagement people employ and express themselves physically, cognitively, and emotionally during role performances.” This research regards employee engagement as a three part concept composed of a trait (personality/cognitive) aspect, a state (emotional) aspect, and a behavioural aspect. Research has shown that employee engagement has an unequivocal positive impact on business outcomes, such as profitability, business performance, employee retention and productivity. Employee engagement can be regarded as a culture if it is abundant within the organization’s employee population. Gatenby et al. (2009) propose that employee engagement is fostered by creating the desire and opportunity for employees to connect with colleagues, managers and the wider organisation. This standpoint is supported by Kular et al. (2008) who state that the “key drivers of employee engagement identified include communication, opportunities for employees to feed their views upward and thinking that their managers are committed to the organisation.” Further indicators of employee engagement include strong leadership (particularly in the form of servant leadership), accountability, a positive and open organisational culture, autonomy, and opportunities for development. One of the key facets of employee engagement is connection. A complementary definition of social media, an umbrella under which enterprise social networks fall, is that “(it) is more of a relationship channel, a connection channel. Each and every tweet, update, video, post, is a connection point to another human being. And it’s the other human being who will determine your worth to them.” Social media provides participants with access to a larger pool of resources and relationships than they would normally have access to. This enlarged relationship/resource pool is a result of expanding human and social capital enabled through social media tools. In order to produce a theory of enterprise social networking sustaining and growing a culture of employee engagement a rigorous grounded theory methodology coupled with a case study methodology was applied. The case study methodology was used to identify a suitable research site and interesting participants within the site while the grounded theory process was used to produce both qualitative and quantitative data sets in a suitability rigorous fashion. The corroborative data was then used to discover and define the emergent theory.
- Full Text:
The origin of endorheic pans on the African erosion surface North of Grahamstown, South Africa
- Authors: Alistoun, Judith Robyn
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4775 , http://hdl.handle.net/10962/d1011048
- Description: Pans on the African Erosion Surface near Grahamstown are small features, which, perhaps due to their small size have been neglected by researchers. From the outset the striking difference of these pans relative to other pans in southern Africa, is that the host rock is silcrete, a highly resistant rock well known as being associated with deeply weathered plateaus. The dominant origin theory for pans in southern Africa was developed by Goudie and Thomas (1985), and focuses on mechanisms relating to erosion and deflation. This model does not fit in well with the pans that have formed on substrate that has largely been unaffected by erosion in recent geological history (thousands to 10 000 years). As such this study examined the role of prolonged chemical weathering of Dwyka Tillite, that has led to the formation of silcrete. The hypothesis was that such deep weathering is responsible for local scale volume changes, which have in turn led to the formation of a depression. The centre of the pan indicated the highest concentration of Al₂O₃ and kaolinite at mid depths, and their concentrations decreased vertically away from these depths, and laterally towards the margins of the pan. Similar results were noted for SiO₂, while CaO and MgO (and calcite and dolomite) were highest at mid depths along the margins of the pan, and decreased laterally toward the centre of the pan. Results indicated that there was a positive relationship in the centre of the pan between: - the degree of chemical weathering and volume losses, - relative elevation of the pan and volume changes. Geochemically and mineralogically, there was a link between the high concentrations of Ca and Mg carbonates and volume gains in the margin of the pans. It is proposed that transpiration of vegetation along the margin of the pan caused the lateral movement of solutes, and the selective exclusion of these solutes by plants was associated with carbonate precipitation, leading to the creation of local relief. These results provide evidence to suggest that weathering and precipitation processes occurring over geological time scales are responsible for minor scale relief features, whose origin has been mistakenly attributed to deflation processes occurring over hundreds to thousands of years.
- Full Text:
- Authors: Alistoun, Judith Robyn
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4775 , http://hdl.handle.net/10962/d1011048
- Description: Pans on the African Erosion Surface near Grahamstown are small features, which, perhaps due to their small size have been neglected by researchers. From the outset the striking difference of these pans relative to other pans in southern Africa, is that the host rock is silcrete, a highly resistant rock well known as being associated with deeply weathered plateaus. The dominant origin theory for pans in southern Africa was developed by Goudie and Thomas (1985), and focuses on mechanisms relating to erosion and deflation. This model does not fit in well with the pans that have formed on substrate that has largely been unaffected by erosion in recent geological history (thousands to 10 000 years). As such this study examined the role of prolonged chemical weathering of Dwyka Tillite, that has led to the formation of silcrete. The hypothesis was that such deep weathering is responsible for local scale volume changes, which have in turn led to the formation of a depression. The centre of the pan indicated the highest concentration of Al₂O₃ and kaolinite at mid depths, and their concentrations decreased vertically away from these depths, and laterally towards the margins of the pan. Similar results were noted for SiO₂, while CaO and MgO (and calcite and dolomite) were highest at mid depths along the margins of the pan, and decreased laterally toward the centre of the pan. Results indicated that there was a positive relationship in the centre of the pan between: - the degree of chemical weathering and volume losses, - relative elevation of the pan and volume changes. Geochemically and mineralogically, there was a link between the high concentrations of Ca and Mg carbonates and volume gains in the margin of the pans. It is proposed that transpiration of vegetation along the margin of the pan caused the lateral movement of solutes, and the selective exclusion of these solutes by plants was associated with carbonate precipitation, leading to the creation of local relief. These results provide evidence to suggest that weathering and precipitation processes occurring over geological time scales are responsible for minor scale relief features, whose origin has been mistakenly attributed to deflation processes occurring over hundreds to thousands of years.
- Full Text:
An investigation of the intention to leave or stay of health care professionals at St. Andrews Hospital
- Authors: Amanambu, Rochelle Aneeta
- Date: 2014
- Subjects: Medical personnel -- Job satisfaction -- South Africa -- Eastern Cape -- Case studies Medical personnel -- Job stress -- South Africa -- Eastern Cape -- Case studies Hospitals -- South Africa -- Eastern Cape -- Administration Hospitals -- Medical staff -- South Africa -- Eastern Cape Hospitals -- Officials and employees -- South Africa -- Eastern Cape -- Turnover Health services administration -- South Africa -- Eastern Cape Health planning -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:823 , http://hdl.handle.net/10962/d1011091
- Description: Background: The demand for and retention of talent worldwide is aggravated by revolutionary trends that include global competition, demographic changes and technological advances. In South Africa this phenomenon according to Frost (2002) is further challenged by the emigration of skilled people; the relative scarcity of specialist and managerial employees; employment equity and affirmative action procedures. But the development of strategies first requires an understanding of the factors which influence decisions to leave or stay particularly in rural and remote areas. St. Andrews Hospital is a rural district hospital in Ugu District, KZN. Its remoteness from urban areas and the lack of resources contributes towards challenges of attracting and retaining health care professionals to the area. It is the aim of this study to identify the ten most prevalent turnover and retention factors in a rural district hospital with the intention of making recommendations towards strategies to mitigate turnover and improve retention of health care professionals. This study will not only serve the local Human Resource Department but may also be used to inform district and provincial policies as well as departments’ decisions in the design or the review of current retention strategies aimed at reducing turnover. Method: The survey method was used to collect the primary data by distribution of self-administered questionnaires to Health Care Professionals at St. Andrews Hospital. Of the one hundred and fifty questionnaires distributed, one hundred and seven were returned (71% response rate) and formed the basis of the study. Results: Based on the impact scores, the top three turnover factors identified were, the way the organisation is led by top management (0.934); the size of the workload (0.862); and the way problems are dealt with by managers in the organisation (0.817). No statistically significant relationships were found between turnover factors and biographical variable. Availability of quality health services was ranked as the external factor that had the highest influence (78%) on turnover, while geographical location was ranked the lowest. The main reason given by respondents for leaving their previous employment was promotion, followed by distance and personal/family reasons. The top three retention factors identified from the impact scores were the quality of relationships with colleagues (1.698); the amount of support received from managers and colleagues (1.484); and the level of engagement and involvement with the job (1.390). This demonstrates that the salary package often thought to be a first priority factor Mobley, Horner and Hollingsworth (1978); Mobley (1982) and Herzberg (2003) is far less of a determining factor at St. Andrews Hospital than management support, job involvement and person-organisation fit as well as the social relationships formed in the workplace. A positive relationship was found between leadership and job dimension factors at the 1% level of significance. This supports the strong social bond (person-organisation fit) formed in the work environment between management and colleagues that supports retention and increases level of commitment. An important result of the study was that 46% of the respondents were thinking of leaving the town within the year while 29% were considering resigning from St. Andrews Hospital within the year. Conclusion: The results reveal a complex interaction of factors impacting on turnover and retention. The Human Resource Management function has a pivotal role to play in improving its ability to attract and retain professionals through developing comprehensive strategies based on external and internal and environmental factors. The study conveys to the St. Andrews Hospital management that turnover and retention factors are unique to the location and the working environment and differs amongst Health Care Professionals – this should be deliberated on when formulating Hospital Human Resource retention policies.
- Full Text:
- Authors: Amanambu, Rochelle Aneeta
- Date: 2014
- Subjects: Medical personnel -- Job satisfaction -- South Africa -- Eastern Cape -- Case studies Medical personnel -- Job stress -- South Africa -- Eastern Cape -- Case studies Hospitals -- South Africa -- Eastern Cape -- Administration Hospitals -- Medical staff -- South Africa -- Eastern Cape Hospitals -- Officials and employees -- South Africa -- Eastern Cape -- Turnover Health services administration -- South Africa -- Eastern Cape Health planning -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:823 , http://hdl.handle.net/10962/d1011091
- Description: Background: The demand for and retention of talent worldwide is aggravated by revolutionary trends that include global competition, demographic changes and technological advances. In South Africa this phenomenon according to Frost (2002) is further challenged by the emigration of skilled people; the relative scarcity of specialist and managerial employees; employment equity and affirmative action procedures. But the development of strategies first requires an understanding of the factors which influence decisions to leave or stay particularly in rural and remote areas. St. Andrews Hospital is a rural district hospital in Ugu District, KZN. Its remoteness from urban areas and the lack of resources contributes towards challenges of attracting and retaining health care professionals to the area. It is the aim of this study to identify the ten most prevalent turnover and retention factors in a rural district hospital with the intention of making recommendations towards strategies to mitigate turnover and improve retention of health care professionals. This study will not only serve the local Human Resource Department but may also be used to inform district and provincial policies as well as departments’ decisions in the design or the review of current retention strategies aimed at reducing turnover. Method: The survey method was used to collect the primary data by distribution of self-administered questionnaires to Health Care Professionals at St. Andrews Hospital. Of the one hundred and fifty questionnaires distributed, one hundred and seven were returned (71% response rate) and formed the basis of the study. Results: Based on the impact scores, the top three turnover factors identified were, the way the organisation is led by top management (0.934); the size of the workload (0.862); and the way problems are dealt with by managers in the organisation (0.817). No statistically significant relationships were found between turnover factors and biographical variable. Availability of quality health services was ranked as the external factor that had the highest influence (78%) on turnover, while geographical location was ranked the lowest. The main reason given by respondents for leaving their previous employment was promotion, followed by distance and personal/family reasons. The top three retention factors identified from the impact scores were the quality of relationships with colleagues (1.698); the amount of support received from managers and colleagues (1.484); and the level of engagement and involvement with the job (1.390). This demonstrates that the salary package often thought to be a first priority factor Mobley, Horner and Hollingsworth (1978); Mobley (1982) and Herzberg (2003) is far less of a determining factor at St. Andrews Hospital than management support, job involvement and person-organisation fit as well as the social relationships formed in the workplace. A positive relationship was found between leadership and job dimension factors at the 1% level of significance. This supports the strong social bond (person-organisation fit) formed in the work environment between management and colleagues that supports retention and increases level of commitment. An important result of the study was that 46% of the respondents were thinking of leaving the town within the year while 29% were considering resigning from St. Andrews Hospital within the year. Conclusion: The results reveal a complex interaction of factors impacting on turnover and retention. The Human Resource Management function has a pivotal role to play in improving its ability to attract and retain professionals through developing comprehensive strategies based on external and internal and environmental factors. The study conveys to the St. Andrews Hospital management that turnover and retention factors are unique to the location and the working environment and differs amongst Health Care Professionals – this should be deliberated on when formulating Hospital Human Resource retention policies.
- Full Text:
Voting and meaning in Hooggenoeg, Grahamstown : an audience's reception of Grocott's Mail's 2011 municipal election coverage
- Authors: Amzat, Ajibola Taofeek
- Date: 2014
- Subjects: Grocott's Mail (Grahamstown, South Africa) Local elections -- South Africa -- Grahamstown Elections -- South Africa Press and politics -- South Africa -- Grahamstown Journalism -- Objectivity -- South Africa -- Grahamstown Newspapers -- Objectivity Journalism -- Political aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5970 , http://hdl.handle.net/10962/d1011729
- Description: This thesis examines the meanings that residents of the township of Hooggenoeg (in Grahamstown, in the Eastern Cape province of South Africa) made of the election coverage in the Grocott’s Mail newspaper during 2011 municipal elections in South Africa. In addition, this study also sought to understand the particular set of ‘normative roles’ played by the paper, both with reference to the well-established body of theory about the normative roles of journalism in a democracy, and in terms of the paper’s own conceptualisation of its role in the functioning of local democracy. Grocott’s Mail, the oldest independent newspaper in South Africa, provided extensive pre-election coverage, which included producing and distributing an unprecedented free edition of the paper. The paper also facilitated a town hall debate in order to encourage residents to vote, and empower them to make a more informed choice about their vote. Three qualitative research methods, namely qualitative content analysis, focus group interviews, and individual interviews were used to examine the relationship between the content provided by the paper and the audience’s process of ‘making sense’ and deriving meaning from the content provided. The study concludes that Grocott’s attempt to encourage democratic culture in Grahamstown, in keeping with the more ‘facilitative’ normative roles that the local media can play, was only partially successful. Much of the election reporting subordinated the voices of the ordinary people, and privileged reporting that focussed narrowly on the voting process, and which foregrounded the views of political parties. Overall this coverage largely failed to resonate with the Grocott’s readers who live in Hooggenoeg (a largely ‘coloured’ area of Grahamstown), whose key concerns in terms of their daily life – such as poverty, unemployment, crime, lack of services – seemed, to them, unaddressed by this election coverage and, consequently, was not as engaging or convincing as the publishers/editors had hoped it would be. It can be also argued that Grocott’s narrow conceptualisation of democracy as entailing only public participation in electoral processes failed to cater for how audiences can be made aware of how they can participate in governance beyond the election period.
- Full Text:
- Authors: Amzat, Ajibola Taofeek
- Date: 2014
- Subjects: Grocott's Mail (Grahamstown, South Africa) Local elections -- South Africa -- Grahamstown Elections -- South Africa Press and politics -- South Africa -- Grahamstown Journalism -- Objectivity -- South Africa -- Grahamstown Newspapers -- Objectivity Journalism -- Political aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5970 , http://hdl.handle.net/10962/d1011729
- Description: This thesis examines the meanings that residents of the township of Hooggenoeg (in Grahamstown, in the Eastern Cape province of South Africa) made of the election coverage in the Grocott’s Mail newspaper during 2011 municipal elections in South Africa. In addition, this study also sought to understand the particular set of ‘normative roles’ played by the paper, both with reference to the well-established body of theory about the normative roles of journalism in a democracy, and in terms of the paper’s own conceptualisation of its role in the functioning of local democracy. Grocott’s Mail, the oldest independent newspaper in South Africa, provided extensive pre-election coverage, which included producing and distributing an unprecedented free edition of the paper. The paper also facilitated a town hall debate in order to encourage residents to vote, and empower them to make a more informed choice about their vote. Three qualitative research methods, namely qualitative content analysis, focus group interviews, and individual interviews were used to examine the relationship between the content provided by the paper and the audience’s process of ‘making sense’ and deriving meaning from the content provided. The study concludes that Grocott’s attempt to encourage democratic culture in Grahamstown, in keeping with the more ‘facilitative’ normative roles that the local media can play, was only partially successful. Much of the election reporting subordinated the voices of the ordinary people, and privileged reporting that focussed narrowly on the voting process, and which foregrounded the views of political parties. Overall this coverage largely failed to resonate with the Grocott’s readers who live in Hooggenoeg (a largely ‘coloured’ area of Grahamstown), whose key concerns in terms of their daily life – such as poverty, unemployment, crime, lack of services – seemed, to them, unaddressed by this election coverage and, consequently, was not as engaging or convincing as the publishers/editors had hoped it would be. It can be also argued that Grocott’s narrow conceptualisation of democracy as entailing only public participation in electoral processes failed to cater for how audiences can be made aware of how they can participate in governance beyond the election period.
- Full Text:
Distribution of heavy minerals sand in Namalope deposit, Moma district, Mozambique
- Authors: Assane, Ali Ossufo
- Date: 2014
- Subjects: Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5056 , http://hdl.handle.net/10962/d1012169 , Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Description: The spatial distribution of heavy minerals along the mine paths 2014 and 2015 at the wet concentrate plant B shows an increase of heavy minerals sand concentration northwards and slime contents southwards, and it is commonly associated with depth and grain sorting; the increase of heavy minerals concentration with depth is considered to be from the surface formed by Unit 6 to the bottom of Unit 7. The Unit 82 is characterized by low heavy minerals concentrations and high slime contents declining northwards. The mineral proportion estimation suggests that ilmenite is the most abundant heavy mineral in the entire area followed by zircon, rutile and mozanite, and some accessory minerals such as chromite, kyanite, staurolite, tourmaline, epidote, spinel and quartz. The ilmenite occurrence is divided into ilmenite low (< 53% TiO₂) and high (> 53% TiO₂); the ilmenite high with zircon and rutile shows tendency to increase northwards while ilmenite low increase southwards. Zircon, monazite, rutile, chromite, kyanite and staurolite show low variability, which is probably associated with high resistance of minerals for abrasion during transportation and diagenesis. The depositional model of the Namalope deposit, in the flat area and wet concentrate plant B in particular, suggests deposition in a shallow marine environment associated with regression for deposition of Unit 6, 7 and 9 and transgression during deposition of Unit 82. The spatial distribution of heavy minerals in the Namalope deposit and its environment of deposition are the key points for discovery of new deposits around the Namalope with the same characteristic of mineral assemblage and they are used for mine strategic plans such as update block model and mine design.
- Full Text:
- Authors: Assane, Ali Ossufo
- Date: 2014
- Subjects: Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5056 , http://hdl.handle.net/10962/d1012169 , Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Description: The spatial distribution of heavy minerals along the mine paths 2014 and 2015 at the wet concentrate plant B shows an increase of heavy minerals sand concentration northwards and slime contents southwards, and it is commonly associated with depth and grain sorting; the increase of heavy minerals concentration with depth is considered to be from the surface formed by Unit 6 to the bottom of Unit 7. The Unit 82 is characterized by low heavy minerals concentrations and high slime contents declining northwards. The mineral proportion estimation suggests that ilmenite is the most abundant heavy mineral in the entire area followed by zircon, rutile and mozanite, and some accessory minerals such as chromite, kyanite, staurolite, tourmaline, epidote, spinel and quartz. The ilmenite occurrence is divided into ilmenite low (< 53% TiO₂) and high (> 53% TiO₂); the ilmenite high with zircon and rutile shows tendency to increase northwards while ilmenite low increase southwards. Zircon, monazite, rutile, chromite, kyanite and staurolite show low variability, which is probably associated with high resistance of minerals for abrasion during transportation and diagenesis. The depositional model of the Namalope deposit, in the flat area and wet concentrate plant B in particular, suggests deposition in a shallow marine environment associated with regression for deposition of Unit 6, 7 and 9 and transgression during deposition of Unit 82. The spatial distribution of heavy minerals in the Namalope deposit and its environment of deposition are the key points for discovery of new deposits around the Namalope with the same characteristic of mineral assemblage and they are used for mine strategic plans such as update block model and mine design.
- Full Text:
Planning for the future: mapping anticipated environmental and social impacts in a nascent tourism destination
- Aswani, Shankar, Diedrich, Amy, Currier, Kitty
- Authors: Aswani, Shankar , Diedrich, Amy , Currier, Kitty
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145415 , vital:38436 , DOI: 10.1080/08941920.2015.1020582
- Description: Tourism is a significant driver of social and ecological change in developing countries, particularly in small-island states, which are susceptible to tourism impacts due to their particular social and environmental characteristics. In this article we present a participatory mapping approach to obtaining spatially explicit local perceptions of future environmental and social change resulting from tourism development, as well as addressing the different community conflicts that may arise through the introduction of tourism in the future in a Solomon Islands community. The results show that spatial conflicts within a community over territory and associated resources are likely to occur when designing natural resource management and tourism development plans. This knowledge can help us increase the future sustainability of tourism in nascent small-islands destinations, particularly in vulnerable regions such as Roviana, which have experienced very little tourism development and will likely experience more in the near future.
- Full Text:
- Authors: Aswani, Shankar , Diedrich, Amy , Currier, Kitty
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145415 , vital:38436 , DOI: 10.1080/08941920.2015.1020582
- Description: Tourism is a significant driver of social and ecological change in developing countries, particularly in small-island states, which are susceptible to tourism impacts due to their particular social and environmental characteristics. In this article we present a participatory mapping approach to obtaining spatially explicit local perceptions of future environmental and social change resulting from tourism development, as well as addressing the different community conflicts that may arise through the introduction of tourism in the future in a Solomon Islands community. The results show that spatial conflicts within a community over territory and associated resources are likely to occur when designing natural resource management and tourism development plans. This knowledge can help us increase the future sustainability of tourism in nascent small-islands destinations, particularly in vulnerable regions such as Roviana, which have experienced very little tourism development and will likely experience more in the near future.
- Full Text:
Human harvesting impacts on managed areas: ecological effects of socially-compatible shellfish reserves
- Aswani, Shankar, Flores, Carola F, Broitman, Bernardo R
- Authors: Aswani, Shankar , Flores, Carola F , Broitman, Bernardo R
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124664 , vital:35644 , https://doi.10.1007/s11160-014-9376-4
- Description: We examined how human harvesting impacts on managed areas affect the abundance and size distribution of the edible mangrove shellfish Anadara granosa and Polymesoda spp. in the Roviana Lagoon, Solomon Islands. We tested two hypotheses: (1) in areas permanently and temporally closed to human exploitation, abundance and size distribution of these shellfish species is significantly greater than in sites open to exploitation and (2) moderate human disturbance of shell beds, particularly of Polymesoda spp., increases their abundance. Firstly, we studied perceptions of environmental states and processes coupled to foraging and management interventions to assess sociocultural influences on harvesting practices and ascertain the types of management regime that people would consider in a context where poaching and interloping are common practices. Secondly, we compared shellfish abundance and shell size from areas that were permanently protected, temporally reserved for communal harvest, and permanently open for exploitation. Thirdly, drawing from women’s local knowledge, we measured the abundance of Polymesoda spp. in relation to mud compactness in quadrats across the three management regimes. Results showed that both species were significantly more abundant in permanent and temporally closed sites than in open sites. In the mud compactness study, however, while shell abundance was greater in moderately compacted quadrats, there was no statistical relationship between mud compactness and shell abundance within or across the three management regimes. Results suggest that even under the strong impacts of poaching, temporally closed areas have more clams than open areas and are as effective as areas that are permanently closed nominally. The results also suggest that human harvesting regimes can influence the effectiveness of local management decisions and thus are important when designing community-based conservation programs in the Solomon Islands and other Pacific Islands.
- Full Text:
- Authors: Aswani, Shankar , Flores, Carola F , Broitman, Bernardo R
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124664 , vital:35644 , https://doi.10.1007/s11160-014-9376-4
- Description: We examined how human harvesting impacts on managed areas affect the abundance and size distribution of the edible mangrove shellfish Anadara granosa and Polymesoda spp. in the Roviana Lagoon, Solomon Islands. We tested two hypotheses: (1) in areas permanently and temporally closed to human exploitation, abundance and size distribution of these shellfish species is significantly greater than in sites open to exploitation and (2) moderate human disturbance of shell beds, particularly of Polymesoda spp., increases their abundance. Firstly, we studied perceptions of environmental states and processes coupled to foraging and management interventions to assess sociocultural influences on harvesting practices and ascertain the types of management regime that people would consider in a context where poaching and interloping are common practices. Secondly, we compared shellfish abundance and shell size from areas that were permanently protected, temporally reserved for communal harvest, and permanently open for exploitation. Thirdly, drawing from women’s local knowledge, we measured the abundance of Polymesoda spp. in relation to mud compactness in quadrats across the three management regimes. Results showed that both species were significantly more abundant in permanent and temporally closed sites than in open sites. In the mud compactness study, however, while shell abundance was greater in moderately compacted quadrats, there was no statistical relationship between mud compactness and shell abundance within or across the three management regimes. Results suggest that even under the strong impacts of poaching, temporally closed areas have more clams than open areas and are as effective as areas that are permanently closed nominally. The results also suggest that human harvesting regimes can influence the effectiveness of local management decisions and thus are important when designing community-based conservation programs in the Solomon Islands and other Pacific Islands.
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Investigating coral reef ethnobiology in the western Solomon Islands for enhancing livelihood resilience:
- Authors: Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145425 , vital:38437 , DOI: 10.15286/jps.123.3.237-276
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about people's local classifications and their social and ecological relationships with these habitats. In the case of island peoples, coral reefs are more than just resource exploitation areas; they are also géomorphologie features that allow or bar people from navigating, markers that define property rights of the seascape in relation to other coastal and terrestrial habitats, and cultural and historical features that embody tribal identity and ideology. Building upon over two decades of research, this paper uses published and unpublished data to describe people's ecological and socio-economic relationships with coral reefs in two extensive lagoon ecosystems in the Western Solomon Islands.
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- Authors: Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145425 , vital:38437 , DOI: 10.15286/jps.123.3.237-276
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about people's local classifications and their social and ecological relationships with these habitats. In the case of island peoples, coral reefs are more than just resource exploitation areas; they are also géomorphologie features that allow or bar people from navigating, markers that define property rights of the seascape in relation to other coastal and terrestrial habitats, and cultural and historical features that embody tribal identity and ideology. Building upon over two decades of research, this paper uses published and unpublished data to describe people's ecological and socio-economic relationships with coral reefs in two extensive lagoon ecosystems in the Western Solomon Islands.
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Development of styrene based imprinted sorbents for selective clean-up of metalloporphyrins in organic media
- Authors: Awokoya, Kehinde Nurudeen
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54521 , vital:26580
- Description: Most crude oils contain traces of vanadium and nickel complex with porphyrins (VTPP and NTPP) within their asphaltene fraction. Although these metals are only present in trace quantities, they have a significant and detrimental impact on the refining process by degrading the quality of intermediate and end products. Therefore, their selective removal is highly desirable. This thesis presents the development of nickel porphyrin, nickel vanadyl porphyrin imprinted nanofibers and vanadyl porphyrin imprinted polymer (MIP) particles for application as selective sorbents. Computational model based on the combination of molecular dynamics simulations and quantum mechanics was successfully applied to the styrene functional monomer selection. The particle was prepared by bulk polymerization and the nanofibers by a novel approach combining molecular imprinting and electrospinning technology. The morphologies, thermal stabilities and porosities of the imprinted sorbents were studied using SEM, TGA, and BET nitrogen gas adsorption. Chloroform was found to swell the polymer particles to a higher degree than methanol and acetonitrile. The adsorption characteristics of the imprinted sorbents best fitted with Freundlich isotherm model. The imprinted sorbents recorded high extraction efficiencies (EEs) of > 99 % in selectively extracting the metalloporphyrins. The impact of the template on the affinity of recognition for NTPP was evaluated. The results showed that the NTPP adsorption capacity increased as the molar ratio of NTPP to styrene was increased from 1:1 to 3:1. The optimal ratio of template to functional monomer which yielded the best specific affinity and highest recovery (99.9 %) was 3:1. The effects of trifluoroacetic acid (TFA), dichloromethane (DCM), dimethyl sulphoxide (DMSO), pentane (PEN) on electro-spinnability of the polymer solutions and the morphological appearance of the nanofibers were investigated. The imprinted nanofibers exhibited the same selectivity specialism for both NTPP and VTPP. A remarkable stability in relation to reusability was observed when imprinted nanofibers were used, as they could be reused nine times without incurring any significant loss in removal efficiency. The results were validated by analysing a certified reference material. The imprinted sorbents were therefore found to be selective sorbents that are well suited for handling trace metals in organic media.
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- Authors: Awokoya, Kehinde Nurudeen
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54521 , vital:26580
- Description: Most crude oils contain traces of vanadium and nickel complex with porphyrins (VTPP and NTPP) within their asphaltene fraction. Although these metals are only present in trace quantities, they have a significant and detrimental impact on the refining process by degrading the quality of intermediate and end products. Therefore, their selective removal is highly desirable. This thesis presents the development of nickel porphyrin, nickel vanadyl porphyrin imprinted nanofibers and vanadyl porphyrin imprinted polymer (MIP) particles for application as selective sorbents. Computational model based on the combination of molecular dynamics simulations and quantum mechanics was successfully applied to the styrene functional monomer selection. The particle was prepared by bulk polymerization and the nanofibers by a novel approach combining molecular imprinting and electrospinning technology. The morphologies, thermal stabilities and porosities of the imprinted sorbents were studied using SEM, TGA, and BET nitrogen gas adsorption. Chloroform was found to swell the polymer particles to a higher degree than methanol and acetonitrile. The adsorption characteristics of the imprinted sorbents best fitted with Freundlich isotherm model. The imprinted sorbents recorded high extraction efficiencies (EEs) of > 99 % in selectively extracting the metalloporphyrins. The impact of the template on the affinity of recognition for NTPP was evaluated. The results showed that the NTPP adsorption capacity increased as the molar ratio of NTPP to styrene was increased from 1:1 to 3:1. The optimal ratio of template to functional monomer which yielded the best specific affinity and highest recovery (99.9 %) was 3:1. The effects of trifluoroacetic acid (TFA), dichloromethane (DCM), dimethyl sulphoxide (DMSO), pentane (PEN) on electro-spinnability of the polymer solutions and the morphological appearance of the nanofibers were investigated. The imprinted nanofibers exhibited the same selectivity specialism for both NTPP and VTPP. A remarkable stability in relation to reusability was observed when imprinted nanofibers were used, as they could be reused nine times without incurring any significant loss in removal efficiency. The results were validated by analysing a certified reference material. The imprinted sorbents were therefore found to be selective sorbents that are well suited for handling trace metals in organic media.
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Effect of diet and sex-sorting on growth and gonad development in farmed South African abalone, Haliotis midae
- Authors: Ayres, Devin William Philip
- Date: 2014
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5357 , http://hdl.handle.net/10962/d1010856 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Description: Abalone, Haliotis midae, farmers in South Africa that feed formulated diets reported a periodic drop in abalone growth during periods of increased gonad development. A large drop in abalone biomass was noticed after presumed spawning events. This study was aimed to determine the effect of diet and sex-sorting on gonad development in abalone. Experiments were conducted on a commercial abalone farm from July 2012 to the end of June 2013. Isonitrogenous and isoenergetic diets were formulated with two protein sources. A fishmeal and soybean meal (S-diet) diet and a fishmeal only (F-diet) diet were fed to abalone (50 - 70 g abalone⁻¹) over 12 months. Weight and length gain, gonad bulk index (GBI), visceral index (%) and meat mass index (%) were determined monthly and seasonally. A histological study on the female gonads was conducted. This study also included an experiment to test the effect of sex-sorting (70 - 80 g abalone⁻¹) on growth and body composition with treatments including males (M), females (F) and equal numbers of males and females (MF). Weight gain and length gain were faster in S-diet-fed abalone (RM-ANOVA, F ₍₁, ₁₆₎ = 7.77, p = 0.01; F ₍₁, ₆₉₎ = 49.9, p < 0.001, respectively). Gonad development was significantly affected by the inclusion of soybean meal with S-diet-fed abalone showing higher GBI-values than F-diet-fed abalone (RM-ANOVA, F ₍₁, ₃₃)= 16.22, p = 0.0003). Male abalone had higher GBI-values than females (RM-ANOVA, F ₍₁, ₃₃₎ = 39.87, p < 0.0001). There was no significant difference in average feed conversion ratio (FCR) between diets over time (RM-ANOVA, F ₍₁, ₂₁₎ = 0.008, p = 0.97). However, average FCR-values were significantly highest between November 2012 and March 2013, the presumed spawning season. The visceral mass (gut and gonad) as a proportion of whole mass (visceral index, %) was significantly higher in abalone fed the S-diet (RM-ANOVA; F ₍₁, ₆₉₎ = 68.06, p < 0.0001). There was no difference in meat mass index (%) between diets for both male and female abalone (RM-ANOVA; F ₍₇, ₂₄₈₎ = 0.80, p = 0.60; F ₍₇, ₂₄₁₎ = 1.7, p = 0.11,respectively). Meat mass index significantly decreased from September 2012 to February 2013 coinciding with the period of high GBI-values. The distribution of oocyte maturity stages differed between diets. The majority of oocytes within S-diet-fed abalone were fully mature stage 8 oocytes compared to a majority of stage 7 oocytes in F-diet-fed abalone. Histology corroborated peaks in GBI-values for abalone fed both diets. There was no significant difference in growth, GBI, visceral index (%) and meat mass index (%) between abalone sorted into monosex and mixed-sex populations. Thus, the presence of the opposite sex did not have an effect on growth and gonad mass in H. midae. The phytoestrogens daidzin, glycitin, genistin, daidzein, glycitein and genistein were present in soybean meal and only traceable amounts were found in the F-diet. This study provided evidence that soybean meal present in formulated feed affected growth and gonad development in H.midae. The difference in the distribution of the maturity stages of oocytes was affected by diet. Sex-sorting abalone into monosex and mixed-sex populations had no influence on weight and length gain and gonad development.
- Full Text:
- Authors: Ayres, Devin William Philip
- Date: 2014
- Subjects: Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5357 , http://hdl.handle.net/10962/d1010856 , Haliotis midae -- South Africa , Haliotis midae fisheries -- South Africa , Abalone culture -- South Africa , Abalones -- Physiology -- South Africa , Abalones -- South Africa -- Growth , Abalones -- Feeding and feeds -- South Africa
- Description: Abalone, Haliotis midae, farmers in South Africa that feed formulated diets reported a periodic drop in abalone growth during periods of increased gonad development. A large drop in abalone biomass was noticed after presumed spawning events. This study was aimed to determine the effect of diet and sex-sorting on gonad development in abalone. Experiments were conducted on a commercial abalone farm from July 2012 to the end of June 2013. Isonitrogenous and isoenergetic diets were formulated with two protein sources. A fishmeal and soybean meal (S-diet) diet and a fishmeal only (F-diet) diet were fed to abalone (50 - 70 g abalone⁻¹) over 12 months. Weight and length gain, gonad bulk index (GBI), visceral index (%) and meat mass index (%) were determined monthly and seasonally. A histological study on the female gonads was conducted. This study also included an experiment to test the effect of sex-sorting (70 - 80 g abalone⁻¹) on growth and body composition with treatments including males (M), females (F) and equal numbers of males and females (MF). Weight gain and length gain were faster in S-diet-fed abalone (RM-ANOVA, F ₍₁, ₁₆₎ = 7.77, p = 0.01; F ₍₁, ₆₉₎ = 49.9, p < 0.001, respectively). Gonad development was significantly affected by the inclusion of soybean meal with S-diet-fed abalone showing higher GBI-values than F-diet-fed abalone (RM-ANOVA, F ₍₁, ₃₃)= 16.22, p = 0.0003). Male abalone had higher GBI-values than females (RM-ANOVA, F ₍₁, ₃₃₎ = 39.87, p < 0.0001). There was no significant difference in average feed conversion ratio (FCR) between diets over time (RM-ANOVA, F ₍₁, ₂₁₎ = 0.008, p = 0.97). However, average FCR-values were significantly highest between November 2012 and March 2013, the presumed spawning season. The visceral mass (gut and gonad) as a proportion of whole mass (visceral index, %) was significantly higher in abalone fed the S-diet (RM-ANOVA; F ₍₁, ₆₉₎ = 68.06, p < 0.0001). There was no difference in meat mass index (%) between diets for both male and female abalone (RM-ANOVA; F ₍₇, ₂₄₈₎ = 0.80, p = 0.60; F ₍₇, ₂₄₁₎ = 1.7, p = 0.11,respectively). Meat mass index significantly decreased from September 2012 to February 2013 coinciding with the period of high GBI-values. The distribution of oocyte maturity stages differed between diets. The majority of oocytes within S-diet-fed abalone were fully mature stage 8 oocytes compared to a majority of stage 7 oocytes in F-diet-fed abalone. Histology corroborated peaks in GBI-values for abalone fed both diets. There was no significant difference in growth, GBI, visceral index (%) and meat mass index (%) between abalone sorted into monosex and mixed-sex populations. Thus, the presence of the opposite sex did not have an effect on growth and gonad mass in H. midae. The phytoestrogens daidzin, glycitin, genistin, daidzein, glycitein and genistein were present in soybean meal and only traceable amounts were found in the F-diet. This study provided evidence that soybean meal present in formulated feed affected growth and gonad development in H.midae. The difference in the distribution of the maturity stages of oocytes was affected by diet. Sex-sorting abalone into monosex and mixed-sex populations had no influence on weight and length gain and gonad development.
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Klazinga - response to allegations
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: Text
- Identifier: vital:7875 , http://hdl.handle.net/10962/d1016424
- Full Text:
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: Text
- Identifier: vital:7875 , http://hdl.handle.net/10962/d1016424
- Full Text:
A response to the South African Jewish report and Ms Klazinga on "Jews unwelcome at Rhodes"
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:7883 , http://hdl.handle.net/10962/d1016432
- Description: On 1 January 2014, the South African Jewish Report and Ms Larissa Klazinga made a number of unfounded claims and unsubstantiated allegations against Rhodes University. Stripped of the hysteria, lies and inaccuracies, the central claim made is that Rhodes University is hostile to Jews and seeks to be rid of Jews. We reject with contempt these baseless and self-serving claims and allegations of the South African Jewish Report and Klazinga. Rhodes is committed to an institutional culture that respects and promotes equity, human dignity and human rights, embraces difference and diversity and is comfortable for all people irrespective of ‘race’, gender, language, culture, nationality, sexual orientation and religion. Rhodes welcomes all and will continue to strive to be a Home for All.
- Full Text:
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:7883 , http://hdl.handle.net/10962/d1016432
- Description: On 1 January 2014, the South African Jewish Report and Ms Larissa Klazinga made a number of unfounded claims and unsubstantiated allegations against Rhodes University. Stripped of the hysteria, lies and inaccuracies, the central claim made is that Rhodes University is hostile to Jews and seeks to be rid of Jews. We reject with contempt these baseless and self-serving claims and allegations of the South African Jewish Report and Klazinga. Rhodes is committed to an institutional culture that respects and promotes equity, human dignity and human rights, embraces difference and diversity and is comfortable for all people irrespective of ‘race’, gender, language, culture, nationality, sexual orientation and religion. Rhodes welcomes all and will continue to strive to be a Home for All.
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