Synthesis, characterization and anticancer studies of Oxovanadium(iv) Dithiocarbamate complexes
- Authors: Hlobo, Priscilla Vuyiswa
- Date: 2019
- Subjects: Inorganic compounds -- Synthesis Chemistry, Inorganic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19131 , vital:39880
- Description: Eight new oxovanadium(IV) dithiocarbamate complexes, formed by the interaction of vanadyl sulfate pentahydrate and as-synthesized dithiocarbamate ligands, potassium N-morpholine-4- dithiocarbamate ligand (L1), potassium N-piperidinedithiocarbamate (L2), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-diallyldithiocarbamate ligand (L4), potassium N-phenyldithiocarbamate ligand (L5), potassium N-dibenzylminedithiocarbamate ligand (L6), potassium N-(4-methylphenyl)dithiocarbamate ligand (L7), N-(1Himidazoledithiocarbamate) fluoride ligand (L8) in aqueous ethanol are described. The resulting complexes were elemental analyses, molar conductance, infrared, electronic, and nuclear magnetic resonance spectral studies. The spectral studies confirmed the formation of the ligands and complexes. Four complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] derived from potassium N-morpholine-4-dithiocarbamate ligand (L1), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-dibenzylminedithiocarbamate ligand (L6), and N-(1H-imidazoledithiocarbamate) fluoride ligand (L8) were characterized using cyclic voltammetry, to study their electrochemical behavior. Square pyramid oxovanadium(IV) complexes were proposed with the metal ion coordinated to two bidentate dithiocarbamate ligands through sulphur to complete its square pyramidal geometry. The anticancer screening of four oxovanadium(IV) dithiocarbamate complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] are described.
- Full Text:
- Date Issued: 2019
- Authors: Hlobo, Priscilla Vuyiswa
- Date: 2019
- Subjects: Inorganic compounds -- Synthesis Chemistry, Inorganic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19131 , vital:39880
- Description: Eight new oxovanadium(IV) dithiocarbamate complexes, formed by the interaction of vanadyl sulfate pentahydrate and as-synthesized dithiocarbamate ligands, potassium N-morpholine-4- dithiocarbamate ligand (L1), potassium N-piperidinedithiocarbamate (L2), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-diallyldithiocarbamate ligand (L4), potassium N-phenyldithiocarbamate ligand (L5), potassium N-dibenzylminedithiocarbamate ligand (L6), potassium N-(4-methylphenyl)dithiocarbamate ligand (L7), N-(1Himidazoledithiocarbamate) fluoride ligand (L8) in aqueous ethanol are described. The resulting complexes were elemental analyses, molar conductance, infrared, electronic, and nuclear magnetic resonance spectral studies. The spectral studies confirmed the formation of the ligands and complexes. Four complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] derived from potassium N-morpholine-4-dithiocarbamate ligand (L1), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-dibenzylminedithiocarbamate ligand (L6), and N-(1H-imidazoledithiocarbamate) fluoride ligand (L8) were characterized using cyclic voltammetry, to study their electrochemical behavior. Square pyramid oxovanadium(IV) complexes were proposed with the metal ion coordinated to two bidentate dithiocarbamate ligands through sulphur to complete its square pyramidal geometry. The anticancer screening of four oxovanadium(IV) dithiocarbamate complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] are described.
- Full Text:
- Date Issued: 2019
Synthesis, characterization and in vitro antibacterial analysis of carvacrol based-hybrid analogues
- Authors: Mbese, Zintle
- Date: 2019
- Subjects: Medicinal plants Herbs -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14527 , vital:39998
- Description: he focus of this research was to synthesize and characterize carvacrol hybrid analogues. Twenty-one (21) carvacrol analogues were synthesized by reacting carvacrol with (1. 4- aminosalicylic acid, 2. ferrocene keto-butanoic acid, 3. Ferrocene butanoic acid, 4. succinic anhydride, 5. folic acid, 6. cinnamic acid, 7. leucovorin, 8. oleanolic acid, 9. artesunate, 10. cholesterol, 11. cholesterol succinate, 12. curcumin, 13. curcumin succinate, 14. zidovudine, 15. Zidovudine succinate, 16. 8-hydroxyquinoline, 17. 8-hydroxyquinoline succinate, 18. 2- (7-chloroquinolin-4-ylamino)ethyl 5-isopropyl-2-methylphenyl, 19. 2-(7-chloroquinolin-4- ylamino)ethyl 5-isopropyl-2-methylphenyl succinate, 20. 2-(2-(7-chloroquinolin-4- ylamino)ethoxy)ethyl 5-isopropyl-2-methylphenyl, 21. 2-(2-(7-chloroquinolin-4- ylamino)ethoxy)ethyl 5-isopropyl-2-methylphenyl succinate). The carvacrol analogues were characterized using FTIR, UHPLC-HRMS, 1H- and 13C-NMR spectroscopy. The antibacterial analysis was performed to evaluate the carvacrol analogues against bacterial strains. FTIR spectra of carvacrol analogues were found to exhibit peaks of C-O stretch and Ar-C in a range of 1014-1280 cm-1 and a range of 1414-1697 cm-1 which confirm the successful formation of esters. The proposed structures of carvacrol analogues were confirmed by the 1H- and 13C-NMR. The selected 1H-NMR signal for aromatic protons ranged at 6.00-8.95 ppm/δ. The selected 13C-NMR signal for ester carbon and aromatic carbons ranged at 160.0-175.0 ppm/δ and at 110.00-154.00 ppm/δ. The structures were also confirmed by UHPLC-HRMS. Carvacrol analogues exhibited the highest inhibitory effect against Gram-positive and Gram-negative tested bacterial strains.
- Full Text:
- Date Issued: 2019
- Authors: Mbese, Zintle
- Date: 2019
- Subjects: Medicinal plants Herbs -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14527 , vital:39998
- Description: he focus of this research was to synthesize and characterize carvacrol hybrid analogues. Twenty-one (21) carvacrol analogues were synthesized by reacting carvacrol with (1. 4- aminosalicylic acid, 2. ferrocene keto-butanoic acid, 3. Ferrocene butanoic acid, 4. succinic anhydride, 5. folic acid, 6. cinnamic acid, 7. leucovorin, 8. oleanolic acid, 9. artesunate, 10. cholesterol, 11. cholesterol succinate, 12. curcumin, 13. curcumin succinate, 14. zidovudine, 15. Zidovudine succinate, 16. 8-hydroxyquinoline, 17. 8-hydroxyquinoline succinate, 18. 2- (7-chloroquinolin-4-ylamino)ethyl 5-isopropyl-2-methylphenyl, 19. 2-(7-chloroquinolin-4- ylamino)ethyl 5-isopropyl-2-methylphenyl succinate, 20. 2-(2-(7-chloroquinolin-4- ylamino)ethoxy)ethyl 5-isopropyl-2-methylphenyl, 21. 2-(2-(7-chloroquinolin-4- ylamino)ethoxy)ethyl 5-isopropyl-2-methylphenyl succinate). The carvacrol analogues were characterized using FTIR, UHPLC-HRMS, 1H- and 13C-NMR spectroscopy. The antibacterial analysis was performed to evaluate the carvacrol analogues against bacterial strains. FTIR spectra of carvacrol analogues were found to exhibit peaks of C-O stretch and Ar-C in a range of 1014-1280 cm-1 and a range of 1414-1697 cm-1 which confirm the successful formation of esters. The proposed structures of carvacrol analogues were confirmed by the 1H- and 13C-NMR. The selected 1H-NMR signal for aromatic protons ranged at 6.00-8.95 ppm/δ. The selected 13C-NMR signal for ester carbon and aromatic carbons ranged at 160.0-175.0 ppm/δ and at 110.00-154.00 ppm/δ. The structures were also confirmed by UHPLC-HRMS. Carvacrol analogues exhibited the highest inhibitory effect against Gram-positive and Gram-negative tested bacterial strains.
- Full Text:
- Date Issued: 2019
Targeted attack detection by means of free and open source solutions
- Authors: Bernardo, Louis F
- Date: 2019
- Subjects: Computer networks -- Security measures , Information technology -- Security measures , Computer security -- Management , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92269 , vital:30703
- Description: Compliance requirements are part of everyday business requirements for various areas, such as retail and medical services. As part of compliance it may be required to have infrastructure in place to monitor the activities in the environment to ensure that the relevant data and environment is sufficiently protected. At the core of such monitoring solutions one would find some type of data repository, or database, to store and ultimately correlate the captured events. Such solutions are commonly called Security Information and Event Management, or SIEM for short. Larger companies have been known to use commercial solutions such as IBM's Qradar, Logrythm, or Splunk. However, these come at significant cost and arent suitable for smaller businesses with limited budgets. These solutions require manual configuration of event correlation for detection of activities that place the environment in danger. This usually requires vendor implementation assistance that also would come at a cost. Alternatively, there are open source solutions that provide the required functionality. This research will demonstrate building an open source solution, with minimal to no cost for hardware or software, while still maintaining the capability of detecting targeted attacks. The solution presented in this research includes Wazuh, which is a combination of OSSEC and the ELK stack, integrated with an Network Intrusion Detection System (NIDS). The success of the integration, is determined by measuring postive attack detection based on each different configuration options. To perform the testing, a deliberately vulnerable platform named Metasploitable will be used as a victim host. The victim host vulnerabilities were created specifically to serve as target for Metasploit. The attacks were generated by utilising Metasploit Framework on a prebuilt Kali Linux host.
- Full Text:
- Date Issued: 2019
- Authors: Bernardo, Louis F
- Date: 2019
- Subjects: Computer networks -- Security measures , Information technology -- Security measures , Computer security -- Management , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92269 , vital:30703
- Description: Compliance requirements are part of everyday business requirements for various areas, such as retail and medical services. As part of compliance it may be required to have infrastructure in place to monitor the activities in the environment to ensure that the relevant data and environment is sufficiently protected. At the core of such monitoring solutions one would find some type of data repository, or database, to store and ultimately correlate the captured events. Such solutions are commonly called Security Information and Event Management, or SIEM for short. Larger companies have been known to use commercial solutions such as IBM's Qradar, Logrythm, or Splunk. However, these come at significant cost and arent suitable for smaller businesses with limited budgets. These solutions require manual configuration of event correlation for detection of activities that place the environment in danger. This usually requires vendor implementation assistance that also would come at a cost. Alternatively, there are open source solutions that provide the required functionality. This research will demonstrate building an open source solution, with minimal to no cost for hardware or software, while still maintaining the capability of detecting targeted attacks. The solution presented in this research includes Wazuh, which is a combination of OSSEC and the ELK stack, integrated with an Network Intrusion Detection System (NIDS). The success of the integration, is determined by measuring postive attack detection based on each different configuration options. To perform the testing, a deliberately vulnerable platform named Metasploitable will be used as a victim host. The victim host vulnerabilities were created specifically to serve as target for Metasploit. The attacks were generated by utilising Metasploit Framework on a prebuilt Kali Linux host.
- Full Text:
- Date Issued: 2019
Targeting allosteric sites of Escherichia coli heat shock protein 70 for antibiotic development
- Authors: Okeke, Chiamaka Jessica
- Date: 2019
- Subjects: Heat shock proteins , Escherichia coli , Allosteric proteins , Antibiotics , Molecular chaperones , Ligands (Biochemistry) , Molecular dynamics , Principal components analysis , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115998 , vital:34287
- Description: Hsp70s are members of the heat shock proteins family with a molecular weight of 70-kDa and are the most abundant group in bacterial and eukaryotic systems, hence the most extensively studied ones. These proteins are molecular chaperones that play a significant role in protein homeostasis by facilitating appropriate folding of proteins, preventing proteins from aggregating and misfolding. They are also involved in translocation of proteins into subcellular compartments and protection of cells against stress. Stress caused by environmental or biological factors affects the functionality of the cell. In response to these stressful conditions, up-regulation of Hsp70s ensures that the cells are protected by balancing out unfolded proteins giving them ample time to repair denatured proteins. Hsp70s is connected to numerous illnesses such as autoimmune and neurodegenerative diseases, bacterial infection, cancer, malaria, and obesity. The multi-functional nature of Hsp70s predisposes them as promising therapeutic targets. Hsp70s play vital roles in various cell developments, and survival pathways, therefore targeting this protein will provide a new avenue towards the discovery of active therapeutic agents for the treatment of a wide range of diseases. Allosteric sites of these proteins in its multi-conformational states have not been explored for inhibitory properties hence the aim of this study. This study aims at identifying allosteric sites that inhibit the ATPase and substrate binding activities using computational approaches. Using E. coli as a model organism, molecular docking for high throughput virtual screening was carried out using 623 compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/) against identified allosteric sites. Ligands with the highest binding affinity (good binders) interacting with critical allosteric residues that are druggable were identified. Molecular dynamics (MD) simulation was also performed on the identified hits to assess for protein-inhibitor complex stability. Finally, principal component analysis (PCA) was performed to understand the structural dynamics of the ligand-free and ligand-bound structures during MD simulation.
- Full Text:
- Date Issued: 2019
- Authors: Okeke, Chiamaka Jessica
- Date: 2019
- Subjects: Heat shock proteins , Escherichia coli , Allosteric proteins , Antibiotics , Molecular chaperones , Ligands (Biochemistry) , Molecular dynamics , Principal components analysis , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115998 , vital:34287
- Description: Hsp70s are members of the heat shock proteins family with a molecular weight of 70-kDa and are the most abundant group in bacterial and eukaryotic systems, hence the most extensively studied ones. These proteins are molecular chaperones that play a significant role in protein homeostasis by facilitating appropriate folding of proteins, preventing proteins from aggregating and misfolding. They are also involved in translocation of proteins into subcellular compartments and protection of cells against stress. Stress caused by environmental or biological factors affects the functionality of the cell. In response to these stressful conditions, up-regulation of Hsp70s ensures that the cells are protected by balancing out unfolded proteins giving them ample time to repair denatured proteins. Hsp70s is connected to numerous illnesses such as autoimmune and neurodegenerative diseases, bacterial infection, cancer, malaria, and obesity. The multi-functional nature of Hsp70s predisposes them as promising therapeutic targets. Hsp70s play vital roles in various cell developments, and survival pathways, therefore targeting this protein will provide a new avenue towards the discovery of active therapeutic agents for the treatment of a wide range of diseases. Allosteric sites of these proteins in its multi-conformational states have not been explored for inhibitory properties hence the aim of this study. This study aims at identifying allosteric sites that inhibit the ATPase and substrate binding activities using computational approaches. Using E. coli as a model organism, molecular docking for high throughput virtual screening was carried out using 623 compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/) against identified allosteric sites. Ligands with the highest binding affinity (good binders) interacting with critical allosteric residues that are druggable were identified. Molecular dynamics (MD) simulation was also performed on the identified hits to assess for protein-inhibitor complex stability. Finally, principal component analysis (PCA) was performed to understand the structural dynamics of the ligand-free and ligand-bound structures during MD simulation.
- Full Text:
- Date Issued: 2019
Taxonomic and trait-based responses of the orders Ephemeroptera, Plecoptera, Odonata, And Trichoptera (EPOT) to sediment stress in the Tsitsa River and its tributaries, Eastern Cape, South Africa
- Akamagwuna, Frank Chukwuzuoke
- Authors: Akamagwuna, Frank Chukwuzuoke
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68082 , vital:29196
- Description: Increased urbanization and industrialisation due to human population growth and associated high demand for food have led to widespread disturbances of freshwater ecosystems and associated resources. A widely recognised consequence of these disturbances is the excessive delivery of sediments into the freshwater ecosystems, which severely affects the functioning and integrity of these systems.. The major water quality impairment in the Tsitsa River and its tributaries, situated in the Mzimvubu catchment in the Eastern Cape Province of South Africa, is known to be excessive sediment input. In this study, the application of macroinvertebrates taxonomic-based and trait-based approaches was used to assess the responses and vulnerability of Ephemeroptera, Plecoptera, Odonata and Trichoptera (EPOT) species to settled and suspended sediments stress in eight selected sampling sites in the Tsitsa River and its tributaries. The eight selected sites were Site 1 (Tsitsa upstream), Site 2 (Tsitsa downstream), Site 3 (Qurana tributary), Site 4 (Pot River upstream), Site 5 (Pot River downstream), Site 6 (Little Pot River), Site 7 (Millstream upstream) and Site 8 (Millstream downstream). The methods used in this study involved the analysis of water physico-chemical variables as well as sediment characteristics, derivation of five EPOT metrics, EPOT species-level taxonomic analysis, individual EPOT trait analysis and the development of a novel trait-based approach using a combination of traits. The sampling of EPOT taxa was done using the SASS5 protocols. Identification of EPOT was done to genus/species level and all data were subjected to relevant statistical analysis. The results of ecological categories derived for the physico-chemical variables generally indicated the ecological categories A and B, which was indicative of good water quality conditions. The result of sediment particle analysis revealed four distinct site groups: site group 1 (Tsitsa River upstream and Qurana tributary), site group 2 (Tsitsa River downstream and Millstream upstream), site group 3 (Pot River, both upstream and downstream, and Millstream downstream) and site group 4 (Little Pot River). The species-level taxonomic analysis of EPOT revealed that site group 1 was the most sediment-influenced sites whereas site group 4 was the least sediment-influenced. Species such as Paragopmhus sp., Aeshna sp. and Baetis sp. were considered sediment-tolerant with strong positive association with site group 1. The novel trait-based approach developed in this study proved useful in predicting the responses of EPOT species to sediment stress, and further discriminated between the study sites. The approach was used to group EPOT species into four vulnerability classes. The result showed that filter feeding EPOT species that have filamentous gills, preferring stone biotopes and feeding on detritus (FPOM) were mostly classified as highly vulnerable to sediment stress and indicated no significant association with the highly sediment-influenced site group 1. The TBA largely corresponded well to the predictions made with the relative abundance of the vulnerable class decreasing in the sediment-influenced sites compared to the tolerant and highly tolerant classes. Overall, the study revealed the importance of the complementary use of taxonomic and trait-based approaches to biomonitoring.
- Full Text:
- Date Issued: 2019
- Authors: Akamagwuna, Frank Chukwuzuoke
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68082 , vital:29196
- Description: Increased urbanization and industrialisation due to human population growth and associated high demand for food have led to widespread disturbances of freshwater ecosystems and associated resources. A widely recognised consequence of these disturbances is the excessive delivery of sediments into the freshwater ecosystems, which severely affects the functioning and integrity of these systems.. The major water quality impairment in the Tsitsa River and its tributaries, situated in the Mzimvubu catchment in the Eastern Cape Province of South Africa, is known to be excessive sediment input. In this study, the application of macroinvertebrates taxonomic-based and trait-based approaches was used to assess the responses and vulnerability of Ephemeroptera, Plecoptera, Odonata and Trichoptera (EPOT) species to settled and suspended sediments stress in eight selected sampling sites in the Tsitsa River and its tributaries. The eight selected sites were Site 1 (Tsitsa upstream), Site 2 (Tsitsa downstream), Site 3 (Qurana tributary), Site 4 (Pot River upstream), Site 5 (Pot River downstream), Site 6 (Little Pot River), Site 7 (Millstream upstream) and Site 8 (Millstream downstream). The methods used in this study involved the analysis of water physico-chemical variables as well as sediment characteristics, derivation of five EPOT metrics, EPOT species-level taxonomic analysis, individual EPOT trait analysis and the development of a novel trait-based approach using a combination of traits. The sampling of EPOT taxa was done using the SASS5 protocols. Identification of EPOT was done to genus/species level and all data were subjected to relevant statistical analysis. The results of ecological categories derived for the physico-chemical variables generally indicated the ecological categories A and B, which was indicative of good water quality conditions. The result of sediment particle analysis revealed four distinct site groups: site group 1 (Tsitsa River upstream and Qurana tributary), site group 2 (Tsitsa River downstream and Millstream upstream), site group 3 (Pot River, both upstream and downstream, and Millstream downstream) and site group 4 (Little Pot River). The species-level taxonomic analysis of EPOT revealed that site group 1 was the most sediment-influenced sites whereas site group 4 was the least sediment-influenced. Species such as Paragopmhus sp., Aeshna sp. and Baetis sp. were considered sediment-tolerant with strong positive association with site group 1. The novel trait-based approach developed in this study proved useful in predicting the responses of EPOT species to sediment stress, and further discriminated between the study sites. The approach was used to group EPOT species into four vulnerability classes. The result showed that filter feeding EPOT species that have filamentous gills, preferring stone biotopes and feeding on detritus (FPOM) were mostly classified as highly vulnerable to sediment stress and indicated no significant association with the highly sediment-influenced site group 1. The TBA largely corresponded well to the predictions made with the relative abundance of the vulnerable class decreasing in the sediment-influenced sites compared to the tolerant and highly tolerant classes. Overall, the study revealed the importance of the complementary use of taxonomic and trait-based approaches to biomonitoring.
- Full Text:
- Date Issued: 2019
Terrestrial alien ferns (Polypodiophyta): a global assessment of traits associated with invasiveness and their distribution and status in South Africa
- Authors: Jones, Emily Joy
- Date: 2019
- Subjects: Biodiversity -- South Africa , Alien plants -- South Africa , Botany -- South Africa , Plant ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39995 , vital:35643
- Description: Globally, invasive alien plants (IAPs) are one of the greatest threats to biodiversity, ecosystems and ecosystem services. The threats posed by IAPs have prompted inventory compilations and screening exercises which aim to understand why some taxa become invasive and others do not. Ferns are a diverse taxon that appear to have a high invasive potential, however ferns have been vastly understudied in the field of invasion biology. This study aimed to establish a basic understanding of terrestrial alien true ferns (Polypodiophyta, hereafter ‘alien ferns’) at both global and national (South African) scales. We developed a global inventory of alien ferns comprising 157 species using published literature and online inventories. Our global inventory indicated that there are significantly more alien fern species than previously estimated (60 species). We used generalised linear models with binomial response variables to determine which traits influenced the probability that an alien fern would become naturalised or invasive. Our models explained 30-40 % of the variance associated with invasiveness and showed that ground-dwelling life forms, reproductive plasticity, tolerance to disturbances and varied light conditions, and a broad introduced range (interpreted as high environmental tolerance and popularity in horticulture) were important determinants of invasiveness in alien ferns. Ultimately, we found that the probability of alien ferns becoming naturalised or invasive is more than 50 %. We further established which geographic regions and fern families had the highest incidences of alien ferns and identified species that were invasive over extensive introduced ranges. For the national scale study, we aimed to assess the distribution, abundance, invasion status, and habitat associations of terrestrial alien fern species present outside of cultivation in South Africa. Field surveys were conducted across the country in habitats suitable for ferns, guided by pre-existing records of alien fern occurrences. Thirteen species occurred outside of cultivation, all of which were classified as invasive, and among these, approximately 5000 plants were recorded across 300 localities. Species richness and abundance peaked along the Indian Ocean Coastal Belt and the Afro-montane phytogeographical regions. A multiple correspondence analysis revealed that alien ferns in South Africa were most strongly associated with indigenous forest habitats and the majority of species selected for shaded conditions, close to water. Only two species were closely associated with open habitats under high light conditions, with plantations also infrequently selected by alien ferns. Habitat generalists were closely associated with disturbance, but avoided open habitats, far from water. Compared to the most prominent angiosperm invaders in South Africa, alien ferns have a lower potential for widespread ii invasion and range expansion, probably due to their habitat specificity. We identified four species as potential targets for eradication and which should be listed as Category 1a under the Alien and Invasive Species regulations of the National Environmental Management: Biodiversity Act of South Africa. The remaining species should be listed as Category 1b since they occupied an extensive geographic range. The most prominent ferns included Adiantum raddianum, Sphaeropteris cooperi, Deparia japonica and Cyrtomium falcatum. Our study informed appropriate regulation for several species of alien ferns that were deemed to be data deficient and in need of assessment by a recent report on the status of biological invasions in South Africa. A risk analysis completed for S. cooperi confirmed that the species has a high invasion risk in South Africa and should be listed as Category 1b. Given that the outcomes of the risk analysis completed for S. cooperi matched the findings from our field surveys, this study supported risk analysis as a reliable (literature-based) method to evaluate IAPs. The findings of our assessments at the global and national scale corresponded in that various traits that promoted invasiveness in alien ferns globally were also facilitating invasion in South Africa. Additionally, of the eleven species found to be invasive over extensive introduced ranges at global scale, only two (Lygodium microphyllum and Angiopteris evecta) were not yet recorded in South Africa. Since horticulture was established as the primary pathway for the introduction of alien ferns, the management of alien ferns (globally and in South Africa) should focus on regulating trade. The sources of cultivation and the pathways of dissemination across the globe also need consideration. Basic environmental and biological associations of alien ferns were evident in this study, but to fully understand their invasive potential further research should focus on niche-based modelling to predict potential invasion ranges, the effects of biological traits on invasiveness, and the potential ecological impacts of these species.
- Full Text:
- Date Issued: 2019
- Authors: Jones, Emily Joy
- Date: 2019
- Subjects: Biodiversity -- South Africa , Alien plants -- South Africa , Botany -- South Africa , Plant ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39995 , vital:35643
- Description: Globally, invasive alien plants (IAPs) are one of the greatest threats to biodiversity, ecosystems and ecosystem services. The threats posed by IAPs have prompted inventory compilations and screening exercises which aim to understand why some taxa become invasive and others do not. Ferns are a diverse taxon that appear to have a high invasive potential, however ferns have been vastly understudied in the field of invasion biology. This study aimed to establish a basic understanding of terrestrial alien true ferns (Polypodiophyta, hereafter ‘alien ferns’) at both global and national (South African) scales. We developed a global inventory of alien ferns comprising 157 species using published literature and online inventories. Our global inventory indicated that there are significantly more alien fern species than previously estimated (60 species). We used generalised linear models with binomial response variables to determine which traits influenced the probability that an alien fern would become naturalised or invasive. Our models explained 30-40 % of the variance associated with invasiveness and showed that ground-dwelling life forms, reproductive plasticity, tolerance to disturbances and varied light conditions, and a broad introduced range (interpreted as high environmental tolerance and popularity in horticulture) were important determinants of invasiveness in alien ferns. Ultimately, we found that the probability of alien ferns becoming naturalised or invasive is more than 50 %. We further established which geographic regions and fern families had the highest incidences of alien ferns and identified species that were invasive over extensive introduced ranges. For the national scale study, we aimed to assess the distribution, abundance, invasion status, and habitat associations of terrestrial alien fern species present outside of cultivation in South Africa. Field surveys were conducted across the country in habitats suitable for ferns, guided by pre-existing records of alien fern occurrences. Thirteen species occurred outside of cultivation, all of which were classified as invasive, and among these, approximately 5000 plants were recorded across 300 localities. Species richness and abundance peaked along the Indian Ocean Coastal Belt and the Afro-montane phytogeographical regions. A multiple correspondence analysis revealed that alien ferns in South Africa were most strongly associated with indigenous forest habitats and the majority of species selected for shaded conditions, close to water. Only two species were closely associated with open habitats under high light conditions, with plantations also infrequently selected by alien ferns. Habitat generalists were closely associated with disturbance, but avoided open habitats, far from water. Compared to the most prominent angiosperm invaders in South Africa, alien ferns have a lower potential for widespread ii invasion and range expansion, probably due to their habitat specificity. We identified four species as potential targets for eradication and which should be listed as Category 1a under the Alien and Invasive Species regulations of the National Environmental Management: Biodiversity Act of South Africa. The remaining species should be listed as Category 1b since they occupied an extensive geographic range. The most prominent ferns included Adiantum raddianum, Sphaeropteris cooperi, Deparia japonica and Cyrtomium falcatum. Our study informed appropriate regulation for several species of alien ferns that were deemed to be data deficient and in need of assessment by a recent report on the status of biological invasions in South Africa. A risk analysis completed for S. cooperi confirmed that the species has a high invasion risk in South Africa and should be listed as Category 1b. Given that the outcomes of the risk analysis completed for S. cooperi matched the findings from our field surveys, this study supported risk analysis as a reliable (literature-based) method to evaluate IAPs. The findings of our assessments at the global and national scale corresponded in that various traits that promoted invasiveness in alien ferns globally were also facilitating invasion in South Africa. Additionally, of the eleven species found to be invasive over extensive introduced ranges at global scale, only two (Lygodium microphyllum and Angiopteris evecta) were not yet recorded in South Africa. Since horticulture was established as the primary pathway for the introduction of alien ferns, the management of alien ferns (globally and in South Africa) should focus on regulating trade. The sources of cultivation and the pathways of dissemination across the globe also need consideration. Basic environmental and biological associations of alien ferns were evident in this study, but to fully understand their invasive potential further research should focus on niche-based modelling to predict potential invasion ranges, the effects of biological traits on invasiveness, and the potential ecological impacts of these species.
- Full Text:
- Date Issued: 2019
Testing potential groundwater reservoir connectivity using isotopes in the south-central Karoo region
- Authors: Dlakavu, Sinazo
- Date: 2019
- Subjects: Groundwater -- South Africa -- Karoo , Hydrogeology -- South Africa Water-supply -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39447 , vital:35248
- Description: Documenting areas with natural groundwater reservior connectivity using isotopes before the anticipated shale gas development in the Karoo Basin of South Africa could contribute to developing legislative framework for hydraulic fracturing. In this study, groundwater dynamics (primarily connectivity between old/deep and low temperature modern/shallow (<25°C) groundwater) are studied using isotopes (14C, δ18O-δ2H, 3H, and δ13C) in conjunction with geochemical parameters (sampling depth (masl) and (mbgl), temperature (°C), Electrical Conductivity (EC) (μS/m) and sustainable yield (l/s)). Previous groundwater studies conducted in the Karoo Basin suggest that 14C (pMC) has the least overlap among isotope signature constraints between the different aquifer/groundwater groups. The outcomes of 14C analysis for this study suggest that one groundwater sample is an old/deep groundwater sample (<53 pMC), and that three groundwater samples are composed of shallow/young groundwater mixed with old/deep groundwater (<74 pMC). These four relatively older samples have calculated 14C ages ≥ 1700 years and were collected from boreholes that are north-east of the Cape Mountains (~50 km). The position of these samples suggests that deep-seated faults within the Cape Mountains and the basement of the southern Karoo Basin act as preferential pathways for deep groundwater migration (as is consistent with existing deep geophysical data) to shallower depths (<60 mbgl) where it cools and/or mixes with low temperature groundwater (<25°C). Three more groundwater samples were found to match the relatively old calculated 14C ages (≥ 1700 years) of the groundwater samples collected close to the Cape Mountains even though they have modern 14C (pMC) concentrations (>74 pMC). This implies that adjusting the 14C content in Dissolved Inorganic Carbon (DIC) based on its dilution by 14C free carbonates is influential in controlling the mixed groundwater ages, and that relatively older groundwater occurs at shallow depths in other parts of the study area possibly due to linked fault systems between deep and shallow aquifers. δ18O-δ2H relationships for the sampled groundwater suggest that groundwater samples collected within the main drainage of the Great Fish River plot close to the Global Meteoric Water Line (GMWL) indicating that the recharge water to this groundwater does not experience significant evaporation. The average isotope composition of the recharging water for the all of the sampled groundwater is -7.90 ‰ and -46.72 ‰ for δ18O and δ2H, respectively. This result plots halfway between rainwater 18O-2H relationship lines for the Indian Ocean and the Atlantic Ocean. This suggests that the rainwater from which the sampled groundwater was derived from evolved from both the Indian and Atlantic Ocean waters.
- Full Text:
- Date Issued: 2019
- Authors: Dlakavu, Sinazo
- Date: 2019
- Subjects: Groundwater -- South Africa -- Karoo , Hydrogeology -- South Africa Water-supply -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39447 , vital:35248
- Description: Documenting areas with natural groundwater reservior connectivity using isotopes before the anticipated shale gas development in the Karoo Basin of South Africa could contribute to developing legislative framework for hydraulic fracturing. In this study, groundwater dynamics (primarily connectivity between old/deep and low temperature modern/shallow (<25°C) groundwater) are studied using isotopes (14C, δ18O-δ2H, 3H, and δ13C) in conjunction with geochemical parameters (sampling depth (masl) and (mbgl), temperature (°C), Electrical Conductivity (EC) (μS/m) and sustainable yield (l/s)). Previous groundwater studies conducted in the Karoo Basin suggest that 14C (pMC) has the least overlap among isotope signature constraints between the different aquifer/groundwater groups. The outcomes of 14C analysis for this study suggest that one groundwater sample is an old/deep groundwater sample (<53 pMC), and that three groundwater samples are composed of shallow/young groundwater mixed with old/deep groundwater (<74 pMC). These four relatively older samples have calculated 14C ages ≥ 1700 years and were collected from boreholes that are north-east of the Cape Mountains (~50 km). The position of these samples suggests that deep-seated faults within the Cape Mountains and the basement of the southern Karoo Basin act as preferential pathways for deep groundwater migration (as is consistent with existing deep geophysical data) to shallower depths (<60 mbgl) where it cools and/or mixes with low temperature groundwater (<25°C). Three more groundwater samples were found to match the relatively old calculated 14C ages (≥ 1700 years) of the groundwater samples collected close to the Cape Mountains even though they have modern 14C (pMC) concentrations (>74 pMC). This implies that adjusting the 14C content in Dissolved Inorganic Carbon (DIC) based on its dilution by 14C free carbonates is influential in controlling the mixed groundwater ages, and that relatively older groundwater occurs at shallow depths in other parts of the study area possibly due to linked fault systems between deep and shallow aquifers. δ18O-δ2H relationships for the sampled groundwater suggest that groundwater samples collected within the main drainage of the Great Fish River plot close to the Global Meteoric Water Line (GMWL) indicating that the recharge water to this groundwater does not experience significant evaporation. The average isotope composition of the recharging water for the all of the sampled groundwater is -7.90 ‰ and -46.72 ‰ for δ18O and δ2H, respectively. This result plots halfway between rainwater 18O-2H relationship lines for the Indian Ocean and the Atlantic Ocean. This suggests that the rainwater from which the sampled groundwater was derived from evolved from both the Indian and Atlantic Ocean waters.
- Full Text:
- Date Issued: 2019
The challenges of professional women in a male-dominated South African construction industry
- Authors: Tyindyana, Xolile
- Date: 2019
- Subjects: Construction industry -- South Africa , Construction industry -- South Africa -- Management Women industrialists -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44962 , vital:38192
- Description: The opinions that South African construction industry is the most untransformed sector, highly gender active and men have difficulty in accepting women in the construction industry, hindered the development of the South African economy. The improved number of professional women entering the statuses of this male dominance is noticeable, but the percentage of men still speak volume. Hence, there are imbalances that are correspondent to discrimination trials. This study explore challenges faced by professional women in the construction industry of South Africa, in the Eastern Cape. The study embraced exploratory research design in order to formulate preliminary investigations based on relatively unknown areas of professional women in construction industry. Therefore, this qualitative method incorporated interpretivism as its research philosophy, with the motive that this paradigm succeeds individual ontology that does not perceive as objective and independent. The purposeful sampling technique deployed in identifying the research participants, coupled by ten (10) women rendering professional services in the construction industry. Data collected was analysed thematically, which gave rise to presented themes, deliberated and construed in headings framed from research objectives. The study revealed that professional women still trapped between resisting, accommodating masculine politics and femininity distinctions regardless of evolutions. Most participants attested to the gender imbalances that propagates marginalisation, which is in line with the revelations. The study also suggest that men reject professionalism identity in the context of women. Other key challenges were not limited to backgrounds of the industry, outlook and progression that necessitated women taking executive positions. Further still, participants are aware of flouted construction industry policies and the strategies to use to by their counterparts to obscure them. Hence, the study suggested monitoring and review of policies in place by the policy makers. A recommended that similar research be carried out in South Africa, particularly provinces, as a literature gap has been identified. These recommended studies could enhance professional women, men and policy makers in profound consideration of the challenges faced by professional women in the construction industry.
- Full Text:
- Date Issued: 2019
- Authors: Tyindyana, Xolile
- Date: 2019
- Subjects: Construction industry -- South Africa , Construction industry -- South Africa -- Management Women industrialists -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44962 , vital:38192
- Description: The opinions that South African construction industry is the most untransformed sector, highly gender active and men have difficulty in accepting women in the construction industry, hindered the development of the South African economy. The improved number of professional women entering the statuses of this male dominance is noticeable, but the percentage of men still speak volume. Hence, there are imbalances that are correspondent to discrimination trials. This study explore challenges faced by professional women in the construction industry of South Africa, in the Eastern Cape. The study embraced exploratory research design in order to formulate preliminary investigations based on relatively unknown areas of professional women in construction industry. Therefore, this qualitative method incorporated interpretivism as its research philosophy, with the motive that this paradigm succeeds individual ontology that does not perceive as objective and independent. The purposeful sampling technique deployed in identifying the research participants, coupled by ten (10) women rendering professional services in the construction industry. Data collected was analysed thematically, which gave rise to presented themes, deliberated and construed in headings framed from research objectives. The study revealed that professional women still trapped between resisting, accommodating masculine politics and femininity distinctions regardless of evolutions. Most participants attested to the gender imbalances that propagates marginalisation, which is in line with the revelations. The study also suggest that men reject professionalism identity in the context of women. Other key challenges were not limited to backgrounds of the industry, outlook and progression that necessitated women taking executive positions. Further still, participants are aware of flouted construction industry policies and the strategies to use to by their counterparts to obscure them. Hence, the study suggested monitoring and review of policies in place by the policy makers. A recommended that similar research be carried out in South Africa, particularly provinces, as a literature gap has been identified. These recommended studies could enhance professional women, men and policy makers in profound consideration of the challenges faced by professional women in the construction industry.
- Full Text:
- Date Issued: 2019
The characterization of the interaction between Streptococcus pneumoniae PspC and Homo sapiens pIgR
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
The cultivation of Gracilaria gracilis in the Swartkops estuary, South Africa
- Authors: Blewett, Alec
- Date: 2019
- Subjects: Gracilaria -- South Africa -- Port Elizabeth , Marine algae Algae -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31446 , vital:31391
- Description: Gracilaria gracilis (Stackhouse) M. Steentoft, L. M. Irvine & W. F. Farnham is a species of red macroalgae which occurs naturally within the Swartkops Estuary in South Africa. Bunches of the species were inserted into the lay of ropes, which were then either suspended in the water column at the Tiger Bay Marina, or staked at the surface of the sediment in the mudflats where the initial material was harvested from. The first site was used for the suspended growth trial, while the second site was for the bottom grown trial. Both of the growth trials ran for the same time period, which was approximately three weeks per season. This study examined three facets of the G. gracilis material that was grown. The growth rate and biomass were recorded in order to examine the potential for the growth of the species on longlines within the estuary. Secondly, the crude nutritional content of the species was determined in order to assess its potential for use as an abalone feed, specifically the dry and ashed weights, and the protein, carbohydrate and lipid contents. Lastly, the cultivated biomass was examined in terms of its agar gel yield and properties, which included the gel strength and the gel –melting and –forming temperatures. The growth rates for the cultivated G. gracilis were poor, and the largest positive growth rate of 1.17 ± 3.2% was found in spring, for the bottom grown trial. This season also saw the only increase in biomass above that which was seeded onto the line, and the final average weight after 22 days was 354.28 ± 68.04 g. All other growth rates were negative, and biomass declined in both growth trials across all the seasons. The suspended growth trials showed more extreme declines, and were heavily contaminated with epiphytic material, while the bottom grown trial had more gradual decrease, and it is likely that conditions associated with the culture systems were not ideal. The largest percentage of protein was found in autumn, where the bottom grown trial had a value of 88 ± 2.32%. For all the seasons, the lipid content had an average percentage of 1.80 ± 0.75% for the bottom grown trial, while the suspended trial was very similar, and had a value of 1.74 ± 0.58%. The nutritional composition of the cultivated biomass was not found to be a good abalone feed in comparison to other studies in land-based aquaculture facilities. Agar characteristics extracted in the present study showed the greatest potential for use as a valuable economic resource. The native agar extracted from the cultivated material was very close to the standards set by United States Pharmacopeia for all the characteristics, and has the potential to possibly be improved further by using an alkali treatment.
- Full Text:
- Date Issued: 2019
- Authors: Blewett, Alec
- Date: 2019
- Subjects: Gracilaria -- South Africa -- Port Elizabeth , Marine algae Algae -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31446 , vital:31391
- Description: Gracilaria gracilis (Stackhouse) M. Steentoft, L. M. Irvine & W. F. Farnham is a species of red macroalgae which occurs naturally within the Swartkops Estuary in South Africa. Bunches of the species were inserted into the lay of ropes, which were then either suspended in the water column at the Tiger Bay Marina, or staked at the surface of the sediment in the mudflats where the initial material was harvested from. The first site was used for the suspended growth trial, while the second site was for the bottom grown trial. Both of the growth trials ran for the same time period, which was approximately three weeks per season. This study examined three facets of the G. gracilis material that was grown. The growth rate and biomass were recorded in order to examine the potential for the growth of the species on longlines within the estuary. Secondly, the crude nutritional content of the species was determined in order to assess its potential for use as an abalone feed, specifically the dry and ashed weights, and the protein, carbohydrate and lipid contents. Lastly, the cultivated biomass was examined in terms of its agar gel yield and properties, which included the gel strength and the gel –melting and –forming temperatures. The growth rates for the cultivated G. gracilis were poor, and the largest positive growth rate of 1.17 ± 3.2% was found in spring, for the bottom grown trial. This season also saw the only increase in biomass above that which was seeded onto the line, and the final average weight after 22 days was 354.28 ± 68.04 g. All other growth rates were negative, and biomass declined in both growth trials across all the seasons. The suspended growth trials showed more extreme declines, and were heavily contaminated with epiphytic material, while the bottom grown trial had more gradual decrease, and it is likely that conditions associated with the culture systems were not ideal. The largest percentage of protein was found in autumn, where the bottom grown trial had a value of 88 ± 2.32%. For all the seasons, the lipid content had an average percentage of 1.80 ± 0.75% for the bottom grown trial, while the suspended trial was very similar, and had a value of 1.74 ± 0.58%. The nutritional composition of the cultivated biomass was not found to be a good abalone feed in comparison to other studies in land-based aquaculture facilities. Agar characteristics extracted in the present study showed the greatest potential for use as a valuable economic resource. The native agar extracted from the cultivated material was very close to the standards set by United States Pharmacopeia for all the characteristics, and has the potential to possibly be improved further by using an alkali treatment.
- Full Text:
- Date Issued: 2019
The delivery of low-income housing in Sarah Baartman District from 2012 to 2017
- Authors: Mazondwa, Sivuyile
- Date: 2019
- Subjects: Low-income housing -- South Africa -- Eastern Cape , Public housing -- South Africa -- Eastern Cape Housing development -- South Africa -- Eastern Cape Project management -- South Africa -- Eastern Cape Construction industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41537 , vital:36502
- Description: Access to basic housing for the poor is one of the Government’s key focus areas. Housing delivery started to decline in Sarah Baartman, leading to total non-delivery in the local municipalities within the district. This has led to community unrest, in which the national and regional roads will be blocked, due to the demand for houses. The study seeks to find the causes of the situation; since it cannot be an issue to be tackled by the Department of Human Settlements alone. There are certain sector departments or municipalities which ought to have done certain roles or tasks prior to the delivery of houses. The study aimed at establishing the factors that affect the delivery trends of Human Settlements projects between 2012 and 2017. It further sought to suggest possible solutions; to factors that negatively affected the delivery, mainly focusing on the alignment of sector department plans, project planning, procurement and contract administration. The research design followed is a qualitative research; since it sought opinions rather than figures. The study was conducted in the Sarah Baartman District, which covers seven local municipalities as a population. The sampling frame comprised officials that were likely to be involved in housing delivery – from initiation to the close-out of projects. A total of 33 questionnaires were distributed electronically; but only 23 were returned fully completed, thereby representing 69, 8% response rate. The key findings or revelations of the study indicated that there is a disjuncture that exists between the sector departments’ plans and the municipal plans. There is lack of technical oversight during project planning, leading to the unavailability of land and bulk services and a lack of budget. In as much as there are Supply-Chain Management (SCM) committees for procurement, there is an issue of commitment and the availability of members for the sittings of the committees. Contract administration is affected by poor performance monitoring and inexperienced staff. The key recommendations in response to the above challenges are that municipalities need to revisit and rework all the integrated human settlements project plans, together with other sector departments that play a pivotal role in the delivery of human settlements. There is a need for provincial government sector departments and municipalities to interact and have employees with the planning expertise and technical capacity to guide them in the right direction, when conducting strategic and project planning. Supply-Chain Management (SCM) committees should be prioritised by members nominated to serve in them; and members must be accountable; and they need to understand the bigger picture of how the meetings/sittings affect project delivery. A proper procurement plan and procurement schedule should be created and revised quarterly, so that members can align their working schedules to the procurement schedule. Employees must be constantly capacitated and their performance must be constantly monitored; so that there can be some sense of accountability for each and every action taken.
- Full Text:
- Date Issued: 2019
- Authors: Mazondwa, Sivuyile
- Date: 2019
- Subjects: Low-income housing -- South Africa -- Eastern Cape , Public housing -- South Africa -- Eastern Cape Housing development -- South Africa -- Eastern Cape Project management -- South Africa -- Eastern Cape Construction industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41537 , vital:36502
- Description: Access to basic housing for the poor is one of the Government’s key focus areas. Housing delivery started to decline in Sarah Baartman, leading to total non-delivery in the local municipalities within the district. This has led to community unrest, in which the national and regional roads will be blocked, due to the demand for houses. The study seeks to find the causes of the situation; since it cannot be an issue to be tackled by the Department of Human Settlements alone. There are certain sector departments or municipalities which ought to have done certain roles or tasks prior to the delivery of houses. The study aimed at establishing the factors that affect the delivery trends of Human Settlements projects between 2012 and 2017. It further sought to suggest possible solutions; to factors that negatively affected the delivery, mainly focusing on the alignment of sector department plans, project planning, procurement and contract administration. The research design followed is a qualitative research; since it sought opinions rather than figures. The study was conducted in the Sarah Baartman District, which covers seven local municipalities as a population. The sampling frame comprised officials that were likely to be involved in housing delivery – from initiation to the close-out of projects. A total of 33 questionnaires were distributed electronically; but only 23 were returned fully completed, thereby representing 69, 8% response rate. The key findings or revelations of the study indicated that there is a disjuncture that exists between the sector departments’ plans and the municipal plans. There is lack of technical oversight during project planning, leading to the unavailability of land and bulk services and a lack of budget. In as much as there are Supply-Chain Management (SCM) committees for procurement, there is an issue of commitment and the availability of members for the sittings of the committees. Contract administration is affected by poor performance monitoring and inexperienced staff. The key recommendations in response to the above challenges are that municipalities need to revisit and rework all the integrated human settlements project plans, together with other sector departments that play a pivotal role in the delivery of human settlements. There is a need for provincial government sector departments and municipalities to interact and have employees with the planning expertise and technical capacity to guide them in the right direction, when conducting strategic and project planning. Supply-Chain Management (SCM) committees should be prioritised by members nominated to serve in them; and members must be accountable; and they need to understand the bigger picture of how the meetings/sittings affect project delivery. A proper procurement plan and procurement schedule should be created and revised quarterly, so that members can align their working schedules to the procurement schedule. Employees must be constantly capacitated and their performance must be constantly monitored; so that there can be some sense of accountability for each and every action taken.
- Full Text:
- Date Issued: 2019
The development of a larval feeding regimen for dusky kob, Argyrosomus japonicus, with a specific focus on the effect of weaning period on larval development and survival
- Authors: Keet, Thomas
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/96897 , vital:31344
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
- Date Issued: 2019
- Authors: Keet, Thomas
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/96897 , vital:31344
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
- Date Issued: 2019
The development of a larval feeding regimen for dusky kob, Argyrosomus japonicus, with a specific focus on the effect of weaning period on larval development and survival
- Authors: Keet, Thomas
- Date: 2019
- Subjects: Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Larvae , Argyrosomus -- Larvae , Argyrosomus japonicus -- Larvae -- Nutrition , Argyrosomus -- Larvae -- Nutrition
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146577 , vital:38538
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
- Date Issued: 2019
- Authors: Keet, Thomas
- Date: 2019
- Subjects: Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Larvae , Argyrosomus -- Larvae , Argyrosomus japonicus -- Larvae -- Nutrition , Argyrosomus -- Larvae -- Nutrition
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146577 , vital:38538
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
- Date Issued: 2019
The development of high-throughput assays to screen for potential anticancer and antimalarial compounds that target ADP-ribosylation factor 6 and its signalling machineries
- Authors: Khan, Farrah Dilshaad
- Date: 2019
- Subjects: ADP-ribosylation , Proteins -- Metabolism , Nucleoproteins , Malaria -- Chemotherapy , Cancer -- Chemotherapy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92952 , vital:30810
- Description: ADP-ribosylation factors (Arfs) are small GTP-binding proteins that cycle between active GTP-bound forms and inactive GDP-bound forms. GDP/GTP cycling is regulated by large families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). ArfGEFs activate Arfs by mediating the exchange of GDP for GTP, while ArfGAPs terminate Arf function by stimulating the hydrolysis of the terminal phosphate group of GTP. Arf6 is a major regulator of endocytic trafficking and reorganization of the actin cytoskeleton in eukaryotic organisms. Owing to its participation in wide range of fundamentally distinct cellular processes, Arf6 may be a drug target for cancer and malaria amongst other diseases. As with cancer cells, rapid growth and viability of eukaryotic pathogens likely places a heavy burden on their endocytic pathways and a critical reliance on Arf6 activity. A putative malarial homolog of Arf6 (PfArf6) localises to numerous puncta along the periphery of the parasite in the mature trophozoite life stage of the parasite (T. Swart, MSc dissertation). Owing to highly inefficient parasite transfection procedures and a relative shortage of well described and validated parasite organelle markers, the possible functions of PfArf6 were explored using HeLa cells as a surrogate model for parasites by fluorescence microscopy of cells transfected with GFP-tagged PfArf6. Partial co-localisation was observed with the mammalian markers HsArf6 and LC3, which suggested possible roles in Arf6-dependent endocytosis and autophagy, respectively. While these possible roles are currently under investigation in parasites, an overall long-term goal which was initiated in this study was to determine whether PfArf6 is a valid drug target. To chemically validate PfArf6 as a drug target, a potent inhibitor needs to be identified. This requires the development of assays that may be employed for high-throughput screening of compound libraries. To support this goal, a novel plate-based assay was developed using human Arf6. The assay relies on the selective binding of an Arf effector protein domain (GGA3) fused to glutathione-S-transferase (GST), to His-tagged Arf6 immobilised on a nickel-coated plate. The assay format was developed and could robustly distinguish HsArf6-GDP (inactive) from HsArf6-GTP (active). Furthermore, it could be employed to detect the deactivation of Arf6 by ArfGAP1-stimualted GTP hydrolysis, but not Arf6 activation by ARNO-stimulated GDP/GTP exchange (ARNO is an ArfGEF). The ArfGAP1 deactivation assay was chemically validated using a known ArfGAP inhibitor, QS11. An improved assay was developed that employs JIP4 as an Arf6-specific binding partner instead of GGA3. In addition to superior performance, the alternative assay format could potentially be exploited for cancer drug discovery, since Arf6-JIP4 interaction has been implicated in cancer cell invasion and metastasis. Both assays may be employed to explore alternative ArfGEFs and ArfGAPs that act on Arf6 and contribute to the advancement of cancer. In parallel experiments, where development of PfArf6 assays was the focus, several issues arose. Firstly, we could not prepare GDP- and GTP-bound forms of PfArf6 since EDTA-mediated nucleotide exchange appeared to irreversibly destabilise the protein. However, PfArf6 activation (i.e. the preparation of PfArf6-GTP) was possible when mediated by ARNO and assessed by tryptophan fluorescence kinetic assays, suggesting that PfArf6 may be expressed in GDP-bound form in E. coli. As with human Arf6, ARNO-mediated GDP/GTP exchange on PfArf6 was not detectable in the immobilised PfArf6-GGA interaction GST assay format. However, a more sensitive assay was developed which relies on the use of nickel-horseradish peroxidase to detect the binding of His-tagged PfArf6 to JIP4-GST immobilised on glutathione plates and could detect ARNO-mediated PfArf6 activation. Since we could not prepare PfArf6-GTP (that did not rely on the presence of the ArfGEF, ARNO), malarial ArfGAP deactivation studies were conducted using PfArf1 instead of PfArf6 in the GGA-GST interaction assay. Both PfArfGAP1and PfArfGAP2 stimulated GTP hydrolysis by PfArf1, but only the former was inhibited by the standard human ArfGAP inhibitor, QS11. The development of these simple, cost-effective assays can be used in the high-throughput screening of novel anticancer and antimalarial compounds that target Arf signalling machineries. In theory, the assay could be extended as a tool to identify novel inhibitors of the multitude of Arfs, ArfGEFs and ArfGAPs originating from any organism and hence has broad clinical significance.
- Full Text:
- Date Issued: 2019
- Authors: Khan, Farrah Dilshaad
- Date: 2019
- Subjects: ADP-ribosylation , Proteins -- Metabolism , Nucleoproteins , Malaria -- Chemotherapy , Cancer -- Chemotherapy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92952 , vital:30810
- Description: ADP-ribosylation factors (Arfs) are small GTP-binding proteins that cycle between active GTP-bound forms and inactive GDP-bound forms. GDP/GTP cycling is regulated by large families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). ArfGEFs activate Arfs by mediating the exchange of GDP for GTP, while ArfGAPs terminate Arf function by stimulating the hydrolysis of the terminal phosphate group of GTP. Arf6 is a major regulator of endocytic trafficking and reorganization of the actin cytoskeleton in eukaryotic organisms. Owing to its participation in wide range of fundamentally distinct cellular processes, Arf6 may be a drug target for cancer and malaria amongst other diseases. As with cancer cells, rapid growth and viability of eukaryotic pathogens likely places a heavy burden on their endocytic pathways and a critical reliance on Arf6 activity. A putative malarial homolog of Arf6 (PfArf6) localises to numerous puncta along the periphery of the parasite in the mature trophozoite life stage of the parasite (T. Swart, MSc dissertation). Owing to highly inefficient parasite transfection procedures and a relative shortage of well described and validated parasite organelle markers, the possible functions of PfArf6 were explored using HeLa cells as a surrogate model for parasites by fluorescence microscopy of cells transfected with GFP-tagged PfArf6. Partial co-localisation was observed with the mammalian markers HsArf6 and LC3, which suggested possible roles in Arf6-dependent endocytosis and autophagy, respectively. While these possible roles are currently under investigation in parasites, an overall long-term goal which was initiated in this study was to determine whether PfArf6 is a valid drug target. To chemically validate PfArf6 as a drug target, a potent inhibitor needs to be identified. This requires the development of assays that may be employed for high-throughput screening of compound libraries. To support this goal, a novel plate-based assay was developed using human Arf6. The assay relies on the selective binding of an Arf effector protein domain (GGA3) fused to glutathione-S-transferase (GST), to His-tagged Arf6 immobilised on a nickel-coated plate. The assay format was developed and could robustly distinguish HsArf6-GDP (inactive) from HsArf6-GTP (active). Furthermore, it could be employed to detect the deactivation of Arf6 by ArfGAP1-stimualted GTP hydrolysis, but not Arf6 activation by ARNO-stimulated GDP/GTP exchange (ARNO is an ArfGEF). The ArfGAP1 deactivation assay was chemically validated using a known ArfGAP inhibitor, QS11. An improved assay was developed that employs JIP4 as an Arf6-specific binding partner instead of GGA3. In addition to superior performance, the alternative assay format could potentially be exploited for cancer drug discovery, since Arf6-JIP4 interaction has been implicated in cancer cell invasion and metastasis. Both assays may be employed to explore alternative ArfGEFs and ArfGAPs that act on Arf6 and contribute to the advancement of cancer. In parallel experiments, where development of PfArf6 assays was the focus, several issues arose. Firstly, we could not prepare GDP- and GTP-bound forms of PfArf6 since EDTA-mediated nucleotide exchange appeared to irreversibly destabilise the protein. However, PfArf6 activation (i.e. the preparation of PfArf6-GTP) was possible when mediated by ARNO and assessed by tryptophan fluorescence kinetic assays, suggesting that PfArf6 may be expressed in GDP-bound form in E. coli. As with human Arf6, ARNO-mediated GDP/GTP exchange on PfArf6 was not detectable in the immobilised PfArf6-GGA interaction GST assay format. However, a more sensitive assay was developed which relies on the use of nickel-horseradish peroxidase to detect the binding of His-tagged PfArf6 to JIP4-GST immobilised on glutathione plates and could detect ARNO-mediated PfArf6 activation. Since we could not prepare PfArf6-GTP (that did not rely on the presence of the ArfGEF, ARNO), malarial ArfGAP deactivation studies were conducted using PfArf1 instead of PfArf6 in the GGA-GST interaction assay. Both PfArfGAP1and PfArfGAP2 stimulated GTP hydrolysis by PfArf1, but only the former was inhibited by the standard human ArfGAP inhibitor, QS11. The development of these simple, cost-effective assays can be used in the high-throughput screening of novel anticancer and antimalarial compounds that target Arf signalling machineries. In theory, the assay could be extended as a tool to identify novel inhibitors of the multitude of Arfs, ArfGEFs and ArfGAPs originating from any organism and hence has broad clinical significance.
- Full Text:
- Date Issued: 2019
The development of palladium nanoparticles for radiopharmaceutical application
- Authors: Gandidzanwa, Sendibitiyosi
- Date: 2019
- Subjects: Nanotechnology , Nanostructures Nanofluids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42163 , vital:36631
- Description: The dissertation describes an in-depth synthesis and optimisation of palladium(0) nanoparticles of three distinct size ranges, respective capping agents, and cellular uptake studies using a non-toxic concentration (10 μM), laying a foundation for the design of palladium-based folate receptor-targeted theranostic nanoradiopharmaceutical. In the preliminary selection to determine the optimal diamines for the study, ethylenediamine, hexamethylenediamine, 1,10-diaminodecane, 1,12-diaminododecane, 1,4- diaminobenzene, 4,4’-ethylenedianiline, 1,2-diphenyl-1,2-diaminoethane, and tetraaminophthalocyanine were employed. The characterisation of the nanoparticles obtained from the in situ reduction of palladium(II) salt at room temperature by either 1,2,3- trihydroxybenze (pyrogallol), citric acid, sodium metabisulphite, sodium borohydride, hydrazine hydrate, or formaldehyde was performed. Ethylenediamine and sodium borohydride were found to be the best diamine capping and reducing agent, respectively. Systematic investigations determined that the nanoparticle synthesis was dependent on various reaction parameters: such as reaction temperature, time, reductant reducing power, and capping agents. The parameters effects on the nanoparticle size, morphology, shape, stability, crystallinity, and surface charge were investigated. The optical properties, elemental composition, functional group, concentration and molecular weight for the synthesised nanoparticles or conjugates were determined. These properties were analysed using Ultraviolet–visible spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM) coupled with selective area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), zeta potential (ZP), dynamic light scattering (DLS), elemental analysis (EA), 1H and 13C-nuclear magnetic resonance (1H- and 13CNMR), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and liquid chromatography-mass spectroscopy (LC-MS). The in vitro cytotoxicity, cell uptake, and internalisation studies of palladium nanoparticles (10 μM) ranging in size and different types of capping agent were performed using three breast cancer cell lines: MDA-MB-468 , MCF-7 and MDA-MB-231 , and a non-tumorigenic MCF-10A breast cell line. The cell uptake and internalisation were investigated using ICP-OES and TEM. A high dependence between reduction rate and concentration of palladium precursor was observed for the room temperature synthesis of palladium nanoparticles, and the employed synthesis procedure will be applied to the hot palladium isotope (109Pd). A facile, green, aqueous synthesis route for palladium nanoparticles at room temperature was developed, and the synthesised nanoparticles indicated narrow size distributions. A concentration dependence between cytotoxicity and palladium nanoparticles was observed, with lower concentrations (10 μM) exhibiting minimal cytotoxicity relative to higher concentrations (100 μM). The cellular uptake of palladium nanoparticles was found to be concentration, folate-receptor, capping agent, and cell line proliferation-dependent. Well-defined, monodispersed, and negatively charged folate-ethylenediamine and folate-phthalocyanine capped palladium nanoparticles were taken up by cells, with higher nanoparticle internalisation in folate receptor positive tumorigenic cells relative to folate receptor negative non-tumorigenic cells. It can be concluded that palladium(0) nanoparticles can be synthesised from the reduction of palladium(II) by sodium borohydride at room temperature. The folate-conjugated palladium nanoparticles are non-cytotoxic at 10 μM and were successfully optimised and selectively delivered to folate receptor-positive breast cancer cells (MDA-MB-231 and MCF-7) relative to non-tumorigenic breast cells (MCF-10A) and folate receptor negative cancer cells (MDA-MB-468).
- Full Text:
- Date Issued: 2019
- Authors: Gandidzanwa, Sendibitiyosi
- Date: 2019
- Subjects: Nanotechnology , Nanostructures Nanofluids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42163 , vital:36631
- Description: The dissertation describes an in-depth synthesis and optimisation of palladium(0) nanoparticles of three distinct size ranges, respective capping agents, and cellular uptake studies using a non-toxic concentration (10 μM), laying a foundation for the design of palladium-based folate receptor-targeted theranostic nanoradiopharmaceutical. In the preliminary selection to determine the optimal diamines for the study, ethylenediamine, hexamethylenediamine, 1,10-diaminodecane, 1,12-diaminododecane, 1,4- diaminobenzene, 4,4’-ethylenedianiline, 1,2-diphenyl-1,2-diaminoethane, and tetraaminophthalocyanine were employed. The characterisation of the nanoparticles obtained from the in situ reduction of palladium(II) salt at room temperature by either 1,2,3- trihydroxybenze (pyrogallol), citric acid, sodium metabisulphite, sodium borohydride, hydrazine hydrate, or formaldehyde was performed. Ethylenediamine and sodium borohydride were found to be the best diamine capping and reducing agent, respectively. Systematic investigations determined that the nanoparticle synthesis was dependent on various reaction parameters: such as reaction temperature, time, reductant reducing power, and capping agents. The parameters effects on the nanoparticle size, morphology, shape, stability, crystallinity, and surface charge were investigated. The optical properties, elemental composition, functional group, concentration and molecular weight for the synthesised nanoparticles or conjugates were determined. These properties were analysed using Ultraviolet–visible spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM) coupled with selective area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), zeta potential (ZP), dynamic light scattering (DLS), elemental analysis (EA), 1H and 13C-nuclear magnetic resonance (1H- and 13CNMR), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and liquid chromatography-mass spectroscopy (LC-MS). The in vitro cytotoxicity, cell uptake, and internalisation studies of palladium nanoparticles (10 μM) ranging in size and different types of capping agent were performed using three breast cancer cell lines: MDA-MB-468 , MCF-7 and MDA-MB-231 , and a non-tumorigenic MCF-10A breast cell line. The cell uptake and internalisation were investigated using ICP-OES and TEM. A high dependence between reduction rate and concentration of palladium precursor was observed for the room temperature synthesis of palladium nanoparticles, and the employed synthesis procedure will be applied to the hot palladium isotope (109Pd). A facile, green, aqueous synthesis route for palladium nanoparticles at room temperature was developed, and the synthesised nanoparticles indicated narrow size distributions. A concentration dependence between cytotoxicity and palladium nanoparticles was observed, with lower concentrations (10 μM) exhibiting minimal cytotoxicity relative to higher concentrations (100 μM). The cellular uptake of palladium nanoparticles was found to be concentration, folate-receptor, capping agent, and cell line proliferation-dependent. Well-defined, monodispersed, and negatively charged folate-ethylenediamine and folate-phthalocyanine capped palladium nanoparticles were taken up by cells, with higher nanoparticle internalisation in folate receptor positive tumorigenic cells relative to folate receptor negative non-tumorigenic cells. It can be concluded that palladium(0) nanoparticles can be synthesised from the reduction of palladium(II) by sodium borohydride at room temperature. The folate-conjugated palladium nanoparticles are non-cytotoxic at 10 μM and were successfully optimised and selectively delivered to folate receptor-positive breast cancer cells (MDA-MB-231 and MCF-7) relative to non-tumorigenic breast cells (MCF-10A) and folate receptor negative cancer cells (MDA-MB-468).
- Full Text:
- Date Issued: 2019
The dispersion measure in broadband data from radio pulsars
- Authors: Rammala, Isabella
- Date: 2019
- Subjects: Pulsars , Radio astrophysics , Astrophsyics , Broadband communication systems
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67857 , vital:29157
- Description: Modern day radio telescopes make use of wideband receivers to take advantage of the broadband nature of the radio pulsar emission. We ask how does the use of such broadband pulsar data affect the measured pulsar dispersion measure (DM). Previous works have shown that, although the exact pulsar radio emission processes are not well understood, observations reveal evidence of possible frequency dependence on the emission altitudes in the pulsar magnetosphere, a phenomenon known as the radius-to-frequency mapping (RFM). This frequency dependence due to RFM can be embedded in the dispersive delay of the pulse profiles, normally interpreted as an interstellar effect (DM). Thus we interpret this intrinsic effect as an additional component δDM to the interstellar DM, and investigate how it can be statistically attributed to intrinsic profile evolution, as well as profile scattering. We make use of Monte-Carlo simulations of beam models to simulate realistic pulsar beams of various geometry, from which we generate intrinsic profiles at various frequency bands. The results show that the excess DM due to intrinsic profile evolution is more pronounced at high frequencies, whereas scattering dominates the excess DM at low frequency. The implications of these results are presented with relation to broadband pulsar timing.
- Full Text:
- Date Issued: 2019
- Authors: Rammala, Isabella
- Date: 2019
- Subjects: Pulsars , Radio astrophysics , Astrophsyics , Broadband communication systems
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67857 , vital:29157
- Description: Modern day radio telescopes make use of wideband receivers to take advantage of the broadband nature of the radio pulsar emission. We ask how does the use of such broadband pulsar data affect the measured pulsar dispersion measure (DM). Previous works have shown that, although the exact pulsar radio emission processes are not well understood, observations reveal evidence of possible frequency dependence on the emission altitudes in the pulsar magnetosphere, a phenomenon known as the radius-to-frequency mapping (RFM). This frequency dependence due to RFM can be embedded in the dispersive delay of the pulse profiles, normally interpreted as an interstellar effect (DM). Thus we interpret this intrinsic effect as an additional component δDM to the interstellar DM, and investigate how it can be statistically attributed to intrinsic profile evolution, as well as profile scattering. We make use of Monte-Carlo simulations of beam models to simulate realistic pulsar beams of various geometry, from which we generate intrinsic profiles at various frequency bands. The results show that the excess DM due to intrinsic profile evolution is more pronounced at high frequencies, whereas scattering dominates the excess DM at low frequency. The implications of these results are presented with relation to broadband pulsar timing.
- Full Text:
- Date Issued: 2019
The distribution of South African loggerhead sea turtles (Caretta caretta) as indicated by epibionts and stable isotopes
- Authors: Nolte, Christopher Robin
- Date: 2019
- Subjects: Sea turtles -- South Africa , Loggerhead turtle -- South Africa Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31611 , vital:31625
- Description: Many marine species undertake long-distance migrations as part of their life history strategies, and so form an important part of marine ecosystems performing a range of functions, across many habitats. However, these migratory species, including sea turtles, face multiple threats and anthropogenic impacts across their ranges and knowing their movement and distribution patterns enables more effective and appropriate conservation strategies to be devised. Satellite telemetry has provided invaluable information on spatial distribution of marine migrants, but applying this approach to a large proportion of a population is often unfeasible and costly. This study aimed to identify alternative, more cost effective methods that could assist with tracking animal movements across a larger proportion of a population of marine focal species, such as sea turtles. This study used nesting loggerhead sea turtles (Caretta caretta) from the iSimangaliso Wetland Park, South Africa as a model species to test these alternative methods and subsequently combine body condition, habitat use, and distribution range in the South West Indian Ocean. First, epibiont community assemblages were investigated as a proxy to determine sea turtle body condition. A body condition index was created using plastron shape, injuries and skin deformities. Sixty turtles were classified into four body condition categories ranging from poor to very good and this was reflected in their epibiont communities as both species abundance and richness increased with a decline in body condition. A total of twenty-eight epibiont taxa were identified from a range of systematic groups including, but not limited to, Amphipoda, Cirripedia, Brachyura and Polychaeta. The barnacle Chelonibia testudinaria showed the greatest variation among different body conditions with an increase in abundance as turtle body condition deteriorated. These results suggest that epibiont load can be used as an indicator of body condition that is easy to implement in the field. Second, a combination of organic δ13C and δ15N isotopic signatures of turtle epidermis and epibiont communities was used to infer foraging habitat. One hundred and seventy turtles were sampled for stable isotope analysis. These turtles were clustered into two groups based on δ13C at -13.61 ‰ with relative depletion or enrichment indicating foraging in oceanic or neritic environments, respectively. The epibiont communities of IV 80 turtles closely followed this cluster grouping; turtles with depleted δ13C had a higher abundance and frequency of oceanic epibiont species, such Lepas spp. Similarly, three neritic epibionts (Hyale grandicornis, Hyachelia tortugae and Podocerus africanus) were the other habitat-specific species driving community assemblages, with higher occurrence and abundance on turtles in the enriched δ13C cluster. Additionally, the size of the dietary niche was determined by a Bayesian analysis of δ13C and δ15N for 46 turtles in different body condition categories. Although there was overlap among categories, individuals in very good body condition had the smallest dietary niche. These results show the complementarity of using epibionts and stable isotope analysis in determining foraging area. Third, Chelonibia testudinaria barnacles on sea turtles were analysed for δ18O and inorganic δ13C. The δ18O of expected calcite fractionation was mapped for the known migration routes of eight turtles in the South West Indian Ocean. The inorganic carbon values were not very informative on movement, however, the δ18O analysis of the barnacle showed the range of the turtle host moving through the isoscape. Most of the turtles migrated from the north in the Mozambique Channel, to the southern rookery in South Africa, which is in accordance with reports from tag recoveries and satellite telemetry studies. Using this approach to track migratory species that have epibiotic barnacles can provide complimentary approach to satellite tracking that can be used on more individuals within a population. This study aids in providing alternative methods to study body condition, habitat use and regional movement of loggerhead sea turtles. These approaches can be applied to other sea turtle species and migratory marine fauna to help better understand their movement patterns thereby promoting more effective conservation strategies. Future work should consider incorporating different cohorts, examining other epibionts such as meiofauna and diatoms, including additional isotope and trace elements for analysis on habitat and improving the resolution of the isoscape data for δ18O of seawater in the SWIO.
- Full Text:
- Date Issued: 2019
- Authors: Nolte, Christopher Robin
- Date: 2019
- Subjects: Sea turtles -- South Africa , Loggerhead turtle -- South Africa Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31611 , vital:31625
- Description: Many marine species undertake long-distance migrations as part of their life history strategies, and so form an important part of marine ecosystems performing a range of functions, across many habitats. However, these migratory species, including sea turtles, face multiple threats and anthropogenic impacts across their ranges and knowing their movement and distribution patterns enables more effective and appropriate conservation strategies to be devised. Satellite telemetry has provided invaluable information on spatial distribution of marine migrants, but applying this approach to a large proportion of a population is often unfeasible and costly. This study aimed to identify alternative, more cost effective methods that could assist with tracking animal movements across a larger proportion of a population of marine focal species, such as sea turtles. This study used nesting loggerhead sea turtles (Caretta caretta) from the iSimangaliso Wetland Park, South Africa as a model species to test these alternative methods and subsequently combine body condition, habitat use, and distribution range in the South West Indian Ocean. First, epibiont community assemblages were investigated as a proxy to determine sea turtle body condition. A body condition index was created using plastron shape, injuries and skin deformities. Sixty turtles were classified into four body condition categories ranging from poor to very good and this was reflected in their epibiont communities as both species abundance and richness increased with a decline in body condition. A total of twenty-eight epibiont taxa were identified from a range of systematic groups including, but not limited to, Amphipoda, Cirripedia, Brachyura and Polychaeta. The barnacle Chelonibia testudinaria showed the greatest variation among different body conditions with an increase in abundance as turtle body condition deteriorated. These results suggest that epibiont load can be used as an indicator of body condition that is easy to implement in the field. Second, a combination of organic δ13C and δ15N isotopic signatures of turtle epidermis and epibiont communities was used to infer foraging habitat. One hundred and seventy turtles were sampled for stable isotope analysis. These turtles were clustered into two groups based on δ13C at -13.61 ‰ with relative depletion or enrichment indicating foraging in oceanic or neritic environments, respectively. The epibiont communities of IV 80 turtles closely followed this cluster grouping; turtles with depleted δ13C had a higher abundance and frequency of oceanic epibiont species, such Lepas spp. Similarly, three neritic epibionts (Hyale grandicornis, Hyachelia tortugae and Podocerus africanus) were the other habitat-specific species driving community assemblages, with higher occurrence and abundance on turtles in the enriched δ13C cluster. Additionally, the size of the dietary niche was determined by a Bayesian analysis of δ13C and δ15N for 46 turtles in different body condition categories. Although there was overlap among categories, individuals in very good body condition had the smallest dietary niche. These results show the complementarity of using epibionts and stable isotope analysis in determining foraging area. Third, Chelonibia testudinaria barnacles on sea turtles were analysed for δ18O and inorganic δ13C. The δ18O of expected calcite fractionation was mapped for the known migration routes of eight turtles in the South West Indian Ocean. The inorganic carbon values were not very informative on movement, however, the δ18O analysis of the barnacle showed the range of the turtle host moving through the isoscape. Most of the turtles migrated from the north in the Mozambique Channel, to the southern rookery in South Africa, which is in accordance with reports from tag recoveries and satellite telemetry studies. Using this approach to track migratory species that have epibiotic barnacles can provide complimentary approach to satellite tracking that can be used on more individuals within a population. This study aids in providing alternative methods to study body condition, habitat use and regional movement of loggerhead sea turtles. These approaches can be applied to other sea turtle species and migratory marine fauna to help better understand their movement patterns thereby promoting more effective conservation strategies. Future work should consider incorporating different cohorts, examining other epibionts such as meiofauna and diatoms, including additional isotope and trace elements for analysis on habitat and improving the resolution of the isoscape data for δ18O of seawater in the SWIO.
- Full Text:
- Date Issued: 2019
The ecology of Impala (Aepyceros melampus) in a dystrophic system: a case study from Welgevonden Game Reserve, Limpopo Province, South Africa
- Authors: Pieterse, Marilize
- Date: 2019
- Subjects: Impala -- Habitat -- South Africa -- Limpopo province , Impala -- Feeding and feeds -- South Africa -- Limpopo province Ecology -- South Africa -- Limpopo province
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43240 , vital:36768
- Description: Impala (Aepyceros melampus) have been extensively researched and are known to flourish in Savanna ecosystems. They are a very adaptable species switching easily between grazing and browsing hence their classification as mixed feeders. However, little published research has been done on impala and their adaptability to sour nutrient-poor savannas. On Welgevonden Game Reserve (WGR), situated in the dystrophic Waterberg Mountain Range, impala have poor body condition and negative growth rates. Research shows that impala are on the threshold of being sexually dimorphic which can lead to a difference in the habitat selection and preference, diet composition and diet quality of adult male and female animals. This study served as a baseline study to understand the adaptability and ecology of impala in the Waterberg. The key research question was: How do male and female impala adapt to the area in terms of habitat selection and preference, and diet composition and quality, across the seasons of a year in the sour nutrient-poor Waterberg Mountain Range? This was the first study on impala in the area that looked at all the above-mentioned factors. A combination of observational studies, for habitat selection and preference, and faecal analysis, for diet composition and diet quality (faecal Nitrogen (Nf) and Phosphorous (Pf)), were used. It should be noted that WGR received below average rainfall and above average maximum temperatures over the past seven years. Impala on WGR are limited by the availability of suitable habitat and the quantity and quality of forage. They therefore suffer from nutrient deficiency. Spatial and ecological segregation between male and female animals occurred due to differences in sexual status and the constraints associated with this. Overall, very little variation in habitat use occurred between Wet and Dry seasons, emphasizing limited suitable impala habitat. Impala on WGR showed a distinct preference and avoidance of different habitat types. Both male and female preferred Short Grassland throughout the year. This is the smallest habitat type on the reserve and is dominated by Cynodon dactylon, which mostly occurs in the low-lying areas of the reserve. Both male and female impala avoided Hill Slope and Long Grassland throughout the year. These habitat types are characterized by steep slopes, medium to extensive rock cover, long sparse grass and dense tree cover. The Long Grassland habitat type consist mainly of old lands in different stages of regeneration dominated by dense unpalatable grasses. Both male and female impala were highly selective towards the most nutrient rich areas, which predominantly included the Short Grassland habitat type. The factors important to impala habitat selection are short to medium grass height (6-25 cm), ecotones in low lying areas between Short Grassland and woodland, proximity to water (0.96-1.5 km), moderate to no slopes, a burn interval of less than 3 years, the dominant occurrence of Cynodon dactylon, and the presence of Dichrostachys cinerea, Grewia flavescens, Dombeya rotundifolia and Indigofera melanodenia. The impala population on WGR appears to be limited by a lack of quality forage. The diet composition of impala on WGR followed a seasonal pattern, with a higher grass to browse content during the Wet seasons, and a higher browse to grass content during the Dry seasons. Furthermore, impala on WGR have a higher browse content in their diet than in other areas of South Africa. The higher content of browse in the impala’s diet on WGR is probably due to the impala optimizing their diet quality due to a lack of quality grasses, such as Cynodon dactylon, available to them on the reserve. Females consumed higher amounts of browse than males during lactation in order to optimize their diet quality. In general, impala experienced nutrient deficiencies during the Dry seasons as indicated by Nf and Pf values which were below the accepted threshold values for impala. This appears to have affected their body condition, reproductive success and survival. The below threshold values of Nf and Pf indicate that their numbers exceeded the ecological capacity of the reserve at the time of the study. This dystrophic savanna is marginal for impala. This indicates that even large reserves in the sour bushveld communities of the Waterberg Mountains are unlikely to sustain impala populations in a healthy productive state.
- Full Text:
- Date Issued: 2019
- Authors: Pieterse, Marilize
- Date: 2019
- Subjects: Impala -- Habitat -- South Africa -- Limpopo province , Impala -- Feeding and feeds -- South Africa -- Limpopo province Ecology -- South Africa -- Limpopo province
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43240 , vital:36768
- Description: Impala (Aepyceros melampus) have been extensively researched and are known to flourish in Savanna ecosystems. They are a very adaptable species switching easily between grazing and browsing hence their classification as mixed feeders. However, little published research has been done on impala and their adaptability to sour nutrient-poor savannas. On Welgevonden Game Reserve (WGR), situated in the dystrophic Waterberg Mountain Range, impala have poor body condition and negative growth rates. Research shows that impala are on the threshold of being sexually dimorphic which can lead to a difference in the habitat selection and preference, diet composition and diet quality of adult male and female animals. This study served as a baseline study to understand the adaptability and ecology of impala in the Waterberg. The key research question was: How do male and female impala adapt to the area in terms of habitat selection and preference, and diet composition and quality, across the seasons of a year in the sour nutrient-poor Waterberg Mountain Range? This was the first study on impala in the area that looked at all the above-mentioned factors. A combination of observational studies, for habitat selection and preference, and faecal analysis, for diet composition and diet quality (faecal Nitrogen (Nf) and Phosphorous (Pf)), were used. It should be noted that WGR received below average rainfall and above average maximum temperatures over the past seven years. Impala on WGR are limited by the availability of suitable habitat and the quantity and quality of forage. They therefore suffer from nutrient deficiency. Spatial and ecological segregation between male and female animals occurred due to differences in sexual status and the constraints associated with this. Overall, very little variation in habitat use occurred between Wet and Dry seasons, emphasizing limited suitable impala habitat. Impala on WGR showed a distinct preference and avoidance of different habitat types. Both male and female preferred Short Grassland throughout the year. This is the smallest habitat type on the reserve and is dominated by Cynodon dactylon, which mostly occurs in the low-lying areas of the reserve. Both male and female impala avoided Hill Slope and Long Grassland throughout the year. These habitat types are characterized by steep slopes, medium to extensive rock cover, long sparse grass and dense tree cover. The Long Grassland habitat type consist mainly of old lands in different stages of regeneration dominated by dense unpalatable grasses. Both male and female impala were highly selective towards the most nutrient rich areas, which predominantly included the Short Grassland habitat type. The factors important to impala habitat selection are short to medium grass height (6-25 cm), ecotones in low lying areas between Short Grassland and woodland, proximity to water (0.96-1.5 km), moderate to no slopes, a burn interval of less than 3 years, the dominant occurrence of Cynodon dactylon, and the presence of Dichrostachys cinerea, Grewia flavescens, Dombeya rotundifolia and Indigofera melanodenia. The impala population on WGR appears to be limited by a lack of quality forage. The diet composition of impala on WGR followed a seasonal pattern, with a higher grass to browse content during the Wet seasons, and a higher browse to grass content during the Dry seasons. Furthermore, impala on WGR have a higher browse content in their diet than in other areas of South Africa. The higher content of browse in the impala’s diet on WGR is probably due to the impala optimizing their diet quality due to a lack of quality grasses, such as Cynodon dactylon, available to them on the reserve. Females consumed higher amounts of browse than males during lactation in order to optimize their diet quality. In general, impala experienced nutrient deficiencies during the Dry seasons as indicated by Nf and Pf values which were below the accepted threshold values for impala. This appears to have affected their body condition, reproductive success and survival. The below threshold values of Nf and Pf indicate that their numbers exceeded the ecological capacity of the reserve at the time of the study. This dystrophic savanna is marginal for impala. This indicates that even large reserves in the sour bushveld communities of the Waterberg Mountains are unlikely to sustain impala populations in a healthy productive state.
- Full Text:
- Date Issued: 2019
The effect of bait on fine-scale habitat associations of reef fish investigated with remote underwater video systems
- Authors: Schmidt, Nicholas C
- Date: 2019
- Subjects: Baited remote underwater stereo-video systems (stereo-BRUVs) , Remote underwater stereo-video systems , Underwater videography in wildlife monitoring -- South Africa -- Tsitsikamma , Fish stock assessment -- South Africa -- Tsitsikamma , Fish populations -- Monitoring -- South Africa -- Tsitsikamma , Fishes -- Habitat -- South Africa -- Tsitsikamma
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68380 , vital:29249
- Description: Establishing the associations between fish and their habitats can aid in the monitoring of fish stocks and the design of effective marine protected areas (MPAs). Baited remote underwater stereo-video systems (stereo-BRUVs) are now commonly used to asses fish populations. The habitats seen in the video footage of stereo-BRUVs can be used to link fish fauna to preferred habitat types. However, the application of bait potentially attracts fish from surrounding habitats, and might result in a biased understanding of fish–habitat associations. A field study was conducted in the Tsitsikamma National Park MPA to determine the effect of bait on fine-scale fish–habitat associations, using remote photographic and video methods. The study was conducted over the summer season of 2015 and 2016. Data were collected within a 1x1 km shallow (9–44 m) reef complex. Within the sampling area, 944 photo-quadrats of the macrobenthos were taken 30 m apart by means of a drop camera. By separating the macrobenthos into broad taxonomic groups, five habitat types were identified, namely Shallow Sand, Shallow Reef, Deep Reef, Deep Sand and Patch Reef. The results show that even on a fine scale, depth is an important predictor of macrobenthic distribution and assemblage structure. Baited (stereo-BRUVs) and unbaited (stereo-RUVs) surveys were then conducted to sample the fish community in the same area during the period under study. Higher abundances of fish were observed in reef than in sandy habitats, and bait was seen to have a positive effect on species richness and fish abundance. When comparing habitats, fish abundance and composition on reef habitats were significantly different from sand habitats. This was observed in both the stereo-RUVs and stereo-BRUVs methods. High counts of roman (Chrysoblephus laticeps), fransmadam (Boopsoidea inornata) and steentjie (Spondyliosoma emarginatum) in reef habitats were contrasted by high counts of white sea catfish (Galeichthys feliceps), evil-eye puffer (Amblyrhynchotes honckenii) and lesser guitarfish (Rhinecanthus annulatus) in sandy habitats. Overall, the underlying patterns in fish diversity recorded with the two video methods were generally comparable. However, stereo-RUVs appeared to be unable to detect species that were present in sand habitats, while stereo-BRUVs increased the number and abundance of species recorded in all habitat types. In the stereo-RUVs footage, differences between reef habitats were dampened by the presence of highly abundant fish species. In the stereo-BRUVs footage, although bait appeared to have an effect on the observed fish assemblage, this manifested in an increase in species richness, higher fish abundances and a better overall ability to detect fish–habitat relationships. As such, stereo-BRUVs are considered a robust, effective and recommended method for detecting fish–habitat relationships, even over a fine scale.
- Full Text:
- Date Issued: 2019
- Authors: Schmidt, Nicholas C
- Date: 2019
- Subjects: Baited remote underwater stereo-video systems (stereo-BRUVs) , Remote underwater stereo-video systems , Underwater videography in wildlife monitoring -- South Africa -- Tsitsikamma , Fish stock assessment -- South Africa -- Tsitsikamma , Fish populations -- Monitoring -- South Africa -- Tsitsikamma , Fishes -- Habitat -- South Africa -- Tsitsikamma
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68380 , vital:29249
- Description: Establishing the associations between fish and their habitats can aid in the monitoring of fish stocks and the design of effective marine protected areas (MPAs). Baited remote underwater stereo-video systems (stereo-BRUVs) are now commonly used to asses fish populations. The habitats seen in the video footage of stereo-BRUVs can be used to link fish fauna to preferred habitat types. However, the application of bait potentially attracts fish from surrounding habitats, and might result in a biased understanding of fish–habitat associations. A field study was conducted in the Tsitsikamma National Park MPA to determine the effect of bait on fine-scale fish–habitat associations, using remote photographic and video methods. The study was conducted over the summer season of 2015 and 2016. Data were collected within a 1x1 km shallow (9–44 m) reef complex. Within the sampling area, 944 photo-quadrats of the macrobenthos were taken 30 m apart by means of a drop camera. By separating the macrobenthos into broad taxonomic groups, five habitat types were identified, namely Shallow Sand, Shallow Reef, Deep Reef, Deep Sand and Patch Reef. The results show that even on a fine scale, depth is an important predictor of macrobenthic distribution and assemblage structure. Baited (stereo-BRUVs) and unbaited (stereo-RUVs) surveys were then conducted to sample the fish community in the same area during the period under study. Higher abundances of fish were observed in reef than in sandy habitats, and bait was seen to have a positive effect on species richness and fish abundance. When comparing habitats, fish abundance and composition on reef habitats were significantly different from sand habitats. This was observed in both the stereo-RUVs and stereo-BRUVs methods. High counts of roman (Chrysoblephus laticeps), fransmadam (Boopsoidea inornata) and steentjie (Spondyliosoma emarginatum) in reef habitats were contrasted by high counts of white sea catfish (Galeichthys feliceps), evil-eye puffer (Amblyrhynchotes honckenii) and lesser guitarfish (Rhinecanthus annulatus) in sandy habitats. Overall, the underlying patterns in fish diversity recorded with the two video methods were generally comparable. However, stereo-RUVs appeared to be unable to detect species that were present in sand habitats, while stereo-BRUVs increased the number and abundance of species recorded in all habitat types. In the stereo-RUVs footage, differences between reef habitats were dampened by the presence of highly abundant fish species. In the stereo-BRUVs footage, although bait appeared to have an effect on the observed fish assemblage, this manifested in an increase in species richness, higher fish abundances and a better overall ability to detect fish–habitat relationships. As such, stereo-BRUVs are considered a robust, effective and recommended method for detecting fish–habitat relationships, even over a fine scale.
- Full Text:
- Date Issued: 2019
The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla under farm conditions
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
- Date Issued: 2019