Trophic interactions in an austral temperate ephemeral pond inferred using stable isotope analysis
- Dalu, Tatenda, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68022 , vital:29185 , https://doi.org/10.1007/s10750-015-2533-5
- Description: Publisher version , Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.
- Full Text: false
- Date Issued: 2016
- Authors: Dalu, Tatenda , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68022 , vital:29185 , https://doi.org/10.1007/s10750-015-2533-5
- Description: Publisher version , Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.
- Full Text: false
- Date Issued: 2016
Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
- Paterson, Iain D, Mangan, Rose, Downie, Douglas A, Coetzee, Julie A, Hill, Martin P, Burke, Ashley M, Downey, Paul O, Henry, Thomas J, Compton, Stephen G
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
Two new species of Xosopsaltria Kirkaldy, 1904, with a key to the species of South African pygmy bladder cicadas (Hemiptera Cicadidae Cicadettinae Tettigomyiini)
- Sanborn, Allen F, Villet, Martin H
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441274 , vital:73873 , https://mapress.com/zt/article/view/zootaxa.4092.2.3
- Description: Two species, Xosopsaltria brachyptera n. sp. and Xosopsaltria vitripennis n. sp., are described as new. Notes on their biology and a key to the South African pygmy bladder cicadas are also provided.
- Full Text:
- Date Issued: 2016
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441274 , vital:73873 , https://mapress.com/zt/article/view/zootaxa.4092.2.3
- Description: Two species, Xosopsaltria brachyptera n. sp. and Xosopsaltria vitripennis n. sp., are described as new. Notes on their biology and a key to the South African pygmy bladder cicadas are also provided.
- Full Text:
- Date Issued: 2016
Two uses of DNA sequence variation in tracing evolutionary processes in Old World primates (Primates: Catarrhini)
- Authors: Dosi, Banele
- Date: 2016
- Subjects: Primates -- Evolution Monkeys Cercopithecidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8022 , vital:31464
- Description: Primate evolution is particularly interesting to humans, because it includes our own history. Molecular genetics is by far the most dynamic field in contemporary biology, and offers a host of new techniques for investigating evolutionary processes and patterns. In the mid-twentieth century molecular genetics evolved from being a means of visualising hidden variation (e.g. allozymes) to tracing phylogenetic relationships between and among species (evolutionary histories of populations), and now has a wide variety of applications in medicine, species identification and relationships, and even wildlife forensics. For my Master’s project I investigated two applications of molecular genetic analysis to questions regarding the evolution of Old World monkeys (Catarrhini). First, I participated in a study designed to test the hypothesis that different primate social structures – particularly mating systems – may be reflected in the structure of a species genome. We investigated whether increased sperm production as a result of sexual selection increases the number of copy number variations (CNVs) that can be detected by comparing the male specific region Y (MSY) located on the Y chromosome in a sample of primate species. We did not find a clear differentiation between the primate species as hypothesised, which thus requires a more complex explanation, e.g. in terms of the type of environment rather than the mating system of the species, or possibly the active/inactive status of the genes. The second part of my study was phylogeographic in approach. I collaborated with researchers studying the distribution of Afromontane samango monkeys (Cercopithecus albogularis labiatus) in the Eastern Cape. I sequenced tissues from 5 samango monkey specimens found opportunistically in the Hogsback and coastal forests and analysed their genetic variation relative to the data published by Dalton et al. 2015. The Hogsback sample was not monophyletic relative to the sample from the coastal forests, indicating that, on the basis of this very small sample size, these populations have not been separated historically. In order to validate this conclusion, I will need to investigate a larger sample size. From this study I developed valuable skills in the areas of the laboratory techniques involved in molecular sequence analysis, and an appreciation for the importance of large sample sizes in deriving reliable results. I intend to continue in the future with a phylogeographic study of samango monkeys.
- Full Text:
- Date Issued: 2016
- Authors: Dosi, Banele
- Date: 2016
- Subjects: Primates -- Evolution Monkeys Cercopithecidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8022 , vital:31464
- Description: Primate evolution is particularly interesting to humans, because it includes our own history. Molecular genetics is by far the most dynamic field in contemporary biology, and offers a host of new techniques for investigating evolutionary processes and patterns. In the mid-twentieth century molecular genetics evolved from being a means of visualising hidden variation (e.g. allozymes) to tracing phylogenetic relationships between and among species (evolutionary histories of populations), and now has a wide variety of applications in medicine, species identification and relationships, and even wildlife forensics. For my Master’s project I investigated two applications of molecular genetic analysis to questions regarding the evolution of Old World monkeys (Catarrhini). First, I participated in a study designed to test the hypothesis that different primate social structures – particularly mating systems – may be reflected in the structure of a species genome. We investigated whether increased sperm production as a result of sexual selection increases the number of copy number variations (CNVs) that can be detected by comparing the male specific region Y (MSY) located on the Y chromosome in a sample of primate species. We did not find a clear differentiation between the primate species as hypothesised, which thus requires a more complex explanation, e.g. in terms of the type of environment rather than the mating system of the species, or possibly the active/inactive status of the genes. The second part of my study was phylogeographic in approach. I collaborated with researchers studying the distribution of Afromontane samango monkeys (Cercopithecus albogularis labiatus) in the Eastern Cape. I sequenced tissues from 5 samango monkey specimens found opportunistically in the Hogsback and coastal forests and analysed their genetic variation relative to the data published by Dalton et al. 2015. The Hogsback sample was not monophyletic relative to the sample from the coastal forests, indicating that, on the basis of this very small sample size, these populations have not been separated historically. In order to validate this conclusion, I will need to investigate a larger sample size. From this study I developed valuable skills in the areas of the laboratory techniques involved in molecular sequence analysis, and an appreciation for the importance of large sample sizes in deriving reliable results. I intend to continue in the future with a phylogeographic study of samango monkeys.
- Full Text:
- Date Issued: 2016
Uhlalutyo ngokwesithako sobunzululwazi nkcubeko-ntlalo yaseAfrika kwinoveli yesiXhosa: Inkululeko isentabeni
- Authors: Bali, Nolundi Monica
- Date: 2016
- Subjects: Xhosa literature -- History and criticism
- Language: Xhosa
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/9077 , vital:26462
- Description: Kule ngxoxo kuqwalaswele indlela amasiko nezithethe asetyenziswe ngayo kwincwadi kaSaule, ethi, Inkululeko isentabeni. Le ngxoxo ijolise ekuncomeni indlela lo kaSaule awasebenzise ngayo amasiko kunye nezithethe zakwaNtu ukwakha isizwe esimnyama. Konke oku kudandalazisa ukubaluleka kokusetyenziswa kwawo ukwakha isizwe. Injongo yolu phando kukuphendla indlela umtshato, isithembu, ulwaluko, imbeleko, intonjane, ukufa, ukukhapha, ukubuyisa nokungenwa ezaziqhutywa ngayo nezizathu zoko. Le ngxoxo iza kuphonononga ixhaswe ngezithako eziziimbono zeengcali zohlalutyo kwintlalo kaNtu. Ingxoxo le yahlulwe yazizahluko ezintandathu. Isahluko sokuqala sivula ngentshayelelo, ze sidandalazise intsusamabandla yolu phando, kushukuxwe imbangeli yophando, ze kwenziwe uphengululo lweencwadi zeengcali kwisithako sobuNzululwazi Nkcubeko-Ntlalo. Isahluko sesibini, siqwalasela ukuxabiseka kolwendo ngokwengcinga yesiNtu kwincwadi kaSaule. Indlela isiko lokuthwala lalisenziwa ngalo mandulo xa kuthelekiswa kweyangoku, nemiceli-mngeni elijamelene nalo eli siko. Isahluko sesithathu, sijongene nesithembu, iimeko ezazinyanzelisa ukuthathwa komfazi wesibini nangaphezulu nemiceli-mngeni ekhoyo kwesi sithethe. Isahluko sesine, singolwaluko ngemihla yamandulo size sithelekiswe nale mihla siphila kuyo. Iingxaki ezikhoyo kweli siko ezibangelwa kukungakhathali kwengcibi, namakhankatha. Esesihlanu, isahluko singamasiko nezithethe, iindlela ezazisaya kusetyenziswa mandulo kuthelekiswa nezeli xesha lokhanyo ekwenzeni la masiko nezi zithethe. Isahluko sesithandathu, sesokuphetha, siyintyilazwi yeengxoxo ezikolu hlalutyo, kuxilongwa ubuzaza besithako sobunzululwazi nkcubeko-ntlalo.
- Full Text:
- Date Issued: 2016
- Authors: Bali, Nolundi Monica
- Date: 2016
- Subjects: Xhosa literature -- History and criticism
- Language: Xhosa
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/9077 , vital:26462
- Description: Kule ngxoxo kuqwalaswele indlela amasiko nezithethe asetyenziswe ngayo kwincwadi kaSaule, ethi, Inkululeko isentabeni. Le ngxoxo ijolise ekuncomeni indlela lo kaSaule awasebenzise ngayo amasiko kunye nezithethe zakwaNtu ukwakha isizwe esimnyama. Konke oku kudandalazisa ukubaluleka kokusetyenziswa kwawo ukwakha isizwe. Injongo yolu phando kukuphendla indlela umtshato, isithembu, ulwaluko, imbeleko, intonjane, ukufa, ukukhapha, ukubuyisa nokungenwa ezaziqhutywa ngayo nezizathu zoko. Le ngxoxo iza kuphonononga ixhaswe ngezithako eziziimbono zeengcali zohlalutyo kwintlalo kaNtu. Ingxoxo le yahlulwe yazizahluko ezintandathu. Isahluko sokuqala sivula ngentshayelelo, ze sidandalazise intsusamabandla yolu phando, kushukuxwe imbangeli yophando, ze kwenziwe uphengululo lweencwadi zeengcali kwisithako sobuNzululwazi Nkcubeko-Ntlalo. Isahluko sesibini, siqwalasela ukuxabiseka kolwendo ngokwengcinga yesiNtu kwincwadi kaSaule. Indlela isiko lokuthwala lalisenziwa ngalo mandulo xa kuthelekiswa kweyangoku, nemiceli-mngeni elijamelene nalo eli siko. Isahluko sesithathu, sijongene nesithembu, iimeko ezazinyanzelisa ukuthathwa komfazi wesibini nangaphezulu nemiceli-mngeni ekhoyo kwesi sithethe. Isahluko sesine, singolwaluko ngemihla yamandulo size sithelekiswe nale mihla siphila kuyo. Iingxaki ezikhoyo kweli siko ezibangelwa kukungakhathali kwengcibi, namakhankatha. Esesihlanu, isahluko singamasiko nezithethe, iindlela ezazisaya kusetyenziswa mandulo kuthelekiswa nezeli xesha lokhanyo ekwenzeni la masiko nezi zithethe. Isahluko sesithandathu, sesokuphetha, siyintyilazwi yeengxoxo ezikolu hlalutyo, kuxilongwa ubuzaza besithako sobunzululwazi nkcubeko-ntlalo.
- Full Text:
- Date Issued: 2016
Ukuzotywa kwabalinganiswa ababhinqileyo abaziintloko kwiidrama zolwimi lwesiXhosa bezotywa ngababhali abasini sobuduna kwakunye nabo babhinqileyo
- Authors: Bukula, Andiswa
- Date: 2016
- Subjects: Xhosa literature -- Research Gender identity in literature , Gender nonconformity Women -- South Africa -- Drama
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18431 , vital:28645
- Description: Eli phepha lithiywe “Ukuzotywa kwabalinganiswa ababhinqileyo, abazintloko kwidrama zolwimi lwesiXhosa, bezotywa ngababhali besini sobuduna nesini sobukhomokazi liza kube lijongene nendlela apho ababhali abasini esohlukileyo, abathi babazobe ngayo abalinganiswa abayintloko, abangamabhinqa kwizibhalo zabo zedrama zelwimi lwesiXhosa. Apha kuzobe kujongwe ingakumbi ababhali abasini sobuduna, ngenjongo yokuveza umba wokuba ababhali besini sobukhomokazi babazoba abalinganiswa ababhinqileyo nje ngabantu abangenamiqolo okuzimela ngaphandle kokuba kubekho indoda obomini babo. Aba babhali babazoba abalinganiswa ababhiqileyo phansti kwala ngcamango yokuba, apho umntu obhinqileyo ekumela afumaneke khona kusezimbizeni apho baphekela usapho lwabo rhoqo, ekucoceni umzi nasekukhuliseni abantwana, hayi enye into engaphaya koko. Ngoko ke eli phepha libhalwe ngenjongo yokuphelisa oku dodobalisa loo ngcamango. Baninzi kea bantu abaphikisana nale ndlela yaphotho lwamabhinqa ngamadoda abo, nangamanye amadoda nje jikilele, eli phepha lizobe lingqinelana nolo ninzi lwabantu abathi loo mpatho mbi yamabhinqa mayiphele, kuvezwe imeko yokuba kukho ulingano phakathi kwamabhinqa kunye nababt abasini sobukhomakazi. Int ethetha ukuba eli phepha lizakuti ligqithele lijonge kwaye liveze indlela apho kungati kuekho ulingwano phathi kwezini zimbini, nendlela apho uwonke wonke angakwazi ukuphila ngentlonipho omnye komnye kungekho zimpatho mbi, okanye sini sinesikhundla esiphakamileyo kunesinye.
- Full Text:
- Date Issued: 2016
- Authors: Bukula, Andiswa
- Date: 2016
- Subjects: Xhosa literature -- Research Gender identity in literature , Gender nonconformity Women -- South Africa -- Drama
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18431 , vital:28645
- Description: Eli phepha lithiywe “Ukuzotywa kwabalinganiswa ababhinqileyo, abazintloko kwidrama zolwimi lwesiXhosa, bezotywa ngababhali besini sobuduna nesini sobukhomokazi liza kube lijongene nendlela apho ababhali abasini esohlukileyo, abathi babazobe ngayo abalinganiswa abayintloko, abangamabhinqa kwizibhalo zabo zedrama zelwimi lwesiXhosa. Apha kuzobe kujongwe ingakumbi ababhali abasini sobuduna, ngenjongo yokuveza umba wokuba ababhali besini sobukhomokazi babazoba abalinganiswa ababhinqileyo nje ngabantu abangenamiqolo okuzimela ngaphandle kokuba kubekho indoda obomini babo. Aba babhali babazoba abalinganiswa ababhiqileyo phansti kwala ngcamango yokuba, apho umntu obhinqileyo ekumela afumaneke khona kusezimbizeni apho baphekela usapho lwabo rhoqo, ekucoceni umzi nasekukhuliseni abantwana, hayi enye into engaphaya koko. Ngoko ke eli phepha libhalwe ngenjongo yokuphelisa oku dodobalisa loo ngcamango. Baninzi kea bantu abaphikisana nale ndlela yaphotho lwamabhinqa ngamadoda abo, nangamanye amadoda nje jikilele, eli phepha lizobe lingqinelana nolo ninzi lwabantu abathi loo mpatho mbi yamabhinqa mayiphele, kuvezwe imeko yokuba kukho ulingano phakathi kwamabhinqa kunye nababt abasini sobukhomakazi. Int ethetha ukuba eli phepha lizakuti ligqithele lijonge kwaye liveze indlela apho kungati kuekho ulingwano phathi kwezini zimbini, nendlela apho uwonke wonke angakwazi ukuphila ngentlonipho omnye komnye kungekho zimpatho mbi, okanye sini sinesikhundla esiphakamileyo kunesinye.
- Full Text:
- Date Issued: 2016
Ultra-high precision grinding of BK7 glass
- Authors: Onwuka, Goodness Raluchukwu
- Date: 2016
- Subjects: Machining , Machine-tools -- Monitoring , Acoustic emission
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/5203 , vital:20820
- Description: With the increase in the application of ultra-precision manufactured parts and the absence of much participation of researchers in ultra-high precision grinding of optical glasses which has a high rate of demand in the industries, it becomes imperative to garner a full understanding of the production of these precision optics using the above-listed technology. Single point inclined axes grinding configuration and Box-Behnken experimental design was developed and applied to the ultra-high precision grinding of BK7 glass. A high sampling acoustic emission monitoring system was implemented to monitor the process. The research tends to monitor the ultra-high precision grinding of BK7 glass using acoustic emission which has proven to be an effective sensing technique to monitor grinding processes. Response surface methodology was adopted to analyze the effect of the interaction between the machining parameters: feed, speed, depth of cut and the generated surface roughness. Furthermore, back propagation Artificial Neural Network was also implemented through careful feature extraction and selection process. The proposed models are aimed at creating a database guide to the ultra-high precision grinding of precision optics.
- Full Text:
- Date Issued: 2016
- Authors: Onwuka, Goodness Raluchukwu
- Date: 2016
- Subjects: Machining , Machine-tools -- Monitoring , Acoustic emission
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/5203 , vital:20820
- Description: With the increase in the application of ultra-precision manufactured parts and the absence of much participation of researchers in ultra-high precision grinding of optical glasses which has a high rate of demand in the industries, it becomes imperative to garner a full understanding of the production of these precision optics using the above-listed technology. Single point inclined axes grinding configuration and Box-Behnken experimental design was developed and applied to the ultra-high precision grinding of BK7 glass. A high sampling acoustic emission monitoring system was implemented to monitor the process. The research tends to monitor the ultra-high precision grinding of BK7 glass using acoustic emission which has proven to be an effective sensing technique to monitor grinding processes. Response surface methodology was adopted to analyze the effect of the interaction between the machining parameters: feed, speed, depth of cut and the generated surface roughness. Furthermore, back propagation Artificial Neural Network was also implemented through careful feature extraction and selection process. The proposed models are aimed at creating a database guide to the ultra-high precision grinding of precision optics.
- Full Text:
- Date Issued: 2016
Ulwaluko kwa Xhosa: young Xhosa men's lived experiences in the context of traditional male initiation
- Authors: Siswana, Anele
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3271 , http://hdl.handle.net/10962/d1020840
- Description: This thesis explores the lived experiences of young amaXhosa men in relation to U!walukokwa Xhosa (traditional male initiation [TMI]) and its impact on their sense of masculinity. The conceptual framework of this study is located within African epistemology focusing on indigenous knowledge systems (IKS) in South Africa. The study aimed at enabling young amaXhosa men who had undergone TMI to reflect on their first-hand, personal accounts of Ulwa/ukokwa Xhosa and manhood. Six semistructured interviews and a follow up focus group discussion were held with 23-27 years old amaXhosa men residing in Joza Township in Grahamstown, Eastern Cape. Participants were identified through purposive sampling. The thesis reports on the following findings: (a) the significance of the place/location of initiation, and the guise of modernity; (b) feelings of anticipation experienced by the young men; (c) the theme on ubudoda(manhood) affirmation Ndiyindoda!; (d) the theme on the concealment of pain (perseverance); (e) the theme on respect for self and others and ubuntu;(f) Uzimelegeqe (independence and autonomy) and (g) social role and responsibility. The paper argues for the relevance of TMI as a significantrite of passage from boyhood to manhood among amaXhosa men.
- Full Text:
- Date Issued: 2016
- Authors: Siswana, Anele
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3271 , http://hdl.handle.net/10962/d1020840
- Description: This thesis explores the lived experiences of young amaXhosa men in relation to U!walukokwa Xhosa (traditional male initiation [TMI]) and its impact on their sense of masculinity. The conceptual framework of this study is located within African epistemology focusing on indigenous knowledge systems (IKS) in South Africa. The study aimed at enabling young amaXhosa men who had undergone TMI to reflect on their first-hand, personal accounts of Ulwa/ukokwa Xhosa and manhood. Six semistructured interviews and a follow up focus group discussion were held with 23-27 years old amaXhosa men residing in Joza Township in Grahamstown, Eastern Cape. Participants were identified through purposive sampling. The thesis reports on the following findings: (a) the significance of the place/location of initiation, and the guise of modernity; (b) feelings of anticipation experienced by the young men; (c) the theme on ubudoda(manhood) affirmation Ndiyindoda!; (d) the theme on the concealment of pain (perseverance); (e) the theme on respect for self and others and ubuntu;(f) Uzimelegeqe (independence and autonomy) and (g) social role and responsibility. The paper argues for the relevance of TMI as a significantrite of passage from boyhood to manhood among amaXhosa men.
- Full Text:
- Date Issued: 2016
Un Langage, des Visions, une Passerelle:
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146177 , vital:38502 , ISBN 9789074816496 , https://books.google.co.za/books?id=QDSdAQAACAAJanddq=Creer+en+postcolonie:+Voix+et+dissidences+belgo-congolaise+2010-2015andhl=enandsa=Xandved=0ahUKEwjts_Si_b_pAhXvShUIHWXwCd4Q6AEIJzAA
- Description: Book abstract. The authors and artists (Baloji, Toma Muteba Luntumbue, Nganji Laeh, Nina Miskina, Joëlle Sambi, Sarah Arens, Heleen Debeuckelaere, Bénédicte Kumbi ...) who contributed to the work to debate the Belgian postcolonial question and it will be punctuated by poetic and musical stops.
- Full Text:
- Date Issued: 2016
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146177 , vital:38502 , ISBN 9789074816496 , https://books.google.co.za/books?id=QDSdAQAACAAJanddq=Creer+en+postcolonie:+Voix+et+dissidences+belgo-congolaise+2010-2015andhl=enandsa=Xandved=0ahUKEwjts_Si_b_pAhXvShUIHWXwCd4Q6AEIJzAA
- Description: Book abstract. The authors and artists (Baloji, Toma Muteba Luntumbue, Nganji Laeh, Nina Miskina, Joëlle Sambi, Sarah Arens, Heleen Debeuckelaere, Bénédicte Kumbi ...) who contributed to the work to debate the Belgian postcolonial question and it will be punctuated by poetic and musical stops.
- Full Text:
- Date Issued: 2016
Understanding how grade 8 Physical Science teachers make use of learners’ prior everyday knowledge when teaching static electricity: A case study
- Authors: Iyambo, Toini
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1320 , vital:20046
- Description: Over the last decade of my teaching I have been grappling with how to incorporate learners’ prior everyday knowledge into my Physical Science lessons to enable me to close the gap between school science and everyday knowledge. I conducted this case study in two schools, one in Omusati region and one in Ohangwena Region, Namibia. Its purpose was to investigate how grade 8 Physical Science teachers make use of learners’ prior everyday knowledge when teaching the topic of static electricity. Underpinned by an interpretive paradigm, the study made use of document analysis, observation (lessons were also video-taped) and semi-structured interviews to generate the data. Three data generating techniques were used for triangulation and validation purposes. To further validate the data, transcripts of video-taped lessons and interviews were sent back to the research participants for member checking. The main findings of my study are that teachers did incorporate learners’ prior knowledge in the lesson presentation on static electricity. It emerged from the study that, learners possess a great deal of prior everyday scientific and non-scientific knowledge and experiences about static electricity that they had acquired from their communities. Also, mobilization of learners' everyday knowledge and experiences about static electricity enabled learner engagement during the science lessons. Likewise, engaging learners in demonstrations on static electricity helped them to make meaning of the scientific concepts involved in the topic. It also emerged from this study that teachers face challenges of lack of documentation of indigenous knowledge which is potentially a form of prior knowledge, language barriers and a lack of resources. Based on my research findings, I therefore, recommend that learners' prior everyday knowledge and experiences about static electricity should be incorporated during the teaching and learning process.
- Full Text:
- Date Issued: 2016
- Authors: Iyambo, Toini
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1320 , vital:20046
- Description: Over the last decade of my teaching I have been grappling with how to incorporate learners’ prior everyday knowledge into my Physical Science lessons to enable me to close the gap between school science and everyday knowledge. I conducted this case study in two schools, one in Omusati region and one in Ohangwena Region, Namibia. Its purpose was to investigate how grade 8 Physical Science teachers make use of learners’ prior everyday knowledge when teaching the topic of static electricity. Underpinned by an interpretive paradigm, the study made use of document analysis, observation (lessons were also video-taped) and semi-structured interviews to generate the data. Three data generating techniques were used for triangulation and validation purposes. To further validate the data, transcripts of video-taped lessons and interviews were sent back to the research participants for member checking. The main findings of my study are that teachers did incorporate learners’ prior knowledge in the lesson presentation on static electricity. It emerged from the study that, learners possess a great deal of prior everyday scientific and non-scientific knowledge and experiences about static electricity that they had acquired from their communities. Also, mobilization of learners' everyday knowledge and experiences about static electricity enabled learner engagement during the science lessons. Likewise, engaging learners in demonstrations on static electricity helped them to make meaning of the scientific concepts involved in the topic. It also emerged from this study that teachers face challenges of lack of documentation of indigenous knowledge which is potentially a form of prior knowledge, language barriers and a lack of resources. Based on my research findings, I therefore, recommend that learners' prior everyday knowledge and experiences about static electricity should be incorporated during the teaching and learning process.
- Full Text:
- Date Issued: 2016
Understanding how the incorporation of indigenous knowledge (IK) enables or constrains the teaching and learning of alcoholic fermentation in Life Sciences in Grade 11
- Authors: Mutanho, Chrispen
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1264 , vital:20041
- Description: There is growing interest in the role of indigenous knowledge (IK) in science education in many parts of the world. In South Africa, this comes against the backdrop of a long history of cultural alienation, neglect and suppression of the IK of the indigenous people by colonial governments. Hence, the first post-independence National Curriculum Policy Statement (Curriculum, 2005) and its subsequent modified versions emphasised the need to redress the imbalances of the past so as to make science accessible to learners from diverse cultural backgrounds. However, literature reveals that the efforts to implement an IK-based curriculum are constrained by the lack of clarity, knowledge and skills on how to effectively make use of IK in the classroom situation so as to bring about effective teaching and learning. Against this background, this study sought to understand how the incorporation of IK enables or constrains the teaching and learning of alcoholic fermentation. Underpinned by an interpretive paradigm, a qualitative case study was conducted at a high school in Mthatha District in the Eastern Cape Province of South Africa. The study comprised of a sample of ten Life Sciences teachers from four neighbouring high schools, two Grade 11 Life Sciences teachers and their classes and two focus groups of six learners from each class. Convenience and purposive sampling were used to select the participants and the research site. The study made use of a questionnaire, document analysis, lesson observation, stimulated recall interviews and focus group interviews to generate data. The questionnaire sought to get an overview of Life Sciences teachers’ attitudes, opinions and experiences on incorporating IK in science teaching. The data gathered were then used as baseline information to inform the main study. The lesson observations, stimulated recall interviews and the focus group interviews sought to understand how the incorporation of IK enables or constrains the teaching and learning of alcoholic fermentation. Document analysis, lesson observation, stimulated recall interviews and focus group interviews were conducted to understand the experience of incorporating IK in a real life classroom situation. The study was informed by Vygotsky’s socio-cultural constructivism and Shulman’s pedagogical content knowledge (PCK) theory. From Vygotsky’s theory I borrowed the idea of mediated learning, scaffolding (Bruner, 1986), zone of proximal development (ZPD), as well as the use of language and cultural artefacts as tools of analysis of the classroom interaction between the teacher and the learners during the teaching-learning process. Shulman’s theory of PCK was also used to analyse how teachers apply IK in teaching Science. The data obtained were coded inductively and presented in tables, graphs and thick descriptive texts to make it easy to understand. The findings of this research show that incorporating IK improved the teaching-learning process by arousing learners’ interest in science, increasing learners’ participation and motivation, meaning making, language use, questioning and engagement in the learning process. Teaching became learner-centred, for it was directed by learners’ questions. Collaborative learning through group discussions, debates, arguments and brainstorming emerged to be an effective way of engaging learners in learning. The teachers used probing to encourage critical thinking before scaffolding learners. However, even though teachers generally accept IK as valuable in their teaching they lack the pedagogical content knowledge to effectively incorporate it into meaningful teaching and learning. Furthermore, teachers viewed cultural diversity as a constraint to their efforts to incorporate IK in teaching science. On the contrary, their learners held the view that having cultural diversity in classrooms created an opportunity to learn from other people’s cultures. Variables such as experience and difference in the cultural background of learners and teachers alike, tended to affect the teachers’ ability to incorporate IK.
- Full Text:
- Date Issued: 2016
- Authors: Mutanho, Chrispen
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1264 , vital:20041
- Description: There is growing interest in the role of indigenous knowledge (IK) in science education in many parts of the world. In South Africa, this comes against the backdrop of a long history of cultural alienation, neglect and suppression of the IK of the indigenous people by colonial governments. Hence, the first post-independence National Curriculum Policy Statement (Curriculum, 2005) and its subsequent modified versions emphasised the need to redress the imbalances of the past so as to make science accessible to learners from diverse cultural backgrounds. However, literature reveals that the efforts to implement an IK-based curriculum are constrained by the lack of clarity, knowledge and skills on how to effectively make use of IK in the classroom situation so as to bring about effective teaching and learning. Against this background, this study sought to understand how the incorporation of IK enables or constrains the teaching and learning of alcoholic fermentation. Underpinned by an interpretive paradigm, a qualitative case study was conducted at a high school in Mthatha District in the Eastern Cape Province of South Africa. The study comprised of a sample of ten Life Sciences teachers from four neighbouring high schools, two Grade 11 Life Sciences teachers and their classes and two focus groups of six learners from each class. Convenience and purposive sampling were used to select the participants and the research site. The study made use of a questionnaire, document analysis, lesson observation, stimulated recall interviews and focus group interviews to generate data. The questionnaire sought to get an overview of Life Sciences teachers’ attitudes, opinions and experiences on incorporating IK in science teaching. The data gathered were then used as baseline information to inform the main study. The lesson observations, stimulated recall interviews and the focus group interviews sought to understand how the incorporation of IK enables or constrains the teaching and learning of alcoholic fermentation. Document analysis, lesson observation, stimulated recall interviews and focus group interviews were conducted to understand the experience of incorporating IK in a real life classroom situation. The study was informed by Vygotsky’s socio-cultural constructivism and Shulman’s pedagogical content knowledge (PCK) theory. From Vygotsky’s theory I borrowed the idea of mediated learning, scaffolding (Bruner, 1986), zone of proximal development (ZPD), as well as the use of language and cultural artefacts as tools of analysis of the classroom interaction between the teacher and the learners during the teaching-learning process. Shulman’s theory of PCK was also used to analyse how teachers apply IK in teaching Science. The data obtained were coded inductively and presented in tables, graphs and thick descriptive texts to make it easy to understand. The findings of this research show that incorporating IK improved the teaching-learning process by arousing learners’ interest in science, increasing learners’ participation and motivation, meaning making, language use, questioning and engagement in the learning process. Teaching became learner-centred, for it was directed by learners’ questions. Collaborative learning through group discussions, debates, arguments and brainstorming emerged to be an effective way of engaging learners in learning. The teachers used probing to encourage critical thinking before scaffolding learners. However, even though teachers generally accept IK as valuable in their teaching they lack the pedagogical content knowledge to effectively incorporate it into meaningful teaching and learning. Furthermore, teachers viewed cultural diversity as a constraint to their efforts to incorporate IK in teaching science. On the contrary, their learners held the view that having cultural diversity in classrooms created an opportunity to learn from other people’s cultures. Variables such as experience and difference in the cultural background of learners and teachers alike, tended to affect the teachers’ ability to incorporate IK.
- Full Text:
- Date Issued: 2016
Understanding sexual concurrency and HIV/AIDS: implicit and explicit attitudes in a South African student population
- Authors: Malataliana, Maleeto Lucy
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3335 , vital:20484
- Description: There are more people infected with HIV in South Africa, than in any other country in the world. Studies indicate a plausible relationship between concurrently organised sexual partnership and the spread of STIs, with concurrency being accountable for as much as 74% of HIV infections in South Africa. Understanding sexual concurrency is therefore of vital importance, especially in the South African perspective. It has, however, become increasingly unreliable to rely solely on explicit self-measures to study sexual concurrency, and research has suggested that implicit cognition is a reliable alternative to understanding sexual behaviour and attitudes towards sexuality, which cannot be directly measured by explicit means. The purpose of this study was to understand sexual concurrency among a population of university students by researching their implicit and explicit attitudes towards sexual concurrency; and thereby to aid in understanding sexual concurrency in relation to the spread of HIV. A quantitative research methodology was used to analyse results from explicit measures of sexual concurrency in the form of a questionnaire, and implicit measures of sexual concurrency in the form of the Implicit Association Test (IAT). Although no correlation existed between implicit and explicit measures attitudes towards sexual concurrency, it was, however, observed that sexual concurrency has and is being broadly practiced, and that age is a key determinant for sexual concurrency.
- Full Text:
- Date Issued: 2016
- Authors: Malataliana, Maleeto Lucy
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3335 , vital:20484
- Description: There are more people infected with HIV in South Africa, than in any other country in the world. Studies indicate a plausible relationship between concurrently organised sexual partnership and the spread of STIs, with concurrency being accountable for as much as 74% of HIV infections in South Africa. Understanding sexual concurrency is therefore of vital importance, especially in the South African perspective. It has, however, become increasingly unreliable to rely solely on explicit self-measures to study sexual concurrency, and research has suggested that implicit cognition is a reliable alternative to understanding sexual behaviour and attitudes towards sexuality, which cannot be directly measured by explicit means. The purpose of this study was to understand sexual concurrency among a population of university students by researching their implicit and explicit attitudes towards sexual concurrency; and thereby to aid in understanding sexual concurrency in relation to the spread of HIV. A quantitative research methodology was used to analyse results from explicit measures of sexual concurrency in the form of a questionnaire, and implicit measures of sexual concurrency in the form of the Implicit Association Test (IAT). Although no correlation existed between implicit and explicit measures attitudes towards sexual concurrency, it was, however, observed that sexual concurrency has and is being broadly practiced, and that age is a key determinant for sexual concurrency.
- Full Text:
- Date Issued: 2016
Unpacking Pandora’s box: Understanding and categorising ecosystem disservices for environmental management and human wellbeing
- Shackleton, Charlie M, Ruwanza, Sheunesu, Sinasson Sanni, Giséle K, Bennett, S, De Lacy, Peter, Modipa, Rebone D, Mtati, Nosiseko, Sachikonye, Mwazvita T B, Thondhlana, Gladman
- Authors: Shackleton, Charlie M , Ruwanza, Sheunesu , Sinasson Sanni, Giséle K , Bennett, S , De Lacy, Peter , Modipa, Rebone D , Mtati, Nosiseko , Sachikonye, Mwazvita T B , Thondhlana, Gladman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182113 , vital:43801 , xlink:href="https://doi.org/10.1007/s10021-015-9952-z"
- Description: Research into the benefits that ecosystems contribute to human wellbeing has multiplied over the last few years following from the seminal contributions of the international Millennium Ecosystem Assessment. In comparison, the fact that some ecosystem goods and services undermine or harm human wellbeing has been seriously overlooked. These negative impacts have become known as ecosystem disservices. The neglect of ecosystem disservices is problematic because investments into the management or reduction of ecosystem disservices may yield better outcomes for human wellbeing, or at a lower investment, than management of ecosystem services. Additionally, management to optimise specific ecosystem services may simultaneously exacerbate associated disservices. We posit that one reason for the neglect of ecosystem disservices from the discourse and policy debates around ecosystems and human wellbeing is because there is no widely accepted definition or typology of ecosystem disservices. Here, we briefly examine current understandings of the term ecosystem disservices and offer a definition and a working typology to help generate debate, policy and management options around ecosystem disservices. We differentiate ecosystem disservices from natural hazards and social hazards, consider some of their inherent properties and then classify them into six categories. A variety of examples are used to illustrate the different types of, and management strategies to, ecosystem disservices.
- Full Text:
- Date Issued: 2016
- Authors: Shackleton, Charlie M , Ruwanza, Sheunesu , Sinasson Sanni, Giséle K , Bennett, S , De Lacy, Peter , Modipa, Rebone D , Mtati, Nosiseko , Sachikonye, Mwazvita T B , Thondhlana, Gladman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182113 , vital:43801 , xlink:href="https://doi.org/10.1007/s10021-015-9952-z"
- Description: Research into the benefits that ecosystems contribute to human wellbeing has multiplied over the last few years following from the seminal contributions of the international Millennium Ecosystem Assessment. In comparison, the fact that some ecosystem goods and services undermine or harm human wellbeing has been seriously overlooked. These negative impacts have become known as ecosystem disservices. The neglect of ecosystem disservices is problematic because investments into the management or reduction of ecosystem disservices may yield better outcomes for human wellbeing, or at a lower investment, than management of ecosystem services. Additionally, management to optimise specific ecosystem services may simultaneously exacerbate associated disservices. We posit that one reason for the neglect of ecosystem disservices from the discourse and policy debates around ecosystems and human wellbeing is because there is no widely accepted definition or typology of ecosystem disservices. Here, we briefly examine current understandings of the term ecosystem disservices and offer a definition and a working typology to help generate debate, policy and management options around ecosystem disservices. We differentiate ecosystem disservices from natural hazards and social hazards, consider some of their inherent properties and then classify them into six categories. A variety of examples are used to illustrate the different types of, and management strategies to, ecosystem disservices.
- Full Text:
- Date Issued: 2016
Unraveling the biogeographic origins of the Eurasian watermilfoil (Myriophyllum spicatum) invasion in North America
- Moody, Michael L, Palomino, Nayell, Weyl, Philip S R, Coetzee, Julie A, Newman, Raymond M, Harms, Nathan E, Liu, Xing, Thum, Ryan A
- Authors: Moody, Michael L , Palomino, Nayell , Weyl, Philip S R , Coetzee, Julie A , Newman, Raymond M , Harms, Nathan E , Liu, Xing , Thum, Ryan A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478949 , vital:78242 , https://doi.org/10.3732/ajb.1500476
- Description: Using phylogeographic analyses to determine the geographic origins of biological invaders is important for identifying environmental adaptations and genetic composition in their native range as well as biocontrol agents among indigenous herbivores. Eurasian watermilfoil (Myriophyllum spicatum) and its hybrid with northern watermilfoil (M. sibiricum) are found throughout the contiguous United States and southern Canada, forming one of the most economically costly aquatic plant invasions in North America, yet the geographic origin of the invasion remains unknown. The objectives of our study included determining the geographic origin of Eurasian watermilfoil in North America as well as the maternal lineage of the hybrids.
- Full Text:
- Date Issued: 2016
- Authors: Moody, Michael L , Palomino, Nayell , Weyl, Philip S R , Coetzee, Julie A , Newman, Raymond M , Harms, Nathan E , Liu, Xing , Thum, Ryan A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478949 , vital:78242 , https://doi.org/10.3732/ajb.1500476
- Description: Using phylogeographic analyses to determine the geographic origins of biological invaders is important for identifying environmental adaptations and genetic composition in their native range as well as biocontrol agents among indigenous herbivores. Eurasian watermilfoil (Myriophyllum spicatum) and its hybrid with northern watermilfoil (M. sibiricum) are found throughout the contiguous United States and southern Canada, forming one of the most economically costly aquatic plant invasions in North America, yet the geographic origin of the invasion remains unknown. The objectives of our study included determining the geographic origin of Eurasian watermilfoil in North America as well as the maternal lineage of the hybrids.
- Full Text:
- Date Issued: 2016
Uphicotho nzulu lwendima yepragmatiki ekuphononongeni incwadi ezikhethiweyo zesiXhosa
- Authors: Cutalele, Pumla Pamella
- Date: 2016
- Subjects: Xhosa literature , Pragmatics , Translating and interpreting
- Language: Xhosa
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5442 , vital:20845
- Description: Olu phando luqwalasela indima yepragmatiki ekuphononongeni iincwadi ezikhethiweyo zesiXhosa. Isahluko sokuqala sinika okuqulathwe lolu phando, iinjongo zolu phando nezibe ngunobangela wokuba kukhethwe esi sihloko, imethodi yophando, imo yophando, ulwakhiwo lophando nalapho kukrotyiswa kokuqulathwe sisahluko ngasinye. Uphengululo lweencwadi lwenziwe eziqulathe umxholo wepragmatiki lwenziwe kwakuso esi sahluko. Ingcaciso yamagama aya kuthi asetyenziswe rhoqo inikiwe kwakuso esi sahluko Isahluko sesibini sijonga nzulu iingcingane eziya kuthi zisetyenziswe njengesikhokelo ekwenzeni olu phando. Ingcingane yolwimi kunye nengcingane yoncwadi zijongiwe kwesi sahluko. Ingcingane zepragmatiki eziquka leyo kaGrice nengundoqo kwipragmatiki nayo ithe yaqwalaselwa. Le ngcingane iye izise iindidi zeentsingiselo namasolotya azo. Ingcingane kaGrice ethi iphuhlise intsingiselo efihlakeleyo, intsingiselo ethe ngqo kunye nocingelo ziya- jongwa gabalala kwesi sahluko. Ingcingane yentetho ntshukumo iya kuthi ijongwe ze kujongwe nonxibelelo lwayo kuncwadi. Isahluko sesithathu sijonga nzulu ukusetyenziswa kwentsingisselo efihlakeleyo kwiincwadi ezikhethelwe esi sifundo. Umgaqo wonxibelelwano nezaci zawo ezizezi; isaci somgangatho, isaci sokungakanani, isaci sonxulumano kunye nesaci sobunjani zijongiwe kwiintetho zabalinganiswa nakwizimvo zombhali. Isaci esizihambelayo nesivela kakhulu ngokusetyenziswa kwesigqebelo namaqhalo naso sithe sajongwa ngokubhekiselele kwiincwadi ezikhethelwe esi sifundo.Isahluko sesine siqwalasele ukusetyenziswa kocingelo. Ucingelo nelilelinye isolotya lepragmatiki. Iindidi zocingelo zithe zajongwa, nezizezi: ucingelo lokukhoyo nokunokwenzeka, ucingelo lokuqonda, ucingelo lonobangela nesiphumo kunye nocingelo lwezichazi nezihlomelo. Izichukumisi zocingelo zijongiwe kugxilwe kwiincwadi zesiXhosa ezikhwethelwe esi sifundo. Isahluko sesihlanu siqwalasele intsingiselo ethe ngqo. Imiba yentsingiselo ethe ngqo efana nokuzigqibela, ukuvala isikhewu, ukunqanda ubumbaxa kunye nokusetyenziswa kwemiqondiso kuthe kwaqwalaselwa kwesi sahluko. Indlela ethe ngqo abalinganiswa abathile abathiywe ngayo ngababhali kwiincwadi ezikhethelwe esi sifundo iye izise intsingiselo ethe ngqo, oko ke kuthe kwaqwalaselwa kwesi sahluko.
- Full Text:
- Date Issued: 2016
- Authors: Cutalele, Pumla Pamella
- Date: 2016
- Subjects: Xhosa literature , Pragmatics , Translating and interpreting
- Language: Xhosa
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5442 , vital:20845
- Description: Olu phando luqwalasela indima yepragmatiki ekuphononongeni iincwadi ezikhethiweyo zesiXhosa. Isahluko sokuqala sinika okuqulathwe lolu phando, iinjongo zolu phando nezibe ngunobangela wokuba kukhethwe esi sihloko, imethodi yophando, imo yophando, ulwakhiwo lophando nalapho kukrotyiswa kokuqulathwe sisahluko ngasinye. Uphengululo lweencwadi lwenziwe eziqulathe umxholo wepragmatiki lwenziwe kwakuso esi sahluko. Ingcaciso yamagama aya kuthi asetyenziswe rhoqo inikiwe kwakuso esi sahluko Isahluko sesibini sijonga nzulu iingcingane eziya kuthi zisetyenziswe njengesikhokelo ekwenzeni olu phando. Ingcingane yolwimi kunye nengcingane yoncwadi zijongiwe kwesi sahluko. Ingcingane zepragmatiki eziquka leyo kaGrice nengundoqo kwipragmatiki nayo ithe yaqwalaselwa. Le ngcingane iye izise iindidi zeentsingiselo namasolotya azo. Ingcingane kaGrice ethi iphuhlise intsingiselo efihlakeleyo, intsingiselo ethe ngqo kunye nocingelo ziya- jongwa gabalala kwesi sahluko. Ingcingane yentetho ntshukumo iya kuthi ijongwe ze kujongwe nonxibelelo lwayo kuncwadi. Isahluko sesithathu sijonga nzulu ukusetyenziswa kwentsingisselo efihlakeleyo kwiincwadi ezikhethelwe esi sifundo. Umgaqo wonxibelelwano nezaci zawo ezizezi; isaci somgangatho, isaci sokungakanani, isaci sonxulumano kunye nesaci sobunjani zijongiwe kwiintetho zabalinganiswa nakwizimvo zombhali. Isaci esizihambelayo nesivela kakhulu ngokusetyenziswa kwesigqebelo namaqhalo naso sithe sajongwa ngokubhekiselele kwiincwadi ezikhethelwe esi sifundo.Isahluko sesine siqwalasele ukusetyenziswa kocingelo. Ucingelo nelilelinye isolotya lepragmatiki. Iindidi zocingelo zithe zajongwa, nezizezi: ucingelo lokukhoyo nokunokwenzeka, ucingelo lokuqonda, ucingelo lonobangela nesiphumo kunye nocingelo lwezichazi nezihlomelo. Izichukumisi zocingelo zijongiwe kugxilwe kwiincwadi zesiXhosa ezikhwethelwe esi sifundo. Isahluko sesihlanu siqwalasele intsingiselo ethe ngqo. Imiba yentsingiselo ethe ngqo efana nokuzigqibela, ukuvala isikhewu, ukunqanda ubumbaxa kunye nokusetyenziswa kwemiqondiso kuthe kwaqwalaselwa kwesi sahluko. Indlela ethe ngqo abalinganiswa abathile abathiywe ngayo ngababhali kwiincwadi ezikhethelwe esi sifundo iye izise intsingiselo ethe ngqo, oko ke kuthe kwaqwalaselwa kwesi sahluko.
- Full Text:
- Date Issued: 2016
Urban agriculture and access to microfinance in Snake Park, Zimbabwe
- Authors: Makoni, Charmaine Tafadzwa
- Date: 2016
- Subjects: Urban agriculture -- Zimbabwe , Economic development -- Zimbabwe -- Finance , Economic development projects -- Zimbabwe -- Finance
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8099 , vital:24993
- Description: The role that urban farming plays in the food supply of cities and towns to compliment rural agriculture is increasingly gaining traction. In Zimbabwe, urban agriculture has equally become an important contributor of urban food, particularly for low income households. Urban agriculture is increasingly being viewed as a viable measure to ameliorate urban food insecurity. In spite of the important role it serves in the urban landscape, it is yet to attain political legitimacy and more importantly to gain recognition from the formal financial economy. This in turn has limited the contribution that the urban agriculture can make towards poverty alleviation and inequality for the urban poor. Access to finance and lines of credit for the urban poor can have a significant impact towards not only their agricultural productivity but also their ability to weather economic shocks. This study therefore sought to investigate factors that limit access of small scale urban farmers to agricultural microcredit. The findings of this study are derived from qualitative and quantitative data collected from small scale urban farmers in Snake Park and key informant interviews conducted in Harare, Zimbabwe. The study establishes that the lack of information on credit opportunities, loan apathy and too high interest rates were some of the reasons divulged by farmers in not seeking credit from financial institutions. The results reveal that married women have an added constraint to accessing finance by virtue of husband being head of the house, mean that they hold power to cede assets as collateral. The findings from the financial institution indicated that though the majority of firms focused on large scale commercial farming ventures, some did offer microcredit for small scale urban farmers. The results also showed that though collateral facilitated access to credit and finance for urban agriculture, proven business record, group solidarity (a form of guarantee) and character were equally important. The study recommends amongst others that farmers form groups and embark on savings schemes. Added to this, bankers and farmer associations need to meet to arrive at realistic forms of security for small loans.
- Full Text:
- Date Issued: 2016
- Authors: Makoni, Charmaine Tafadzwa
- Date: 2016
- Subjects: Urban agriculture -- Zimbabwe , Economic development -- Zimbabwe -- Finance , Economic development projects -- Zimbabwe -- Finance
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8099 , vital:24993
- Description: The role that urban farming plays in the food supply of cities and towns to compliment rural agriculture is increasingly gaining traction. In Zimbabwe, urban agriculture has equally become an important contributor of urban food, particularly for low income households. Urban agriculture is increasingly being viewed as a viable measure to ameliorate urban food insecurity. In spite of the important role it serves in the urban landscape, it is yet to attain political legitimacy and more importantly to gain recognition from the formal financial economy. This in turn has limited the contribution that the urban agriculture can make towards poverty alleviation and inequality for the urban poor. Access to finance and lines of credit for the urban poor can have a significant impact towards not only their agricultural productivity but also their ability to weather economic shocks. This study therefore sought to investigate factors that limit access of small scale urban farmers to agricultural microcredit. The findings of this study are derived from qualitative and quantitative data collected from small scale urban farmers in Snake Park and key informant interviews conducted in Harare, Zimbabwe. The study establishes that the lack of information on credit opportunities, loan apathy and too high interest rates were some of the reasons divulged by farmers in not seeking credit from financial institutions. The results reveal that married women have an added constraint to accessing finance by virtue of husband being head of the house, mean that they hold power to cede assets as collateral. The findings from the financial institution indicated that though the majority of firms focused on large scale commercial farming ventures, some did offer microcredit for small scale urban farmers. The results also showed that though collateral facilitated access to credit and finance for urban agriculture, proven business record, group solidarity (a form of guarantee) and character were equally important. The study recommends amongst others that farmers form groups and embark on savings schemes. Added to this, bankers and farmer associations need to meet to arrive at realistic forms of security for small loans.
- Full Text:
- Date Issued: 2016
Urban agriculture and the enhancement of food security and household Income in Grahamstown, Makana Municipality
- Authors: Mahandana, Funzani Nicholas
- Date: 2016
- Subjects: Urban agriculture -- South Africa -- Grahamstown , Income -- South Africa -- Grahamstown , Food security -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/8467 , vital:26367
- Description: This study draws on the relationship between household food security and household income through small scale community gardens and backyard vegetable gardens in Grahamstown Townships within Makana Municipality of the Eastern Cape Province, South Africa. The study explores the contribution of vegetable gardens in household food security and income and finding ways in which this contribution may be enhanced. This study offers insights into the relationships among individuals, households, stakeholders (Government institutions, NGOs, Municipalities, Farmers Associations etc.), and broader community dynamics that are central to understanding the local gardening projects and the dynamics of food security and household income. The implications of this research includes and understanding of how the challenges faced by the community and backyards gardens could be addressed.
- Full Text:
- Date Issued: 2016
- Authors: Mahandana, Funzani Nicholas
- Date: 2016
- Subjects: Urban agriculture -- South Africa -- Grahamstown , Income -- South Africa -- Grahamstown , Food security -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/8467 , vital:26367
- Description: This study draws on the relationship between household food security and household income through small scale community gardens and backyard vegetable gardens in Grahamstown Townships within Makana Municipality of the Eastern Cape Province, South Africa. The study explores the contribution of vegetable gardens in household food security and income and finding ways in which this contribution may be enhanced. This study offers insights into the relationships among individuals, households, stakeholders (Government institutions, NGOs, Municipalities, Farmers Associations etc.), and broader community dynamics that are central to understanding the local gardening projects and the dynamics of food security and household income. The implications of this research includes and understanding of how the challenges faced by the community and backyards gardens could be addressed.
- Full Text:
- Date Issued: 2016
User experience factors for mobile banking adoption: South African case study
- Authors: Louw, Jacques Gerrit
- Date: 2016
- Subjects: Consumer satisfaction -- South Africa , Banks and banking -- Technological innovations -- South Africa , Mobile commerce -- South Africa , Telecommunication -- South Africa -- Finance
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39207 , vital:35059
- Description: Smartphone devices are driving the transformation of online banking to satisfy the needs and desires of the consumer. This has led South African commercial banks to launch mobile banking applications on smartphones to enhance the growth of the economy and to provide more opportunities to improve the deprived sector of the economy, at acceptable rates. Moreover, opportunities exist for revenue growth, such as the delivery of greater real-time access to products and the offering of a wide variety of banking services. South African commercial banks could realise opportunities for economical and revenue growth should they focus on specific criteria that could enhance mobile banking adoption. Such criteria could not until recently, be realised by commercial banks in South Africa as the adoption rate of mobile banking remained low at 9%. Numerous South African studies have attempted to determine factors that could enhance mobile banking adoption in South Africa. There is, however, a lack of South African studies attempting to identify user experience factors that could enhance mobile banking adoption in South Africa. User experience refers to the subjective feeling of the user that results from their interaction or intention to interact with a product, to perform a specific task in a specific environment. One of the most important components for the success of any product is a positive user experience. When the user interface and functionality of a product match the expectations of the users and make the users effective and efficient, feel safe and attain some level of self-worth from using or possessing the product, their interaction with the product becomes more satisfactory. Consequently, the importance of designing for a positive user experience opens up the potential for identifying potential user experience factors that could enhance mobile banking adoption in South Africa. The user experience factors identified in this study infer their components from the user experience aspect of persuasive design and its elements, namely persuasion and trust, that led to the emergence of scarcity, reciprocation and security factors that could enhance mobile banking adoption in South Africa. A case study was employed to confirm the factors that could enhance mobile banking adoption in South Africa. The findings from the case study and the extensive literature review culminated in a set of user experience factors that in future could enhance the adoption of mobile banking in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Louw, Jacques Gerrit
- Date: 2016
- Subjects: Consumer satisfaction -- South Africa , Banks and banking -- Technological innovations -- South Africa , Mobile commerce -- South Africa , Telecommunication -- South Africa -- Finance
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39207 , vital:35059
- Description: Smartphone devices are driving the transformation of online banking to satisfy the needs and desires of the consumer. This has led South African commercial banks to launch mobile banking applications on smartphones to enhance the growth of the economy and to provide more opportunities to improve the deprived sector of the economy, at acceptable rates. Moreover, opportunities exist for revenue growth, such as the delivery of greater real-time access to products and the offering of a wide variety of banking services. South African commercial banks could realise opportunities for economical and revenue growth should they focus on specific criteria that could enhance mobile banking adoption. Such criteria could not until recently, be realised by commercial banks in South Africa as the adoption rate of mobile banking remained low at 9%. Numerous South African studies have attempted to determine factors that could enhance mobile banking adoption in South Africa. There is, however, a lack of South African studies attempting to identify user experience factors that could enhance mobile banking adoption in South Africa. User experience refers to the subjective feeling of the user that results from their interaction or intention to interact with a product, to perform a specific task in a specific environment. One of the most important components for the success of any product is a positive user experience. When the user interface and functionality of a product match the expectations of the users and make the users effective and efficient, feel safe and attain some level of self-worth from using or possessing the product, their interaction with the product becomes more satisfactory. Consequently, the importance of designing for a positive user experience opens up the potential for identifying potential user experience factors that could enhance mobile banking adoption in South Africa. The user experience factors identified in this study infer their components from the user experience aspect of persuasive design and its elements, namely persuasion and trust, that led to the emergence of scarcity, reciprocation and security factors that could enhance mobile banking adoption in South Africa. A case study was employed to confirm the factors that could enhance mobile banking adoption in South Africa. The findings from the case study and the extensive literature review culminated in a set of user experience factors that in future could enhance the adoption of mobile banking in South Africa.
- Full Text:
- Date Issued: 2016
User interface design guidelines for digital television virtual remote controls
- Authors: Wentzel, Alicia Veronica
- Date: 2016
- Subjects: Remote control , User interfaces (Computer systems) , Television broadcasting , Human-computer interaction
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1158 , http://hdl.handle.net/10962/d1020617
- Description: The remote control is a pivotal component in households worldwide. It helps users enjoy leisurely television (TV) viewing. The remote control has various user interfaces that people interact with. For example, the physical user interface includes the shape of the remote and the physical buttons; the logical user interface refers to how the information is laid out; and the graphical user interface refers to the colours and aesthetic features of the remote control. All of the user interfaces together with the context of use, cultural factors, social factors, and prior experiences of the user influences the ways people interact with their remote control and ultimately has an effect on their user experiences. Advances in the broadcasting sector and transformations of the TV physical remote control have compounded the simple remote control into a multifaceted, indispensable device, overcrowded with buttons. The usability and ultimately the user experience of physical remote controls (PRCs) have been affected by the overloaded functionality and small button sizes. The usability issues with current PRCs, the evolution of mobile phones into touchscreen smartphones, and the trend of global companies moving towards virtual remote controls (VRCs) have prompted this research to discover what user interface design features will contribute towards an enhanced user experience for digital TV VRCs. This research used the design science research process model (DSRP), which comprised six steps, to investigate this topic area further. A review of the domain literature pertaining to mobile user experiences (MUX) and all the encompassing factors, mobile human computer interaction (MHCI) and the physical, logical, graphical and natural user interfaces was completed, as well as a review of the literature regarding the usability issues of PRCs and VRCs. A contextual task analysis (CTA) of a single South African digital TV PRC was used to identify how users utilise PRCs to perform tasks, and the usability issues they encountered during the tasks. Brainstorming focus groups were used to understand how to represent certain user interface elements and attempted to source ideas from users about what potential functionality digital TV VRCs should contain. Together with all the other results gathered from the previous chapters amalgamated into a set of user interface design guidelines for digital TV VRCs. The proposed user interface guidelines were used to instantiate a digital TV VRC prototype that underwent usability testing in order to validate the proposed user interface design guidelines. The results of the usability testing revealed that the user interface design guidelines for digital TV VRCs were successful, with the addition of one guideline that was discovered during the usability testing.
- Full Text:
- Date Issued: 2016
- Authors: Wentzel, Alicia Veronica
- Date: 2016
- Subjects: Remote control , User interfaces (Computer systems) , Television broadcasting , Human-computer interaction
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1158 , http://hdl.handle.net/10962/d1020617
- Description: The remote control is a pivotal component in households worldwide. It helps users enjoy leisurely television (TV) viewing. The remote control has various user interfaces that people interact with. For example, the physical user interface includes the shape of the remote and the physical buttons; the logical user interface refers to how the information is laid out; and the graphical user interface refers to the colours and aesthetic features of the remote control. All of the user interfaces together with the context of use, cultural factors, social factors, and prior experiences of the user influences the ways people interact with their remote control and ultimately has an effect on their user experiences. Advances in the broadcasting sector and transformations of the TV physical remote control have compounded the simple remote control into a multifaceted, indispensable device, overcrowded with buttons. The usability and ultimately the user experience of physical remote controls (PRCs) have been affected by the overloaded functionality and small button sizes. The usability issues with current PRCs, the evolution of mobile phones into touchscreen smartphones, and the trend of global companies moving towards virtual remote controls (VRCs) have prompted this research to discover what user interface design features will contribute towards an enhanced user experience for digital TV VRCs. This research used the design science research process model (DSRP), which comprised six steps, to investigate this topic area further. A review of the domain literature pertaining to mobile user experiences (MUX) and all the encompassing factors, mobile human computer interaction (MHCI) and the physical, logical, graphical and natural user interfaces was completed, as well as a review of the literature regarding the usability issues of PRCs and VRCs. A contextual task analysis (CTA) of a single South African digital TV PRC was used to identify how users utilise PRCs to perform tasks, and the usability issues they encountered during the tasks. Brainstorming focus groups were used to understand how to represent certain user interface elements and attempted to source ideas from users about what potential functionality digital TV VRCs should contain. Together with all the other results gathered from the previous chapters amalgamated into a set of user interface design guidelines for digital TV VRCs. The proposed user interface guidelines were used to instantiate a digital TV VRC prototype that underwent usability testing in order to validate the proposed user interface design guidelines. The results of the usability testing revealed that the user interface design guidelines for digital TV VRCs were successful, with the addition of one guideline that was discovered during the usability testing.
- Full Text:
- Date Issued: 2016
Using bioinformatics tools to screen for trypanosomal cathepsin B cysteine protease inhibitors from the SANCDB as a novel therapeutic modality against Human African Trypanosomiasis (HAT)
- Authors: Mokhawa, Gaone
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3304 , vital:20470
- Description: Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a fatal chronic disease that is caused by flagellated protozoans, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. HAT is spread by a bite from an infected tsetse fly of the Glosina genus. Up to 60 million people in 36 countries in sub-Saharan Africa are at a risk of infection from HAT with up to 30 000 deaths reported every year. Current chemotherapy for HAT is insufficient since the available drugs exhibit unacceptable side effects (toxicity) and parasite resistance. Novel treatments and approaches for development of specific and more potent drugs for HAT are therefore required. One approach is to target vital proteins that are essential to the life cycle of the parasite. The main interest of this study is to explore Trypanosoma brucei cathepsin B-like protease (TbCatB) structural and functional properties with the primary goal of discovering non peptide small molecule inhibitors of TbCatB using bioinformatics approaches. TbCatB is a papain family C1 cysteine protease which belongs to clan CA group and it has emerged as a potential HAT drug target. Papain family cysteine proteases of Clan CA group of Trypanosoma brucei (rhodesain and TbCatB) have demonstrated potential as chemotherapeutic targets using synthetic protease inhibitors like Z-Phe-Ala-CHN2 to kill the parasite in vitro and in vivo. TbCatB has been identified as the essential cysteine protease of T. brucei since mRNA silencing of TbCatB killed the parasite and resulted in a cure in mice infected with T. brucei while mRNA silencing of rhodesain only extended mice life. TbCatB is therefore a promising drug target against HAT and the discovery and development of compounds that can selectively inhibit TbCatB without posing any danger to the human host represent a great therapeutic solution for treatment of HAT. To understand protein-inhibitor interactions, useful information can be obtained from high resolution protease-inhibitor crystal structure complexes. This study aims to use bioinformatics approaches to carry out comparative sequence, structural and functional analysis of TbCatB protease and its homologs from T. congolense, T, cruzi, T. vivax and H. sapien as well as to identify non-peptide small molecule inhibitors of TbCatB cysteine proteases from natural compounds of South African origin. Sequences of TbCatB (PDB ID: 3HHI) homologs were retrieved by a BLAST search. Human cathepsin B (PDB ID: 3CBJ) was selected from a list of templates for homology modelling found by HHpred. MODELLER version 9.10 program was used to generate a hundred models for T. congolense, T, cruzi and T. vivax cathepsin B like proteases using 3HHI and 3CBJ as templates. The best models were chosen based on their low DOPE Z scores before validation using MetaMQAPII, ANOLEA, PROCHECK and QMEAN6. The DOPE Z scores and the RMSD (RMS) values of the calculated models indicate that the models are of acceptable energy (stability) and fold (conformation). Results from the different MQAPs indicate the models are of acceptable quality and they can be used for docking studies. High throughput screening of SANCDB using AutoDock Vina revealed nine compounds, SANC00 478, 479, 480, 481, 482, 488, 489, 490 and 491, having a strong affinity for Trypanosoma spp. cathepsin B proteases than HsCatB. SANC00488 has the strongest binding to Trypanosoma spp. cathepsin B proteases and the weakest binding to HsCatB protease. Molecular dynamics (MD) simulations show that the complexes between SANC00488 and TbCatB, TcCatB, TcrCatB and TvCatB are stable and do not come apart during simulation. The complex between this compound and HsCatB however is unstable and comes apart during simulation. Residues that are important for the stability of SANC00488-TbCatB complex are Gly328 of the S2 subsite, Phe208, and Ala256. In conclusion SANC00488 is a good candidate for development of a drug against HAT.
- Full Text:
- Date Issued: 2016
- Authors: Mokhawa, Gaone
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3304 , vital:20470
- Description: Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a fatal chronic disease that is caused by flagellated protozoans, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. HAT is spread by a bite from an infected tsetse fly of the Glosina genus. Up to 60 million people in 36 countries in sub-Saharan Africa are at a risk of infection from HAT with up to 30 000 deaths reported every year. Current chemotherapy for HAT is insufficient since the available drugs exhibit unacceptable side effects (toxicity) and parasite resistance. Novel treatments and approaches for development of specific and more potent drugs for HAT are therefore required. One approach is to target vital proteins that are essential to the life cycle of the parasite. The main interest of this study is to explore Trypanosoma brucei cathepsin B-like protease (TbCatB) structural and functional properties with the primary goal of discovering non peptide small molecule inhibitors of TbCatB using bioinformatics approaches. TbCatB is a papain family C1 cysteine protease which belongs to clan CA group and it has emerged as a potential HAT drug target. Papain family cysteine proteases of Clan CA group of Trypanosoma brucei (rhodesain and TbCatB) have demonstrated potential as chemotherapeutic targets using synthetic protease inhibitors like Z-Phe-Ala-CHN2 to kill the parasite in vitro and in vivo. TbCatB has been identified as the essential cysteine protease of T. brucei since mRNA silencing of TbCatB killed the parasite and resulted in a cure in mice infected with T. brucei while mRNA silencing of rhodesain only extended mice life. TbCatB is therefore a promising drug target against HAT and the discovery and development of compounds that can selectively inhibit TbCatB without posing any danger to the human host represent a great therapeutic solution for treatment of HAT. To understand protein-inhibitor interactions, useful information can be obtained from high resolution protease-inhibitor crystal structure complexes. This study aims to use bioinformatics approaches to carry out comparative sequence, structural and functional analysis of TbCatB protease and its homologs from T. congolense, T, cruzi, T. vivax and H. sapien as well as to identify non-peptide small molecule inhibitors of TbCatB cysteine proteases from natural compounds of South African origin. Sequences of TbCatB (PDB ID: 3HHI) homologs were retrieved by a BLAST search. Human cathepsin B (PDB ID: 3CBJ) was selected from a list of templates for homology modelling found by HHpred. MODELLER version 9.10 program was used to generate a hundred models for T. congolense, T, cruzi and T. vivax cathepsin B like proteases using 3HHI and 3CBJ as templates. The best models were chosen based on their low DOPE Z scores before validation using MetaMQAPII, ANOLEA, PROCHECK and QMEAN6. The DOPE Z scores and the RMSD (RMS) values of the calculated models indicate that the models are of acceptable energy (stability) and fold (conformation). Results from the different MQAPs indicate the models are of acceptable quality and they can be used for docking studies. High throughput screening of SANCDB using AutoDock Vina revealed nine compounds, SANC00 478, 479, 480, 481, 482, 488, 489, 490 and 491, having a strong affinity for Trypanosoma spp. cathepsin B proteases than HsCatB. SANC00488 has the strongest binding to Trypanosoma spp. cathepsin B proteases and the weakest binding to HsCatB protease. Molecular dynamics (MD) simulations show that the complexes between SANC00488 and TbCatB, TcCatB, TcrCatB and TvCatB are stable and do not come apart during simulation. The complex between this compound and HsCatB however is unstable and comes apart during simulation. Residues that are important for the stability of SANC00488-TbCatB complex are Gly328 of the S2 subsite, Phe208, and Ala256. In conclusion SANC00488 is a good candidate for development of a drug against HAT.
- Full Text:
- Date Issued: 2016