List of Titles

Beauveria and Metarhizium against false codling moth (Lepidoptera: Tortricidae): a step towards selecting isolates for potential development of a mycoinsecticide

- Coombes, Candice A, Hill, Martin P, Moore, Sean D, Dames, Joanna F, Fullard, T

Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F , Fullard, T
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/405757 , vital:70203 , xlink:href="https://hdl.handle.net/10520/EJC167505"
Description: False codling moth, Thaumatotibia leucotreta Meyrick (1912) (Lepidoptera: Tortricidae), can cause both pre- and post-harvest damage to citrus fruit. Not only can this result in reduced crop yield, but more importantly because of the moth's endemism to sub-Saharan Africa, it is classified as a phytosanitary pest by many export markets. An entire consignment of citrus may be rejected in the presence of a single moth (Moore 2012). Since the bulk of citrus fruit production in South Africa is exported, the control of T. leucotreta is critical (Citrus Growers Association, South Africa 2012). Traditionally, control has been achieved through the use of chemical insecticides; however, residue restrictions, resistance development and concerns about environmental pollution have substantially reduced the dependence on chemical pesticides in citrus. Research on T. leucotreta control has therefore focused on the use of biological organisms (e.g. parasitoids and viruses), which are used as control agents within an integrated pest management (IPM) programme in citrus. These biological control agents, however, only targeted the aboveground life stages of the pest, not the soil-dwelling life stages (late fifth instars, prepupae, pupae), which is the subject of this contribution (Moore 2012).
Full Text:
Date Issued: 2015

Quick View

Being a Born Free: the misunderstandings and missed opportunities facing young South Africans

- Malila, Vanessa

Authors: Malila, Vanessa
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/158680 , vital:40220 , https://hdl.handle.net/10520/EJC175765
Description: Young South Africans are often referred to as the Born Frees - a term which sometimes means people born after 1994, sometimes people born after 1990, or young people who came of age politically after 1994. I've come to really dislike the term Born Frees and particularly the way it is used by the media and the politicians. By calling young people Born Frees, society is using apartheid as a reference point to identify a post-apartheid generation. This reference point (the transition to a 'free' society) unfortunately does not resonate with many of the young people that I've encountered in my research and many feel insulted by the implications of this term, which does not apply to them in any way. Should South African society really be using the transition from apartheid to define its young people and how does it relate to the lives of real young people in South Africa today? Are they really Born Free, free from what, free to do what, free individuals or free as a collective? I will look at some of the stereotypes being used in the mainstream media of Born Frees, and then look at the reaction to this term by some real young South Africans.
Full Text:
Date Issued: 2015

Quick View

Being at Home: Race, Institutional Culture and Transformation at South African Higher Education Institutions

- Tabensky, Pedro, Matthews, Sally

Authors: Tabensky, Pedro , Matthews, Sally
Date: 2015
Language: English
Type: text , book
Identifier: http://hdl.handle.net/10962/142084 , vital:38048 , ISBN 9781869142902 , https://books.google.co.za/books?id=49o8rgEACAAJanddq=Being+at+home:+Race,+institutional+culture+and+transformation+at+South+African+higher+education+institutionandhl=enandsa=Xandved=0ahUKEwiPgsa6mpjjAhXNN8AKHbNwAtoQ6AEIKDAA
Description: This edited work has gathered together contributions on how to transform universities in South Africa; as many are struggling to shift their institutional culture. In a South African context, transformation means to attempt to change higher education institutions such that they no longer reflect the values promoted by apartheid but rather reflect the values embodied in South Africa's 1996 Constitution. Institutional culture is the main subject for discussion in this book. In order to transform South Africa's universities, the contributors begin by analyzing the idea of what a university is, and relatedly, what its ideal aims are. A second theme is to understand what institutional culture is and how it functions. Moreover, transformation cannot occur without transforming the broader cultures of which they are a part. Related to this theme is a general concern about how contemporary moves towards the instrumentalization of higher education affect the ability to transform institutions. These institutions are being pushed to conform to goals that are outside the traditional idea of a university, such as concerns that universities are being 'bureaucratized' and becoming corporations, instead of a place of learning open to all. In conclusion it can be said that the contemporary South African academic community has an opportunity to recreate itself as the end of apartheid created space for engaging in transformative epistemic projects. The transformation of the tertiary sector entails a transformation of institutional cultures.
Full Text:
Date Issued: 2015

Quick View

Biotechnology from bench to market: the design, scale-up and commercialisation strategy development of a disruptive bioprocess for potable ethanol production

- Dhanani, Karim Colin Hassan

Authors: Dhanani, Karim Colin Hassan
Date: 2015
Language: English
Type: text , Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/55863 , vital:26750
Description: The capacity of research institutions to engage in technology transfer activities has important implications on both economic development and technological advancement. This thesis explores the developmental and commercialisation processes involved in the transfer of a potentially disruptive bioprocessing technology for beverage alcohol production. Ethanolic fermentation strategies are of interest due to their global economic importance and their potential to produce clean renewable fuels in the future. Currently used methods are both energetically wasteful and economically inefficient. To this end more effective bioprocessing methods and implementation strategies are required to enable commercially viable decentralised small-scale ethanol production. Perfusion reactors have a number of advantages over batch and other continuous fermentation strategies. This study aimed to develop and study the fermentative efficiency of a perfusion tower bioreactor system at the bench scale, and subsequently through a scale up process to a low level commercial capacity. An HPLC method was developed for the Simultaneous quantification of common fermentation analytes; this was used to determine bench scale fermentation efficacies over an operational period. At steady state the ethanol volumetric productivity of the bench scale bioreactor system was 3.40 g. L-1.h-1, the average yield of ethanol to consumed sugar was 0.467 g.g -1, with an average sugar conversion percentage of 96%. Results showed that the tower perfusion bioreactor was appropriate for high performance ethyl alcohol fermentations. This reactor design was then scaled up to pilot scale and then commercial scale ca pacity. Similar efficienCies were achieved with these larger systems. Based on the process performance data obtained, a commercialisation strategy was developed and market performance was projected. It was found that productivity rates per unit volume were favourable, and the bioreactor system was determined to be very cost effective for a decentralised ethanolic beverage manufacturing model.
Full Text:
Date Issued: 2015

Quick View

Book Review Growing the next generation of researchers: A handbook for emerging researchers and their mentors, Holness, L

- Motshoane, Puleng, Muthama, Evelyn, McKenna, Sioux

Authors: Motshoane, Puleng , Muthama, Evelyn , McKenna, Sioux
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/187205 , vital:44579 , xlink:href="https://doi.org/10.14426/cristal.v3i2.56"
Description: South Africa urgently needs more researchers (NRF, 2008; NDP, 2011). We also need a transformation in the demographics of our researchers. One indicator of this is that currently only 14% of university professors are black African, and only 2% are black African females (DHET, 2012). The Staffing South Africa's Universities Framework includes a number of initiatives to drive the process of growing the next generation of academics. For example, the nGAP project has inserted 125 new posts into the higher education system in 2015, with more to follow. This project allows for new academics to undertake postgraduate study and develop as teachers and researchers through mentorship, a reduced teaching load and so on.
Full Text:
Date Issued: 2015

Quick View

Book Review: A Renegade called Simphiwe

- Magadla, Siphokazi

Authors: Magadla, Siphokazi
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/298595 , vital:57719 , xlink:href="https://doi.org/10.1177/0021909614533638"
Description: A Renegade called Simphiwe is a “creative-intellectual portrait” of the public (and private) life of the musician Simphiwe Dana (p. 150). Gqola defines the book as “one writer’s engagement with the Simphiwe Dana of the South African public imagination [who]… troubles many categories of belonging in the South African public imagination in remarkable ways” (pp. 17, 32). The book comes at a poignant time as South Africa reflects on the success and challenges of the first 20 years of democracy. Fittingly, Gqola positions Dana within a long tradition of griots in Africa whose art always spoke truth to power.
Full Text:
Date Issued: 2015

Quick View

Book Review: Global Governance and the New Wars

- Magadla, Siphokazi

Authors: Magadla, Siphokazi
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/298640 , vital:57723 , xlink:href="https://doi.org/10.1080/02589346.2015.1008676"
Description: Mark Duffield's second edition of ‘Global Governance and the New Wars’ offers an important and biting critique of how different actors within the security and development discourse have adapted to the various transformations of war in the post-cold war era. In this picture drawn by Duffield, the power of states in the South continues to be eroded by an exclusionary market that is driven by the global political economy wherein state's development and security responsibilities are increasingly assumed by non-state actors (predominately constituted by Western aid agencies). Those who fall outside the bounds of the state, development and humanitarian aid agencies can be found operating in an expanding shadow economy that is also shaped by a global dynamics which make the conditions for ‘network war' possible. In this context, the lines between ‘war' and peace” are difficult to distinguish. Overall, the book paints a depressing picture on the lack of substantive changes in the livelihoods of the poor as attention has been directed to discussions about ‘new wars' or altered forms of violence that have characterized the post-cold war era. The book unforgivingly exposes the failures of the discursive changes post-cold war to reconceptualize development and security in terms that move beyond description and into substantive change especially regarding shifting the development discourse from its historic modernizing impulses.
Full Text:
Date Issued: 2015

Quick View

Brown hyena habitat selection varies among sites in a semi-arid region of southern Africa

- Welch, Rebecca J, Tambling, Craig J, Bissett, Charlene, Gaylard, Angela, Müller, Konrad, Slater, Kerry, Strauss, W Maartin, Parker, Daniel M

Authors: Welch, Rebecca J , Tambling, Craig J , Bissett, Charlene , Gaylard, Angela , Müller, Konrad , Slater, Kerry , Strauss, W Maartin , Parker, Daniel M
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/123277 , vital:35423 , https://doi.10.1093/jmammal/gyv189
Description: In the last 50 years, the human impact on ecosystems has been greater than during any other time period in human history (Millennium Ecosystem Assessment 2003). Large carnivores face anthropogenic threats worldwide, specifically persecution, habitat degradation, and habitat fragmentation (Everatt et al. 2014; Groom et al. 2014; Ripple et al. 2014; Wolfe et al. 2015). Because large carnivores often occupy high trophic levels, their presence influences species at lower levels through trophic cascades (Ripple et al. 2014). Natural experiments, taking advantage of large carnivore management, have shown that large predators provide fundamental ecosystem and economic services that help maintain healthy and diverse ecosystems (Ripple et al. 2014). Additionally, carnivores play an important role in other ecosystem processes, for example, scavenging carnivores may provide regulatory services, such as waste removal, nutrient cycling, and disease regulation. Such services add stability to ecosystems and ensure energy flow through multiple trophic levels (DeVault et al. 2003; Wilson and Wolkovich 2011).
Full Text:
Date Issued: 2015

Quick View

Can perceptions of environmental and climate change in island communities assist in adaptation planning locally?

- Aswani, Shankar, Vaccaro, Ismael, Abernethy, Kirsten Elizabeth, Albert, Simon, de Pablo, Javier Fernández-López

Authors: Aswani, Shankar , Vaccaro, Ismael , Abernethy, Kirsten Elizabeth , Albert, Simon , de Pablo, Javier Fernández-López
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/123310 , vital:35426 , https://doi.10.1007/s00267-015-0572-3
Description: Local perceptions of environmental and climate change, as well as associated adaptations made by local populations, are fundamental for designing comprehensive and inclusive mitigation and adaptation plans both locally and nationally. In this paper, we analyze people’s perceptions of environmental and climate-related transformations in communities across the Western Solomon Islands through ethnographic and geospatial methods. Specifically, we documented people’s observed changes over the past decades across various environmental domains, and for each change, we asked respondents to identify the causes, timing, and people’s adaptive responses. We also incorporated this information into a geographical information system database to produce broad-scale base maps of local perceptions of environmental change. Results suggest that people detected changes that tended to be acute (e.g., water clarity, logging intensity, and agricultural diseases). We inferred from these results that most local observations of and adaptations to change were related to parts of environment/ecosystem that are most directly or indirectly related to harvesting strategies. On the other hand, people were less aware of slower insidious/chronic changes identified by scientific studies. For the Solomon Islands and similar contexts in the insular tropics, a broader anticipatory adaptation planning strategy to climate change should include a mix of local scientific studies and local observations of ongoing ecological changes.
Full Text:
Date Issued: 2015

Quick View

Caring for a child with disabilities: a psychosocial case study

- Saville Young, Lisa, Berry, Jessie

Authors: Saville Young, Lisa , Berry, Jessie
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/143860 , vital:38289 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
Description: This paper presents a psychosocial analysis of an interview with a mother of a child with disabilities. A psychosocial perspective (conceptualizing the subject as both discursively and psychically constituted) has been argued for recently in critical disability studies by Goodley (2011) who advocates for psychoanalysis’ rich vocabulary for affective processes to explore the emotional elements of disablism, where disablism refers to ways in which society discriminates against people with disabilities (‘barriers out there’). While rejecting the use of psychoanalytic theory to pathologise and individualise people with disabilities, Goodley argues that how “oppression is felt psychically, subjectively and emotionally” (p.716) (‘barriers in here’) should not be overlooked, alongside subjectivity as always socially, politically, culturally and economically produced. This psychosocial analysis of a carer’s perspective thickens our understanding of how the caregiver is a social being, both not disabled but at the receiving end of disablism, and an interpersonal subject who may also be an ‘agent’ or ‘carrier’ of disablism.
Full Text:
Date Issued: 2015

Quick View

Challenges of post-apartheid state-owned company pension fund reform: a case study of the controversy around the Transnet-Transport Pension Fund

- Goqoza, Noluyolo Juliet

Authors: Goqoza, Noluyolo Juliet
Date: 2015
Language: English
Type: text , Thesis , Masters , MSocSc
Identifier: http://hdl.handle.net/10962/54766 , vital:26610
Description: This thesis examines the restructuring of the pension funds of Transnet, a South African state-owned company involved in transportation, from the 1990s. Two of its main pension funds, the Transport-Transnet Pension sub-Fund (TTPF) and the Transnet Second Defined Benefit Fund (TSDBF), have been surrounded by controversy, with major court actions brought by aggrieved pensioners in 2006-2012 and again from 2013, and smaller cases in 1997-1999 and 2004. (There were also a number of smaller cases, mostly unsuccessful, but the thesis will not examine them). The case that started in 2013 is the biggest class action in the country‟s history, and makes claims of serious mismanagement and bad faith against the Transnet management. But the fundamental grievance is that (according to the 2013 legal case) “more than 80% of pensioners earn less than R4 000.00 a month… 62 % earn less than R2 500.00… 45% of the pensioners earn less than the state‟s ordinary old-age pension” grant for the poor. Although that case is ongoing, this thesis examines the background and controversies that frame the case. It provides an overview of the history and development of the South African pensions system and South African state-owned companies; it examines how these have been shaped by the apartheid and post-apartheid periods, and by the rise of neo-liberalism; it examines the evolution of Transnet and its pensions systems, from the early days of the South African Railways and Harbours Administration (SAR&H, formed 1910), to its restructuring into the South African Transport Services (SATS) in 1982, and then into Transnet in 1990. The thesis shows that the operations of the TTPF and TSDBF, which are closed to new members, have had serious effects on pensioners that rely upon them. Pensions are very low (the main reason for the various court cases), and this is for a range of reasons. Annual increases in pensions are formally set at below-inflation levels, leading to falling real incomes. More pressure on pensioners‟ livelihoods has arisen from Transnet‟s cuts to other benefits, like the medical aid Transmed, provided to pensioners. While the schemes are solvent, the pensions generally started at a low base, partly because most pensioners were relatively poorly paid workers before retirement (and the pensions were linked to former salaries). There is also a racial dimension: while most white workers at SAR&H/ SATS and Transnet were poorly paid, black, Coloured and Indian workers were paid even worse, and, further, were only brought into the pension schemes late. Both TTPF and TSDBF are defined benefit funds, which means members are guaranteed specific benefits at retirement, with the employer obligated to inject funds to meet shortfalls where needed. Yet neither the state nor Transnet has been willing to take actions to lift the basic pensions, such as investments into the funds, or to make systematic ex gratia payments to bring the pensions to a reasonable level, to remove historic racial inequalities between pensioners, to increase medical aid co-payments or coverage or to otherwise address the pensioners‟ situation. It does not seem that the reason for the problems is that the two funds have been severely mismanaged or asset-stripped, as alleged in the 2013 class action: it must be noted that both funds report surpluses. But the surpluses are possible because the pensions are low and falling in real terms, and the numbers of pensioners declining due to deaths. It seems clear that Transnet is unable or unwilling to act to decisively improve the situation of the pensioners: ensuring a surplus on existing pension funds is a major goal. This is partly because Transnet itself has ongoing financial problems, and partly because it operates in the context of neo-liberal restructuring, like corporatisation, commercialisation and privatisation, which places limits on the additional funding of the funds. At the same time, the pensioners have very little real, as opposed to a nominal, say in the administration of the pension schemes, limiting their ability to affect the rules and administration or raise issues. The thesis seeks to use historical institutionalism, which sees policies and major institutions, including state-owned companies, as shaped by power and conflict, especially between classes. This is used to try and explain changing state policies and the changing role and actions of state-owned companies, as a way of understanding Transnet‟s actions, as well as its treatment of its pensioners.
Full Text:
Date Issued: 2015

Quick View

Change in Roviana Lagoon Coral Reef ethnobiology:

- Aswani, Shankar, Albert, Simon

Authors: Aswani, Shankar , Albert, Simon
Date: 2015
Language: English
Type: text , book
Identifier: http://hdl.handle.net/10962/145460 , vital:38440 , ISBN 9783319237633 , DOI: 10.1007/978-3-319-23763-3_10
Description: Coral reefs are iconic for their beauty and biodiversity, and are of great socioeconomic and cultural importance for many coastal communities across the tropics. However, little is known about people’s local classification and their social and ecological relationship with these habitats. This chapter describes Roviana people’s changing ecological and social relationship with their coral reefs, which are increasingly being damaged by humans. First, we combined ecological and social data to describe people’s classification of local coral reefs in tandem with the productive practices conducted in these habitats. Second, we examined local perceptions and recognized effects of environmental and climatic changes on reefs over the last two decades. Finally, we measured changes in fishing activities and in the taxonomic systems (between 1995 and 2011) to evaluate if recent social and economic change has led to the erosion of marine indigenous ecological knowledge and associated practices. Studying people’s changing perceptions of their coral reefs is crucial to understand their ability to identify and adapt to environmental transformations. Simply, the way local people perceive the state of the environment is not only important in terms of changes in local epistemology but also has important implications for how resources are used and managed, and this information can be coupled with scientific one for a broader management strategy.
Full Text:
Date Issued: 2015

Quick View

Characterisation of the HSP70-HSP90 organising protein gene and its link to cancer

- Weeks, Stacey

Authors: Weeks, Stacey
Date: 2015
Language: English
Type: text , Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/56006 , vital:26764
Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
Full Text:
Date Issued: 2015

Quick View

Characterization and analysis of NTP amplification based DDoS attacks

- Rudman, Lauren, Irwin, Barry V W

Authors: Rudman, Lauren , Irwin, Barry V W
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/429285 , vital:72573 , 10.1109/ISSA.2015.7335069
Description: Network Time Protocol based DDoS attacks saw a lot of popularity throughout 2014. This paper shows the characterization and analysis of two large datasets containing packets from NTP based DDoS attacks captured in South Africa. Using a series of Python based tools, the dataset is analysed according to specific parts of the packet headers. These include the source IP address and Time-to-live (TTL) values. The analysis found the top source addresses and looked at the TTL values observed for each address. These TTL values can be used to calculate the probable operating system or DDoS attack tool used by an attacker. We found that each TTL value seen for an address can indicate the number of hosts attacking the address or indicate minor routing changes. The Time-to-Live values, as a whole, are then analysed to find the total number used throughout each attack. The most frequent TTL values are then found and show that the migratory of them indicate the attackers are using an initial TTL of 255. This value can indicate the use of a certain DDoS tool that creates packets with that exact initial TTL. The TTL values are then put into groups that can show the number of IP addresses a group of hosts are targeting.
Full Text:
Date Issued: 2015

Quick View

Characterization of porphyrin nanorods on fluorine doped tin oxide glass sheet

- George, Reama C, Falgenhauer, Jane, Geis, Clemens, Nyokong, Tebello, Schlettwein, Derck

Authors: George, Reama C , Falgenhauer, Jane , Geis, Clemens , Nyokong, Tebello , Schlettwein, Derck
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/193542 , vital:45344 , xlink:href="https://doi.org/10.1142/S1088424615500923"
Description: Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS4)4) served as negatively charged counterpart for the positively charged metallo meso-tetra(4-NN-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During cyclic voltammetry either applying negative potentials from 0.0 V to -1.0 V or positive potentials from 0.0 V to ++2.2 V irreversible reduction or oxidation reactions were detected for the films. Consistently, SEM images taken following cyclic voltammetry showed the disintegration of the PNR on the films into smaller subunits. Spectroelectrochemical measurements showed the formation of porphyrin anionic radicals during oxidation by a decrease in the absorption intensities and broadening of spectra with an additional band appearing around 900 nm. A similar trend was observed when negative potentials were applied but in this case the cationic radical was produced. In both cases the decrease of the intensity of the J-aggregate confirms a loss of intermolecular coupling, again consistent with the smaller subunits observed in SEM analysis.
Full Text:
Date Issued: 2015

Quick View

Characterization of the co-chaperones of Hsp70 and Hsp90 in Trypanosoma brucei and their potential partnerships

- Mokoena, Fortunate

Authors: Mokoena, Fortunate
Date: 2015
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/54543 , vital:26583
Description: African Trypanosomiasis, which is caused by Trypanosoma brucei, is one of the crippling agents of social and economic development in Africa. T. brucei cycles between the cold-blooded insect vector, the tsetse fly (Glossina spp), and warm-blooded mammalian hosts. T. brucei, T. cruzi and L. major are mammal infecting kinetoplastid parasites that are collectively referred to as TriTryps. These parasites experience extreme environments as they move between their warm-blooded mammalian hosts and cold-blooded insect vectors which trigger extensive morphological transformations during the life-cycle of the parasite. Molecular chaperones have been implicated in parasite differentiation. TriTryps display significant expansions and diversity in the gene complements encoding molecular chaperones, especially J-proteins. Generally, J-proteins function as co-chaperones of Hsp70s, forming part of vital protein homeostasis processes. Hsp70s show a high degree of conservation, while J-proteins appear to be an extreme case of taxonomic radiation. Although several studies have focused on the molecular and cell biology of Hsp70s in some kinetoplastid parasites, knowledge is still lacking pertaining to J-proteins and their partnerships with Hsp70s. This thesis focused on the classification of kinetoplastid Jproteins into the four types by examining the domain organizations using T. brucei as a guide. The potential partnership of J-proteins and Hsp70s were postulated based on predicted subcellular localization. Kinetoplastid parasites, particularly T. brucei, have evolved an expanded and specialized J-protein machinery, likely to be a consequence of an evolutionary fitness/trait to adapt to diverse environment present in hosts and vectors. These analyses will yield insight into the process of parasite differentiation as well as provide new leads for chemotherapeutic treatments. The presence of the STI1 mediated Hsp90 hetero-complex formation has not been confirmed in T. brucei. To this end, in silico and biochemical techniques were used to characterize the role of TbSTI1, as an adaptor protein of Hsp70 and Hsp90. Through domain architecture analysis, sequence alignments, phylogenetic analysis and three-dimensional structure prediction, TbSTI1 was demonstrated to be the most conserved TPR containing co-chaperone of Hsp70 and Hsp83 in T. brucei and also shown to be highly similar to its eukaryotic homologues. Recombinant TbSTI1 was overproduced and purified in E.coli cells and subsequently shown to associate with TcHsp70 in a concentration dependent manner and associate weakly with TbHsp70.4. TbSTI1 and TbHsp83 were also demonstrated to be expressed and upregulated upon exposure to heat shock at the bloodstream stage of parasite development. In conclusion, this study is the first to report the interaction of TbSTI1 with a chaperone. Interactions between TbSTI1 and Hsp70s were demonstrated and therefore, the formation of the hetero-complex is predicted based the similarity of TbSTI1 to other STI1 proteins.
Full Text:
Date Issued: 2015

Quick View

CHIP: a co-chaperone for degradation by the proteasome

- Edkins, Adrienne L

Authors: Edkins, Adrienne L
Date: 2015
Language: English
Type: text , book
Identifier: http://hdl.handle.net/10962/164863 , vital:41179 , ISBN 978-3-319-11730-0 , DOI: 10.1007/978-3-319-11731-7_11
Description: Protein homeostasis relies on a balance between protein folding and protein degradation. Molecular chaperones like Hsp70 and Hsp90 fulfil well-defined roles in protein folding and conformational stability via ATP dependent reaction cycles. These folding cycles are controlled by associations with a cohort of non-client protein co-chaperones, such as Hop, p23 and Aha1. Pro-folding co-chaperones facilitate the transit of the client protein through the chaperone mediated folding process. However, chaperones are also involved in ubiquitin-mediated proteasomal degradation of client proteins. Similar to folding complexes, the ability of chaperones to mediate protein degradation is regulated by co-chaperones, such as the C terminal Hsp70 binding protein (CHIP).
Full Text:
Date Issued: 2015

Quick View

Classification System for Wetlands and Other Aquatic Ecosystems in South Africa:

- Ellery, William F N

Authors: Ellery, William F N
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/144454 , vital:38347 , https://doi.org/10.2989/10220119.2015.1025843
Description: There have been several attempts to develop a wetland classification for South Africa, with merit in each, but a system that satisfies the needs of a wide range of professionals has been elusive. This is partly to be expected since classification systems are often user-specific. Nevertheless, and at last, the authors of Classification System for Wetlands and Other Aquatic Ecosystems in South Africa. User Manual: Inland Systems (SANBI Biodiversity Series 22) have developed a robust and comprehensive wetland classification system for South Africa that likely will have broad appeal and be widely used. Working for Wetlands, the Water Research Commission (WRC) and SANBI provided considerable support for the development of this system and there was expert input from a wide range of stakeholders.
Full Text:
Date Issued: 2015

Quick View

Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)

- Nyoni, Stephen, Nyokong, Tebello

Authors: Nyoni, Stephen , Nyokong, Tebello
Date: 2015
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
Full Text:
Date Issued: 2015

Showing items 61 - 80 of 351