Characterization of putative DD-carboxypeptidase-interacting partners in mycobacterium smegmatis

Dissertation submitted to the Faculty of Health Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Medicine. June 2016Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is responsible for the largest number of deaths due to a single bacterial pathogen. The persistence of TB in society is exacerbated by multiple factors, including the emergence of drug resistant forms of M. tuberculosis such as multi-, extensively- and totally-drug strains, which have fuelled a race for the discovery of new drugs with novel modes of action. However, the metabolic flexibility inherent in the tubercle bacillus has made the identification of vulnerable drug targets difficult. The peptidoglycan (PG) layer in the mycobacterial cell wall plays an essential role in bacterial growth, survival and antibiotic resistance but has not been exploited for TB drug development. In this study, we characterized the physiological function of mycobacterial DD-Carboxypeptidases (DD-CPases), a subgroup of Low Molecular Weight penicillin binding proteins (LMW PBPs), implicated in modulating the amount of PG cross-linking, thereby regulating the growth and remodelling of the PG polymer. Given that DD-CPases have not been characterized in actinobacteria, this study comprised the identification of M. smegmatis DD-CPases interacting partners, using the mycobacterial Protein Fragment complementation assay (mPFC), and interrogation of the functionality of the M. tuberculosis DD-CPase homologues through heterologous complementation in M. smegmatis. The Two DD-CPases, encoded by the MSMEG_2433 and MSMEG_6113 loci in M. smegmatis, were chosen for the identification of putative interacting partners. Screening of a genomic library using the mPFC assay identified 30 and 10 possible interacting partners for MSMEG_2433 and MSMEG_6113 respectively. Notably, some of these interacting partners included key regulators of cell elongation (PonA1) or division (PbpA and PbpB) and point to an important function for DD-CPases during mycobacterial growth. To further assess if genetic multiplicity for DD-CPases in M. tuberculosis is reflective of an underlying functional redundancy between these enzymes, the M. tuberculosis DD-CPase homologues (Rv2911, Rv3627c and Rv3330) were assessed for functionality through ectopic expression in M. smegmatis. The resulting heterologous M. smegmatis strains displayed altered colony morphology, with smooth colonies that displayed a mucoid surface and cording defects. Ectopic expression of the M. tuberculosis DD-CPases in M. smegmatis also resulted in aberrant biofilm formation and affected bacterial sliding on semi-solid agar, indicative of an alteration in the three-dimensional packing of cells in a community or changes in membrane properties. Over-expression of Rv2911 and Rv3627c resulted in reduced bacterial cell length accompanied by division defects. Transmission electron microscopy revealed that the M. tuberculosis DD-CPase homologues are involved in maintaining normal bacterial cell wall architecture. Over-expression of these homologues in native wild type M. tuberculosis H37RvS revealed a role for Rv3627c in regulating bacterial colony morphology. Cellular localization studies with rseGFP C-terminally tagged derivatives of these proteins revealed that they localize at the poles, mid-cell or and quartercell positions, further suggestive of a role in temporal and spatial co-ordination of cell growth and division. Collectively, the data point to important, possibly redundant roles for the multiple DD-CPases-encoding genes in M. tuberculosis and highlights these proteins as possible new drug targets for TB.MB201

Teaching English First Additional Language to grades 10 and 11 progressed learners to enhance communication proficiency

Abstracts in English, Sesotho and XhosaThrough learner progression in South African primary and lower secondary public schools, many learners proceed to the Further Education and Training (FET) Phase without proficiency in English First Additional Language (EFAL), the language of learning and teaching (LoLT). Compelled by this challenge, this multiple-case study aimed to explore the lived experiences of grades 10 and 11 teachers in teaching progressed learners to enhance communication proficiency in EFAL. The study was informed by a qualitative research approach, embedded in a constructivist paradigm, guided by Vygotsky (1978) social development theory. Observations and one-on-one, semi-structured interviews were used to collect data from a sample frame of five grades 10 and 11 EFAL teachers in selected rural secondary schools and thematic analysis was used for data analysis. Findings revealed that in this era where learner diversity requires differentiated teaching that appeals to the needs of diverse learners, teachers hold on to the past training one-size-fits-all teaching methods. Consequently, teachers experience challenges related to lack of exposure to teach complex grades of able and progressed learners together. Among others, recommendations are made to policy makers that the Curriculum Assessment Policy Statement (CAPS) for EFAL be aligned with the needs of diverse learners. The EFAL teachers should also engage in a culture of reading and lifelong learning to empower themselves professionally in order to overcome challenges in the inclusive teaching of able and progressed learners who have barriers to learning the language.Ka leano la ho fetisa baithuti leha ba sa atleha likolong tsa mathomo, le tse mahareng Africa Boroa, baithuti ba bangata ba fetela mokhahlelong oa thuto e phahameng ntle le bokhoni ba puo ea mantlha ea Senyesemane, puo ea ho ithuta le ho ruta. Ka ho susumetsoa ke qholotso ena, lipatlisiso tsena li entsoe ho hlahloba boiphihlelo ba mesuoe ea sehlopha sa leshome le leshome le motso o mong, ho ntlafatsa tsebo ea ho ruta ka Senyesemane. Boithuto bona bo ile ba etsoa ka lipatlisiso tsa boleng tse kenelletsang tataiso le khopolo ea ntšetso-pele ea sechaba ea Vygotsky (1978). Litebello le puisano tse hlophisitsoeng le mosuoe kapa mosuoetsana ka mong, li sebelisitsoe ho bokella lintlha ka ho qotsa le ho batlisisa ho mesuoe e mehlano ea puo ea mantlha likolong eleng Senyesemane. Ho khethiloe lihlopha tse bohareng le hlahlobo ea mantlha e sebelisitsoe ho shebisisa liphuputso. Se senotsoeng ke liphuputso tsena ke hore nakong eona ena eo barutoana ba hlokang thuto e ikhethang, e ipapisitseng le litlhoko tsa boiphihlelo ba bona, mesuoe e bonahala e tsitlalletse mokhoeng oa khale oa ho ruta, o nkang joalokaha eka barutuoa bohle bana le boinahano le boiphihlelo bo tšoanang. Ka lebaka leo, mesuoe e tobana le bothata ba ho ruta ka boiphihlelo baithuti ba atlehileng le ba fetisitsoeng ha ba kopa-kopane ka litsebo tse arohaneng. Mehato e nkiloeng ka boithuto bona e kenyeletsa ho eletsa baetsi ba manene-thuto hore Tokomane ea Leano la Lenane-thuto ea puo ea Senyesemane ea pele e lokele ho arabela litlhoko tsa baithuti ka bokhoni ba bona bo fapaneng, ‘me mesuoe e lokela ho ikoetlisa ho-ea-ho-ile e le ho ichorisa le ho itlhahlella thutong ea senyesemane e kenyelelitseng baithuti bohle le ba fetisitsoeng ba e-na le bothata ba puo ena.Ngokuqhubela phambili kwabafundi kwzikolo zikarhulumente eziziiprayimari nezizezantsi ezikarhurumente, abafundi abaninzi baya kwinqanaba leMfundo ePhakamileyo noQeqesho ngaphandle kobuchule besiNgesi uLwimi lokuQala oLongezelelweyo, ulwimi lokufunda nokufundisa. Benyanzelwe ngulo mngeni, esi sifundo sinamacala amaninzi sijilise ekuhloleni amava aphilayo ootitshala beBanga le-10 nele-11 ekufundiseni abaqhubela phambili abafundi ukomeleza ubuchule bonxibelelwano kulwimi olongezelelweyo lesiNgesi. Olu phononongo lwalwaziswe ngendlela yophando olusemgangathweni, olungeniswe kwiparadise yabafundi, ekhokelwa yithiyori yophuhliso lwentlalo yaseVygotsky. Ukuqwalaselwa, udliwanondlebe olwenziwe ngamnye ngamnye eyakhelweyo, nohlalutyo lwamaxwebhu kwasetyenziswa ukuqokelela idatha kwisakhelo sesampula yootitshala abaLwimi abahlanu abakwiBanga leShumi elinanye ku-11 kwizikolo eziziisekondari ezikhethiweyo, kwaye nohlalutyo lobugcisa lwalusetyenziselwa ukuhlalutya idatha. Iziphumo zophando zibonisa ukuba ngeli xesha apho ukwahluka kwabafundi kufuna ukufundiswa okwahlukileyo okubonakalisa iimfuno zabafundi abahlukeneyo, ootitshala babambelela kuqeqesho lwangaphambili ngokweendlela zokufundiisa. Ngenxa yoko, ootitshala bafumana imiceli mingeni enxulumene nokungafikeli ekufundiseni amabanga anobunzima abafundi abakwaziyo nokuqhubela phambili kunye. Phakathi kokunye, izindululo zenziwa kubaqulunqi bomgaqo-nkqubo zokuba iNkcazo yoMgago-nkqubo woVavanyo lweKharityhulamu yolwimi lwesiNgesi oLongezelelweyo mayihambelane neemfuno zabafundi abahlukeneyo, kwaye ootitshala kufuneka bazixhobise kangangoko ukufunda ukuze bazixhobisele ukukwazi ukufundisa abantwana ngokwale mfundo iqukayo.Curriculum and Instructional StudiesM. Ed. (Curriculum Studies

The challenges of rural connectivity: eight case studies of Thusong Service Centres in Mopani District

Thesis (M.M. (ICT Policy and Regulation))--University of the Witwatersrand, Faculty of Commerce, Law and Management, Graduate School of Public and Development Management, 2014.The research aimed to investigate the supply and demand side factors that enables or hinders the effectiveness of rural connectivity provided through public access points such as the Thusong Service Centres (TSCs). The lack of broadband and terrestrial infrastructure is often cited as the main reason why rural people are not able to participate in the information society. The status of the Mopani District rural connectivity indicates that the digital divide is not always due to the lack of infrastructure, but due to the etic approach towards the deployment of connectivity and the failure to locate rural connectivity within the broader community development goals. The failure to understand the user requirements contributes to the misconception that Very Small Apparatus Terminals (VSAT) satellite technology is an inadequate solution which must be replaced by fixed broadband. On the other hand, the failure of the Department of Public Service and Administration (DPSA) blueprint indicates the poor level of e-government readiness within the public service sector. The status of the Mopani TSCs also shows that there is a lack of accountability, cooperation and collaboration across the three spheres of government and that there is a misuse of public funds in cases where connectivity resources are duplicated and not optimally used. The separation of the public service connectivity from the public connectivity creates the digital inequality in the targeted communities. The separation has resulted in connectivity being available to some and not to all, because accessibility is based on personal relationships. In other cases there is constructed denied access due to local politics. 16 years later since the establishment of the Universal Service and Access Agency of South Africa (USAASA), the South African Community Informatics (CI) sector is struggling to achieve outputs that produce the desired impact in the targeted communities

ZnO Nanowire Field-Effect Transistor for Biosensing: A Review

The last 19 years have seen intense research made on zinc oxide (ZnO) material, mainly due to the ability of converting the natural n-type material into p-type. For a long time, the p-type state was impossible to attain and maintain. This chapter focuses on ways of improving the doped ZnO material which acts as a channel for nanowire field-effect transistor (NWFET) and biosensor. The biosensor has specific binding which is called functionalization that is achieved by attaching a variety of compounds on the designated sensing area. Reference electrodes and buffers are used as controllers. Top-down fabrication processes are preferred over bottom-up because they pave way for mass production. Different growth techniques are reviewed and discussed. Strengths and weaknesses of the FET and sensor are also reviewed

The integration of smart mobility systems on the revised taxi recapitalisation program as a strategy to modernise the taxi industry

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2060This research was about establishing the extent to which digital technologies have impacted the institutional arrangements, efficiency of operational procedures, and coverage of the Revised Taxi Recapitalisation Program. However, the approach in executing this study consisted of two aspects, the first one entailed conducting field investigations to determine the geographical locations of taxi rank facilities within the study area and the categories of minibus taxis thereof, whilst establishing the type of technology systems used to manage the infrastructure and fleet within this sector. The second aspect was to assess the methods used to apply for the taxi scrapping subsidy and reviewing the government’s annual performance reports regarding the Revised Taxi Recapitalisation Program. Based on data obtained from these two approaches and using The Open Group Architecture Framework, a Taxi-Vehicle Monitoring System conceptual framework was developed. This system is anticipated to serve as a basis for incorporating and integrating smart mobility systems within the taxi industry to keep this sector competitive in the rapidly evolving digital transformation era. In addition, it is further envisaged that this system will enable the taxi industry to migrate from the current traditional methods to technologybased platforms that are integrated and efficient, thereby expediting the taxi scrapping program whilst expanding its scope to cater for all categories of taxis that transport commuters and to unlock additional government subsidies that can be introduced as a strategy to attract and enhance public-private partnerships

3D simulation investigating ZnO NWFET characteristics

3D Simulation was carried out and compared with fabricated ZnO NWFET. The device had the following electrical output characteristics: mobility value of 10.0 cm2 /Vs at a drain voltage of 1.0 V, threshold voltage of 24 V, and subthreshold slope (SS) of 1500 mV/decade. The simulation showed that the device output results are influenced by two main issues: (i) contact resistance (Rcon ≈ 11.3 MΩ) and (ii) interface state trapped charge number density (QIT = 3.79 x 1015 cm-2). The QIT was derived from the Gaussian distribution that depends on two parameters added together. These parameters are: an acceptor-like exponential band tail function gGA(E) and an acceptor-like Gaussian deep state function gTA(E). By de-embedding the contact resistance, the simulation is able to improve the device by producing excellent field effect mobility of 126.9 cm2 /Vs

Violent Crimes in Selected Post - 2000 South African Novels

MA (English)Department of EnglishThrough an examination of Angela Makholwa’s Red Ink (2007) and Black Widow Society (2013), Deon Meyer’s Blood Safari (2009) and Trackers (2012), Margie Orford’s Daddy’s Girl (2009), and Water Music (2013), Sifizo Mzobe’s Young Blood (2011) and finally Lazola Pambo’s The Path Which Shapes Us (2012)-eight post-2000 South African crime novels, this study is positioned within major discourses about crime and violence in the country today. The study examined South African crime fiction by writers of different genders, race and social classes and from different literary generations. This enabled me to grapple with multiple current perceptions of violent crimes in South African from different backgrounds. Clearly, the background of these writers influences the way they depict violence, criminality, and the various fictitious ways they portray these uncomfortable realities. Through a post-colonial, feminism, Neo-Marxist lens and theories of space, the study explored the many ways South African crime writers narrate contemporary realities of violent crimes in the country today. The post-apartheid crime novel is a significant tool in helping the country understands its traumatic and violent criminal past which has spilled over into the post-apartheid period in many ways. The novels examined in this study showed that the crime novel can be appreciated both for its aesthetic quality and allegorical value. Furthermore, the post-2000 South African crime novel provides readers with a fictitious space where they see their deep-seated desires for justice fulfilled, law and order restored and maintained through the disruptive power and flexibility of the crime novel in creating a parallel universe of im/possibilities. The dissertation also notes that the burgeoning of crime fiction in South Africa today is an attempt by many writers to respond to the alarming levels of gender-based violence, eco-crimes, spatial crimes and how the political instabilities of the post-apartheid continues to drive the masses into various forms of criminality and violence.NR