Showing papers by "University of Johannesburg published in 2008"

DNA barcoding the floras of biodiversity hotspots

Abstract: DNA barcoding is a technique in which species identification is performed by using DNA sequences from a small fragment of the genome, with the aim of contributing to a wide range of ecological and conservation studies in which traditional taxonomic identification is not practical. DNA barcoding is well established in animals, but there is not yet any universally accepted barcode for plants. Here, we undertook intensive field collections in two biodiversity hotspots (Mesoamerica and southern Africa). Using >1,600 samples, we compared eight potential barcodes. Going beyond previous plant studies, we assessed to what extent a “DNA barcoding gap” is present between intra- and interspecific variations, using multiple accessions per species. Given its adequate rate of variation, easy amplification, and alignment, we identified a portion of the plastid matK gene as a universal DNA barcode for flowering plants. Critically, we further demonstrate the applicability of DNA barcoding for biodiversity inventories. In addition, analyzing >1,000 species of Mesoamerican orchids, DNA barcoding with matK alone reveals cryptic species and proves useful in identifying species listed in Convention on International Trade of Endangered Species (CITES) appendixes.

The Place of Subject Matter Knowledge in Pedagogical Content Knowledge: A case study of South African teachers teaching the amount of substance and chemical equilibrium

Abstract: This paper presents two South African case studies designed to explore the influence of subject matter knowledge on pedagogical content knowledge (PCK). In the first case study on teaching the mole in two township schools, the findings illustrate that the participant teachers favoured procedural approaches at the expense of conceptual understanding. The second case study examines the teaching of chemical equilibrium to students on a bridging programme in a tertiary institution. Through these data the authors present a model to assist in understanding the amalgamation of subject matter knowledge (SMK) with other teacher knowledge domains to produce what we describe as ‘manifestations’. The model was useful in interpreting the teachers’ practice, especially to highlight the role of SMK, and therefore offers interesting insights into the nature of PCK and its influence on science teaching.

Perception of organisational commitment, job satisfaction and turnover intentions in a post-merger South African tertiary institution

Abstract: A merger can be considered both a phenomenological and signifcant life event for an organisation and its employees, and how people cope with and respond to a merger has a direct impact on the institutional performance in the short to medium term. It is within this context that post-merger perceptions of a tertiary institution were investigated. A predictive model (determined the “best” of 15 predefned models) of turnover intentions was developed for employees of a South African tertiary institution (having undergone its own recent merging process). A systematic model-building process was carried out incorporating various techniques, among others structural equation modelling and step-wise linear regression. The fnal predictive model explained 47% of the variance in turnover intentions. Contrary to expectations, commitment does not correlate more strongly than satisfaction does with turnover intentions.

Iridaceae ‘Out of Australasia’? Phylogeny, Biogeography, and Divergence Time Based on Plastid DNA Sequences

Abstract: The current infrafamilial taxonomy of the Iridaceae recognizes four subfamilies; Isophysidoideae (1: 1); Nivenioideae (6: ca. 92), Iridoideae (29: 890), and Crocoideae (29: 1032). Phylogenetic analyses of sequences of five plastid DNA regions, rbcL, rps4, trnL–F, matK, and rps16, confirm most aspects of this classification and the evolutionary patterns that they imply, importantly the sisiter relationship of Isophysidoideae to the remainder of the family and the monophyly of Iridoideae. Subfamily Nivenioideae is, however, paraphyletic; Crocoideae is consistently found nested within it, sister to the core Nivenioideae, the woody Klattia, Nivenia, and Witsenia. This clade is sister to Aristea, which in turn is sister to the Madagascan Geosiris, and then to the Australasian Patersonia. We treat Aristea, Geosiris, and Patersonia as separate subfamilies, Aristeoideae and the new Geosiridaceae and Patersonioideae, rendering Nivenioideae and Crocoideae monophyletic. The alternative, uniting a widely cir...

The effect of low level laser irradiation on adult human adipose derived stem cells

Abstract: This study investigated the effect of low level laser irradiation on primary cultures of adult human adipose derived stem cells (ADSC) using a 635-nm diode laser, at 5 J/cm(2) with a power output of 50.2 mW and a power density of 5.5 mW/cm(2). Cellular morphology did not appear to change after irradiation. Using the trypan blue exclusion test, the cellular viability of irradiated cells increased by 1% at 24 h and 1.6% at 48 h but was not statistically significant. However, the increase of cellular viability as measured by ATP luminescence was statistically significant at 48 h (p < 0.05). Proliferation of irradiated cells, measured by optical density, resulted in statistically significant increases in values compared to nonirradiated cells (p < 0.05) at both time points. Western blot analysis and immunocytochemical labeling indicated an increase in the expression of stem cell marker beta1-integrin after irradiation. These results indicate that 5 J/cm(2) of laser irradiation can positively affect human adipose stem cells by increasing cellular viability, proliferation, and expression of beta1-integrin.

Rise in seawater sulphate concentration associated with the Paleoproterozoic positive carbon isotope excursion: evidence from sulphate evaporites in the ∼2.2–2.1 Gyr shallow-marine Lucknow Formation, South Africa

Abstract: Past oceanic sulphate concentration is important for under- standing how the oceansredox state responded to atmospheric oxygen levels. The absence of extensive marine sulphate evaporites before 1.2 Gyr probably reflects low seawater sulphate and ⁄ or higher carbonate concentrations. Sulphate evaporites formed locally during the 2.22-2.06 Gyr Lomagundi positive d 13 C excursion. However, the 2.2-2.1 Gyr Lucknow Formation, South Africa, provides the first direct evidence for seawater sulphate precipitation on a carbonate platform with open ocean access and limited terrestrial input. These marginal marine deposits contain evidence for evaporite molds, pseudomorphs after selenite gypsum, and solid inclusions of Ca-sulphate in quartz. Carbon and sulphur isotope data match the global record and indicate a marine source of the evaporitic brines. The apparent precipitation of gypsum before halite requires ‡2.5 mM L )1 sulphate concentration, higher than cur- rent estimates for the Paleoproterozoic. During the Lomagundi event, which postdates the 2.32 Gyr initial rise in atmospheric oxygen, seawater sulphate concentration rose from Archean values of £200 lM L )1 , but dropped subsequently because of higher pyrite burial rates and a lower oceanic redox state.

Governance and support in the sponsoring of projects and programs

Abstract: Several factors have combined to draw attention to the importance of sponsoring projects and programs. One factor is that after several decades of attempting to improve success rates of projects by focusing on project-based management and the project manage- ment competence of practitioners, convincing evidence demonstrates that success or failure of projects is not entirely within the control of the proj- ect manager and project team. Contextual issues are crucial in influencing the progress and outcomes of projects, and a key theme that has emerged is the importance of top management support. Another fac- tor that has drawn attention to the sponsorship role is increased focus on corporate governance resulting from numerous high-profile corporate collapses, which have highlighted the need for accountability, transparency, and the ability to implement strategy. The sponsorship role provides the critical link between corporate and project governance and is important in ensuring that governance requirements are met and that support is provided to projects and programs. This article reports on research designed to address both formal and informal aspects of the sponsorship role and to provide guidance to organi- zations and professional organizations by defining the role and responsibilities of the sponsor within corporate and project governance frameworks and identifying the characteristics of effective perform- ance of the sponsor role. First, the role of sponsor- ship in the governance context is introduced; this is followed by a review of the literature relating to the sponsorship role, including its treatment in project and general management literature and in standards. The research methodology was specifically designed to take a holistic view of the sponsorship role, by examining the role in its project/program and organi- zational context and ensuring inclusion of views and experiences of sponsors as well as those of project managers, team members, and other stakeholders. A qualitative approach was adopted, focusing on a small number of case-study organizations and proj- ects/programs enabling researchers to gain a rich understanding of the environment in which the role of the sponsor is realized. Over 108 interviews relat- ing to 36 projects/programs in nine organizations from five geographic regions (Australia, China, Europe, North America, and South Africa) were recorded, transcribed, and then coded by the five researchers involved in the study. A priori codes derived from five preliminary studies were used for primary coding of the data. As the transcripts were coded, the researchers reviewed the data for emer- gent themes that might suggest additional codes. Analysis of the literature and the extensive qualita- tive data led to the development of a conceptual model for making sense of the sponsor's role. This model reflects the differing perspectives that may exist at the interface of the act of governing the proj- ect, which requires that the project be looked at from the perspective of the parent organization (gover- nance), and the act of providing top management support, which requires looking at the parent organi- zation from the perspective of the project (support). Under differing circumstances, the sponsor may need to emphasize the provision of governance, or support, or both. Utilizing this conceptual model, sec- ondary codes were created reflecting quotations per- taining to governance, support, and behaviors of sponsors. Review of quotations provided a rich illus- tration of the governance and support aspects of the sponsorship role and gave substance to effective behaviors, which led to the discovery of useful oppor- tunities for connection with mainstream general management literature to further enhance under- standing. The conceptual model has significant potential to provide organizations and sponsors with guidance in understanding and defining the effective contextual conduct of the sponsorship role.

The State and New-build Gentrification in Central Cape Town, South Africa

Abstract: The objective of this investigation is to assess the relevance and potential of current international trends in the study of gentrification in the contemporary South African urban context. Against the backdrop of `new' gentrification experiences and debates it is argued that recent developments in the central-city districts of large South African cities present numerous opportunities for `new' gentrification processes to emerge as a central part of urban regeneration. Moreover, it is contended that specific state policies and interventions focused on inner-city regeneration underpin new forms of gentrification in South Africa.

Social entrepreneurship in South Africa

Abstract: Purpose – Various theoretical issues and debates were investigated in order to measure quantitatively social entrepreneurship (SE) activity (SEA), together with the different skills associated with successful SE in South Africa.Design/methodology/approach – This was primarily an exploratory study, using factor analysis and inferential statistical testing, based on a surveyed sample of 287 respondents, undertaken to measure SEA and concomitant SE skills. Empirical findings were interrogated in the context of existing research and comparisons with established SEA rates were made.Findings – The findings were modest, particularly about the number of active and future social entrepreneurs. Moreover the validity and reliability of the instrument used to measure skills was established, offering insights into SEA and the types of skills associated with SE.Research limitations/implications – The study is limited by being in the early stage of theoretical development on the SE construct. The interpretation of the e...

Self/nonself perception and recognition mechanisms in plants: a comparison of self-incompatibility and innate immunity.

Abstract: Analyses of emerging concepts indicate that parallels exist between self-incompatibility and pathogen recognition. In the case of surveillance of 'nonself', plant immune responses are triggered either by pattern recognition receptors (PRRs) that detect conserved pathogen-associated molecular patterns (PAMPs) or by resistance (R) proteins recognizing isolate-specific pathogen effectors. PAMP detection is an important component of innate immunity in plants and serves as an early warning system for the presence of potential pathogens and activation of plant defense mechanisms. In the Brassicaceae, the recognition of 'self' and self-incompatibility are components of a receptor-ligand based mechanism that utilizes an S receptor kinase (SRK) to perceive and reject 'self'-pollen. SRK is an S-domain receptor-like kinase (RLK), which in turn is part of the RLK family, some members of which represent PRRs involved in the detection of PAMPs. S-domain RLKs also occur in species that do not exhibit self-incompatibility and are up-regulated in response to wounding, PAMPs and pathogen recognition. Although evolution may have driven expansion of certain RLK families to serve roles in particular physiological processes, this may not exclude these receptor types from functioning in different programs. Recent findings on self/nonself recognition are reviewed and conceptual and mechanistic links between microbial recognition and self-incompatibility are discussed.

Genesis of High-Grade Iron Ores of the Archean Iron Ore Group around Noamundi, India

Abstract: High-grade hematite ores of the Iron Ore Group in the Noamundi area, Jharkhand state, India, are hosted by a laterally extensive, 220-m-thick banded iron formation (BIF) in a folded greenstone belt succession of Paleoarchean age. Single orebodies, which are up to 3 km long along strike and several hundred meters wide, depending on dip of the beds, are strata bound and composed of two major ore types—namely, hard hematite ore that is of ancient geologic origin and ores related to recent weathering along a lateritized Cretaceous-Cenozoic land surface. The ancient hard hematite orebodies comprise laminated hematite ores in which microplaty hematite is dominant, and massive ores composed almost entirely of martite. Supergene ores, in contrast, are comprised of goethite-rich duricrust and soft saprolitic hematite ores representing the leached zone of the Cretaceous-Cenozoic laterite profile. Hard hematite-martite ores formed by hydrothermal replacement of BIF protolith, not only through leaching of silica but possibly also through introduction of iron by hydrothermal fluids of meteoric origin. Hematite iron ore pebbles in a conglomerate at the base of the Meso- to Neoproterozoic Kolhan Group near Noamundi attest to the antiquity of the hard hematite orebodies. Soft saprolitic iron ores formed as a product of lateritic weathering processes in Cretaceous-Cenozoic times. Supergene alteration took place under the influence of reducing and acidic meteoric water, which is typical for lateritic soil profiles developed under humid tropical climatic conditions with lush plant cover. Goethitic duri-crusts capping the laterite profile suggest alternating wet and dry seasons in this environment.

Factors Influencing Teen Mothers' Enrollment and Participation in Prevention of Mother-to-Child HIV Transmission Services in Limpopo Province, South Africa

Abstract: In this article, we examine barriers to HIV testing uptake and participation in prevention of mother-to-child HIV transmission (PMTCT) services among adolescent mothers aged 15 to 19 years in rural and urban Limpopo Province, South Africa. We used the narrative research method involving key informants constructing typical case studies of adolescent experiences with HIV testing and entry into PMTCT. Case studies formed the basis of a community-based questionnaire and focus group discussions with adolescent mothers. Client-counselor dynamics during pretest counseling were pivotal in determining uptake and participation, and counselor profile strongly influenced the nature of the interaction. Other factors found to influence adherence to PMTCT recommendations included HIV and early premarital pregnancy stigma, fear of a positive test result, and concerns over confidentiality and poor treatment by health care providers. Adolescents described elaborate strategies to avoid HIV disclosure to labor and delivery staff, despite knowing this would mean no antiretroviral therapy for their newborn infants. Theoretical, methodological, and programmatic implications of study findings are also discussed.

Organisational culture of hospitals to predict turnover intentions of professional nurses

Abstract: The objective of this study was to determine if organisational culture predicts turnover intentions of professional nurses A predictive model with organisational culture and various proposed mediating variables, namely knowledge sharing, organisational commitment, organisational citisenship behaviour and job satisfaction, as well as various demographic variables was developed to determine turnover intentions through applying General Linear Modelling A correlational design with questionnaires was used A sample of professional nurses (N = 530) in private and provincial hospitals was obtained The results indicate that organisational culture has a significantly negative correlation with turnover intentions Organisational culture also interacted with job satisfaction, knowledge sharing, and the white professional nurses’ category to decrease turnover intentions and with Organisational Citisen Behaviours to increase turnover intentions in a final predictive model It is therefore recommended that nursing employers seriously embark on strategies to improve the organisational culture to retain their talent Opsomming Die doel van die studie was om te bepaal of organisasie-kultuur arbeidsomset-voornemens van professionele verpleegkundiges voorspel ‘n Voorspellingsmodel met organisasiekultuur en verskeie voorgestelde tussenkomende veranderlikes, naamlik kennisdeling, organisasieverbintenis, organisasie-burgerskapsgedrag en werkstevredenheid, asook verskeie demografiese veranderlikes was ontwikkel deur Algemene Liniere Modellering ’n Korrelasie-ontwerp met behulp van vraelyste is gebruik ‘n Steekproef van professionele verpleegkundiges (N = 530) in private en provinsiale hospitale is verkry Die resultate toon dat organisasie-kultuur betekenisvol negatief korrelleer met arbeidsomsetvoornemens Organisasiekultuur het ook in interaksie met werkstevredenheid en kennisdeling, asook die kategorie blanke verpleegkundiges in ‘n finale model arbeidsomsetvoornemens verlaag en saam met organisasieburgerskapsgedrag arbeidsom-setvoornemens verhoog Daar word aanbeveel dat werkgewers oorweging skenk aan intervensies wat die organisasiekultuur gunstiger maak om personeel te behou

Efficacy of three different laser wavelengths for in vitro wound healing

Abstract: Background and objective: Despite contradictory reports on the effect of laser light on cell proliferation, studies have shown that appropriate doses and wavelengths of laser light are therapeutically beneficial in tissue repair and pain control. This study aimed to establish if the dose and/or wavelength influenced the biological responses of irradiated in vitro fibroblasts – 1 h after laser irradiation. Materials and methods: This study aimed to establish cellular responses of normal and wounded human skin fibroblasts to helium-neon (632.8 nm), diode (830 nm) and Nd:YAG (1064 nm) laser irradiation using one exposure of 5 or 16 J/cm2 on day 1 and again on day 4. Results: Wounded cells exposed to 5 J/cm2 using 632.8 nm showed an increase in cell migration and haptotaxis, a stable increase in the release of interleukin-6 (IL-6), a decrease in caspase 3/7 activity, an increase in ATP viability and an increase in cell proliferation – 1 h after the final exposure. The results confirm that changes in parameters such as ATP viability, cytokine expression (IL-6), cell proliferation (alkaline phosphatase enzyme activity) and DNA damage can be observed directly after the laser irradiation. The amount of DNA damage and cytotoxicity may be related to duration of the laser irradiation, which is dependent on the power density (mW/cm2) of each laser. Conclusion: The results indicate that 5 J/cm2 using 632.8 nm results in a stimulatory effect that is more effective than 830 and 1064 nm. The results suggest possible mechanisms by which the wavelength may potentially influence the cellular responses of wounded cells.

Significance of periodogram peaks and a pulsation mode analysis of the Beta Cephei star V403 Car

Abstract: We discuss some commonly used methods for determining the significance of peaks in the periodograms of time series. We review methods for constructing the classical significance tests, their corresponding false alarm probability functions and the role played in these by independent random variables and by empirical and theoretical cumulative distribution functions. We discuss the concepts of independent frequencies and oversampling in periodogram analysis. We then compare the results of new Monte Carlo simulations for evenly spaced time series with results obtained previously by other authors, and present the results of Monte Carlo simulations for a specific unevenly spaced time series obtained for V403 Car.

Modulation of heat shock factors accompanies salicylic acid-mediated potentiation of Hsp70 in tomato seedlings

Abstract: In plants, salicylic acid (SA) is a signalling molecule regulating disease resistance responses such as systemic acquired resistance (SAR) and the hypersensitive response (HR), and has been implicated in both basal and acquired thermotolerance. It has been shown that SA enhances heat-induced Hsp/Hsc70 accumulation in plants. To investigate the mechanism of how SA influences the heat shock response (HSR) in plants, tomato seedlings were treated with SA alone, heat shock, or a combination of both before analyses of hsp70 mRNA, heat shock factor (Hsf)–DNA binding, and gene expression of hsp70, hsfA1, hsfA2, and hsfB1. SA alone led to activation of Hsf–DNA binding, but not induction or transcription of hsp70 mRNA. SA had no significant effect on hsfA2 and hsfB1 gene expression, but potentiated the basal levels of hsfA1. In heat-shocked plants, Hsf–DNA binding was established, and increased hsfA1, hsfA2, and hsfB1 expression was followed by accumulation of Hsp70. SA plus heat shock showed enhanced Hsf–DNA binding, enhanced induction of hsp70 mRNA transcription, and gene expression of hsfA1, hsfA2, and hsfB1, resulting in potentiated levels of Hsp/Hsc70. Since increased hsp70 and hsf gene expression coincide with increased levels of Hsp70 accumulation, it is concluded that SA-mediated potentiation of Hsp70 is due to modulation of these Hsfs by SA. In our efforts to understand the role of Hsp70 in heat-related disease susceptibility, the degree of the complexity of the cross-talk between the pathways in which SA is involved, inter alia, the plant defence response, the HSR and thermotolerance, was further underscored.

In vitro evaluation of dichloro-bis(pyrazole)palladium(II) and dichloro-bis(pyrazole)platinum(II) complexes as anticancer agents.

Abstract: Cisplatin (cis-diamminedichloroplatinum) was first identified for its anti-bacterial activity, and was later also shown to be an efficient anticancer agent. However, the therapeutic use of this anticancer drug is somewhat limited by its toxic side effects, which include nephrotoxicity, nausea, and vomiting. Furthermore the development of drug-resistant tumours is commonly observed following therapy with cisplatin. Hence there is a need for improved platinum derived drugs to overcome these limitations. Apoptosis contributes significantly to the cytotoxic effects of anticancer agents such as cisplatin; therefore in this study the potential anticancer properties of a series of pyrazole palladium(II) and platinum(II) complexes, [(3,5-R2pz)2PdCl2] {R = H (1), R = Me (2)} and [(3,5-R2pz)2PtCl2] {R = H (3), R = Me (4)}, were evaluated by assessment of their pro-apoptotic activity. The induction of apoptosis was measured in CHO cells by the detection of phosphatidylserine (PS) exposure using the annexin V and APOPercentage™ assays; DNA fragmentation using the Terminal deoxynucleotide transferase dUTP Nick End Labelling (TUNEL) assay; and the detection of activated caspase-3. The platinum complexes were shown to be considerably more active than the palladium complexes, with complex 3 demonstrating the highest level of cytotoxic and pro-apoptotic activity. The LD50 values for complex 3 and cisplatin were 20 and 70 μM, respectively, demonstrating that the cytotoxic activity for complex 3 was three times higher than for cisplatin. Various human cancer cell lines, including CaSki, HeLa, as well as the p53 mutant Jurkat T cell line were also shown to be susceptible to complex 3. Collectively, this in vitro study provides insights into action of palladium and platinum complexes and demonstrates the potential use of these compounds, and in particular complex 3, in the development of new anticancer agents.

A test of _psbK-psbI_ and _atpF-atpH_ as potential plant DNA barcodes using the flora of the Kruger National Park (South Africa) as a model system

Abstract: A DNA barcode consists of a standardized short sequence of DNA (400-800bp) used to identify the taxonomic species a small organic fragment belongs to. Even though it has been easy to discriminate animal species by using the mitochondrial gene _cox1_, this is still difficult for plants seeing that the mitochondrial genome is not variable enough on the species level. During the Second International Barcode of Life Conference in Tapei (September 2007), different plastid regions were proposed as potential plant DNA barcodes, such as _atpF-atpH_ and _psbK-psbI_, but no consensus on which region to use was reached during the meeting. The largest plant DNA barcoding study to date proposed _matK_ as the best candidate and suggested that in combination with _trnH-psbA_ a slight increase in performance could be achieved. However, no study has tested the suitability of the newly proposed _psbK-psbI_ and _atpF-atpH_ for plant barcoding purposes. Four potential DNA barcodes, _matK_, _trnH-psbA_, _atpF-atpH_, and _psbK-psbI_, were amplified and sequenced for a selective sampling including mainly trees and shrubs of the flora of the Kruger National Park Africa (South Africa). The performance of each region and also each possible combination of these were tested by applying a battery of metrics and statistical tests. Our results confirm that the second half (5’ end) of _matK_ is the best candidate in a single locus barcoding approach reaching 87.5% of species correctly identified. Combining _matK_ with _trnH-psbA_ and _psbK-psbI_ increased only slightly the performance in discriminating species. The results from this study show that the use of a ‘three-region barcode’ does not significantly outperform _matK_ in a single-locus barcoding approach. We therefore argue against the ‘multiple barcode approach’ proposed by the plant working group, and instead propose to keep barcoding plants in line with the approach taken for animals, i.e. using one barcode: _cox1_ for animals and _matK_ for plants.