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Dissolved and particulate iron in the Atlantic sector marginal ice zone of the Southern Ocean
No full textThesis (MSc)--Stellenbosch University, 2025.Buchanan, K. 2025. Dissolved and particulate iron in the Atlantic sector marginal ice zone of the Southern Ocean. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/b123284a-b32b-459f-8198-4732a6606a7eLarge regions of the Southern Ocean (SO), particularly the Marginal Ice Zone (MIZ), are characterised by low dissolved iron (dFe) concentrations, often limiting primary productivity. While the seasonal formation and melting of Antarctic sea ice may contribute iron (Fe) to surrounding waters, the biogeochemistry of Fe in the MIZ remains poorly constrained due to limited seasonal data, particularly in remote regions far from the Antarctic shelf. This study investigates seasonal variations in dFe and particulate Fe (pFe) in both sea ice and the surface 500m of the water column across winter and spring (2019- 2022) in the Atlantic sector of the SO, ~1200 km from the Antarctic continent. We present 53 dFe and 19 pFe measurements from 11 sea ice cores, reporting sea ice dFe concentrations ranging from below detection (0.07 nmoljkg) to 9.53 nmoljkg (mean: 0.66 ± 1.51 nmoljkg) and pFe up to 9.78 nmoljkg (mean: 3.46 ± 2.57 nmoljkg) - substantially lower than values reported in shelf-proximal studies. Distinct pFejpAl ratios suggest sea ice does not primarily source its pFe from underlying seawater, with atmospheric deposition, lateral transport, and snow contributions likely playing larger roles. Seasonal differences in seawater pFejpAl ratios, elevated in spring relative to winter, point to enhanced non-lithogenic Fe inputs-likely from biogenic material or melt-related processes. However, seawater profiles reveal that sea ice melt does not significantly elevate surface dFe concentrations during spring. Instead, dFe distributions in winter suggest vertical entrainment through mixing, while spring profiles reflect biological uptake and surface processes. A persistent decoupling between dFe and pFe, especially in spring, and the dominance of refractory pFe (with <40% in labile form) highlight the limited short-term bioavailability of pFe. Nonetheless, these particles may contribute to the long-term dFe pool through gradual remineralisation. Subsurface dFe maxima and elevated pFejpAl ratios in spring indicate a seasonal transition in Fe sources from predominantly lithogenic in winter, to melt or biologically influenced in spring. Longitudinal patterns show relatively uniform dFe across the MIZ, driven by large- scale circulation, whereas pFe exhibits greater spatial variability linked to biological activity and aggregation. Outside the MIZ, local dFe enrichment, such as at sample station WS3, suggests additional inputs possibly from hydrothermal or sedimentary sources. Fe fluxes for the Weddell Sea ice and snow concentrations were estimated to 0.69 moljm2 for dFe and 3.01 moljm2 for pFe, yielding a total Fe (TFe) flux of 3.70 moljm2 every melt season. This represents the first Fe inventory estimate for the Weddell Sea ice region to be 3.81 million mol for dFe, 16.71 million mol for pFe, totalling to 20.52 million mol of TFe. The observed values are markedly lower than previously reported inputs from sea ice, highlighting the importance of localised constrained flux estimates. Together, these results challenge assumptions of sea ice as a major Fe source and emphasise the need to distinguish between Fe fractions, recognise seasonal and spatial variability, and account for both physical and biological drivers when assessing Fe supply and productivity in the MIZ under changing sea ice regimes.Master
Investigation of non-glass heliostat facets
Get PDFThesis (MEng)--Stellenbosch University, 2025.Schnaar-Campbell, J. M. 2025. Investigation of non-glass heliostat facets. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/b13472a9-70e8-4851-829e-803cdf12b250This thesis summarises the process of designing novel heliostat facets using nonglass reflectors. Currently all utility-scale solar power tower systems use silvered float glass. Manufacturers of heliostats often face challenges due to the brittle failure of silvered glass, its high mass, and its complex manufacturing process. The project’s aim was to develop feasible alternatives by generating optimised concepts, selecting the best-performing one, manufacturing it, and demonstrating its performance. The literature study revealed a diverse range of heliostat facet designs and components currently in use. It was found that silvered float-glass reflectors, typically 4mm thick, are the predominant choice in utility-scale solar power tower plants.
Alternate reflector materials identified include reflective films and polished metals. Various facet support structures were identified, such as frames, composite panels, and formed-sheet designs, which are sometimes used with thinner 1mm glass panels. The first type of facet explored was designed for replacing standard 4mm glass panels with glass-equivalent facets. The second type of facet, referred to as long facets, was designed to utilise the extended lengths of non-glass materials, replacing both the facet itself and the support structure of the heliostat. The feasible reflectors and supports identified in the literature study were explored. Various shaping techniques, including hydroforming and mandrel shaping, were evaluated for their applicability. A set of engineering requirements was identified for both types of facets. Concepts were optimised to minimise cost while adhering to the engineering requirements. The performance of each facet was assessed, based on slope error, mass, and cost. The slope error was numerically assessed with finite element analysis using a representative load case. The sandwich-supported facet was selected for further testing. This selection is due to its ease of small-scale construction, design versatility, and potential for low slope errors and facet mass. The distortion of small samples with different reflectors was tested. The polished metal reflector outperformed the reflective film. For this reason the polished metal reflector was selected for prototype manufacturing. Hydroforming proved, in practice, unfeasible for shaping facets with long focal distances, making it unsuitable for solar power tower systems. A larger prototype was constructed and field-tested.
Polished metal reflectors were the most feasible alternative reflector material for heliostat facets. Glass alternate facets proved a potential reduction in facet mass (43.9% for glass-equivalent replacements and 70.0% for long facets). However, the drawback was seen in terms of cost. The estimated cost increases were calculated as 186% and 228% for glass-equivalent and long facets, respectively.Master
Spatial labour market inequality: a comparative analysis of Cape Town, eThekwini, and Gauteng
No full textThesis (PhD)--Stellenbosch University, 2025.Madzudzo, V. 2025. Spatial labour market inequality: a comparative analysis of Cape Town, eThekwini, and Gauteng. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/b2166d61-5280-44aa-b399-2a21623bc8deIncome inequality remains high with the bottom 40 percent of the world’s population receiving less than a quarter of the aggregate income. This threatens the attainment of Sustainable Development Goals (SDGs) in addition to fuelling poverty, crime and violence and constrained economic growth. Although income disparities between countries have improved, the disparity within countries has worsened with 71 percent of the world’s population living in countries where inequality has widened. Labour market inequality has been identified as one of the major determinants of income inequality. Disparities are not only determined by income but also by other important determinants such as gender and location. To achieve Sustainable Development Goals, South Africa, one of the world’s most unequal countries, aims to address labour market inequality. This dissertation investigated three aspects of labour market inequalities through a spatial lens. The first question studies why international trade can have a different impact on the gender wage gap in locations within the same country that share the same international trade agreements. The study specifically examined how export propensity contributes to the gender wage gap in Cape Town and eThekwini, two South African coastal metropoles with distinct sectoral and socio-economic profiles using the Cities Support Program administrative data. The results showed that in Cape Town, trade was associated with a wider gender wage gap while in eThekwini, trade appeared to narrow the gender wage gap. The major takeaway is that there is a heterogeneous sub-national and within-city association between trade and the gender wage gap due to variations in sectoral compositions between two cities in the same country. Policy addressing the gender wage differences should therefore be responsive to local industrial and demographic conditions. This dissertation also investigated the impacts of conflict exposure during the July 2021 riots on total formal employment and on male and female employment in eThekwini and Gauteng, cities in South Africa that have different sectoral compositions. The results showed marginal declines in aggregate formal employment in both eThekwini and Gauteng. The impacts disaggregated by gender showed small and temporary reductions of male and female employment in eThekwini, which is mainly based on the male-dominated manufacturing industry, as well as in Gauteng which is mainly based on the female-dominated tertiary industry. In eThekwini, there was no change in the gender employment gap whereas in Gauteng, the gender employment gap increased. This implies that the gender distribution across sectors with different sensitivity to conflict is important in determining how conflict amplifies or moderates gender gaps. In the service sector, where females tend to dominate, conflict is anticipated to worsen the gender employment gap, whereas in the manufacturing sector, where males tend to dominate, conflict is anticipated to moderate the gender employment gap. Given the dearth of literature on the impact of immigrant special permits on local labour market outcomes and formalization of labour, this dissertation examined the association between the implementation of the Zimbabwe Exemption Permit (ZEP) and local employment outcomes and formalization of foreign labour in Cape Town and eThekwini, cities in South Africa that have different industrial specializations and labour demand. The results showed that the ZEP was associated with formalization of labour and revealed complementarities between local and foreign labour in eThekwini and Cape Town, although in Cape Town, local workers lost jobs to immigrants in the Central Business District only in 2018. The implication is that special permits to undocumented immigrants improve their absorption into the local labour market. Since locals and immigrants are likely to be imperfect substitutes, there will likely be an increase in both local and immigrant employment and a rise in productivity. In conclusion, labour market inequality remains high in South African cities. To attain an equal society, policymakers must take local labour market inequality seriously and consider new place-based policies that take into cognizance industrial specializations and city-wide gender discrimination.Doctora
The Consequences of Female Hospitality: A Study of Women Hosts in 5th century Greek Tragedy
Get PDFThesis (MA)--Stellenbosch University, 2025.Fernandez, K. 2025. The Consequences of Female Hospitality: A Study of Women Hosts in 5th century Greek Tragedy. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/b9838f61-e614-406d-9172-11ce59a1f91fHospitality in ancient Greek literature is shaped by canonical texts such as the Odyssey, which can be reinforced by modern theory to deepen our understanding of ancient cultural dynamics. Within established conventions, the androcentric nature of hospitality is foregrounded, making the presence of female hosts in classical tragedy particularly compelling. Their influence on guests introduces a complexity to their characterization within the broader ritual of hospitality. A key gap emerges in scholarship in the study of feminine manifestations of hospitality, beginning with Homer’s depiction of ideal hostesses such as Arete, contrasted with problematic figures like Circe. Homer offers prescriptive models of ideal and unideal hospitality, and from these portrayals, a pattern emerges that informs accepted convention. The central distinction between Arete and Circe lies in the presence of a male counterpart: Arete hosts alongside her husband, while Circe hosts independently. This suggests a foundational ideal – that for a woman to host appropriately, she must do so in the presence of her husband/a man. This thesis explores whether such a pattern persists in later literary depictions of female hosts. Through comparative analysis of the Odyssey and 5th century Greek tragedy, I examine how tragic hostesses conform to or diverge from Homeric models. Key concepts used to categorize women as ideal or unideal hosts include Host Talking Time, the border, and their relational dynamics with guests. Hamington’s theory of feminist hospitality (2010) informs the development of a distinctly feminine expression of hospitality, which in tragic literature often intersects with violence. Aeschylus’ Clytemnestra anchors this trajectory, presenting an overt display of violent inhospitality that finds nuanced echoes in later playwrights. Sophocles’ Deianeira inadvertently kills her husband upon the arrival of her guest, Iole. Euripides’ Elektra murders her mother-guest, Clytemnestra. Euripides’ Creusa attempts to murder her guest-son, Ion. These examples suggest a recurring pattern: when a woman hosts, violence often ensues. This thesis draws on these findings to offer a new lens through which to view marginalized bodies in Greek literature. Written by men, for male audiences, these texts reflect perceptions of women’s capabilities, justifications, and suffering – as seen in Deianeira’s trauma, Creusa’s grief, and Elektra’s restlessness. These characters are complex and warrant a nuanced appreciation of their roles within the framework of hospitality. By interrogating their portrayals, this study contributes to broader conversations about gender, agency, and the literary construction of feminine power in classical antiquity.Master
Quantum Mechanics on Non-commutative Spaces
Get PDFThesis (PhD)--Stellenbosch University, 2025.Scholtz, F. G. 2025. Quantum Mechanics on Non-commutative Spaces. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/b9e6d500-0427-4c28-8f14-6a088fb23c74We review the development of quantum mechanics on non-commutative spaces
with focus on two- and three dimensional spaces. The consequences of noncommutativity
resulting from three dimensional fuzzy space are reviewed in
detail at both the quantum and classical levels with particular emphasis on the
quantum-to-classical transition. Finally it is shown that Lorentz symmetry is
an emerging phenomenon on three dimensional fuzzy space that brings many
new challenges.Doctora
Investigating the Trends in the Magnitude and Frequency of Extreme Short-Duration Rainfall Depths in South Africa
No full textThesis (MEng)--Stellenbosch University, 2025.Knoetzen, R. 2025. Investigating the Trends in the Magnitude and Frequency of Extreme Short-Duration Rainfall Depths in South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/cd6fe42f-2f99-478d-a974-33fef5bf1eceExtreme short-duration rainfall events pose significant economic, infrastructure and social challenges, yet limited research has investigated the trend in extreme short-duration rainfall in South Africa. This study, therefore, addresses this gap by examining the trends in the magnitude of extreme short-duration rainfall depths (MERD) and their frequency (FERD) across South Africa. The study aimed to determine the trends in MERD and FERD for storm durations ranging from 5 minutes to 24 hours at 18 rainfall stations spanning across all eight homogeneous rainfall zones in South Africa. The short-duration rainfall data were provided by the South African Weather Service, which underwent data quality control, gap filling, and homogeneity tests. The Annual Maximum Series (AMS) and Point Over Threshold Series (POT) were extracted for each storm duration to perform the trend analysis of the MERD and FERD, respectively. The POT series was extracted such that, on average, 3 to 5 annual exceedances occurred. Sub-hourly durations were analysed from 1994 to 2022, whereas at most stations, multi-hourly storm durations were analysed from 1983 to 2022. The trend analysis in this research was performed using the non-parametric Mann-Kendall and Sen’s Slope Estimator, with the robustness of the trends evaluated at significance levels of 1% (very strong), 5% (strong), 10% (moderate), 25% (weak) and 50% (very weak). In general, no dominant national trend direction was apparent as the statistically significant (very weak and very strong) trends occurred in similar proportions for both the MERD and FERD, 29% (27%) and 26% (30%) of the observations, respectively, displayed increasing (decreasing) trends. Although the most robust trends in both indices corresponded with more frequent increasing than decreasing trends, they represented only 8% and 10% of the observations during the MERD and FERD, respectively, indicating that the weak and explanatory trends appeared far more frequently. Regionally, the Western Interior displayed the most consistent increasing trends in both indices, highlighting the need for carefully reconsidering the stationarity assumptions in design rainfall estimates, as well as to prioritise regular maintenance of stormwater infrastructure in this region. By contrast, the most consistent decreasing trends in both indices were observed in the North Western Cape, indicating that the stationarity assumptions in design rainfall estimates are still appropriate within this region. In most regions, the current stationarity assumptions appear to be appropriate, as the weak and insignificant trends appeared more frequently. However, the presence of isolated robust increasing trends within several regions highlights the need for practitioners to make decisions based on station-specific rainfall data rather than regional generalisations.Master
Comparing the influence of regularly prescribed pharmaceuticals on the chemotactic effects of autologous blood clots in the context of diabetic wounds
Get PDFThesis (MSc)--Stellenbosch University, 2025.Armstrong, K. A. 2025. Comparing the influence of regularly prescribed pharmaceuticals on the chemotactic effects of autologous blood clots in the context of diabetic wounds. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/cf24beb9-8330-420b-9b53-4de972ca0422Introduction: Non-healing diabetic foot ulcers (DFUs) are a major complication of type 2 diabetes mellitus (T2DM). Topical autologous blood clot therapy (TABCT) is a novel cellular-based treatment approach involving the application of an autologous blood clot to a non-healing wound. TABCT provides a temporary extracellular matrix (ECM) scaffold, initiating healing through the release of various chemokines and growth factors. It is, however, uncertain whether TABCT would be efficacious in T2DM patients, due to the multifactorial cellular dysregulation prevalent in the diabetic microenvironment, and how systemic levels of pharmaceuticals would influence its efficacy. This study, therefore, compared the effects of regularly prescribed anti-inflammatory (prednisone), anti-glycaemic (metformin), and antibiotic (amoxicillin and rifampicin) agents on chemokine and growth factor release. The pro-regenerative capacity of the TABCT secretome was subsequently compared by assessing peripheral blood mononuclear cell (PBMC) chemotaxis (ex vivo) and fibroblast migration (in vitro). Methods: Twelve study participants were recruited according to specific inclusion criteria and divided into two groups: self-reported healthy controls (n=6) and T2DM patients (n=6). Anthropometric measurements (height, weight, hip, and waist circumference) and metabolic status (blood pressure, blood glucose, and lipid profile) of each participant were assessed. Whole blood samples were collected in one EDTA tube and two citrate tubes. PBMCs were isolated from the EDTA blood sample. The whole blood in the citrate tubes was individually “spiked-in” with the pharmaceuticals of interest prior to ex vivo clot induction. The clot size and protein concentration within the clot secretome were determined. Three separate ELISAs were performed to quantify CCL5, P-selectin and platelet-derived growth factor-BB (PDGF-BB) within the secretome. The chemotactic effects of the clot-derived secretomes on PBMC migration were assessed ex vivo. An in vitro scratch assay was used to determine the effects of the clot-derived secretome on dermal fibroblast-mediated wound closure. Results: As predicted, the T2DM cohort exhibited a poorer metabolic status compared to the controls. Prednisone treatment increased clot size in the control group (1.45 ± 0.19-fold), and elevated clot-derived CCL5 (no treatment 209 ± 107 pg/mL; prednisone 300 ± 104 pg/mL) and PDGF-BB (no treatment 8.7 ± 6.8 pg/mL; prednisone 13.6 ± 10.5 pg/mL) secretion in the diabetic group. Rifampicin upregulated PDGF-BB (no treatment 14.5 ± 4.2 pg/mL; rifampicin 19.9 ± 3.9 pg/mL) expression in the control cohort. Compared with standard cell culture conditions, exposure to the clot secretome reduced PBMC migration velocity and distance, while increasing directionality, confirming the chemotactic effect of blood clots. This chemotactic effect was not influenced by the pharmaceutical treatments, and it did not alter PBMC chemotaxis. The clot secretome stimulated fibroblast migration, with individual variability observed. Metformin significantly enhanced fibroblast migration within the control cohort (no treatment 15.3 ± 2.9%; metformin 21.1 ± 5.5%), but not in the T2DM cohort (no treatment 16.4 ± 4%; metformin 18 ± 4.3%). Conclusion: This study investigated the effects of regularly prescribed pharmaceuticals on the efficacy of TABCT. Based on the specific patient profiles investigated in this study, pro-regenerative effects of the TABC, with and without pharmaceutical treatment, were demonstrated. No major abnormalities were observed in immune cell chemotaxis and in vitro wound closure. However, given the wide variability in disease advancement amongst diabetic patients, pharmaceutical administration should be taken into consideration with the use of TABCT.Master
The changes in acid-base balance during moderate-duration, high-intensity endurance exercise
Get PDFThesis (MSc)--Stellenbosch University, 2025.Jacobs, I. 2025. The changes in acid-base balance during moderate-duration, high-intensity endurance exercise. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/da7227f4-c4b5-4060-aa6f-3fe367ad8704Exercise-induced fatigue (EIF) reduces performance, with metabolic acidosis recognized as a key contributing factor during short-duration, high-intensity exercise. Subsequently, extensive research has examined the efficacy of exogenous buffering agents, most notably sodium bicarbonate, to counteract hydrogen ion (H⁺) accumulation and the associated decline in pH during strenuous exercise (Ak11z et al., 2024; Freis et al., 2017; Krustrup et al., 2015). The acid-base response to exercise of moderate-duration but high-intensity, and the potential for sex-specific differences, are not well documented. Therefore, this study set out to examine changes in acid-base balance during a 10 km running time-trial (TT). Twenty-four healthy men and women took part (mean ± SD: age 22.88 ± 2.69 years, body mass 69.13 ± 13.85 kg, height 173.06 ± 11.04 cm, VO₂max 54.01 ± 4.99 mL·kg⁻¹·min⁻¹). Measurements of blood lactate concentration (B[La]), blood bicarbonate concentration ([HCO₃⁻]), blood pH, and base excess (BE) were collected at baseline (0 km) and again during the TT at 6, 8, and 10 km. The rating of perceived exertion (RPE) was recorded immediately after completion of the 10 km TT. Across time, significant changes were found in BE, [HCO₃⁻], B[La], and pH (p 0.47, p <0.02). Similar perceptual responses were observed between men and women, with RPE values confirming that the 10 km TT was performed at a high intensity (17.65 ± 2.11). Reliability testing showed that TTotal was highly consistent, with excellent reliability (ICC =0.98; CV =1.2%; TEM =45 s). TEnd-sprint demonstrated good reliability, but greater variability (ICC =0.87; CV =4.5%). In summary, the 10 km TT provoked clear and significant disturbances in BE, [HCO₃⁻], pH, and B[La], confirming its nature as a high-intensity exercise challenge. No sex differences were apparent for BE, [HCO₃⁻], or B[La] after adjusting for aerobic capacity. The pH responses retained significant sex and time × sex effects, indicating a genuine sex-specific difference. Although men achieved significantly faster completion times, women reported similar cardiovascular and perceptual strain. The significant correlations between aerobic capacity (VO₂max, Vpeak) and acid-base disturbances emphasize the close connection between endurance fitness and metabolic stress. Furthermore, the excellent reproducibility of this TT supports its use as a reliable performance test for both athletes and researchers. These findings carry implications for training design, evaluation of nutritional strategies, and the development of ergogenic aids that are relevant across sexes.Master
Design, optimisation and validation of molecular diagnostic assays for BRAF p.Val600Glu and associated genetic factors within hairy cell leukemia (HCL) and HCL-like entities at Tygerberg Hospital, South Africa
Get PDFThesis (MMed)--Stellenbosch University, 2025.Mhlongo, Z. J. M. 2025. Design, optimisation and validation of Molecular Diagnostic Assays for BRAF p.Val600Glu and associated genetic factors within Hairy Cell Leukemia (HCL) and HCL-like entities at Tygerberg Hospital, South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/018d655f-4a34-4bad-8a15-cba0c0112431ENGLISH ABSTRACT: The BRAF p.Val600Glu somatic sequence variant is a molecular distinctive feature of hairy cell leukaemia (HCL) and other cancers and an important diagnostic and therapeutic targeted biomarker. Its clonal, heterozygous and detectable via molecular based techniques, such as Amplification Refractory Mutation System Polymerase Chain Reaction (ARMS-PCR). The present study sought to evaluate and validate a molecular diagnostic assay for the identification of the BRAF p.Val600Glu sequence variant for future implementation as a diagnostic tool within our setting. In addition, the design and optimisation of diagnostic assays for other biomarkers, Mitogen-activated protein kinase kinase 1 (MAP2K1) and Kru ppel-like Factor 2 (KLF2) are also evaluated as this would aid in distinguishing HCL from HCL-like patients which is challenging on a morphological level. ARMS-PCR was employed for the BRAF p.Val600Glu assay and compared to Sanger sequencing to determine concordance. Estimated sensitivity and specificity were also determined for the assay validation. For MAP2K1 and KLF2, both PCR and Sanger sequencing were employed to determine various sequence variants in targeted areas. Following successful validation (BRAF) and optimisation (MAP2K1 and KLF2), available HCL and HCL-like tissue samples were screened, comprised of 12 HCL cases and 20 HCL-like cases. The BRAF p.Val600Glu ARMS-PCR based diagnostic assay was successfully validated and a concordance rate of 100% was achieved between ARMS-PCR and Sanger Sequencing. Estimated sensitivity and specificity were also 100%. A satisfactory score via United Kingdom National External Quality Assessment Service (UKNEQAS) external quality assessment (EQA) performance testing was also achieved. Both KLF2 and MAP2K1 diagnostic assays were successfully optimised and a non-synonymous sequence (c311T>C; pLeu104Pro) variant was detected in 1 of 2 splenic marginal zone lymphoma (SMZL) cases, while no sequence variants were detected in MAP2K1. In conclusion, BRAF p.Val600Glu ARMS-PCR based assay was successfully validated and demonstrated to be “fit for use” and ready for clinical use implementation. It is ideal for our resource-limited settings and should be of value in other cancers as well. While KLF2 and MAP2K1 were successfully optimised, a larger sample size cohort of good quality samples are needed. Our study demonstrated the need for accurate sequence variants identification as they influence patient diagnosis and subsequently their treatment plans which is different in HCL and HCL-like patients. This in turn would fast track turnaround time and improve clinical care.AFRIKAANSE OPSOMMING: Die BRAF p.Val600Glu somatiese volgorde variant is 'n molekule re kenmerkende kenmerk van harige sel leukemie (HCL) en ander kankers en 'n belangrike diagnostiese en terapeutiese geteikende biomerker. Die volgorde variant is klonaal, heterosigoties en kan opgespoor word deur molekule re gebaseerde tegnieke, soos Amplifikasie RefraktorieseStelsel Mutasie Polimerase Ketting Reaksie (ARMS-PKR). Die huidige studie het gepoog om 'n molekule re diagnostiese toets te evalueer en te bekragtig vir die identifikasie van die BRAF p.Val600Glu volgorde variant vir toekomstige implementering as 'n diagnostiese hulpmiddel binne ons omliggende instellings. Daarbenewens word die ontwerp en optimalisering van diagnostiese toetse vir ander biomerkers, Mitogeengeaktiveerde proteï enkinase kinase 1 (MAP2K1) en Kru ppel-agtige Faktor 2 (KLF2) ook gee valueer aangesien dit sal help om HCL van HCL-soortgelyke pasie nte te onderskei. ARMS-PKR was gebruik vir die BRAF p.Val600Glu-toets en was vergelyk met Sangervolgordebepaling om konkordansie te bepaal. Geskatte sensitiwiteit en spesifisiteit was ook bepaal vir die toets validering. Vir MAP2K1 en KLF2 beide PCR en Sanger volgordebepaling was gebruik om verskeie volgorde variante in geteikende areas te bepaal. Na suksesvolle validering (BRAF) en optimalisering (MAP2K1 en KLF2), beskikbare HCL en HCL-soortgelyke weefselmonsters was ondersoek, bestaande uit 12 HCL gevalle en HCL-agtige gevalle. Die BRAF p.Val600Glu ARMS-PKR-gebaseerde diagnostiese toets was suksesvol bekragtig en 'n konkordansie koers van 100% was bereik tussen ARMS-PKR en volgordebepaling. Geskatte sensitiwiteit en spesifisiteit was ook 100%. 'n Bevredigende resultaant via United Kingdom National External Quality Assessment Service (UKNEQAS) eksterne kwaliteit assessering (EKA) prestasietoetsing was ook behaal. Beide KLF2 en MAP2K1 diagnostiese toetse was suksesvol geoptimaliseer en 'n nie-sinonieme (c311T>C; pLeu104Pro) variant was opgespoor in 1 van 2 milt marginale sone limfoon (SMZL) gevalle, terwyl geen volgorde variante in MAP2K1 opgespoor was nie. Ten slotte, BRAF p.Val600Glu ARMS-PKR-gebaseerde toets was suksesvol bekragtig en demonstreer dat dit "geskik vir gebruik" en gereed vir kliniese implementering is. Dit is ideaal vir ons hulpbron-beperkte instellings en behoort ook van waarde te wees in ander kankers. Terwyl KLF2 en MAP2K1 suksesvol geoptimaliseer was, is 'n groter steekproefgrootte van goeie gehalte monsters nodig. Ons studie het die behoefte aan akkurate volgordevariante-identifikasie getoon, aangesien dit pasie nt diagnose en gevolglik hul behandelingsplanne wat verskil in HCL en HCL-agtige pasie nte ook beï nvloed.Master
The effects of intergenerational epigenetics of traumatic stress on a sexual defeat rat model
Get PDFNgala, E. M. 2025. The Effects of Intergenerational Epigenetics of Traumatic Stress on a Sexual Defeat Rat Model. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0afae107-97c9-4386-b004-33d5656c8922Thesis (PhD)--Stellenbosch University, 2025.ENGLISH ABSTRACT: Sexual violence is a global issue with profound societal, psychological, and economic consequences. While much research focuses on survivors, limited attention has been paid to the physiological and genetic mechanisms underlying perpetrator behaviour. This study addresses this critical gap by utilizing a modified Sexual Aggression Test (SxAT) in male Wistar rats to investigate the intergenerational effects of traumatic stress on aggression and sexually aggressive behaviours. The study examines the interplay between social isolation, stressinduced neurochemical changes, epigenetic modifications, and aggression-linked gene expression. Social isolation significantly increased aggressive behaviours, including forced mounting and offensive grooming, observed both prior to sexual aggression (Resident-Intruder Test, pre-SxAT) and during the SxAT. Neurochemical analyses revealed that serotonin and oxytocin levels were inversely associated with aggressive behaviours, while corticosterone and vasopressin levels were positively associated, highlighting the role of HPA axis dysregulation in aggression. Epigenetic analyses explored the effects of housing conditions in F0 males and the combined influence of F0 male housing and prenatal stress on DNA methylation (DNAm) patterns in F1 males. In F0 males, social isolation was associated with region-specific changes in DNAm across aggression-linked genes (AR, CRHR1, OXTR, 5-HTR1A), reflecting the impact of chronic stress. In F1 males, the interplay of F0 male housing conditions and prenatal stress resulted in distinct DNAm patterns, with significant region- and gene-specific variations. The study also examined maternal care behaviours and their influence on F1 offspring. Reduced maternal care, influenced by prenatal stress and paternal social isolation, exacerbated aggression and anxiety-like behaviours in F1 males, while higher maternal care mitigated these effects. Maternal care emerged as a critical protective factor against the adverse behavioural and neurobiological outcomes associated with prenatal and postnatal stressors. This study provides novel insights into the biological and epigenetic mechanisms underlying sexual aggression, emphasizing the complex interplay between environmental stressors, neurochemical changes, and epigenetic regulation across generations. The findings underscore the potential for targeted interventions addressing stress and its epigenetic consequences to mitigate aggressive behaviours and prevent the perpetuation of sexual violence.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Doctora