Academy of Science of South Africa (ASSAf): Open Journal Systems
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Climate Change Mitigation at City Level through the Lens of South Africa's Regulatory Framework for Bioenergy
No full textClimate change is one of the most significant challenges of the 21st century. To combat climate change the international community has agreed to keep the average temperature increase well below 2°C above pre-industrial levels. Despite this consideration, the latest scientific evidence suggests that the planet has already warmed by 1.1°C above pre-industrial levels. The slow reaction by national governments to reducing greenhouse gas emissions has prompted cities to take ownership of climate change mitigation action and drive global intervention from the sub-national level. These urban areas are home to more than half of the world's population and have immense energy requirements, and typically rely heavily on fossil fuels to meet this demand. Therefore, a shift to city level climate governance is significant as cities are both the victims and the culprits of climate change. Should cities supplant fossil fuels with renewable energy initiatives in meeting their energy demands, this would provide a significant boost to climate change mitigation efforts. Bioenergy as a form of renewable energy can potentially contribute to the energy mix in cities through biomass exploitation while simultaneously addressing climate change mitigation efforts. This article focusses on the role of bioenergy in the energy discourse in cities and the potential of law and policy to contribute to developing these biomass-based systems. The article provides insight into the South African bioenergy regulatory framework from an energy and climate change perspective and offers an account of what bioenergy can contribute to cities when considering the transition to a low-carbon economy
Mobilities and Cosmopolitanisms in African and Afrodiasporic Literatures (Anna-Leena Toivanen)
No full textIn vitro cytotoxic and apoptotic activity of the Mauritian marine sponge Neopetrosia exigua
No full textMarine sponges belonging to the genus Neopetrosia represent a quasi-inexhaustible source of novel cytotoxic compounds. Yet studies delineating their molecular mechanisms of action in cancer cells remain scarce. We investigated the cytotoxic and apoptosis inducing potential of the Mauritian marine sponge Neopetrosia exigua derived crude extract, hexane and ethyl acetate fraction. Their cytotoxic activity was screened against four cancer cell lines and two non-malignant cell lines via the Alamar Blue metabolic assay. The level of intracellular reactive oxygen species (ROS) production, endogenous antioxidant enzyme activity (catalase and superoxide dismutase) and mitochondrial membrane potential were determined. The ability of the active extract to induce apoptosis in cancer cells and modulate the expression levels of apoptotic markers (caspases and polyADP-ribose polymerase (PARP)) was further evaluated via western blot. The ethyl acetate fraction (NEEAF) displayed the highest inhibitory effect with an IC50 of 6.87 μg/mL against the liver hepatocellular carcinoma cell line (HepG2). Mechanistically, NEEAF induced morphological hallmarks characteristic of apoptosis, increased ROS production, decreased catalase and superoxide dismutase activity and mitochondrial membrane depolarisation in a concentration-dependent manner compared to the control (p<0.05). In addition, NEEAF induced the activation of caspase-9, -7, -3 and cleavage of PARP. Overall, this study provides biochemical evidence for oxidative stress-mediated cytotoxicity and apoptosis in HepG2 cells by NEEAF. Further in-depth investigations are needed to isolate the active constituents, which may potentially lead to the development of novel anticancer therapeutics.
Significance:
Marine sponges represent an untapped goldmine of structurally unique compounds with interesting anticancer properties.
This important initial investigative work will set the stage for more in-depth mechanistic studies and chemical characterisation of potentially novel bioactive compounds from the genus Neopetrosia.
This work will also help to strengthen frameworks oriented towards the conservation of Neopetrosia species in the Western Indian Ocean region
Co-infection of urogenital schistosomiasis and malaria and its association with anaemia and malnutrition amongst schoolchildren in Dutse, Nigeria
No full textSchistosomiasis is a neglected tropical disease. Sub-Saharan Africa accounts for 93% of the world’s 207 million schistosomiasis cases. Urogenital schistosomiasis and malaria are both public health problems in Nigeria, where they are endemic. We determined the co-prevalence of urogenital schistosomiasis and malaria in schoolchildren and assessed its implication on anaemia and malnutrition. This cross-sectional study was conducted amongst primary schoolchildren in the Warwade, Saya Saya and Jigawar Daha villages of Nigeria. Urine samples were collected to detect Schistosoma haematobium eggs, and finger prick blood was used for haemoglobin concentration and malaria diagnosis. Nutritional status was assessed using anthropometric measurements and a pre-tested questionnaire. The overall prevalence and density of S. haematobium were 27.7% and 9 eggs/10 mL, respectively, with significant differences between villages and sexes. The prevalence of malaria and infection density was 10.4% and 330 mps/μL, respectively. Co-infection prevalence was 3.3%. Anaemia prevalence was 66%, with significant variation across villages and between sexes. Prevalence of stunting, underweight, and wasting was 41.7%, 46%, and 29.7%, respectively. Mean haemoglobin concentrations in Plasmodium and children co-infected with urogenital schistosomiasis were significantly lower than those who were negative for the infection. No significant association was observed between malnutrition and single or co-infection of urogenital schistosomiasis and malaria. After adjusting for variables associated with anaemia, village of residence remained a significant predictor of anaemia. Water contact activities, such as fishing, swimming, and irrigation, emerged as independent risk factors of S. haematobium infection.
Significance:
Urogenital schistosomiasis and malaria infections are prevalent in communities around Warwade dam in Dutse, Nigeria, and cause anaemia. Continuous monitoring, proper treatment and regular intervention is desirable in the communities
Construction and testing of a low-cost device for the collection of rainfall samples destined for stable isotope analysis
No full textOxygen- and hydrogen-isotope ratios in rainfall provide important hydroclimatic information, yet despite a global network of rainfall isotope measurements, significant geographical gaps exist in data coverage, with only three long-term stations spanning the southern African region. Project-based, ad hoc collections of rainfall for isotope analysis can improve this coverage. However, all rainfall samples that are destined for stable isotope analysis must be collected in such a way to avoid evaporation and resultant isotope fractionation. While such rainwater collectors are available commercially, both the product and shipping are prohibitively costly. We describe the construction of a simple rainfall collector using a design from the literature and materials that are readily available in South African hardware stores. Our rainwater collector can be constructed for the much lower cost of just under ZAR820 in comparison with the cost of ZAR9300 inclusive of shipping from commercial outlets (2022 prices). Our design modifications have the added advantage of portability, with the rainwater collector housed in a bucket with a handle. The device was tested by comparing its performance, in terms of evaporative water loss and isotopic fractionation, with that of an open bottle, using tap water in both cases. Testing confirmed that the collector prevented evaporation over a one-week period, indicating that it is suitable for weekly or more frequent sampling of rainfall. Although the design described was based on materials procured in South Africa, it could easily be adapted for construction elsewhere.
Significance:
Hydrogen and oxygen isotope composition of rainfall provides valuable climatic information.
Rainwater collectors for stable isotope samples must prevent evaporation, as evaporation will alter the isotopic signature.
We describe the construction and testing of a bespoke, low-cost and portable device that can be used to collect rainfall samples destined for oxygen- and hydrogen-isotope analysis without significant evaporation
Air quality risks pertaining to tailings storage facilities within the Witwatersrand goldfields
No full textA pre and post-test assessment of oral health intervention: caregivers’ knowledge and attitudes at long-term care facilities in the eThekwini district, KwaZulu-Natal.
Get PDFOral health remains a neglected aspect of health care among vulnerable populations residing at long-term care facilities. Routine oral health education and training for caregivers have the potential to improve oral health provision.
Aims and Objectives
To determine the effect of an oral health intervention on caregivers’ knowledge and attitudes.
Methods
This exploratory study utilised a pre/post-test assessment approach. A total of participated. A pre-test questionnaire was distributed among 145 caregivers from seven long-term care facilities in eThekwini district. An online oral health educational intervention was implemented four weeks later. Six months later, a post-test questionnaire was administered. A Mann-Whitney test and paired sample test were used for statistical analysis. p<0.05 was considered statistically significant.
Results
Participants (n=19; 13.1%) reported that brushing twice a day and flossing were the two most important dental habits in the pre-intervention phase, compared to 71% (n=103) in the post-intervention phase. Caregivers (n=124; 85.5%) in the pre-intervention phase reported to feel that they should be trained in providing oral health care, compared to 93.8% (n=136) in the post-intervention phase.
Conclusion
The oral health intervention had a positive effect on caregivers’ knowledge and attitudes. This finding necessitates routine oral health education and training for caregivers
Entomopathogenic fungi associated with cultivated honeybush, Cyclopia spp., in South Africa and their pathogenicity towards a leafhopper pest, Molopopterus sp. (Hemiptera: Cicadellidae)
No full textThe southern and eastern parts of the African Fynbos region favour the production of honeybush tea. Honeybush biomass and extracts are used to prepare a beverage both locally and internationally, mainly as herbal tea with health benefits. Honeybush tea is mostly grown organically requiring natural control measures for pests and diseases. The leafhopper, Molopopterus sp., is one of the most important pests of cultivated honeybush in South Africa, as its feeding compromises the quality and quantity of the yield through leaf discolouration and reduction of the photosynthetic area. Local entomopathogenic fungi (EPF) can provide a pool of potential biocontrol agents for this pest. Therefore, a total of 98 soil samples were collected from organically grown honeybush fields and vegetation surrounding the honeybush fields in the Western Cape province of South Africa. Entomopathogenic fungi were isolated using the insect bait method and were characterised using molecular techniques. Twenty fungal isolates of Metarhizium anisopliae and Fusarium oxysporum were recovered from soil samples, of which 70% were from honeybush fields and 30% were from surrounding vegetation. Fusarium oxysporum isolates comprised 20% of the recovered isolates; M. anisopliae the remainder. Laboratory bioassays of the recovered isolates against adults and nymphs of the leafhopper, showed that F. oxysporum isolates caused 10–45% mortality and M. anisopliae isolates 30–80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both nymphs and adults at a concentration of 1 × 107 conidia/ml.