Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320160005&lang=pt vol. 112 num. 9-10 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>No fee increases: Cascades and calamities</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500001&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>The Golden Ratio (1.62) as a dimensionless biological constant</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500002&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>National Research Foundation celebrates science excellence for development</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500003&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>The Marine Protected Areas debate: implications for the proposed Phakisa Marine Protected Areas Network</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500004&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>AUFWIND: An ambitious German microalgae project for producing third-generation biofuels</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500005&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>The Piltdown case: Further questions</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500006&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Finding an influential voice for academies in Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500007&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Response to Thackeray (2016) - The possibility of lichen growth on bones of <i>Homo naledi: </i>Were they exposed to light?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500008&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>SEAmester - South Africa's <i>first </i>class afloat</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500009&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>South Africa in the Antarctic Circumnavigation Expedition: A multi-institutional and interdisciplinary scientific project</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500010&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>A snow forecasting decision tree for significant snowfall over the interior of South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500011&lng=pt&nrm=iso&tlng=pt Snowfall occurs every winter over the mountains of South Africa but is rare over the highly populated metropolises over the interior of South Africa. When snowfall does occur over highly populated areas, it causes widespread disruption to infrastructure and even loss of life. Because of the rarity of snow over the interior of South Africa, inexperienced weather forecasters often miss these events. We propose a five-step snow forecasting decision tree in which all five criteria must be met to forecast snowfall. The decision tree comprises physical attributes that are necessary for snowfall to occur. The first step recognises the synoptic circulation patterns associated with snow and the second step detects whether precipitation is likely in an area. The remaining steps all deal with identifying the presence of a snowflake in a cloud and determining that the snowflake will not melt on the way to the ground. The decision tree is especially useful to forecast the very rare snow events that develop from relatively dry and warmer surface conditions. We propose operational implementation of the decision tree in the weather forecasting offices of South Africa, as it is foreseen that this approach could significantly contribute to accurately forecasting snow over the interior of South Africa. SIGNIFICANCE: • A method for forecasting disruptive snowfall is provided. It is envisaged that this method will contribute to the improved forecasting of these severe weather events over South Africa. • Weather systems responsible for snowfall are documented and the cloud microphysical aspects important for the growth and melting of a snowflake are discussed. • Forecasting methods are proposed for the very rare events when snow occurs over the interior of South Africa when the air is relatively dry and somewhat warmer. <![CDATA[<b>New light on vitamin B<sub>12</sub>: The adenosylcobalamin-dependent photoreceptor protein CarH</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500012&lng=pt&nrm=iso&tlng=pt Adenosylcobalamin (AdoCbl), or coenzyme B12, is a cofactor for enzymes important in metabolism in humans (and other mammals) and bacteria. AdoCbl contains a Co-C bond and is extremely light sensitive, but, until recently, this light sensitivity appeared to have no physiological function. Recently, AdoCbl has been found to act as cofactor for a photoreceptor protein (CarH) that controls the expression of DNA coding for transcription of the proteins needed for synthesis of carotenes in certain non-photosynthetic bacteria. In 2015, the X-ray crystal structures of two dark states of the photoreceptor protein from the bacterium Thermus thermophilus were determined: CarH bound to AdoCbl and CarH bound to a large portion of the cognate DNA operator (and AdoCbl); a light state was also determined in which CarH was bound to cobalamin in which the Co-C bond had been broken. The breaking of the Co-C bond of Ado-Cbl acts as a trigger for the regulatory switch that allows the transcription of DNA. In the two dark states AdoCbl is bound to a conserved histidine from CarH, which displaces the lower 5,6-dimethylbenzimidazole ligand of AdoCbl. In the light state the 5'-deoxyadenosyl group of AdoCbl is replaced by a second histidine from CarH, giving a bis-histidine cobalamin and 4',5'-anhydroadenosine. Genes for B12-dependent photoreceptors are widespread in bacteria. Control of DNA transcription may represent an evolutionarily ancient function of AdoCbl, possibly pre-dating its function as a protein cofactor. SIGNIFICANCE: • A new function for adenosylcobalamin, a light-sensitive form of vitamin B12 with a Co-C bond, has been discovered in bacteria • Some non-photosynthetic bacteria use adenosylcobalamin as a cofactor for the protein CarH, which controls DNA transcription • Three X-ray crystal structures of CarH have been determined: bound to adenosylcobalamin, DNA and after light exposure • A mechanism of action for CarH, based on its structure and on model reactions of vitamin B12, is proposed <![CDATA[<b>Reducing substance use and sexual risk behaviour among men who have sex with men in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500013&lng=pt&nrm=iso&tlng=pt Men who have sex with men have been identified as a population at risk of acquiring and transmitting HIV. Studies in South Africa have reported a high prevalence of HIV, as well as high levels of alcohol and other drug use, among men who have sex with men, and the use of substances (alcohol and drugs) to facilitate their sexual encounters. Since 2007, interventions focused on prevention have been rolled out to vulnerable men who have sex with men and who also use alcohol or other drugs. The interventions include community-based outreach; provision of information on HIV/AIDS, substance abuse, and safer sex practices; and the development of risk-reduction plans. Among 195 men who participated in our study, there were significant reductions in the proportion who used cannabis and ecstasy, including the use of these drugs during sex. No reduction was observed in the use of any other substances. In general, after the intervention our participants reported less frequent use of alcohol and drugs and greater engagement in safer sexual practices. Despite these encouraging findings, the combination of substance use while engaging in sex had actually increased. The study findings suggest that interventions that target men who have sex with men, and who use alcohol and other drugs, could reduce risk behaviours in this population. SIGNIFICANCE: • Contributes to knowledge about risk reduction strategies. • Describes strategies for reducing drug and sexual harm among men who have sex with men. <![CDATA[<b>Do arthropod assemblages fit the grassland and savanna biomes of South Africa?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500014&lng=pt&nrm=iso&tlng=pt The long-standing tradition of classifying South Africa's biogeographical area into biomes is commonly linked to vegetation structure and climate. Because arthropod communities are often governed by both these factors, it can be expected that arthropod communities would fit the biomes. To test this hypothesis, we considered how well arthropod species assemblages fit South Africa's grassy biomes. Arthropod assemblages were sampled from six localities across the grassland and savanna biomes by means of suction sampling, to determine whether the two biomes have distinctive arthropod assemblages. Arthropod samples of these biomes clustered separately in multidimensional scaling analyses. Within biomes, arthropod assemblages were more distinctive for savanna localities than grassland. Arthropod samples of the two biomes clustered together when trophic groups were considered separately, suggesting some similarity in functional assemblages. Dissimilarity was greatest between biomes for phytophagous and predacious trophic groups, with most pronounced differentiation between biomes at sub-escarpment localities. Our results indicate that different arthropod assemblages do fit the grassy biomes to some extent, but the pattern is not as clear as it is for plant species. SIGNIFICANCE: • Provides the first comparison of arthropod composition between grassland and savanna biomes of South Africa. • Explores whether these two biomes show distinct arthropod assemblages. • Documents the characteristics of arthropod assemblages. • Confirms that plant assemblages of biomes are more distinguishable than arthropod assemblages. <![CDATA[<b>Assessment of visualisation skills in biochemistry students</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500015&lng=pt&nrm=iso&tlng=pt In the field of biochemistry, the use of external representations such as static diagrams and animations has increased rapidly in recent years. However, their effectiveness as instructional tools can be hindered if students lack the visual literacy and cognitive skills necessary for processing and interpreting such representations. We aimed to identify and assess visualisation skills necessary for effective processing of external representations in biochemistry. We used a modified Bloom's taxonomy to identify the cognitive skills essential for optimal visual literacy, and designed probes based on those skills to develop a test instrument. Student responses to the probes were scored and processed with the Rasch model. This approach enabled us to rate the degree of difficulty of each visualisation skill on a linear logit scale, and to generate a person-item map to measure biochemistry students' level of visual literacy. The results showed that the identified visualisation skills could be measured reliably, and the Rasch model was effective both for ranking the skills according to level of difficulty and for estimating a student's relative level of visual literacy. SIGNIFICANCE: • Addresses a recurring problem in biochemistry and similar fields. • Identifies relevant skills to inform teaching and learning in biochemistry. <![CDATA[<b>Pesticide management practices among rural market gardening farmers near Harare, Zimbabwe</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500016&lng=pt&nrm=iso&tlng=pt In 2014, we carried out a survey in Chinamhora and Chihota communal lands on the outskirts of Harare city, with the aim of understanding pesticide management practices among market gardening farmers. The farmers grew vegetables that mostly included tomatoes, cabbages, rape, cucumbers, onions and carrots, and they used mainly organophosphates and pyrethroids to control pests. A questionnaire was administered to 119 male heads of households across both study areas. The questionnaire contained 13 closed-ended questions in three sections: source and quality of pesticides, handling and use, and storage and disposal of pesticides used to protect crops. The study identified numerous gaps related to the handling of pesticides. Although the quality of labelling and packaging can largely identify the quality of pesticide, most of the farmers (77.3%) could not distinguish between genuine and counterfeit pesticides; approximately half (47.9%) of the farmers were not concerned about expiry dates; 27% did not observe post-spray periods; and 63% did not take precautions according to colour-coding of the pesticides. Also of concern were the large numbers of farmers who were not using protective coveralls (54.3%); a substantial number who were not using knapsacks for spraying (21.8%); poor storage of the pesticides, as shown by the variation in storage facilities; the use of empty pesticide containers for domestic purposes (20.2%); and lack of strict adherence to recommended dose levels, with some farmers (28.6%) merely estimating the dilution of pesticides. Training through outreach programmes is recommended. SIGNIFICANCE: • Identifies gaps in the way pesticides are used and stored by rural market gardening farmers. • Highlights the need for government agricultural extension workers to hold regular workshops for farmers. • Indicates the need for government ministries to monitor counterfeit pesticides. <![CDATA[<b>Do African microfinance institutions need efficiency for financial stability and social outreach?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500017&lng=pt&nrm=iso&tlng=pt Microfinance institutions (MFIs) have the dual objective of providing social welfare and financial stability. We evaluated the financial efficiency of MFIs in sub-Saharan African countries by comparing their regional performances during the period 2004-2013. We addressed prevailing MFI heterogeneity by using the concept of 'metafrontier'. The results showed that on an average, more than half the MFIs showed a drop in productivity. The measure of how much one country gets closer to or further away from world frontier technology is commonly known as the TGC score. In world frontier technology, East and South Asian countries have taken the lead (TGC score 1.0048) while sub-Saharan African countries lag behind (TGC score 1.0020). Most East and South Asian countries have a TGC score of 1, and most sub-Saharan African countries have a TGC score less than 1. This signifies that Asian countries lead world frontier technology and most African countries do not. The decomposition of efficiency scores showed that with regard to technical changes, African nations had progressed on average only 0.01%, and efficiency change scores had regressed by 0.59% annually. Significance: • First efficiency study on microfinance institutions and their heterogeneity in Africa. • The results show robust discrimination among the efficiency scores. <![CDATA[<b>San and Nama indigenous knowledge: The case of <i>|nhora (Pteronia camphorata) </i>and its medicinal use</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500018&lng=pt&nrm=iso&tlng=pt A hitherto unidentified medicinal plant is here identified for the first time as Pteronia camphorata (L.) L., an aromatic shrub of the Asteraceae family endemic to the western and southern coastal region of South Africa. The plant was described in this journal by Laidler┬╣ in 1928 as 'D/nhora buchu', and is one of the important types of buchu used by the Nama people. We report the traditional medicinal uses among San and Nama people, based on our interviews with rural participants. These include the treatment of colds, influenza, chest ailments and tuberculosis, as well as convulsions, haemorrhoids and inflammation of the neck. The major and minor chemical compounds of the essential oil that is produced by the plant are identified, together with the site of accumulation of this volatile oil within the leaf. We also investigated the plant's antimicrobial activity against a selection of a yeast and two Gram-negative and one Gram-positive bacteria, all of which are associated with respiratory infections. P. camphorata is scientifically poorly known but is an important San and Nama traditional remedy. Our study not only prevents the potential loss of historically important indigenous knowledge, but also provides the first scientific evidence to validate the traditional use of |nhora against upper and lower respiratory tract infections, including tuberculosis. This detailed study has wider application in demonstrating the fragility of the oral-traditional knowledge of a scientifically neglected indigenous group. It also highlights the scientific and practical importance of preserving traditional plant-use knowledge within a botanically diverse region. SIGNIFICANCE: • Reveals the botanical identity of |nhora, an important Nama medicinal plant. • Presents scientific evidence to validate the traditional uses. • Contributes to the cultural heritage of a scientifically neglected indigenous group. • Demonstrates the fragility of oral-traditional knowledge. <![CDATA[<b>Implications of summer breeding frogs from Langebaanweg, South Africa: Regional climate evolution at 5.1 mya</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500019&lng=pt&nrm=iso&tlng=pt No direct palaeoclimatic proxies have been available to indicate the seasonality or amount of rainfall on the west coast of southern Africa during the Early Pliocene. The Benguela Upwelling System (BUS) is today one of the factors responsible for the present-day aridity on the west coast of southern Africa. The initiation of the BUS is frequently linked to the entrenchment of aridity and the establishment of the current winter rainfall pattern on the west coast; however, marine proxies are inconclusive regarding the effects of past fluctuations in the BUS and sea surface temperatures on the rainfall regime. Neither the fossil evidence nor the fact that plants using the C3 photosynthetic pathway predominate at this time, provide direct evidence of winter rainfall at Langebaanweg. We challenge certain assumptions which are commonly made in the literature regarding the timing of inception of a winter rainfall regime on the west coast and the onset of aridity in the Langebaan region, and provide new evidence as to seasonality of rainfall at Langebaanweg in the Early Pliocene. Herein, the identification of frog species from the genus Ptychadena from Langebaanweg provides new and compelling evidence for a summer rainfall regime, or of at least significant summer rainfall, at 5.1 mya in the southwestern Cape of South Africa. SIGNIFICANCE: • Advances understanding of the evolution of the winter rainfall zone on the west coast of South Africa • Assesses evidence for the inception of aridity and a winter rainfall regime on the west coast of South Africa • Fossil Ptychadenidae from the Early Pliocene site of Langebaanweg provide evidence for a summer rainfall regime at 5.1 mya on the west coast of the southwestern Cape. <![CDATA[<b>Differential involvement of ascorbate and guaiacol peroxidases in soybean drought resistance</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500020&lng=pt&nrm=iso&tlng=pt Soybean (Glycine max L.) is a small but growing component of the agricultural economy of South Africa and is predicted to become a major crop in Africa because of its high protein content. Drought induction at flowering or early stages of pod development has detrimental effects on soybean yield. As antioxidative enzymes play a protective role in plants during various abiotic stress conditions, this study was conducted to investigate how ascorbate (Enzyme Commission (EC) number 1.11.1.1) and guaiacol (EC: 1.11.1.7) peroxidases are involved in soybean drought resistance at different maturity stages (flowering and pod development). We also investigated whether the levels of these enzymes decline with plant maturity. Three tolerant soybean genotypes (G1, G2, G3) and a susceptible genotype (G4*) were used. These cultivars were categorised according to their sensitivity to drought stress in previous studies. The activity of ascorbate peroxidase was significantly induced by drought stress at both growth stages with higher activity in the resistant than susceptible plants, strongly supporting the protective role of this enzyme against drought stress at both developmental stages. The guaiacol peroxidase activity was induced to higher levels in the resistant than in the susceptible plants at flowering only, with no significant increase observed at pod development stage, indicating its selective protective involvement against drought stress. Interestingly, the levels of these enzyme activities were induced in all cultivars at both developmental stages, irrespective of drought stress, indicating that their activities increased with maturity. SIGNIFICANCE: • Guaiacol peroxidase is selectively involved in soybean drought resistance at flowering stage. • The upregulation of ascorbate peroxidase activity at both growth stages in drought-resistant cultivars suggests that this enzyme could be used as a biochemical marker of drought resistance in soybeans. • In contrast to the literature, activities of both enzymes increased with maturity irrespective of whether the plant is drought susceptible or resistant. <![CDATA[<b>Drought, climate change and sustainability of water in agriculture: A roadmap towards the NWRS2</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500021&lng=pt&nrm=iso&tlng=pt The frequency and intensity of drought, extreme events and high wind velocities in South Africa are expected to increase in the next century as a result of the changing climate. The National Water Resource Strategy 2 (NWRS2) has set out the general and strategic directions for water resources management in the country for the next 20 years. However, the strategy does not draw a framework tailored specifically for agricultural use, with specific measures and goals. Therefore, to reach sustainability of water in agriculture, four major strategic goals are suggested, on which research institutions can focus and promote through good governance. The strategy emphasises: (1) crop research to find new drought-and heat- tolerant and resistant breeds and varieties; (2) intensified research in agricultural practices; (3) increasing the efficiency of water use within agriculture; and (4) integrating all these strategic goals within a sustainable research framework. Finally, the research calls for rapid action and implementation. SIGNIFICANCE: • The framework is proposed for stakeholders and policymakers in higher education, agriculture and resources management in South Africa for new research horizons at national level to improve overall agricultural sustainability by 2030 as stipulated by the Millennium Development Goals. <![CDATA[<b>An extended farm site development method</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500022&lng=pt&nrm=iso&tlng=pt The inefficient and ineffective use of arable land in South Africa is one of the numerous challenges within its agricultural sector. Previous research has indicated that a method, the Farm Site Development Method (FSDM), could increase the effective and efficient use of arable land by providing a roadmap to the farm owner for incrementally transforming the current state facilities and resources of a farm towards a future saturation state. The FSDM was then demonstrated at a crop-producing farm and several opportunities existed to extend its utility. Here we suggest its extension for application to a livestock farm, and also include optimisation techniques, demand planning and financial planning. SIGNIFICANCE: • Extension of the Farm Site Development Method, and its demonstration at a livestock farm, for facilities and financial planning within the agricultural sector <![CDATA[<b>Retraction</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000500023&lng=pt&nrm=iso&tlng=pt The inefficient and ineffective use of arable land in South Africa is one of the numerous challenges within its agricultural sector. Previous research has indicated that a method, the Farm Site Development Method (FSDM), could increase the effective and efficient use of arable land by providing a roadmap to the farm owner for incrementally transforming the current state facilities and resources of a farm towards a future saturation state. The FSDM was then demonstrated at a crop-producing farm and several opportunities existed to extend its utility. Here we suggest its extension for application to a livestock farm, and also include optimisation techniques, demand planning and financial planning. SIGNIFICANCE: • Extension of the Farm Site Development Method, and its demonstration at a livestock farm, for facilities and financial planning within the agricultural sector