Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320070003&lang=en vol. 103 num. 5-6 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Rocky roadmap to the future</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Preliminary results of the South African Innovation Survey, 2005</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300002&lng=en&nrm=iso&tlng=en <![CDATA[<b>Asthma, <i>Euphorbia hirta </i>and its anti-inflammatory properties</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300003&lng=en&nrm=iso&tlng=en Euphorbia hirta is a plant used in traditional medicine for a variety of diseases, such as cough, asthma, colic dysentery and genito-urinary infection. This plant, belonging to the family Euphorbiaceae, is also known as the Australian asthma herb or Queensland asthma weed, and is not toxic when taken in typical dosages. In South Africa, it is commonly used for asthma, which is one of the most common respiratory complaints. Although corticosteroids are considered the best means of defence against this debilitating illness, many people, especially in poor countries, rely on herbal remedies for its treatment. We discuss recently published results to assess the effect of the plant using the BALB/c murine asthma model. We also review the different compounds found in plant extracts, in an attempt to understand the reason for its anti-inflammatory properties. We conclude that the flavonoids quercitrin (converted to quercetin in the alimentary canal) and myricitrin, as well as the sterols 24-methy-lene-cycloartenol and -sitosterol, exert note-worthy and dose-dependent anti-inflammatory activity. The triterpene ß-amyrin also seems to exert a similar anti-inflammatory activity. Tannins and tannic acid derivatives, also present in the plant, have antiseptic effects and the two triterpenoids, taraxerone (EH-1) and 11a,12a-oxidotaraxerol (EH-2), in E. hirta demonstrate antibacterial and antifungal properties. The effectiveness of E. hirta in treating asthma may lie predominantly in the synergistic relationships between the flavonoids, sterols and triterpenoids. <![CDATA[<b>Rating the NRF's rating system</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300004&lng=en&nrm=iso&tlng=en Euphorbia hirta is a plant used in traditional medicine for a variety of diseases, such as cough, asthma, colic dysentery and genito-urinary infection. This plant, belonging to the family Euphorbiaceae, is also known as the Australian asthma herb or Queensland asthma weed, and is not toxic when taken in typical dosages. In South Africa, it is commonly used for asthma, which is one of the most common respiratory complaints. Although corticosteroids are considered the best means of defence against this debilitating illness, many people, especially in poor countries, rely on herbal remedies for its treatment. We discuss recently published results to assess the effect of the plant using the BALB/c murine asthma model. We also review the different compounds found in plant extracts, in an attempt to understand the reason for its anti-inflammatory properties. We conclude that the flavonoids quercitrin (converted to quercetin in the alimentary canal) and myricitrin, as well as the sterols 24-methy-lene-cycloartenol and -sitosterol, exert note-worthy and dose-dependent anti-inflammatory activity. The triterpene ß-amyrin also seems to exert a similar anti-inflammatory activity. Tannins and tannic acid derivatives, also present in the plant, have antiseptic effects and the two triterpenoids, taraxerone (EH-1) and 11a,12a-oxidotaraxerol (EH-2), in E. hirta demonstrate antibacterial and antifungal properties. The effectiveness of E. hirta in treating asthma may lie predominantly in the synergistic relationships between the flavonoids, sterols and triterpenoids. <![CDATA[<b>Elephant contraception: Silver bullet or a potentially bitter pill?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300005&lng=en&nrm=iso&tlng=en Elephant contraception is increasingly being identified as a solution to the problem of growing elephant numbers in conservation areas. As a result, it is now being incorporated into elephant management and policy in South Africa. We point out that elephant contraception may have numerous physical, social and ecological side-effects. These side-effects should be identified in advance and their implications incorporated into elephant contraception programmes, in line with the protocols of adaptive management. This provides the opportunity to learn from the process, and may help avoid some of the mistakes made in the course of elephant culling. <![CDATA[<b>Inventory of chlorinated dioxin and furan sources and releases in Potchefstroom, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300006&lng=en&nrm=iso&tlng=en South Africa ratified the stockholm convention on Persistent Organic Pollutants in 2002, and has to formulate a national implementation plan that includes an inventory of sources and releases of these chemicals. An investigation of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzo-furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) was conducted in the Potchefstroom area, using the UNEP Toolkit. These sources, on which negligible information was available, were identified by means of questionnaires and interviews, and the releases quantified using default emission factors. The total estimated release of PCDD/Fs in the study area was calculated as 0.396 g TEQ(toxic equivalency quotient)/yr. The highest amounts were generated from sewage and sewage treatment (0.120 g TEQ/yr) and waste incineration (0.111 g TEQ/yr). This is the first such inventory conducted in this country, and has identified potential sources for which emission factors could be refined under South African conditions. <![CDATA[<b>Bioactive components of the uteroactive medicinal plant, <i>Gunnera perpensa </i>(or <i>ugobo)</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300007&lng=en&nrm=iso&tlng=en Gunnera perpensa l., family gunneraceae, is among the most frequently cited of about 90 species used by South African traditional healers in pregnancy-related medicines. Seven bioactive compounds were isolated from Gunnera perpensa roots, with five of these being novel to the species at the time of identification. These are 3,3',4'-tri-O-methyl ellagic acid lactone, ellagic acid lactone, 1,1'-biphenyl-4,4'-diacetic acid, p-hydroxybenzaldehyde and Z-methyl lespedezate. The known antihaemorrhagic, antimutagenic and anticarcinogenic activities of some of these compounds signifies that they could be beneficial during pregnancy and birth. Two partially characterized phenolic glucosides strongly enhanced the response of isolated rat uterine tissue to acetylcholine. All compounds isolated in this study are phenolic, and such compounds are generally known for their antiseptic and anti-oxidative properties, which could benefit both the fetus and mother during pregnancy. The bioactivities described link to some of the documented properties attributed to this species, therefore supporting confidence of traditional healers in the safety, efficacy, and health benefits of this medicinal plant. <![CDATA[<b>Physical and biological processes at the Subtropical Convergence in the South-west Indian Ocean</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300008&lng=en&nrm=iso&tlng=en A detailed hydrographic and biological survey was conducted in the region of the Subtropical Convergence in the Indian sector of the Southern Ocean in April 2007. Hydrographic data revealed that the subsurface expression of the Subtropical Convergence (at 200 m), marked by the 10°C isotherm, appeared to meander considerably between 41°S and 42°15'S. Total surface chlorophyll-a concentration was low and ranged from 0.03 to 0.42 μg l-1 and was always dominated by the pico- (<2 μm) and nano-(2-120 μm) size classes, which contributed between 81% and 93% of the total pigment. The total chlorophyll-a integrated over the top 150 m of the water column showed no distinct spatial trends, and ranged from 12.8 to 40.1 mg chl-a m². There were no significant correlations between the total integrated chlorophyll-a concentration and temperature and salinity (P &gt; 0.05). The Zooplankton community was dominated, numerically and by biomass, by mesozooplankton comprising mainly copepods of the genera, Oithona, Paraeuchaeta, Pleuromamma, Calanus and Clausocalanus. An exception was recorded at those stations in the region of the front where the tunicate, Salpa thompsoni, dominated the total Zooplankton biomass. <![CDATA[<b>A full-scale static radar cross-section (RCS) measurement facility</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300009&lng=en&nrm=iso&tlng=en We present an overview of a full-scale static RCS near-field measurement facility, and some sample measurements. The measurements, and the target, are in the near-field RCS range. Corrections for distance are made using sophisticated software. <![CDATA[<b>Recovery of the critically endangered river pipefish, <i>Syngnathus watermeyeri, </i>in the Kariega Estuary, Eastern Cape province</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300010&lng=en&nrm=iso&tlng=en An intensive ichthyofaunal SURVEY IN the permanently open Kariega Estuary along the Eastern Cape coast has identified a breeding population of the critically endangered river pipefish, Syngnathus watermeyeri, within the middle and upper reaches of the system. This is the first recorded capture of this species in the estuary for over four decades. We suggest that the presence of S. watermeyeri is the result of the heavy rainfall within the region, which contributed to the establishment of optimum habitat requirements (mesohaline conditions and increased food availability) of the pipefish. <![CDATA[<b>Targeting of glycosylated lipoplexes in HepG2 cells: Anomeric and C-4 epimeric preference of the asialoglycoprotein receptor</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300011&lng=en&nrm=iso&tlng=en <![CDATA[<b>Can water burn?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300012&lng=en&nrm=iso&tlng=en We investigate the possibility of a spontaneous collapse of the nuclei constituting the water molecule. We show that, due to a practically exact agreement of the energy of the p + p + 16O threshold and a resonance state of the 18Ne nucleus, the probability of nuclear fusion involvingp+p+ 16O → 18Ne*(4.522, 1-) in the rotationally excited H2O molecule is significantly enhanced. The calculation of the fusion probability is performed using a scheme analogous to the linear combination of atomic orbitals (LCAO), well known in the theory of molecules. <![CDATA[<b>Antimicrobial activity of rare actinomycetes isolated from natural habitats in KwaZulu-Natal, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300013&lng=en&nrm=iso&tlng=en This paper reports the presence of new antibiotic-producing organisms in the relatively underinvestigated region of KwaZulu-Natal, South Africa. Using a modified agar-streak method and selective isolation media during the primary screening phase, eighty isolates showing antimicrobial activity were isolated from soil samples of various habitats in the KwaZulu-Natal Midlands. The use of selective isolation media, with antibiotic incorporation and/or heat pretreatment, enhanced the isolation of certain rare actinomycete colonies. The number of culturable antibiotic-producing microorganisms constituted about 3% (on average) of the total microbial population in the different samples studied. The highest percentage of antimicrobially active isolates came from a forest soil site whereas the lowest percentage was present in a riparian soil. One of the isolates, N8, tentatively identified as an Intrasporangium species, was isolated from barnyard soil at a poultry farm. It produced at least one broad-spectrum antibiotic active against both Gram-positive and Gram-negative bacteria and fungi and also inhibited the growth of all seven test organisms, especially Pseudomonas fluorescens and Xanthomonas campestris pv campestris at minimum inhibitory concentrations (MIC) of 0.0625 μg/ml and 0.0025 μg/ml, respectively. To our knowledge, members of this actinomycete genus have not been associated previously with antibiotic production. These data confirm that KwaZulu-Natal soils harbour rare actinomycetes that inhibit the growth of Pseudomonas fluorescens and Xanthomonas campestris pv campestris, representatives of two genera which are notoriously difficult to contain in the field. Such antibiotic producers should become more commercially important if the current trend towards the use of biocontrol agents rather than chemical treatments of plant diseases persists. <![CDATA[<b>Evidence for an increasing incidence and severity of Harmful Algal Blooms in the southern Benguela region</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300014&lng=en&nrm=iso&tlng=en Harmful Algal Blooms (HABs) may lead to catastrophic mortality over a range of trophic levels and impact on fisheries, local species' populations, conservation management and the health of both livestock and humans. Consequently, any increase in frequency and/or toxicity of these events is of concern. Recently this concern has been realized, with reported increases in the frequency of HABs from all continents except Antarctica. This reported rise is supported by data from the Benguela coast of western South Africa, where, since 1930, there has been a significant increase in the frequency of HABs and a slight increase in their average severity. There has been a sixfold increase in the number of HABs per decade since the 1960s, with the period 1990-2005 experiencing the greatest number of blooms, as well as the most severe in terms of associated mortality. The recent occurrence of previously unrecorded HAB-causing species in this region may go some way to explaining this trend, and further implies that the increase is unlikely to diminish in the near future. <![CDATA[<b>A theory of quantitative trend analysis and its application to South African general elections</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300015&lng=en&nrm=iso&tlng=en Trends are usually defined as progressive changes in a particular phenomenon. If the phenomenon can be characterized by one variable over time (such as the price of some item), then a trend analysis is fairly simple. Phenomena are often characterized, however, by more than one variable at particular discrete time intervals. In such cases a trend analysis becomes more complex and ambiguous. If enough data are available, however, trends between two subsequent times can be represented by so-called transition matrices. The theory of such matrices for the description of voting patterns was developed in the United Kingdom in the 1970s. South African general elections represent an ideal test case for such theories as both the number of independent results (17 000 voting districts versus about 240 three-way contested constituencies in the U.K.) and the number of parties (about 20 versus 4 in Britain) are much greater in the South African case. This paper reports such a trend analysis using extensions of previous methods, and introduces two new methods to avoid negative transition matrix elements. The applicability of the old and new methods is discussed and their results examined. Other areas of application of transition matrices to trends are briefly reviewed. <![CDATA[<b>On cooling-water systems design for South African industry: Two recent developments</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300016&lng=en&nrm=iso&tlng=en This paper presents two recent developments in the targeting and design of cooling-water systems using process integration. The basis of this work is the observation that true optimization of any cooling-water system, comprising a cooling tower and a network of operations that use cooling water, can be realized only by considering the system as a whole. Traditional approaches have focused separately on either the cooling tower or the operational network. Optimality, in the context of this paper, refers to minimum cooling-water flowrate to the network or maximum return temperature to the source of the cooling water (a cooling tower). Only systems with at least two cooling towers instead a single one are considered here, to highlight the complexity of a typical cooling-water system. The first exercise is based on a graphical technique in which targeting for the minimum cooling water precedes design of the cooling-water network to achieve the target. The second exercise uses mathematical modelling to optimize a superstructure that entails all possible topological arrangements of the cooling-water network. An industrial case study involving a South African explosives manufacturing plant is used to demonstrate the effectiveness of both techniques. Cooling-water savings of more than 20% were realized with modest capital investment. <![CDATA[<b>Lower Triassic postcanine teeth with allotherian-like crowns</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300017&lng=en&nrm=iso&tlng=en The Allotheria are fossil mammals with upper and lower post-canines usually showing two longitudinal rows of cusps separated by a central valley. The group comprises the poorly known haramiyids, mostly represented by isolated teeth, and the notably diverse and long-lived multituberculates; its monophyly is uncertain. The oldest records of this particular group are the Late Triassic (Norian-Rhaetian) haramiyids. We present here postcanines with haramiyid-like crowns that were recovered from the Lower Triassic of South Africa. A distinguishing feature of the new teeth is that they are single-rooted. This is the oldest record of mammal-like teeth with crowns having parallel rows of cusps, representing a temporal extension of some 43 million years from similar crown patterns of haramiyids and tritylodontids. This finding reinforces evidence of the remarkable faunal turnover of therapsids in the Early/Middle Triassic, at which time an explosive origin followed by a rapid early diversification of herbivorous/omnivorous forms with occluding expanded postcanines took place. <![CDATA[<b>Elevated ozone events over Johannesburg based on analysis of tropospheric ozone partial columns</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300018&lng=en&nrm=iso&tlng=en Traditionally, tropospheric column ozone (TCO) is a useful indicator for comparing both temporal and spatial variations in tropospheric ozone. TCO variations over Johannesburg are analysed in this paper with a view to identifying days of enhanced ozone, which could then form the basis of a detailed investigation to determine sources of the elevated ozone. We used ozone data from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) database for the period 1995 to 1998. A fixed tropopause height of 12 km was employed in this analysis as the upper bound of the troposphere. Seasonal and inter-annual variations in TCO provided a context for this study. A clear seasonal cycle exists, with TCO peaking in September and October. Minimum TCO occurs in autumn, when variability is also least. The lower day-to-day variability in autumn and winter is a reflection of the more settled weather at this time. This period is representative of background tropospheric ozone loadings, on which the dynamic and photochemical influences of other months are superimposed. High-TCO events, defined as exceeding 30 DU (Dobson units), occurred predominantly in spring. Enhancements in the lower troposphere are shown to be generally short-lived (1-2 days) and due to the effects of local surface pollution sources, and arise most likely from biomass burning, which peaks in spring. In contrast, events in the upper troposphere prevailed for a longer period and were due to the penetration of ozone-rich air from the stratosphere, as shown in a case study in September 1998. <![CDATA[<b>Characterization of the pitch canker fungus, <i>Fusarium circinatum, </i>from Chile</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300019&lng=en&nrm=iso&tlng=en Fusarium circinatum is the causal agent of the pine disease commonly referred to as pitch canker. During 2001, a Fusarium species was isolated from dying Pinus radiata clonal hedges in various forestry nurseries in Chile and was subsequently identified as F. circinatum. The aim of the study reported here was to provide a detailed characterization of Chilean isolates of the fungus. Morphological characters included microconidia carried on false heads and produced on polyphialides. Sterile coils and conidiophores on erect aerial mycelium were evident on synthetic, low nutrient agar. Furthermore, perithecia exuding viable ascospores were produced when isolates were crossed in all possible combinations with the mating tester strains representing the H mating population of Gibberella fujikuroi species complex. PCR-RFLP analysis of the histone H3 gene region, routinely used to distinguish between members of the G. fujikuroi complex, further confirmed the identification of the isolates as F. circinatum. DNA sequence data obtained for the same gene region placed the isolates within a well-characterized G. circinata clade. These studies provide unequivocal evidence that the pitch canker pathogen is well established on pines in Chilean nurseries. <![CDATA[<b>Do insect distributions fit our biomes?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300020&lng=en&nrm=iso&tlng=en An assessment of biome-specificity in southern African insect assemblages was undertaken using sweep collections in fynbos, grassland, subtropical thicket and Nama-karoo. Insect samples from the same biome generally cluster together in multidimensional scaling analyses, although there is a great variability between sites within each biome. Rich and distinctive insect faunas exist in each biome, including fynbos. In the Baviaanskloof Conservation Area of the southeastern Cape, where the four biomes marginally co-occur, some insect assemblages are enriched relative to sites at the core of the biomes, presumably through the mixing of faunas via transient or persistent establishment of populations recruited from adjacent biomes. <![CDATA[<b>Genetic diversity of <i>Chrysoporthe cubensis </i>in eastern and southern Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000300021&lng=en&nrm=iso&tlng=en Chrysoporthe cubensis is an important fungal pathogen of Eucalyptus species worldwide. The fungus is also known on many other hosts, all residing in the order Myrtales. Previous studies have suggested that Chr. cubensis might be native to South America and southeast Asia and that it has been introduced into Africa. Recently, surveys have been conducted in eastern and southern Africa to assess the distribution of Chrysoporthe spp. in this region. Chr. cubensis was found on Eucalyptus spp. in Kenya, Malawi and Mozambique. The aim of the study reported here was to determine the genetic diversity of Chr. cubensis populations from these countries. Population diversity studies were conducted using five pairs of microsatellite markers previously developed for Chr. cubensis. Results show that there is a very low genetic diversity within the populations of Chr. cubensis from Kenya, Malawi and Mozambique, implying that the fungus was probably recently introduced in these countries. Based on phylogenetic analyses, the origin of East African Chr. cubensis is most likely Asia.