134 research outputs found

    Distribution and habitats of Burnupia trapezoidea (Boettger, 1910) (Gastropoda: Ancylidae) in South Africa

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    This paper deals with the geographical distribution and habitat preferences of B. trapezoidea, the third most widespread species of the 14 species of Burnupia currently on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. Although the 121 loci (1/16 square degrees) from which the 445 samples of B. trapezoidea were collected are much fewer than the number reported for B. capensis, the range of its geographical distribution is almost as widespread as that of B. capensis. The limited distribution of B. trapezoidea in the Limpopo, Northern Cape and Western Cape Provinces can most probably be attributed to the paucity of perennial water bodies in these areas and the fact that Burnupia spp. in general have poor abilities to overcome conditions of desiccation prevalent in these areas. It is therefore not surprising that the majority of samples were collected in perennial rivers and streams. A Random Forest statistical analysis selected water bodies, the presence or absence of marginal and aquatic vegetation, and type of substratum as the most important variables that played a significant role in determining the presence and numbers of specimens of B. trapezoidea in a specific area. In this respect, temperature and turbidity, respectively, played a moderate and minor role. Little is known regarding the conservation status of Burnupia spp, in general, but habitat degradation and climatic warming could be reasons for concern. However, in extensive on-going biodiversity surveys in two rivers and selected tributaries in the North-West Province, many new distribution records of B. trapezoidea are still being created and therefore this species could probably be considered for listing as not endangered. In view of its wide distribution, largely sessile, benthic lifestyle, and ability to bioaccumulate various substances, the feasibility to utilise it as indicator of river ecosystem health in South Africa should be explored.Keywords: Mollusca, Ancylidae, Burnupia trapezoidea, geographical distribution, habitat preferences, conservation status, South Afric

    Distribution and habitats of Bulinus depressus and possible role as intermediate host of economically important helminth parasites in South Africa

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    This article documents the large-scale spatial distribution and ecological descriptors of associated habitats of Bulinus depressus by analysis of samples taken from 552 collection sites on record in the database of the National Freshwater Snail Collection (NFSC) at the Potchefstroom Campus of the North-West University. This snail species is experimentally susceptible to Schistosoma margrebowiei, a helminth parasite of game animals and cattle and can possibly also exploit humans as definitive hosts. The 125 different loci (1/16 degree squares) on record reflect a geographical distribution that is largely limited to the central and western part of the Limpopo Province and westwards down the basins of the Vaal and Orange Rivers. Details of each habitat as described by collectors during surveys, as well as altitude and mean annual air temperature and rainfall for each locality, were processed and chi-square and effect size values calculated. A decision tree constructed from all the available data indicated that temperature and altitude, followed by the type of water-body, seemed to be the more important factors that significantly influenced the distribution of this species in South Africa. The possible role of this species as intermediate host of economically important helminth species is briefly looked at and the urgent need to update the geographical distribution of host snails is emphasised. It is recommended that efforts be made to determine the exact role of B. depressus in the epidemiology of economically important helminth parasites. Keywords: Bulinus depressus, geographical distribution, habitat preferences, Schistosoma margrebowiei Water SA Vol. 31(4) 2005: 491-49

    Start-up of a UASB effluent treatment plant on distillery wastewater

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    Distillery effluent is a contaminated stream with COD values of up to 30 000 mg/l and low pH values of between 3 and 4. The anaerobic biological treatment of distillery effluents is widely applied as an effective step in removing more than 90% of the COD in the effluent stream. This paper reports on the seasonal operation of a UASB treatment plant treating a distillery wastewater stream with particular focus on seasonal start-up conditions after the first process commissioning. The start-up period was typically one week before process stability could be achieved. It is recommended that the loading rate to the plant be controlled between 4 and 8 kg COD/m3·d until the process is stable and COD removal efficiencies remain, on average, higher than 90%. After the start-up period the loading rate applied (4 to 18 kg COD/m3d) did not significantly affect the COD removal efficiency of the plant. High removal efficiencies of higher than 90% were achieved and stop-start operation of the UASB process posed no problem for treatment. WaterSA Vol.28(1) 2002: 63-6

    A comparison of mollusc diversity between the relatively pristine Marico River and the impacted Crocodile River, two major tributaries of the Limpopo River, South Africa

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    A study of the freshwater mollusc diversity was conducted at selected sites in the relatively pristine  Marico River and the impacted Crocodile River, the major tributaries of the Limpopo River. Four  surveys were conducted, two in an early (May 2013 and 2014) and two in a late (November 2013 and 2014) low-flow period. Semi-quantitative surveys were done by sampling the vegetation, as well as the substratum, with a standard SASS net for approximately 15 min each. Environmental parameters including water temperature, electrical conductivity (EC) and pH were measured at each site. Molluscs were identified up to species level, sorted, counted, and the presence of juvenile specimens recorded. Historical data for the 1/16th degree square grids (loci), in which each of the sampling sites of the current study was located, were extracted from the National Freshwater Snail Collection at the Unit for Environmental Sciences and Management, Potchefstroom Campus of the North-West University. During this study, 20 and 9 species were recovered from the Marico and Crocodile Rivers, respectively, as compared to 13 and 12 species on record for these loci, respectively. Juvenile specimens were present during the four surveys at most of the sites. Canonical correspondence analyses were applied which revealed that biotopes, water temperature and EC played the most significant role in the distribution and abundance of species. The relatively high mollusc diversity and the fact that juveniles were present throughout the study, demonstrated that current habitat and environmental conditions were suitable to promote recruitment and the sustainability of diverse mollusc populations in the Marico River and its tributaries. However, in contrast to this, the exploitation of and habitat transformation in the Crocodile River has resulted in the decrease of biotopes which eventually could have led to the  decrease in diversity and the establishment of P. acuta, an exotic invader species.Keywords: freshwater molluscs, biodiversity, Marico River, Crocodile River, environmental variable

    A new distribution record of Chambardia wahlbergi (Krauss, 1848) (Bivalvia: Iridinidae) and Unio caffer (Krauss, 1848) (Bivalvia: Unionidae) in South Africa

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    Little is known with regard to the conservation status of invertebrates of South Africa; however, in the revised edition of the IUCN Red Data List (2011) the conservation status of both Unio caffer and Chambardia wahlbergi is considered as ‘of least concern’. In recent reports on the geographical distribution and habitat preferences of these two species in South Africa, concern was expressed regarding their conservation status. However, specimens of C. wahlbergi collected at several sites on several occasions in the Vaal River were the first evidence that the geographical distribution of this bivalve was wider and not restricted to water bodies located in east-flowing catchments in the warmer areas of South Africa. The fact that populations of C. wahlbergi can become established in habitats on the Highveld was further supported by a number of valves collected on the dry bed of the Schoonspruit (26° 37’ 55.2”S, 26° 35’ 32.3”E), near Klerksdorp in the North West Province, on 16 February 2016. A number of valves of U. caffer which were collected on the same occasion at the same locality are also the first record of this species from this water body

    A semi-quantitative survey of macroinvertebrates at selected sites to evaluate the ecosystem health of the Olifants River

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    This study was conducted to evaluate the ecosystem health of the Olifants River by means of semi-quantitative surveys of the macroinvertebrates at 7 selected sites in the catchment. These surveys were performed during the high- and low-flow seasons for 2 consecutive years. Macroinvertebrates were collected by using a net consisting of a 30 cm square steel frame with a sturdy handle, to which a Perlon gauze net with a mesh of 1 mm was attached. Semi-quantitative surveys were done by sampling the vegetation, as well as the substratum, with the net at each site for approximately 15 min. The pH, water temperature and conductivity were measured in situ at each site during the different surveys. Samples were fixed and preserved in 90% ethanol and thereafter sorted, identified up to family level and counted. The specimens were categorised as tolerant, moderately sensitive or highly sensitive, according to the guidelines set by the South African Scoring System Version 5 (SASS5). Although a total of 95 taxa were recovered during this study, only 7 of these taxa were categorised as highly sensitive, it can be concluded that the water of the Olifants River is in a poor state of health as revealed by the macroinvertebrate assemblages.Keywords: Olifants River, macroinvertebrates, river healt

    An experimental Schistosoma mattheei infection in man

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    Certain aspects of the immune response of a male experimentally infected with 3-day old cercariae of a pure field strain of Schistosoma mattheei were investigated. Among others, aspects such as the reaction of eosinophils, neutrophils and blood platelets after infection, were included in the study. The involvement of IgG and the cross reaction between these antibodies and S. haematobium and S. mansoni were also investigated. The phenomenon that the cercariae were, 3 days after shedding, still capable of penetrating the skin causing an inflammatory response was studied. The results lend some support to the surmise that a pure S. mattheei infection in humans is incapable of any egg production.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.South African Medical Research Council. Potchefstroom University for Chistian Higher Education.mn201

    Natural compulsive-like behaviour in the deer mouse (Peromyscus maniculatus bairdii) is associated with altered gut microbiota composition

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    Obsessive–compulsive disorder (OCD) is a psychiatric illness that significantly impacts affected patients and available treatments yield suboptimal therapeutic response. Recently, the role of the gut–brain axis (GBA) in psychiatric illness has emerged as a potential target for therapeutic exploration. However, studies concerning the role of the GBA in OCD are limited. To investigate whether a naturally occurring obsessive–compulsive‐like phenotype in a rodent model, that is large nest building in deer mice, is associated with perturbations in the gut microbiome, we investigated and characterised the gut microbiota in specific‐pathogen‐free bred and housed large (LNB) and normal (NNB) nest‐building deer mice of both sexes (n = 11 per group, including three males and eight females). Following baseline characterisation of nest‐building behaviour, a single faecal sample was collected from each animal and the gut microbiota analysed. Our results reveal the overall microbial composition of LNB animals to be distinctly different compared to controls (PERMANOVA p < .05). While no genera were found to be significantly differentially abundant after correcting for multiple comparisons, the normal phenotype showed a higher loading of Prevotella and Anaeroplasma, while the OC phenotype demonstrated a higher loading of Desulfovermiculus, Aestuariispira, Peptococcus and Holdemanella (cut‐off threshold for loading at 0.2 in either the first or second component of the PCA). These findings not only provide proof‐of‐concept for continued investigation of the GBA in OCD, but also highlight a potential underlying aetiological association between alterations in the gut microbiota and the natural development of obsessive–compulsive‐like behaviours

    Van buite bekyk: Die teologie van die Nederduitsch Hervormde Kerk van Afrika tussen 1938 en 1950

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    This article depicts the theology of the Nederduitsch Hervormde Kerk van Afrika as embodied in especially influential ecclesiastical publications, namely Die Hervormer, the Almanak van die Nederduitsch Hervormde Kerk van Afrika and the Hervormde Teologiese Studies. These sources indicated the period between 1938 and 1950 to be of significance in the history of the formation of the theology in this church. Hence the delimitation 1938–1950. The memorial dates in 1938, 1939 and 1942 offered the church the opportunity to shape its historical existence theologically. This was done along clear-cut ecclesiastical lines. As the Voortrekkerkerk, the Hervormde Kerk was in fact a Christ confessing church of the (Afrikaner) people. By 1950 a shift in this theological image occurred: from historical identity to a contextual insistence: the racial issue. The traditional theology of the Church was accordingly adapted and contextualised in a praxis of separate development and separate churches. From its own ranks this theology was also critically questioned. The interrogation did not take its departure in either history or context, but argued the case in terms of the church of Christ

    International collaborative project to compare and track the nutritional composition of fast foods

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    Background: Chronic diseases are the leading cause of premature death and disability in the world with over-nutrition a primary cause of diet-related ill health. Excess quantities of energy, saturated fat, sugar and salt derived from fast foods contribute importantly to this disease burden. Our objective is to collate and compare nutrient composition data for fast foods as a means of supporting improvements in product formulation. METHODS/DESIGN: Surveys of fast foods will be done in each participating country each year. Information on the nutrient composition for each product will be sought either through direct chemical analysis, from fast food companies, in-store materials or from company websites. Foods will be categorized into major groups for the primary analyses which will compare mean levels of saturated fat, sugar, sodium, energy and serving size at baseline and over time. Countries currently involved include Australia, New Zealand, France, UK, USA, India, Spain, China and Canada, with more anticipated to follow. DISCUSSION: This collaborative approach to the collation and sharing of data will enable low-cost tracking of fast food composition around the world. This project represents a significant step forward in the objective and transparent monitoring of industry and government commitments to improve the quality of fast foods.E Dunford is supported by a Sydney Medical School Foundation scholarship and B Neal by an Australian Research Council Future Fellowship.http://www.biomedcentral.com/1471-2458/12/559am201
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