Faculty of Natural Sciences

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Synthesis of biogenic gold nanoparticles from terminalia mantaly extracts and the evaluation of their in vitro cytotoxic effects in cancer cells
(MDPI, 202-09-12) Sharma, Jyoti R.; Sibuyi, Nicole Remaliah Samantha; Majoumouo, Michele Stella
Scientists have demonstrated the potential of plant materials as 'green' reducing and stabilizing agents for the synthesis of gold nanoparticles (AuNPs) and opened new ecofriendly horizons to develop effective and less harmful treatment strategies. The current study demonstrated the use of Terminalia mantaly (TM) extracts to synthesize AuNPs with enhanced cytotoxic effects. The TM-AuNPs were synthesized at 25 and 70 °C using water (WTM) and methanolic (MTM) extracts of the leaf, root and stem/bark parts of the plant. The TM-AuNPs were characterized using UV-visible spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy, energy dispersive X-ray (EDX), selection area electron diffraction (SAED) and Fourier transform infrared (FTIR) spectroscopy. Majority of the TM-AuNPs were spherical with a mean diameter between 22.5 and 43 nm and were also crystalline in nature. The cytotoxic effects of TM-AuNPs were investigated in cancer (Caco-2, MCF-7 and HepG2) and non-cancer (KMST-6) cell lines using the MTT assay. While the plant extracts showed some cytotoxicity towards the cancer cells, some of the TM-AuNPs were even more toxic to the cells. The IC50 values (concentrations of the AuNPs that inhibited 50% cell growth) as low as 0.18 µg/mL were found for TM-AuNPs synthesized using the root extract of the plant. Moreover, some of the TM-AuNPs demonstrated selective toxicity towards specific cancer cell types. The study demonstrates the potential of TM extracts to produce AuNPs and describe the optimal conditions for AuNPs using TM extracts. The toxicity of some the TM-AuNPs can possibly be explored in the future as an antitumor treatment.
Inhibition of HIV-1 enzymes, antioxidant and anti-inflammatory activities of Plectranthus barbatus
(Elsevier, 213) Kapewangolo, Petrina; Hussein, Ahmed A.; Meyer, Debra
Ethnopharmacological relevance: Plectranthus barbatus is widely used in African countries as an herbal remedy to manage HIV/AIDS and related conditions. Aim of the study: To investigate the HIV-1 inhibitory, anti-inflammatory and antioxidant properties of P. barbatus and thereby provide empirical evidence for the apparent anecdotal success of the extracts. Materials and methods: Ethanolic extract of P. barbatus's leaves was screened against two HIV-1 enzymes: protease (PR) and reverse transcriptase (RT). Cytotoxicity of the extract was determined through measuring tetrazolium dye uptake of peripheral blood mononuclear cells (PBMCs) and the TZM-bl cell line. Confirmatory assays for cytotoxicity were performed using flow cytometry and real-time cell electronic sensing (RT-CES). The free radical scavenging activity of the extract was investigated with 2,2- diphenyl-1-picrylhydrazyl while the anti-inflammatory properties of the plant extract were investigated using a Th1/Th2/Th17 cytometric bead array technique.
Inleiding tot die eksperimentele Sielkunde
(University of the Western Cape, 1948) Schlebusch, B. J.; Van Rensburg, J. A. J.
Elke skolier wat rue tevrede is om dit op skool slegs met lepels in te kry nie, het seker al gewonder hoe kennis oorspronklik verkry word. In daardie stadium is ons gewoonlik nog tevrede om die feite wat die onderwyser aan ons voorlê, of wat ons in die boeke gelees het, op gesag aan te neem. Maar selfs dan toets ons dikwels daardie gesag deur gewone en terloopse waarnemings. Byvoorbeeld: in die fisika leer ons dat as ons 'n groot en 'n klein klippie gelyktydig van enige hoogte laat val, hulle ook gelyktydig op die aarde sal beland as daar nie met die een klip intussen iets gebeur het wat nie met die ander klip gebeur het nie: met ander woorde as aIle faktore gelyk gebly het. Toe ons van hierdie gelyk-vallende klippies gehoor het, het party van ons op 'n dubbelverdieping gebou, of selfs op die dak van die buitegebou, opgeklim en die twee klippies self laat val om na te gaan of dit werklik so was. En hiermee het ons 'n eenvoudige eksperiment uitgevoer om te toefs of die hennis wat ons geleer het wel reg was. Dit was 'n eenvoudige eksperiment omdat die invloed van die lugdruk, en van die wind wat waai en 'n groter uitwerking op die groot klip het as op die klein klippie, buite rekening gehou is by die waarneming. Ons het ook net van ons oë gebruik gemaak om te kyk of die twee klippe gelyktydig op die aarde beland. Maar as ons middels kon aangewend het om die invloed van die genoemde twee faktore te bepaal, sou dit 'n meer presiese eksperiment gewees het en nie 'n terloopse waarneming nie. Sulke presiese eksperimente word in die laboratorium uitgevoer met die doelom betroubare kennis te kry. Die soort wetenskaplike kennis wat ons op skool leer, is reeds in die verlede deur navorsers vasgestel, en hulle bevindings is nou beskikbaar vir ons in teksboeke. Hulle eksperimente was bedoel om op nuwe kennis uit te kom. Maar die student wat sy verstand gebruik is nie noodwendig tevrede met gesag nie; hy wil self graag eksperimente maak om te sien of wat die gesag beweer werklik so is. Sy eksperimente is bedoel om eerstens te toets of die ander navorsers se resultate reg is, en tweedens 0111 hom oefening te gee met die uitvoering van eksperimente. Navorsers werk op wetenskaplike manier om nuwe kennis te verkry. Dit word vertel dat Newton S)' idee van die aantrekkingskrag van die aarde gekry het toe hy 'n appel sien val het, en dat Archimedes die idee van sy wet: dat voorwerpe in water van hulle gewig verloor, en dat die gewig wat daardie voorwerpe verloor gelykstaan aan die gewig van die volume water wat deur die voorwerpe verplaas word, gekry het terwyl hy besig was om te bad. Waarheid is dat albei allank besig was om oor hulle probleme na te dink en na te soek, en dat toe Newton die appel sien val het en Archimedes die gedagte in die. bad gekry het, dit feite was wat by vorige kennis aangesluit het. Hulle was egter nie daarmee alleen tevrede nie; daarna het albei die gedagte gaan toets .met wetenskaplike proefnemings om op kennis uit te kom. Die proefnemings en wetenskaplike navorsing kan jare en jare se harde werk vereis het. Om die eerste atoombom te laat ontplof het tientalle wetenskaplikes en duisende geskoolde assistente en werksmense jare se werk gekos. So het dit ook baie jare geverg om vas te stel dat mense wat siek word nie getoor is nie maar dat, byvoorbeeld, kieme 'n groot rol kan speel byeen of ander siekteverskynsel; en dit weer het ons aan die wetenskaplike navorsingsmetodes van 'n Pasteur te danke. Die verslag valt wetenshaplilu: navorsers se werk is nou ons wetenskaplike literatuur. Hierdie mense wat 'n eksperiment vir die eerste keer gemaak het, het dit nie gedoen om te toets of ander mense se feite korrek is nie, maar om uit te kom op oorspronklike feite van hul eie. In die Sielkunde is die basis vir die metodes van ondersoek dieselfde as vir ander wetenskappe. Daar is die noodsaaklikheid om deur middel van wetenskaplike proefneming op nuwe kennis uit te kom. Om dit te kan doen moet 'n mens eers leer hoe om 'n proefneming in te rig en moet jy voldoende oefening kry met proefnemings. As studente is dit vir ons 'n vereiste om die verskillende verskynsels self te kan ondersoek en later miskien self op nuwe kennis uit te kom en, wie weet, self een of ander oorspronklike bydrae te maak. Maar dan moet ons weet hoe om 'n eksperiment of ondersoek uit te voer. Om dit geleerd te stel: Ons moet die objektiewe metodes van 'n wetenskaplike eksperiment beheer; ons moet weet hoe om 'n proefneming in te rig.
Metronidazole in the Prophylaxis and treatment of Anaerobic Infection
(Health and Medical Publishing Group, 1978) Applebaum, P.C.; Moodley, J.; Chatterton, S.A.; Cowan, D.B.; Africa, Charlene W.J.
The influence of prophylactic metronidazole on vaginal carriage rates of anaerobes and the development of postoperative anaerobic infection was studied in 104 women who underwent abdominal hysterectomy. Metronidazole prophylaxis in 54 patients led to a decrease in the anaerobe vaginal carriage rate from 65% pre-operatively to 17% and 28% on the 3rd and 7th postoperative days respectively. In the control group (50 patients) no significant decrease in anaerobe yield was noted, corresponding percentages being 72%, 64%, and 74%. Postoperative infection occurred in 36 patients (28 controls; 8 on prophylactic metronidazole). Wound swabs from all 8 patients in the latter group yielded aerobes, and in 1 patient mixed infection (aerobes/anaerobes) occurred. In 7 of these patients (including the patient with mixed infection), the infection resolved spontaneously, while the 8th patient responded to therapy with metronidazole, kanamycin and ampicillin. In the control patients, 21 cases of postoperative wound infection and 4 of vault infection were seen; wound swabs from patients in the former group yielded aerobes in only 6 cases, and mixed growth of aerobes/ anaerobes in 10 cases. Postoperative wound/vault infections in control patients cleared spontaneously in 18 cases and responded to imidazole therapy, with or without ampicillin and kanamycin, in 7 cases.
A comparative study of degeneration of the posterior limbs and girdles of some scelotes species.
(University of the Western Cape, 1981) Wilson, Brain .A; Skinner, J.H; Leonard, C.J
The genus Scelotes was instituted by Fitzinger in 1826 and is represented by nineteen species and subspecies in Southern Africa (Fitzsimons, 1943) . Valuable contributions have been made to our knowledge of the Lacertilia by pioneers such as Gadow (1881) , Cope (1892) , El-Toubi (1938) , King (1964) and Tiedeman et al . (1975) who investigated the osteology and myology. Essex (1927) , Stokely (1947) , Lande (1978) and Leonard (1979) dealt with the evolution of limb loss and pelvic girdle degeneration in the lizards , and especially in the skinks. van der Klaauw (1948), Snyder (1952; 1954) and Gans (1962; 1966; 1973) studied the ecology and behaviour of limbless tetrapods, while De Witte and Laurent (1943) and Greer (1970) contributed to our knowledge on the systematics of the skinks. Partial or complete loss of limbs and degeneration in the pelvic arch have possibly evolved independently in a variety of tetrapods. The genus Scelotes exhibits a full range of degeneration - from fully pentadactyle tetrapodous forms to limbless species. The question arises : Can a general pattern of devolution be observed in this genus? Al though many of the Scelotes species have already been described, it will here for the first time be attempted to compare the different stages of degeneration as exhibited in this genus. A major objective of this work will , therefore be to analyze the pattern of degeneration in Scelotes. Firstly, the osteology of the pelvic girdle and hindlimbs of the Scelotes species will be described and, secondly, these structures will be compared. Thirdly, an attempt will be made to graphically reflect the major trends associated with limb regression by employing morphometric data obtained from the limited number of specimens available
An investigation of the effects of donor age on some haematological characteristics of the Wistar rat (Rattus Norwegicus)
(University of the Western Cape, 1986) Wesso, Iona; Van der Horst, G.
Knowledge of haematological 'normdata', of experimental animals, and the biological variables that affect it is essential in order to recognise variations from the normal. In addition, the haemopoietic system may be regarded in principle as good material for studies of the cellular events associated with ageing. These considerations, together with the well documented effects of age on various physiological processes, prompted an investigation into the effects of donor age on several blood parameters. Review of the literature revealed that age-related changes in blood parameters have been reported for several species, but the documentation thereof is incomplete, inconsistent and inconclusive in many respects. Blood samples from male Wistar rats of nine different biological ages, ranging from birth to 96 weeks of age, were analysed for haematological and biochemical parameters. These included the blood cell counts, erythrocytic indices, haemoglobin concentration, haematocrit, erythrocytic 2,3-diphosphoglycerate and adenosine triphosphate levels, and erythrocytic glucose 6-phosphate dehydrogenase and pyruvate kinase activities. Data was obtained which demonstrates that all blood parameters measured underwent significant, although not al~ays regular, age-related changes. These changes were found to be more marked during the first month of life than at any other period. Evidence is also presented to show that the depressed haemoglobin concentration during the early postnatal life may not imply a condition of 'physiologic anaemia' as was previously thought. Since the blood profile exhibits only slight changes from about 24 weeks of age, it does not seem that the haemopoietic system of the old rat deteriorates significantly as to constitute a limiting factor for the animal's life. However, the importance of taking an animal's age into account when blood parameters constitute experimental results is emphasised. The second phase of this study involved a detailed investigation of the effect of the animal's age on erythrocytes in particular. These cells have limited life-spans, and are often used as models in studies of cellular ageing. Special emphasis was therefore placed on comparing the relative effects of host and cellular ageing on the properties of these cells. Erythrocytes from rats between one and 48 weeks of age were separated into two populations by a modification of the conventional density gradient centrifugation technique. The two populations were assumed to differ in mean cell age and were analysed for erythrocytic indices, phosphate ester concentrations and the activities of glucose 6-phosphate dehydrogenase and pyruvate kinase. Evidence is presented to show that ageing rat erythrocytes exhibit a decrease in volume, phosphate ester content and enzyme activities while the cellular haemoglobin concentration increases. Differences in the mean cell age however, does not seem to account for the donor-age-related effects observed in the whole blood parameters. Rather, the significant differences found in the characteristics of similarly aged red cells, between variously aged donors, demonstrate that the biological age of the organism influences the red cells and probably the ageing thereof in vivo. The contribution of the changing status of the erythrocyte's environment of progressively older animals, to alterations which take place in the ageing red cell is discussed.
Active Principles of Tetradenia riparia; II. Antispasmodic Activity of 8(14), 15-Sandaracopimaradiene-7α, 18-diol
(Georg Thieme Verlag, 1987) Van Puyvelde, Luc; Lefebvre, Romain; Mugabo, Pierre; De Kimpe, Norbert; Schamp, Niceas
Tetradenia riparia is one of the most popular medicinal plants in Rwanda. Previously, several new substances have been isolated from the leaves, including a new diterpenediol, i.e. 8(14),15-sandaracopimaradiene-7α,18-diol. This new diterpenediol exhibits a papaverine-like antispasmodic activity on the contractions of the guinea pig ileum provoked by methacholine, histamine, and barium chloride and on the noradrenaline-induced contractions of the rabbit aorta.
Iterative prophylactic treatment by hematin in two cases of recurrent disabling acute intern1ittent porphyria (AIP)
(Elsevier, 1989) Mugabo, Pierre; Coche, Lefebvre E.; Hassoun, A.
Summary: Hematin is known as a useful drug in the treatment of acute intermittent porphyria (Al P) attacks. We have used it with success as an iterative prophylactic treatment in two cases of AIP with recurrent disabling crises. In one of the two cases, the kinetic study of plasmatic delta amino-fernlinic acid (ALA) has shown an ALA plasma level (40-45 μg/dl) which is considered to be a trigger level for this patient. Cntil now, no side effects due to such a hematin treatment have been observed in either patient. This schedule could represent an improvement in the management of recurrent disabling AI P crises.
The effect of Nicotine exposure on aspects of liver Carbohydrate metabolism
(University of the Western Cape, 1989) Mathews, Jonathan Andrews; Maritz, G.S; van der Horst, G
The liver plays an important role in maintaining the blood glucose concentration. In this respect glycogenolysis and gluconeogenesis play an important role. Interference with these pathways may therefore have an effect on the ability of this organ to maintain blood glucose levels. In this study the effect of in vivo and in vitro nicotine exposure was investigated to establish whether nicotine exposure: i. influences glycogenolysis and in gluconeogenesis, ii. have the same effect on fasted animals and iii. have the same effect on neonates exposed to nicotine via mother's milk. Experimental animals were Wistar rats of : 1. day, 1 week, 2 weeks, 5 weeks, and20 weeks old. Animals were exposed to nicotine (lmgkglday) i.p./s.c. and were killed by means of decapitation on predetermined days, 1 and 24 hours after the final dose. Control animals received 0,9Vo saline instead of nicotine. The volume depended upon the animal's body m1ss. Parameters such as invivo blood glucose,blood wea"invitrolactate, glucose and urea production, and glycogen and orygen utilization were investigated. Maternal exposure to nicotine had no effect on blood glucose levels and the liver glycogen content of L and 7 day old suckling rat pups. However in 2 and 5 week old and adult rats (20 weeks) a decrease in liver glycogen content and a increase in blood glucose concentration was recorded. All groups showed a marked increase in blood urea level. Nicotine had no effect on the in vitro oxygen utilization of rat liver tissue. Under the experimental conditions, the in vitro glycogen utilisation and lactate production of liver tissue slices of 1 and 5 week'old rats (maternally treated during gestation and after weaning) were surpressed whereas liver of fed adult rats showed an increase in glycogen utilization (p < 0,05) invitro. Nicotine decreased the rate of invitro glucose release in fasted female rat liver tissue. Chronic nicotine treatment for 30 days had no significant effect on the blood glucose and urea concentrations and liver glycogen content. It is impossible at this stage to pinpoint the exact mechanism of nicotine's action on the glycogen stores, but it is clear that nicotine in some way or other influences the maturational aspect of some liver enrymes. Nicotine had no effect on the orygen utilization and therefore probably did not affect mitochondrial function. From the investigation it is clear that acute nicotine exposure stimulates glycogenolysis and probably gluconeogenesis resulting in an elevated blood glucose level within the normal range. Chronic nicotine exposure had no apparent effect on liver carbohydrate metabolism of well fed rats probably due to rapid breakdown thereof.
a comparative study of the influence of different copper concentrations on the growth, chemical composition and activities of certain copper containing enzymes in atriplex nummularia lindl. and a. vestita (thunb.) Aell.
(University of the Western Cape, 1990) Green, D H; Aalbers, J
The total amount of native copper in soil depends on the amount of copper in the parent material (Tisdale .et .al.1968). It is usually in greater concentration in the soil than in parent rock because of weathering of the parent rock and the concentration of the element in the upper soil horizons by growing plants. Copper in parent rock exhibits typical chalcopyrite behaviour in that its abundant and stable minerals are sulfides rather than silicates or oxides (Mordtveldt .et .a.J. . 1972). B the most abundant of the copper minerals is which is common in igneous and sedementary rocks. The average ooppe r cxmte e s between 2 to lOOg.m- 3 soil solutions contain about 0.0-lg.m copper ( Devlin 1983). Concentrations higher than this are often regarded as toxic to plants. Two valences of copper are found in naturally occuring compounds i.e. cu+ and cu2 +. The cu 2 + ion is more commonly found in soils, adsorbed to clay minerals or tied up with organic matter.
Population and Physiological Studies of selected Geophytics Species of Lowland Coastal Fynbos in the Southwestern Cape
(University of the Western Cape, 1990) Ruiters, Cornelius; McKenzie, B.
Population and physiological studies were conducted in coastal fynbos in the South-western Cape. Minor ecophysiological studies were also conducted such as the soil moisture content and pH. Two species, viz. Haemanthus pubescens L.f. subspecies fimbriata subspecies Pubescens and Sparaxis grandiflora (de la Roche) Ker. subspecies fimbriata (Lam) Goldbl were selected for the project. H. pubescens subsp. pubescens is a bulbous geophyte belonging to the family Amaryllidaceae and S.grandiflora subsp. fimbriata a cormous geophyte a member of the family Iridaceae. The species were classified either as a perennial geophyte with hysteranthous leaves or an annual geophyte with synathous leaves. Two sites were dermacated on the farm Klein Welmoed at Penhill and near the Blackheath industrial area for the project.
Analyzing chemical data in more than two dimensions: A tutorial on factor and cluster analysis
(Journal of chemical education, 1990) Auf der Heyde, Thomas P. E
This tutorial is intended to introduce factor and cluster analysis at a level that will afford a senior student-and the practicing chemist, for that matter-some insights into the workings of the computer packages employing these methods, without overwhelming him or her with mathematical detail in the process.
The effect of maternal nicotine exposure on rat lung tissue morphology. ' a light and electron microscopic study
(University of the Western Cape, 1991) Woolward, Keryn Miles; Maritz, G. S.
The infants of women who smoke during pregnancy have a lower birth mass than those born of women who abstain. Animal studies reveal that reduced growth due to maternal nicotine exposure during gestation is accompanied by lung hypoplasia. Biochemical analysis suggests that these lungs contain more cells which implies that lung damage occurs. In this study we examined the in vivo effects of maternal nicotine exposure (lmg/Kg/day), the equivalent of 32 cigarettes per day, on the following parameters of fetal and neonatal Wistar rat lung:(i) the content and distribution of glycogen in fetal and neonatal lung (ii) the status of connective tissue in neonatal lung (iii) the cell composition of the alveoli in neonatal lung. Fetal rat lungs of ages 17, 18, 19 and 20 days and neonatal lungs of 1, 7, 14 and 21 day old pups were used. Light microscope techniques and special stains were used to investigate glycogen, connective tissue, macrophage numbers and morphological status of the lungs. Fetal rat lungs of ages 17, 18, 19 and 20 days and neonatal lungs of 1, 7, 14 and 21 day old pups were used. Light microscope techniques and special stains were used to investigate glycogen, connective tissue, macrophage numbers and morphological status of the lungs. Transmission electron microscope (TEM) techniques were employed to investigate the characteristics and composition of the alveolus The results show clearly that maternal nicotine exposure elevates pulmonary alveolar macrophage numbers'(PAM's) and lung glycogen levels. The quantity of elastic fibres in 1 day old neonates was significantly reduced but no changes in the quantity of reticulin and collagen fibres was observed. As a result of this change in connective tissue status, emphysema-like lesions and alveolar collapse was evident in the lungs of nicotine-exposed pups. TEM investigations revealed that changes to the composition of alveoli occurred. These included increased numbers of type II pneumocytes with high numbers of lamellar bodies with degenerative changes. Thickening of the blood-air barrier was also observed. The effect of maternal nicotine exposure has been documented in this study. However, it has not been possible to pinpoint the mechanisms involved but explanations have been proposed. Further research is required to elucidate the mechanisms by which nicotine produces these effects. Information thus obtained could help prevent the harmful effects to the fetus and neonate caused by smoking during pregnancy.
A critical analysis of aspects pertaining to the teaching of the ecology section of the standard eight biology syllabus.
(University of the Western Cape, 1991) Wagiet, R; Herman, H.; Kenzie, M.C
In this study an attempt has been made to investigate how the Ecology section (suitable for fostering awareness and concern for the environment) of the standard eight Biology syllabus is taught. Since fieldwork and related exercises are integral components of ecology, teachers are strongly advised to venture into such activities. It was ascertained that the restraints wh ich inhibited teachers from undertaking meaningful endeavours such as fieldwork include: an inadequate pre-serv ice training in ecology, with limited or no experience of fieldwork techniques; lack of time and, syllabus constraints. It is therefore recommended that there should be a restructuring of the content and approach followed by the tertiary institutions involved in teacher training. Additionally, it should be noted that in the absence of inservice teaching programmes, and, with the weaknesses identified in the textbooks, difficult sections experienced by the teachers (for example, nutrient cycling), will continue to be problematic, and unsuitable methods of ecology teaching will be perpetuated
Seisoensfluktuasies in Industriële produksie en die Aandelemark met spesiale verwysing na die Suid - Afrikaanse situasie
(University of the Western Cape, 1991) Cilliers, Frans Pieter; Smit, E. vd M
In 1976 Rozeff and Kinney found that seasonality exists in the monthly rates of return on the New York Stock Exchange with peak periods in January. By making use of this information and the fact that the rates of return lag real activity by one month, Chang en Pinegar (1986) indicated that rates of return unidirectionally predict future growth rates in industrial production for large companies. They also found that the seasonal growth rates in industrial production partially reflect the January seasonals in the rates of return for small companies. This is inconsistent with the efficient market hypothesis. Altough numerous studies in South Africa have been conducted on the efficiency of the Johannesburg Stock Exchange, no one has departed from the viewpoint of seasonality. The aim of this study is to investigate the efficiency of the Johannesburg stock Exchange with respect to seasonality in industrial production. It will be shown that there is no relationship between rates of return and real activity in the majority of sectors. The clothing sector is inefficient in the sense that real activity unidirectionally predicts rates of return three months in advance. At a six months lag period there are strong relationships, in both ways, between rates of return and real activity for this sector, that also implies inefficiency. Lastly it will be indicated that the November peaks on the Johannesburg stock Exchange do not coincide with the January peaks found overseas and that they do not lag real activity by one month. In the international research the attention was mainly focussed on the size of companies and stock price sensitivity to changes in industrial production while in this paper it focusses on different sectors.
Biomonitoring as a means to determine the pollution level in Stellenbosch
(University of the Western Cape, 1991) Davis, Shaun Andre; Raitt, L M; Aalbers, J
A pollution survey was done in Stellenbosch, along two transects. One was south-east and the north-east of the Oorrobrick brickfield the focal point of this study. Pine and Oak trees, chasman the leaves and lichens were used as bio-indicators for this survey. The levels of fluoride and sulphur decreased with distance from the main pollution source. Exceptionally high levels were recorded in the pine and oak trees within 1.5. km from the brickworks. The availability of calcium and magnesium in the leaves of pine and oak trees appeared to be negatively affected due to their binding with F- to form insoluble compounds. The brickfield proved to be a major source of especially copper and iron, as their levels in the bark material decreased with increasing distance. Lead levels were found to be correlated with vehicular traffic in the area. There was some evidence that the iron levels were also linked to the lead concentrations in the bark.
Vegetation relationships of priority conservation sites on the Cape flats
(University of the Western Cape, 1992) Fredericks, Mogamat Fuad; McKenzi, Bruce
The physical environment of the cape Frats is outlined. The plant communities of twenty-one priority conservation sites are classified. Twenty-five communities, grouped into 15 associations, 8 alliances, 4 orders, 2 subclasses and a single class are defined. This is based entirely on floristic features, following the Braun-Blanquet approach and application of the code of phytosociological Nomenclature. These syntaxa are systematically described with reference to floristic, structural and macroenvironmental features . The distribution of the communities are indicated on 1:10 000 scale maps of the study sites. The communities are described further in relation to soil chemical and physical variables. The analysis indicates that soil chemical variables are more important in determining vegetation-soil relationships than physical variables. The main variables are soil Ca, pH, p, K, Nd, bulk density, moisture regime, t medium sand and t fine sand. The "general summary and recommendations" serve as a guideline for interest groups that adequate representatives of each conserved. is intended to so as to ensure community are
Perceptions of first year Biology students at a college of education towards the relevance of population dynamics as prescribed for current biology syllabusses at matriculation level in South African schools
(University of the Western Cape, 1992) Langenhoven, Keith Roy; Mc Kenzie, B; Herman, B
Throughout this research, an attempt has been made to assess the perceived relevance, if any, of the Population Dynamics topic of the standard ten Biology syllabus, especially of those standard ten pupils enrolling as student teachers at a College of Education. From this investigation, various factors, such as lesson methodology, practical field-work and time restraints amongst others, cause most pupils to misconstrue the relevance of Population Dynamics. Recommendations forwarded suggest an in-depth restructuring of the ecology aspects of the Biology courses at College by integrating content acquisition more closely with methodology than is evident at present- This will foster confidence and skills competence in aspirant teachers as they cultivate an environmental ethos in their classrooms. In addition, attention is focused on Energy FIow as a sample topic for transformation from the theoretical to a more relevant and functional approach. In the absence of a definite commitment to the importance of improving teaching and learning methods in the presentation of this topic, most pupils fail to understand the important role of Population Dynamics in a study of Ecology’ against global degradation.
Trophic ecology of carnivorous zooplankton in the Benguela
(NISC and Taylor & Francis, 1992) Gibbons, Mark J.; Stuart, V.; Verheye, H.M.
Carnivorous zooplankton in the Benguela system have tended to be ignored by all but early taxonomists and a handful of recent researchers. An attempt is made here to address the importance of carnivores in this system but, because the database is poor, it was necessary to apply material from outside the region. The taxa covered include ctenophores, cnidarians (Scyphozoa and Hydrozoa, including Siphonophora), chaetognaths and hyperiid amphipods as well as such minor groups as pelagic gastropods and decapods. Most groups of carnivores within the Benguela are represented by only one or two "common" species. These tend to be epiplanktonic and generally concentrated inshore of the shelf-break, where their distributions are influenced by changes in local hydrography. Their densities frequently exceed those of herbivores. The dominant carnivores share a number of attributes: wide-ranging diets, high assimilation and growth efficiencies and mostly a Type I functional response to food concentration. They fall into two categories. The first is the gelatinous species, which have short lifespans and exhibit rapid growth and often massive reproductive response to high concentrations of food. They are patchily distributed and some appear to have behavioural traits that enable them to stay within localized patches of prey on which they may be dependent because of high metabolic costs. In the second category are crustacean predators and chaetognaths which have slower response times to the food environment but may have longer lifespans, lower daily maintenance needs and an ability to store lipids. They are less dependent on high densities of food organisms and can survive throughout winter, when gelatinous predators are rare. The effect of predation on abundance of copepods is estimated on the basis of both published and unpublished data. Should swarms of predators coincide with a critical gateway of zooplankton or larvae, then there may be total depletion. This applies especially to the nearshore zone of the West Coast and to semi-enclosed bays. The role of carnivorous zooplankton in the diets of commercially important fish species is stressed, but their importance in the regeneration of nutrients may be insignificant.
(p.n.) Reactions on 59co in the intermediate energy range
(University of the Western Cape, 1992) Bester, P.J; van Heerden, I.J.
Detailed theoretical investigations [Chi80,Mos82,Kle85] of (p,n) and (p,p') data indicate that the reaction mechanisms operative at intermediate energies and for energy losses up to several tens of MeV are predominantly single-step in nature. In these direct reactions, only a few nucleons take part in the reaction, with the remaining nucleons of the target serving as passive spectators. Many excited states of the product nucleus can be reached in these reactions.

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