Department of Medical BioSciences

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The department fields specific expertise within the broad research fields of Anatomy, Cardiovascular Physiology, Herbal Sciences, Immunology, Medical Microbiology, Molecular & Cell Biology, Neuroscience, Reproduction, Toxicology and Virology

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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.
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.
Epidemiological study of Tuberculosis in Macassar camp
(University of the Western Cape, 1995) Mohammed, Ashraf; F.R., Prinsloo
The aim of this study was to determine and evaluate the prevalence of TB infection, active TB cases and the risk factors associated with TB infection in Macassar Camp in Macassar (about 40 km from Cape Town on the False Bay coast, with a population of 369). The study design of this epidemiological study was a cross sectional study with a descriptive and an analytic component A comparison between the Mantoux, TB ELISA and X-ray screening tests was performed first. A description of the origin, discovery, characteristics and pathology associated with Mycobacterium tuberculosis as well as the development of the TB epidemic on a global, national and local level, is given. TB was first described to give a South African perspective of the TB epidemic and both the "Virgin Soil" and "Non-Virgin Soil" theory of TB was reviewed. Secondly, ~he TB infection rate in Macassar Camp and the risk factors as well as the determinants of TB infection with regards to overcrowding, ventilation, primary food subsistence level rating (PFSL), social class and employment status were evaluated The third aspect of the study compares prevalence/incidence rates of TB to clinical diagnosis with regards to the symptomatology, radiographs, sputum microscopy, bacteriology and Mantoux test. Lastly the Mantoux test was compared with the TB ELISA test with regards to diagnosis of infection, in new and past confirmed TB cases. The first part of the survey involved the measurement of openable window area and the floor area of each Camp dwelling (to determine if ventilation was within required limits), during the administration of a household questionnaire which was designed to determine the number of occupants, rooms, income, food expenditure per household in the Camp. A personal questionnaire was administered to all Macassar Camp residents to elicit information on demography, knowledge and attitudes to TB, history of past TB, TB contacts, alcohol intake and smoking habits, occupation and BCG status. The Mantoux test were performed on consenting Camp residents in addition to the collection of 5 ml of blood for the TB ELISA tests. The Camp residents heights and weights were recorded prior to the miniature mass chest radiographs being taken. The 'TB suspects' sputa were collected for the microscopy and bacteriological examination. A review of the clinical records of TB patients in the Macassar/Stellenbosch area was also undertaken. The response rate to the household questionnaire was 60 from 63 (95,2%) dwelling units. Whereas the response rate to the personal questionnaire was 296 (80,2%). As for the Mantoux and TB ELISA tests the response rate was 209 (56,6%). Of the 60 dwelling units, 43 (71,7%) were calculated (according to . Batsons Index) to be crowded and 16 (26,7%) dwelling units had an overall ventilation of less than 5% (below the required regulation). There were significantly (p<0,005) more male than female smokers and only 78 (34,2%) of the residents regarded themselves as non-smokers. A similar trend was noted with regards to the alcohol intake of the residents, where only 86 (37,7%) regarded themselves as teetotallers, with significantly more (p=0,003) male than female alcohol consumers. Females sc6red significantly (p=0,002) better than the males with regards to TB knowledge and awareness. Only 199 (67,2%), residents indicated that they had had BeG vaccination. Of the 296 residents responding to the survey, there were 83 children aged 14 years or less. And only 74 of these children were confirmed to have been vaccinated with BeG, resulting in a 89,2% BeG coverage. Two (4,7%) of the 43 children aged 14 years or less were determined to be malnourished on the basis of Z-scores (below -2SD) taking into account height for age as well as weight for height.
The influence of maternal nicotine exposure on neonatal rat lung septal status
(University of the Western Cape, 1995) Thomas, Ruby Ann; Dietrich, D; Maritz, G.S.
The aim of this study was to determine the effect of maternal nicotine exposure on the status of rat lung alveolar septa of 1 to 2l day old offspring. Wistar dams were injected subcutaneously, using a dosage of 1 mg nicotine/kg body mass/day, and treatment commenced 7 days after conception, up to the third week after parturition. The data obtained showed an increase in septal cellularity, with a decrease in type I: type II cell ratio as a result of type I cell destruction and type II cell proliferation. The type I cells appear to be more sensitive to the effect of nicotine than type II cells. Data also illustrate swelling of type II and endothelial cell mitochondria, blebbing of both type I and endothelial cells and rupturing of the blood-air barrier in the nicotine exposed lungs of the rats of all the age groups. Iamellar body count are significantly higher in the type 11 cells of nicotine exposed lungs in all age groups compared to the control lungs. The number of capillaries per unit length of septum was also significantly less than that of the control lungs. Other morphological changes which were also observed in the nicotine exposed offspring in all the age groups are: loss of type II cell microvilli, swelling of type I and endothelial cells, and grouping of type II cells within the septal interstitial (an indication of proliferation). The results clearly indicate that maternal nicotine exposure interfered with the morphometric and morphologic characteristics of the alveolar septal of the lung tissue of the neonatal rats.
Aspects of the reproductive physiology of male vervet monkeys maintained in a laboratory environment
(University of the Western Cape, 1995) Seier, Jurgen Victor; van der Host, Gerhard; Menkveld, Roelof
In biomedical research limited use has been made internationally of African non-human primates. As a result, their reproductive physiology has been less well defined, when compared to the more commonly used macaque species. There have also been no extensive developments in the associated field of assisted reproduction for African non-human primates. To contribute to the knowledge of the reproductive physiology of African non-human primates, this study presents semen characteristics from the vervet monkey. The focus is on abnormal sperm morphology which has not been described in detail. AII individuals utilized here either wild caught or colony bred and maintained in an indoor laboratory breeding colony. A detailed description of the frequency and prevalence of specific morphologically abnormal forms of sperm from vervet monkeys and illustrations of the different types of abnormalities is provided for the first time. Most features, such as the prevalence of tail abnormalities, particularly coiled and bent tails, were similar to what has been reported for other OId World cercopithecines. A total of 28 types of morphologically abnormal forms were found including 13 head abnormalities, seven midpiece abnormalities and eight principal- and endpiece abnormalities. Sperm head abnormalities were rare, occurring at a rate of less than 2t in each group. Except for the nipple defect, there was no difference between colony bred and wild caught individuals in the rate at which defective forms occurred. on the other hand not aII types of abnormalities were found in each group. A relationship between morphology and fertility could not be established because some individuals with the highest rate of abnormal morphology were successful breeders. Evaluation of consecutive ejaculates revealed highly variable semen characteristics both within and amongst different individuals. This observation extends to other sperm characteristics such as the concentration, vitality, speed of forward progression (F.P) and motility. The evaluation of reproductive potential based on one or two ejaculates is therefore not possible. The pH of vervet monkey semen was similar to that of humans. out of two indicator papers tested to determine this variable, only one was found to be reliable in terms of reference values obtained with a pH meter. Another aim of the study was to develop a cryopreservation method which yields a satisfactory post-thaw recover of progressively motile sperm. No specialized equipment other than a liquid nitrogen storage container was needed. Semen samples were diluted with a Tes-Tris extender containing 5% glycerol before being cooled to 50 over 3O minutes. This was followed by aspiration of the samples into paillettes and freezing to a plunge temperature of -139oC for 20 minutes in liquid nitrogen vapour. The paillettes were finally stored in liquid nitrogen. Conspicuous features of this method were the addition of glycerol at 32oc, a short glycerol equilibration time, a fast freezing rate, a low plunge temperature and a fast thawing rate.
Structural and functional aspects of sperm after transit through the fallopian tube of the sheep
(University of the Western Cape, 1996) Hendricks, Shamila; Van der Horst, G.; Van Niekerk, F.
Ejaculated mammalian spermatozoa have the potential for fertilization. The acquisition of the ability to fertilize a fully invested oocyte occurs during the passage through the female reproductive tract. These post-ejaculatory maturational changes include the processes of capacitation and the acrosome reaction. The Fallopian tube has been accepted as the site of completion of these events while their initiation may occur either in the uterus or in the Fallopian tube. The role and/or interaction of the Fallopian tube with sperm to undergo these molecular events, are poorly understood. This study attempts to demonstrate the influence on sperm of the environment of the Fallopian tube which could initiate certain structural and functional alterations with respect to capacitation and the acrosome reaction; this study does not attempt to define the exact nature of the interaction between spermatozoa and the Fallopian tube. In this study the ur vivo situation is mimicked, exposing sperm to the oviduct under laboratory conditions. Pre- and post-migratory sperm were compared. The specific structural and functional aspects examined in this study include motility, morphology, localization of N-acetyl-D-glucosamine receptors and the acrosomal status. Motility is important to ensure successful migration to the site of fertilization. Special attention was focussed on the incidence of hyperactivation after transit through the Fallopian tube. The term hyperactivation has been used to describe the frantic movement of sperm before they undergo the acrosome reaction and often serves as a biological marker for capacitation. Motility analyses were performed using the CASMA system, the Sperm Motility Quantifier (SMQ). The biological state of hyperactivation occurred in a small population of spermatozoa after transit through the Fallopian tube. A morphologically normal sperm is a direct product of spermatogenesis and epididymal maturation. No gross morphological alterations have been reported to occur to sperm within the female. tract, Instead, elimination of sperm with gross morphological aberrations (whether as a direct function of the female tract or intrinsic sperm factors) has been shown. Measurement of the sperm head dimensions were performed in this study using the Flexible Image Processing System (FIPS). No obvious morphological disparities were present in the samples of ram sperm used. No obvious morphological alterations/selections occurred during transit through the Fallopian tube. Ram sperm head dimensions are defined. Fusion between spermatozoa and the egg vestments is a crucial step in fertilization. Exposure of audiogenic structures on sperm is a component of capacitation. The presence of these receptors is important in species-specific interaction and its absence play a significant role in infertility. FITC-conjugated wheatgerm agglutinin was used to identify and localize N-acetyl-D-glucosamine- like receptors on the sperm membrane surface. This surface component is believed to play an important role in sperm-egg interaction. Membrane alterations associated with receptor activity (allowing for sperm -zona binding) appear to have occurred after transit through the Fallopian tube. The acrosome reaction has, to date, been recognised as the most reliable indicator of the completion of capacitation. It is generally accepted that the acrosome reaction of the fertilizing sperm occurs at the zona pellucida surface, that previously acrosome-reacted sperm may also bind to the ZP. FITC- conjugated peanut agglutinin was selected as a probe for acrosomal status extermination. An increase in the incidence of acrosome-reacted sperm was observed after transit through the Fallopian tube. A small population of spermatozoa, therefore, appear to have acquired (wholly or partially) fertilizing potential after transit through the Fallopian tube.
The influence of maternal nicotine exposure on development lung as gas exchanger: the protective effect of copper
(University of the Western Cape, 1998) Dennis, Henriette; Maritz, G.S.; de Kock, M
The influence of tobacco smoking on the developing fetus is well reported. Maternal nicotine exposure during pregnancy and lactation interferes with fetal and neonatal lung growth and development, rendering the lungs more susceptible to damage and disease. interference with the normal developmental processes at any stage may compromise the gas exchange function of the lungs. Maternal nicotine exposure during gestation and lactation causes a decrease in the elastic tissue content of the lturgs, which may lead to the formation of emphysema-like lesions. Elastic tissue is catalysed by lysyl oxidase, an extracellular, copper dependent en4rmq from its soluble to its insoluble state. It is suggested that lesions occur in lturgs exposed to nicotine because of a decrease in lung copper content, which will, in turn, cause decreased lysyl oxidase activity. The aim of this study was thus to determine and quantify the effects of maternal nicotine exposure on the development of the fetal and neonatal rat lung as a gas exchanger and to establish whether copper supplementation will protect the lungs against these adverse effects of maternal nicotine exposure. The pregnant rats were divided into four experimental groups. One group received nicotine (lmdkg body weight/day) subcutaneously. Another received copper (lmg/kg body weighVday), while a third group received nicotine (lmglkg body weight/day) in addition to copper (lmg/kg body weighUday). Control rats received sterile saline. These subcutaneous injections were given throughout gestation and lactation. The results obtained showed that maternal nicotine exposure suppresses alveolarization in the fetal and neonatal lung. The lungs of the offspring exposed to nicotine during gestation and lactation have a reduced radial alveolar count, and a decreased alveolar number. All this points to a reduced internal surface area available for gas exchange. Copper supplementation during gestation and lactation prevents the adverse effects of maternal nicotine exposure on development of the lungs of the offspring. Therefore, the lungs of the copper supplemented animals can develop to its full potential as gas exchangers
The characterization and phylogenetic relationship of the trichoplusia ni single capsid nuclear polyhedrosis virus polyhedrin gene
(Kluwer Academic Publishers, 1999) Fielding, Burtram C.; Davison, Sean
The polyhedrin gene (polh) was identified from the Trichoplusia ni (Tni) single capsid nuclear polyhedrosis virus (SNPV). An EcoRI fragment containing the truncated polyhedrin gene was detected by hybridization with an AcMNPV expression vector probe; the remaining portion of the gene was amplified by reverse PCR. An open reading frame (ORF) of 741 nucleotides (nt), encoding a putative protein of 246 amino acids (a.a) with Mr 28,780 Da was identified. The 50-noncoding region contained the putative late (TAAG) transcription initiation motif. The 30 end, downstream of the translation stop codon, lacked an obvious putative poly (A) signal. Nucleotide and amino acid homology are greater than 80% to that of Mamestra brassicae polyhedrin sequences.Results suggest that T. niSNPV is a member of the group II nuclear polyhedrosis viruses.
The influence of maternal nicotine exposure on neonatal lung development : an enzymatic and metabolic study
(UWC, 1999) KordomC; Maritz, G.S.; de Kock, M
Chapter I, the literature review, gives the reader a sound background knowledge of the following: normal lung structural development in humans and rats, metabolic development with reference to structural development, tobacco smoke, and nicotine, and the effect of nicotine and smoking on metabolism. This will enable the reader to understand the motivation for this study and to give insight into the following chapters. Chapter II comprises the influence of maternal nicotine exposure on the enzymes, hexokinase and phosphofructokinase. The aim of this study was to determine the influence of maternal nicotine exposure during pregnancy and lactation on the enzymes involved in the control of energy metabolism of developing lungs of rats at postnatal days 1, 7,14,21, and 49.
The influence of maternal nicotine exposure on neonatal lung development: An enzymatic and metabolic study
(University of the Western Cape, 1999) Kordom, Chontrelle; Martiz, G.S; de Kock, M
Chapter I, the literature review, gives the reader a sound background knowledge of the following: normal lung structural development in humans and rats, metabolic development with reference to structural development, tobacco smoke and nicotine and the effect of nicotine and smoking on metabolism. This will enable the reader to understand the motivation for this study and to give insight to the following chapters. Chapter II comprises the influence of maternal nicotine exposure on the enzymes, hexokinase and phosphofructokinase. The aim of this study was to determine the influence of maternal nicotine exposure during pregnancy and lactation on the enzymes involved in the control of energy metabolism of developing lungs of rats at postnatal days 1, 7,14,21 and 49. The objectives were to determine the effect of maternal nicotine exposure during gestation and lactation on, (a) the activity of selected allosteric enzymes, hexokinase (HK) andphosphofructokinase (PFK), (b) the influence of various ATP concentrations and ATP/ADP ratios within the reaction medium on the activity of these enzymes and (c) to express the activity of these enzymes as a function of age and (d) to correlate the findings with the stage of neonatal lung structural development as explained in the literature. Female Wistar rats were used in this study. The pregnant rats were randomly assigned as a control and an experimental (nicotine) group. The experimental dams received a single dosage of 1 mg nicotinel/ kg body weight/day subcutaneously and the controls received the same volume of saline. The enzymatic activity was determine by means of spectrophotometery. It was found that HK and PFK activity are age dependent.
Identification and characterization of the Trichoplusia ni Single Capsid Nuclear Polyhedrosis Virus p10 gene
(Springer Verlag, 2000) Fielding, Burtram C.; Davison, Sean
The p10 gene was identified and characterized from the Trichoplusia ni single capsid nuclear polyhedrosis virus (TniSNPV). The p10 open reading frame (ORF) sequence was identified following sequencing of the ends of the EcoRI-G clone. Subsequent sequencing of an EcoRI-SmaI subclone identified the entire p10 and a portion of a p26 homologue. The p10 ORF of 264 basepairs (bps), encoded a predicted protein of 88 amino acids (aas) with Mr 9527 Da. The putative late transcription initiation motif (TAAG) was found upstream of the translation initiation codon at position ÿ46. Downstream of the translation stop codon, a putative poly(A) signal was identified. The p10 amino acid sequence contained the three conserved domains reported for all other p10 genes. The p10 amino acid sequence was most homologous (85% similarity and 67% identity) to that of Buzura suppresaria NPV p10 sequence.
The antioxidant properties of melatonin during chemical hypoxia and reoxygenation injury in rat ventricular myocytes
(University of the Western Cape, 2000) Salie, Ruduwaan; Dietrich, Daneel; Lochner, Amanda
It is well known that ischaemia chemical hypoxia followed by reperfusion is not always accompanied by recovery of myocardial function and often produces further cell damage (Hearse et al., 1973). This phenomenon commonly referred to as the oxygen paradox (Hearse et al., 1973), is usually characterised by extensive tissue damage and the formation of oxygen free radicals / reactive oxygen species (ROS). As the work on free radicals progressed it became apparent that there is a fine balance between cellular systems that produce free radicals and those that sustain their tolerable levels, to maintain normal cell function (Ferrari et al., 1990). The relative importance of free radicals in the production of irreversible cell damage, as well as the mechanisms involved are not fully understood. Using the rat mode of myocardial infarction followed by reperfusion, many investigators employed various antioxidants / free radical scavengers in various combinations at different stages of hypoxia / reoxygenation with the intention of reducing free radical mediated damage (Meerson et al., 1981; Shlafer et al., 1982; Stewart et al., 1983; Hess et a1., 1983; McCord and Fridovich, 1973). There is also an increasing interest in defining new antioxidants of high potency, low toxicity and good solubility properties in aqueous as well as organic phases. Recently it has been shown that melatonin (n-acetyl-5-methoxytryptamine) has the ability to directly scavenge free radicals (Reiter, 1993) It was therefore the aim of this study, to investigate oxidative stress during chemical hypoxia and reoxygenation in isolated rat ventricular myocytes and to study the antioxidant effects sf 6sl4fsnin, employed at different stages of chemical hypoxia and / or reoxygenation. To reveal the phenomenon of oxidative stress using laser scanning confocal microscopy, myocytes were preloaded with tetramethyl rhodamine (TMRM) together with one of the following fluorophores: (i) dihydric loro fluorescein diacetate (DCDHF) or dihydrorhodaminel23 (DHR) to illustrate the formation of HzOz and / or ROS; or (ii) fluo'3, AM (fluo) to show changes in intracellular free calcium. In superfused myocytes, chemical hypoxia was induced for 12.5 min by the addition of 1.5 mM KCN and 20 mM deoxy glucose to the superfusion buffer followed by 0, 1.5 or 15 min reoxygenation. Cells were also exposed to 27 .5 min chemical hypoxia without reoxygetration. Melatonin (50 pM) was added at different time intervals during the experimental protocol. All the myocytes (untreated and melatonin treated), indicated increased DCDHF but not DHR or fluo fluorescence under control oxygenated conditions (norrroxia). This probably implicate nonanal physiological levels of H2O2 and I or ROS and presumably an intact endogenous antioxidant system, since none of the cells suffered any damage. It was also indicated that melatonin had no effect on H2O2 and / or ROS formation and the viability of any of the cells during normoxia. Exposure of myocytes to chemical hypoxia for 12.5 min caused contracture and damage to 70 - 89 % of cells. This was associated with the generation of H2O2 and/ or ROS, an increase in intracellular calcium but maintenance of membrane potential. Early reoxygenation did not exacerbate or improve the changes observed during chemical hypoxia. Melatonin protected myocytes from hypoxic induced damage and increased cell viability from 20 to 80 % (p<0.05). Melatonin treated cells had reduced levels of ROS and intracellular calcium. The protection conferred by melatonin during exposure of cells to 12.5 min chemical hypoxia disappears if chemical hypoxia is prolonged to 27.5 min. After 27 -5 mn chemical hypoxia > 85 Vo of cells showed marked morphological changes and were considered to be irreversibly damaged. Myocytes indicated increased DCDHF; DHR and fluo fluorescence, implicating increased H2O2 and I or ROS formation and increased intracellular calcium respectively, after 12.5 min chemical hypoxia. However, the application of melatonin, effectively scavenged H2O2 and / or ROS and protected cells only for the first 14.5 min of chemical hypoxia, after which all of the cells indicated increased H2O2 and / or ROS formation, increased intracellular calcium and suffered irreversible damage. Presumably, as chemical hypoxia progressed, the accumulation of H2O2, the formation of ROS and degradation of endogenous antioxidant enzymes transpired, which resulted in damage to the majority of cells by the end of this period.
Identification, sequence analysis, and phylogeny of the immediate early gene 1 of the trichoplusia ni single nucleocapsid polyhedrosis virus
(Springer Verlag, 2001) Wang, Weizhou; Leat, Neil; Fielding, Burtram C.; Davison, Sean
Substantial research has been conducted on the immediate early 1 (ie-1) genes from the prototype baculovirus Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV) and the Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV). In both cases ie-1 gene products have been implicated in transcriptional activation and repression. In this study an ie-1 homolog was identified from Trichoplusia ni single nucleocapsid polyhedrosis virus (TniSNPV). Nucleotide sequence analysis indicated that the TniSNPV ie-1 gene consists of a 2217 nucleotide open reading frame (ORF), encoding a protein with a molecular mass of 84.464 kDa. This represents the largest baculovirus ie-1 gene characterised to date. Of the seven ie-1 homologs identified to date, the TniSNPV ie-1 shared most sequence similarity with the ie-1 gene of Spodoptera exigua MNPV (SeMNPV) (41%). At the nucleotide level, expected TATA and CAGT motifs were found to precede each ie-1 ORF. At the protein level, it was confirmed that the N-termini are poorly conserved, but share the characteristic of having a high proportion of acidic amino acids. In addition it was found that N-terminal regions significantly matched the SET domain in the Swiss-Prot prosite database. The C-terminal regions of the deduced IE-1 sequences were found to be substantially more conserved than the N-termini. Several conserved motifs were identified in the C-terminal sequences. A phylogenetic tree of nine baculovirus IE-1 proteins was constructed using maximum parsimony analysis. The phylogenetic estimation of the ie-1 genes shows that TniSNPV is a member of the previously described lepidopteran NPV group II and it is most closely related to SeMNPV.
Circadian activity rhythms and early gene expression in the suprachiasmatic nucleus of a diurnal rodent, Rhabdomys pumilio
(UWC, 2001) Thomas, D; Hofmeyer, MD; Bennett, N; Cooper, HM
Although humans are diurnal in behavior, animal models used for the study of circadian rhythms are mainly restricted to nocturnal rodents. This study focused on circadian behavior and gene expression in a diurnal rodent from South Africa, the four-striped field mouse (Rhabdomys pumilio). In contrast to nocturnal rodents which have rod-dominated retinas, the retina of this field mouse contained approximately an equal amount of cones as rods. The cones included short-wavelength (blue-sensitive) and mid-wavelength (green-sensitive) cones. In order to characterize the behavioral pattern of daily activity, locomotor rhythms were studied under different light regimes using an automated data recording system. Under conditions of natural daylight which include dawn and dusk transitions, R. pumilio showed activity restricted to the daytime period. Activity was concentrated around morning and evening hours with a decrease during mid-day.
Student experiences of life science practicals
(UWC, 2001) Faroe, D.L; Jonker, L.E
Science Educationists seem to agree that practical work should form an important component of any science course. Many students arrive at University without having been exposed to any practical work, while others were exposed to a range of different practical activities. This background seems to impact how students experience and benefit from laboratory work at University. This research is aimed at determining what first-year students' experiences of the life science practical course were. Reflective journals were used as a tool to get students' opinions about their experiences in the practical classes. Interviews served to clarify the problems that seemed to surface.
The genetic organisation of a 2,966 basepair DNA fragment of a Single Capsid Nucleopolyhedrovirus isolated from Trichoplusia ni
(Springer Verlag, 2002) Fielding, Burtram C.; Khan, Sehaam; Wang, Weizhou; Kruger, Courtney; Abrahams, Rayaana; Davison, Sean
In order to investiagte the genomic organization of the Trichoplusia ni Single Capsid Nucleoplyhedrovirus (TnSNPV) , a 2,966 base pairs (bp) genomic fragment was sequenced. The fragment was found to contain five open reading frames (ORF's) homologous to baculovirus genes, including p26, fibrillin (p10), AcMNPV ORF-29, late expression facor 6 (lef 6) and the C-terminal portion of p74, on either stand of DNA. Predicted amini acid sequences for the ORFs were compared and identity values of between 12% and 54% were observed. Clustering and arrangement of the TnSNPV genes were similar to the clustering reported for SeMNPV, confirming TnSNPV was a Group II NPV.
An assessment of Carpobrotus acinaciformis and Cissampelos capensis as potential antimicrobial agents and their effects on animal metabolism
(University of the Western Cape, 2002) Bowie, Andrea; Johnson, Quinton
The definition of a medicinal plant (as formulated by the WHO) is a plant that consists of either one or more plant parts with therapeutic properties that can be used in the development of drugs (sofowora lg82). Various medicinal plants have been used over the years for their healing properties, and it can even be said that this is an ancient practice (Cowan 1999). Plant derived medicines have been part of traditional healthcare in most parts of the world for thousands of years @alombo & Semble 2001- Salie 1998))' Presently, approximately l|%of the world population make use of plants and its extracts (salie 1998; Abelson 1990). Despite this widespread use of medicinal plants, only a fraction has been tested. Many plant derived natural products must be investigated for their pharmacological activity (Mendelson & Balick 1998; Gentry 1993)' Hence it is of utmost importance to study medicinal plants for safety and efficacy @loff 1998)' since there is still an infinite number that must be studied and discovered (Abelson 1990; Sofowora 1982). Hippocratus in the late fifth century B.C.) was a physician who strongly believed in herbal remedies to treat many ailments and recorded the use of approximately 300 to 400 medicinal plants (cowan 1999; Sofowora 1982; Schultes 1978). It is also believed that the Egyptians (1500 B.C) made use of medicinal plants as some records excavated from ancient Egyptian tombs stated (Sofowora 1982). The De Materia Medical medicinal plant catalogue of about 600 medicinal plants, was compiled by the Greek Dioscorides (A. D. 60) and was used by Europeans as a standard reference during medieval times (Cowan Lggg,Sofowora lg82). The works of the physician Galen were used in the middle ages but many of his records were destroyed. In spite of these unfortunate circumstances, present allopathic and homeopathic systems have been derived from the works of Galen (Sofowora 1982)'
An evaluation of the biopesticidal characteristics of Hetichrysum marifolium and Helichrysum patulum and their effects on animal metabolism
(University of the Western Cape, 2002) Speelman, Abigail; Johnson, Quinton
There ate a number of pesticides that are suspected to be endocrine disrupters' Many of these pesticides are man-made. Endocrine disrupters are chemicals that can lead to an increase in birth defects, sexual abnormalities, and reproductive failure. Marine animals seem to be the most vulnerable to the effects of pesticides since the ocean is the final sink for many pollutants. Endocrine disrupters can exert their effects in many ways. They can either bind to the hormone's receptor and mimic the hormone, or block the action of the hormone' An experiment done of newborn female rats injected with 1mg DDT/day on days 2-4 after birth had early onset of puberty and accelerated loss of fertility. ln another experiment, vinclozolin (also a pesticide) at dosage levels of 3mg/kg/day resulted in feminised male rats in the womb and an abnormal number of nipples were observed (11). Pesticides can be absorbed through the skin, by inhalation or oral ingestion. There are, however, important quantitative differences between the various derivatives. The skin poorly absorbs DDT in solution, whereas dieldrin absorption by the skin is very efficient. The major effects of insecticides in humans are qualitatively similar and cause effects on the central nervous system (9). Endocrine disrupters encompass more than just environmental estrogens and include any agent that adversely affects any aspect of the entire endocrine system. Endocrine disrupters are usually either natural products or synthetic chemicals that mimic, enhance or inhibit the action natural hormones (5). Low levels of many endocrine disrupting chemicals can lead to high levels in body tissues of animals and humans. This is due to the fact that many endocrine disrupters are stored in fat$ tissues through biomagnifications
Ecology and conservation of high altitude amphibians
(UWC, 2002) Geland, C; Channing, A
This study looked at the breeding ecology of the anurans, found in the Landdroskop mountain range in Grabouw, and some recommendations as to their conservation are made. There is very little known about the frogs in South Africa and this study aims to el cite some of the factors that influence the vocalization of these frogs and the periods that these frogs breed.
An evaluation of the biopesticidal characteristics of Helichrysum marifolium and Hetichrysum patulum and their effects on animal metabolism
(University of the Western Cape, 2002) Speelman, Abigail; Johnson, Quinton
There ate a number of pesticides that are suspected to be endocrine disrupters' Many of these pesticides are man-made. Endocrine disrupters are chemicals that can lead to an increase in birth defects, sexual abnormalities, and reproductive failure. Marine animals seem to be the most vulnerable to the effects of pesticides since the ocean is the final sink for many pollutants. Endocrine disrupters can exert their effects in many ways. They can either bind to the hormone's receptor and mimic the hormone, or block the action of the hormone' An experiment done of newborn female rats injected with 1mg DDT/day on days 2-4 after birth had early onset of puberty and accelerated loss of fertility. ln another experiment, vinclozolin (also a pesticide) at dosage levels of 3mg/kg/day resulted in feminised male rats in the womb and an abnormal number of nipples were observed (11). Pesticides can be absorbed through the skin, by inhalation or oral ingestion. There are, however, important quantitative differences between the various derivatives. The skin poorly absorbs DDT in solution, whereas dieldrin absorption by the skin is very efficient. The major effects of insecticides in humans are qualitatively similar and cause effects on the central nervous system (9). Endocrine disrupters encompass more than just environmental estrogens and include any agent that adversely affects any aspect of the entire endocrine system. Endocrine disrupters are usually either natural products or synthetic chemicals that mimic, enhance or inhibit the action natural hormones (5). Low levels of many endocrine disrupting chemicals can lead to high levels in body tissues of animals and humans. This is due to the fact that many endocrine disrupters are stored in fat$ tissues through biomagnifications (2). The greatest exposure to endocrine-disrupting chemicals is from food intake and since many are fat-solubte, the highest levels occur in the higher trophic levels' particularly meat, fish, and dairy products. The groups of organisms for which there is substantial evidence of endocrine disruption include snails, oysters, fish, alligators, and other reptiles, and birds such as seagulls and eagles' Many endocrine disrupting chemicals have become widespread contaminants across the globe. This is not due to their vast usage on a worldwide scale, but because some of the pesticides can be transported for thousands of kilometres on air currents (2).

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