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Studies on the bioactivities of selected Eastern Cape seaweeds

- Carter, Anne Margaret

  • Authors: Carter, Anne Margaret
  • Date: 1994
  • Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
  • Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
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  • Date Issued: 1994

Studies related to the process of program development

- Williams, Morgan Howard

  • Authors: Williams, Morgan Howard
  • Date: 1994
  • Subjects: Computer programming
  • Language: English
  • Type: Thesis , Doctoral , DSc
  • Identifier: vital:4680 , http://hdl.handle.net/10962/d1007235
  • Description: The submitted work consists of a collection of publications arising from research carried out at Rhodes University (1970-1980) and at Heriot-Watt University (1980-1992). The theme of this research is the process of program development, i.e. the process of creating a computer program to solve some particular problem. The papers presented cover a number of different topics which relate to this process, viz. (a) Programming methodology programming. (b) Properties of programming languages. aspects of structured. (c) Formal specification of programming languages. (d) Compiler techniques. (e) Declarative programming languages. (f) Program development aids. (g) Automatic program generation. (h) Databases. (i) Algorithms and applications.
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  • Date Issued: 1994

Sunbird Movements: a Review, with Posslble Models

- Craig, Adrian J F K, Hulley, Patrick E

  • Authors: Craig, Adrian J F K , Hulley, Patrick E
  • Date: 1994
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/447856 , vital:74679 , https://doi.org/10.1080/00306525.1994.9639672
  • Description: Based on current fieldwork, we propose four possible models to explain the winter influx of sunbirds which we have observed: the birds may be (1) “winter residents”, which move annually to a wintering area and remain there; (2) “shoppers”, which periodically investigate feeding areas within their home range and feed opportunistically where nectar is most abundant; (3) “tourists”, which successively visit a series of sites on a regular itinerary; (4) “nomads”, which move unpredictably to new areas whenever food supplies decline. and have no home base. Current data on sunbird movements are reviewed, and in a few cases the winter resident model is unlikely, but generally it is not yet possible to eliminate any of the hypotheses. Moult cycles based on both field and museum studies may provide additional information, as movements are unlikely while active wing-moult is in progress; some species show interrupted wing-moult, which may be associated with long-distance flights.
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  • Date Issued: 1994

Sunu Rew

- Tidiane Gaye (lead vocal), Assane Diop (solo guitar), Niankou Sembene (keyboards), Ousseynou Diop (drums), Moussa Sene, Mor Sourang, Thio Mbaye (percussion), Mada Ba (chorus), Galissa (kora), Mamane Thiam (tama), Studio 2000, Samassa Records

Surficial placer gold deposits

- Mann, P L

  • Authors: Mann, P L
  • Date: 1994
  • Subjects: Gold mines and mining , Gold ores -- Geology , Placer deposits
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5088 , http://hdl.handle.net/10962/d1018245
  • Description: This review summarises the factors which control the formation and distribution of surficial gold placer deposits. Regional tectonic and climatic conditions as well as gold source are considered. The characteristics of eluvial, alluvial, marine, glacial and fluvioglacial gold placer deposits are described. Particular attention is paid to the gold grains within these placers. These gold grains have a distinctive morphology and chemical composition which reflect the manner in which they were transported, deposited and concentrated within the placers. The knowledge of the processes which lead to the formation and location of surficial gold placers is then used to guide exploration and target potential deposits, which can then be evaluated.
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  • Date Issued: 1994

Synthesis and conformational studies of indolizines

- George, Rosemary

  • Authors: George, Rosemary
  • Date: 1994
  • Subjects: Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4367 , http://hdl.handle.net/10962/d1005032 , Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
  • Description: The present investigation has involved a kinetic and mechanistic study of the thermal cyclization of 3-acetoxy-3-(2-pyridyl)-2-methylenepropanoate esters and related compounds to 2-substituted indolizines. Substrates for the kinetic study were prepared via the Baylis-Hillmann reaction of pyridine-2-carboxaldehydes with acrylate esters, acrylonitrile and methyl vinyl ketone. The resulting hydroxy compounds were then acetylated to afford the acetoxy derivatives, thermal cyclization of which gave the corresponding 2-substituted indolizines. The cyclization reactions was followed using 'H NMR spectroscopy and were shown to follow firstorder kinetics. The influence of the various substituents on the observed first-order rate constants has been examined and variable temperature studies have permitted evaluation of activation parameters for the formation of methyl indolizine-2-carboxylate and ethyl indolizine-2-carboxylate. An alternative route to 2-substituted indolizines via halogenated derivatives was explored and several halogenated 2-pyridyl derivatives were synthesised and their thermal cyclization to indolizines was attempted. Novel 5-methylindolizine-2-carboxamides were prepared as part of this investigation and dynamic NMR spectroscopy was used to study internal rotation about the amide N-CO bond in these compounds.
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  • Date Issued: 1994

Synthetic and spectroscopic studies of 1,4-benzodiazepine analogues

- Mphahlele, Malose Jack

  • Authors: Mphahlele, Malose Jack
  • Date: 1994
  • Subjects: Benzodiazepines Tranquilizing drugs
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4384 , http://hdl.handle.net/10962/d1005049
  • Description: In this project, an extensive range of benzodiazepine analogues have been synthesised via Schmidt reaction of specially prepared flavanone, 4-quinolone and l-thioflavanone precursors; nitrogen insertion being effected by use of trimethylsilyl azide in trifluoroacetic acid. In some cases, several of the benzodiazepine analogues have also been prepared by alternative cyclisation routes. A detailed kinetic-mechanistic study of the Schmidt reaction of flavanones has been carried out using 'H NMR spectroscopy to explain the observed regiochemistry of nitrogen insertion. The reaction rates, for the formation of both amide and tetrazolo derivatives have been found to be influenced by the electronic effects of the A- and B-ring substituents. A series of benzodiazepine analogues have been shown to undergo regioselective A-ring chlorination with t-butylhypochlorite; the products being characterised by 'H NMR, IR and mass spectroscopy. The mass spectrometric fragmentation patterns of series of 2-aryl-4-quinolones, and 2-aryl-l ,4-benzodiazepinones and their tetrazolo[l ,5-dl analogues have been elucidated using a combination of low-resolution, high-resolution and metastable-peak analyses. The binding affinities of various benzodiazepine analogues for rat brain benzodiazepine receptors have been evaluated using a radioreceptor assay technique. Structure-activity relationships were investigated to establish the effects of various A-, B- and Coring substituents on binding affinity. The conformational preferences of selected systems have been studied using a combination of multi-pulse 'H NMR spectroscopy, X-ray crystallography and computer modelling techniques with a view to establishing the influence of conformation on binding affinity.
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  • Date Issued: 1994

Synthetic and spectroscopic studies of indolizine derivatives

- Bode, Moira Leanne

  • Authors: Bode, Moira Leanne
  • Date: 1994
  • Subjects: Indole alkaloids -- Derivatives Spectrum analysis Chemistry, Organic DNA -- Synthesis
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4385 , http://hdl.handle.net/10962/d1005050
  • Description: The crystalline compound resulting from thermal cyclization of the Baylis-Hillman product, methyl 3-hydroxy-2-methylene-3-(2-pyridyl)propanoate, has been identified as the indolizine derivative, methyl indolizine-2-carboxylate, and this approach involving the reaction of pyridine-2-carboxaldehydes and acrylate analogues has been established as a general route to 2-substituted indolizines. The ease of cyclization the Baylis-Hillman products to indolizines has been shown to increase by converting the hydroxy group to an acetoxy group, and a range of acetylated Baylis-Hillman products were prepared and cyc1ized to the corresponding 2-substituted indolizines, generally in good overall yield. In the reaction of pyridine-2-carboxaldehyde and methyl vinyl ketone, the intermediate cyclized readily and directly to the corresponding indolizine. One- and two-dimensional ¹H and ¹³C NMR analysis of the 2-substituted indolizine products has permitted complete assignment of all ¹H and ¹³C NMR signals, as well as the measurement of all coupling constants for these compounds. A kinetic and mechanistic study has been conducted on the Baylis-Hillman reaction using ¹H NMR spectroscopy. A range of substrates has been examined and the reaction has been found to be third-order overall. A mechanism involving an addition - elimination sequence is proposed, which fits the kinetic data and accounts for observed substituent effects. Reaction of N,N-dimethylacrylamide with pyridine-2-carboxaldehyde in the presence of the tertiary amine catalyst, DABCO, in chloroform, yielded an unexpected product which has been identified by single crystal X-ray diffraction analysis as 1-(2,2,2-trichloro-1-hydroxyethyl)pyridine. Attempted extension of the general indolizine route to the preparation of chromene systems by reacting salicylaldehyde with methyl acrylate in the presence of DABCO, also led to an unexpected, crystalline material, identified by single crystal X-ray diffraction analysis as the coumarin derivative, 3-[(2-formylphenoxy)methyl]coumarin.A series of chloroquine analogues have been prepared from indolizine-2-carboxylic acid, pyrrolo[I,2-a]quinoline-2-carboxylic acid and imidazo[I,2-a]pyridine-2-carboxylic acid by reaction with suitable amines in the presence of the coupling reagent 1, I' -carbonyldiimidazole. This route has been shown to be a vast improvement on earlier procedures and has provided access to both secondary and tertiary indolizine-2-carboxamides. A range of N,N-dialkylindolizine-2-carboxamides have been prepared by this route, and the influence of substituents on their N-CO rotational energy barriers has been determined using variable temperature ¹H and ¹³C NMR techniques. Intercalation with natural DNA by both chloroquine and the synthesized chloroquine analogues has been examined using UV spectrophotometry, and ¹H and ³¹P NMR spectroscopy. The pyrrolo[I,2-a]quinolines have been shown to be DNA intercalators with binding affinities similar to that of the known antimalarial intercalator, chloroquine. In a preliminary study the synthesis of a short oligonucleotide has been undertaken and changes have been observed in the ¹H and ³¹P NMR spectra of the oligonucleotide on addition of the intercalator, chloroquine.
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  • Date Issued: 1994

Systematics and Osteology of the Zoarcidae (Teleostei: Perciformes)

- Anderson, M Eric

  • Authors: Anderson, M Eric
  • Date: 1994
  • Language: English
  • Type: Text
  • Identifier: vital:15033 , http://hdl.handle.net/10962/d1019910 , ISSN 0073-4381 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 60
  • Description: The eelpouts, Zoarcidae, are a group of perciform fishes, most species of which inhabit continental shelves and slopes of boreal seas. There are about 220 valid species of eelpouts; most are rare, deep-sea forms and the systematics and biology of the group has been neglected by most workers. This work is a contribution to the improvement of that state. The anatomy of the Zoarcidae was studied in an attempt to reconstruct phylogeny and establish generic limits. From an analysis of a matrix of 76 characters, the 45 genera recognised here form 4 subfamilies. The Lycozoarcinae contains only the primitive Lycozoarces hubbsi. The others, Zoarcinae, Gymnelinae, and Lycodinae, for the most part, include genera recognised in previous classifications (Gill, 1862, 1864; Andriashev, 1939). The more primitive zoarcids are characterised by having 4-6 suborbital bones arranged in a circular pattern close to the orbit, and “complete” cephalic lateralis pore patterns, except some of the few deep-sea forms. The more derived zoarcids are characterized by having 6-11 suborbital bones arranged in an angled, or “L”-shaped" pattern away from the orbit (except a few which have lost some bones) and the loss of the interorbital pores (except for some reversals in Lycenchelys and Lycodapus). Zoarcids are considered to have originated in the North Pacific Ocean, perhaps as early as the Eocene, when a pre-percoid radiation occurred. The suborder Zoarcoidei (today some 8-9 families) spread across the Pacific rim. Among Zoarcidae, a pre-Miocene radiation took place along the western coasts of the Americas, with areas of endemism forming in the Magellan Province of South America and Antarctica. Subsequent spreading back into northern waters occurred in Melanostigma and Pachycara. , Rhodes University Libraries (Digitisation)
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  • Date Issued: 1994

Tangentially symplectic foliations

- Remsing, Claudiu Cristian

  • Authors: Remsing, Claudiu Cristian
  • Date: 1994
  • Subjects: Geometry Problems, exercises, etc Geometry, Differential Symplectic manifolds Poisson manifolds Foliations (Mathematics)
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5419 , http://hdl.handle.net/10962/d1005233
  • Description: This thesis is concerned principally with tangential geometry and the applications of these concepts to tangentially symplectic foliations. The subject of tangential geometry is still at an elementary stage. The author here systematises current concepts and results and extends them, leading to the definition of vertical connections and vertical G-structures. Tangentially symplectic foliations are then characterised in terms of vertical symplectic forms. Some significant particular cases are discussed.
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  • Date Issued: 1994

The challenge of local government transition

- NUMSA

  • Authors: NUMSA
  • Date: 1994
  • Subjects: NUMSA
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/173594 , vital:42387
  • Description: This pamphlet provides an outline of those features of the Local Government transition process, with which workers will have to deal.
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  • Date Issued: 1994

The challenge of trade union rights in Africa

- ICFTU

  • Authors: ICFTU
  • Date: 1994
  • Subjects: International Confederation of Free Trade Unions (ICFTU)
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/153951 , vital:39540
  • Description: A purely academic observer would probably find significant cause for optimism about the evolution of the trade union rights situation in Africa in the 1990’s, and about the observance of human rights more generally. The continent has lived under the sign of democratization since the beginning of the decade, and the extent of political transformation has been unprecedented and astonishing. Since 1989, at least 25 African nations have adopted entirely new constitutions or major constitutional reforms. To them may be added those countries - for so long an isolated minority - which already operated pluralist democratic systems and those, more numerous, which are still engaged in processes of transition and reform.
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  • Date Issued: 1994

The cicada genus Stagea n. gen. (Homoptera Tibicinidae) systematics

- Villet, Martin H

  • Authors: Villet, Martin H
  • Date: 1994
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/453886 , vital:75296 , https://doi.org/10.1080/03946975.1994.10539259
  • Description: The monotypic genus Stagea n. gen. and the species S. platyptera n. sp. are described. The type was caught in Natal, South Africa. The genus shares several characters with the endemic South African genera Stagira Stål 1861 and Bavea Distant 1905.
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  • Date Issued: 1994

The cicada genus Tugelana Distant 1912 (Homoptera Cicadoidea) systematics and distribution

- Villet, Martin H

  • Authors: Villet, Martin H
  • Date: 1994
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/453920 , vital:75298 , https://doi.org/10.1080/03946975.1994.10539243
  • Description: The cicada genus Tugelana Distant 1912 and its only species are redescribed. The genus is best characterized by the shape of the male urite. T. butleri Distant 1912 is found on the coastal plateau of southern Mocambique and the adjoining tropical part of South Africa. Tugelana is most closely related to the genera Azanicada Villet 1989, Systophlochius Villet 1989 and Platypleura Amyot and Serville 1843, which form a clade within the tribe Platypleurini Schmidt 1918.
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  • Date Issued: 1994

The comprehension of figurative language in English literary texts by students for whom English is not a mother tongue

- Winberg, Christine

  • Authors: Winberg, Christine
  • Date: 1994
  • Subjects: English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2366 , http://hdl.handle.net/10962/d1002649 , English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
  • Description: This study applies Sperber and Wilson's relevance theory to the comprehension of figurative language in poetry. Students' understanding of metaphor as a linguistic category and comprehension of metaphorical texts are analysed in terms of the principle of relevance. Patterns of comprehension in English first language (Ll) and English second language (ESL) students' analyses of metaphorical texts are discussed and through an analysis of similarities and differences in these patterns of comprehension an attempt is made to develop a pedagogy around relevance theory. Relevance theory's particular emphasis on the role played by "context" in cognition is seen to have significance for the teaching of literature in South African universities. Relevance theory's account of cognition generates a range of educational principles which could be specifically applied to the teaching of metaphor. An appraisal of the strengths and difficulties students experience in expressing their understanding of metaphor in an academic context is included. This was done to further develop relevance theory into a pedagogical approach which takes into account the academic context in which writing occurs. The investigation of the particular difficulties that English metaphor poses for ESL students entailed acquiring a working knowledge of the ways in which metaphor is taught and assessed in DET schools. The interpretations of students of different linguistic, social and educational backgrounds reveal unifying elements that could be incorporated into a pedagogy based on relevance theory. Such a pedagogy would be appropriate to the multilingual/multicultural/multiracial nature of classes in South African universities and would be a more empowering approach to the teaching of English metaphor.
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  • Date Issued: 1994

The concept of "the people" in liberation theology

- Menatsi, Richard

  • Authors: Menatsi, Richard
  • Date: 1994
  • Subjects: Liberation theology , Poor -- Religious aspects , Poverty -- Religious aspects -- Christianity , Government, Resistance to -- Religious aspects -- Christianity
  • Language: English
  • Type: Thesis , Masters , MTh
  • Identifier: vital:1297 , http://hdl.handle.net/10962/d1015654
  • Description: The concept of "the people" has become a key concept within the work of several Latin American theologians, Korean Minjung theologians and South African theologians. When liberation theologians use the concept of "the people" in their literature they do so with a lack of clarity, to the extent that the exact meaning of the term is obscure. In their usage of the concept "the people" liberation theologians come up with differing and at times contradictory meanings, particularly as regards the concrete and symbolic meanings of the concept. This thesis sets out to investigate the use of the concept "the people" by liberation theologians by consulting a selection from Latin American theology, Korean Minjung theology, South African liberation theology and Marxism, to detect its influence on the use of this notion. A general overview of the thesis indicates the following. The first chapter provides a detailed analysis of the concept of "the people" in the work of different liberation theologians. Chapter two considers "the people" in relation to poverty and oppression. The third chapter deals with "the people" as subjects of history. In the fourth chapter "the people" as a concept is developed in relation to belief within the Christian church. The final chapter is an evaluation. The thesis reveals that the following characteristics are central to "the people", they are poor and oppressed but are also inclusive of all those persons who identify and actively support the struggle against poverty and oppression. "The people" are subjects of their own history, finally they are Christian believers.
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  • Date Issued: 1994

The contradictions of community politics: the African petty bourgeoisie and the New Brighton Advisory Board, c1937-1952

- Baines, Gary F

  • Authors: Baines, Gary F
  • Date: 1994
  • Language: English
  • Type: Article
  • Identifier: vital:6147 , http://hdl.handle.net/10962/d1003831
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  • Date Issued: 1994

The design and use of a data base for the teaching of history at primary school level

- Paul, James R M

  • Authors: Paul, James R M
  • Date: 1994
  • Subjects: Education -- Data processing History -- Study and teaching (Elementary) -- Data processing Computer-assisted instruction
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1490 , http://hdl.handle.net/10962/d1003371
  • Description: The changes brought about by society's move from an industrial to an information society has brought with it changes in the way that society operates - from the way we do business to the way we entertain ourselves and, increasingly, in the way we educate our children. That the society of tomorrow requires new skills to survive and operate had been, and continues to be, debated in a growing number of books and in the popular media. More and more educationists are calling for schools to 'restructure' so as to be able to provide the skills that this new society requires, especially those related to the management of information. The nature of these skills are discussed, together with the potential provided by information technology, particularly computers, to provide them. The current use of computers in schools is addressed, together with the apparent inability of schools to generate effective change from within using in-service training. The researcher suggests that this makes it imperative that teacher training institutions provide the next generation of teacher-trainees with a thorough understanding of the requirements of an information society and the tools that it uses. The research undertaken attempted to provide final year primary education teacher-trainees with one example of the way in which the electronic database can be used to change the teaching of history. By researching in the field and entering data into a data base, the teacher-trainees were able to look at information in new ways. By selecting and sorting data by different fields, they were able to act as ' true' historians - each interacting with the data in his or her own way to extract knowledge that is arguably unique for each participant. The data base was then used with a class of standard four pupils, with the researcher acting as participant observer. The reactions and responses of the pupils to the data was noted and these are discussed in the results . A non-participant observer, also a primary school history -teacher, provided input with respect to the validity of the learning experience and to act as a control. The research is described, together with the observations of the researcher, teacher-trainees and pupils involved. The observations of the non-participant observer are also discussed. Shortfalls and difficulties encountered are pointed out, and areas for further research suggested.
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  • Date Issued: 1994

The design, implementation and evaluation of an English language development component within a Grahamstown community project

- Jefferay, Charlotte Ruth

  • Authors: Jefferay, Charlotte Ruth
  • Date: 1994
  • Subjects: Grahamstown Tertiary Education Bridging Project , English language -- Study and teaching -- South Africa -- Foreign speakers , English language -- Writing -- Study and teaching -- South Africa -- Foreign speakers
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2351 , http://hdl.handle.net/10962/d1002633 , Grahamstown Tertiary Education Bridging Project , English language -- Study and teaching -- South Africa -- Foreign speakers , English language -- Writing -- Study and teaching -- South Africa -- Foreign speakers
  • Description: The Grahamstown Tertiary Education Bridging Project (GRATEP) was formed in 1991 by a group of post-matriculants from Grahamstown who had not been accepted into any tertiary institution for 1991. The overall aim of GRATEP was to prepare these students for tertiary education. The Academic Skills Programme at Rhodes University offered a programme in English Language Development. The present study aimed to research the design, implementation and evaluation of the GRATEP English Language Development programme which was implemented from May through to October 1991. A multimethod approach has been used to assess the progress made by the students in terms of developing communicative competence in English and to evaluate the course itself. The data included writing samples, questionnaires, exercises in hierarchical organization, a clozetest, comments made by the students and the participant observers. The programme appeared to have been most effective in terms of building confidence, developing academic skills and encouraging the students to take greater responsibility for their own learning. Statistical comparisons of the first and final writing samples revealed no overall significant improvement in communicative competence in English. However, comparisons of the scores in the categories and sub-categories of communicative competence revealed that students had improved in their ability to structure and organize their writing. The research raised questions about the design, implementation and assessment of non-formal language courses of this kind and made suggestions for improvement and further research.
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  • Date Issued: 1994

The dissociation of ammonium salts and their effect on the physiology and biochemistry of L-lysine synthesis by Corynebacterium glutamicum FP6

- Kenyon, Colin Peter

  • Authors: Kenyon, Colin Peter
  • Date: 1994
  • Subjects: Ammonium salts Lysine -- Synthesis Corynebacterium Dissociation -- Research
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4034 , http://hdl.handle.net/10962/d1004094
  • Description: The availability and assimilation of NH₄⁺ plays an integral role in the growth of microorganisms and the production of amino acids by these organisms. This study investigated the dissociation of NH₄⁺in aqueous solution, its availability and effect on the enzymes of NH₄⁺ assimilation and its influence on lysine production by Corynebacterium glutamicum.In aqueous solution the extent of dissociation of NH₄C1, {NH₄)₂S0₄ and (NH₄)₂HP0₄ increases with decreasing concentration. A model is proposed for the dissociation of these molecules. It is believed that at very low concentrations, dissociation to NH₃ plus the respective counter-ions occurs. At these low concentrations the NH₃ acts as the substrate for glutamine synthetase. At the higher concentrations dissociation is to NH₄⁺ which is the substrate for glutamate dehydrogenase. At these higher concentrations the enzyme activities obtained for glutamate dehydrogenase, at equivalent concentrations of the above ammonium salts, were different when based on the total concentration of NH₄⁺, and similar when based on the concentration of free NH₄⁺. L-Iysine occurs in the +1 ionic form, at pH 7,2. The lysine which is produced during fermentation associates with the anionic counter-ion of the ammonium salt used. The concentration of the free NH₄⁺ in the media appears to affect both the rate of lysine synthesis as well as the yield. The lysine fermentation occurs in two stages; a growth (or replicative) phase, during which very little lysine is produced, and a lysine synthesis (or maturation) phase. During the lysine synthesis phase there is no cell replication, however an increase in the mass of the biomass produced is apparent. Evidence is provided for the possible concomitant synthesis of the the cell wall polymer, glycerol teichoic acid, and lysine. On the basis of this evidence, a nucleotide balance is proposed for lysine and teichoic acid synthesis. The replicative phase and the maturation phase have to be effectively separated to obtain optimal lysine yields and titres. It is believed that teichoic acid synthesis during the replicative phase must be kept to a minimum for optimal yields and titres to be obtained, and on completion of the cell wall and therefore teichoic acid synthesis, lysine synthesis ceases. As the production of lysine appears to be affected by the NH₄⁺ concentration in the culture media, it is proposed that a futile cycle may exist around the transport and assimilation of the NH₄⁺. If the fermentations are run at low free NH₄⁺ concentrations, it was shown that lysine yields of 0,66, on the glucose utilised, are attainable during the fermentation.
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  • Date Issued: 1994
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