Phytochemical studies on certain South African species of the rutaceous genera Agathosma Willd. and Zanthoxylum L
- Authors: Finkelstein, Nathan
- Date: 1979
- Subjects: Zanthoxylum Rutaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3725 , http://hdl.handle.net/10962/d1001460
- Description: Selected species of two South African rutaceous genera, Agathosma Willd. and Zanthoxylum L., were phytochemically studied. Two species of the former genus, A. puberula (Steud.) Fourc . and A. elavisepala R. A. Dyer, yielded a novel O-prenylcoumarin, puberul in, the structure of which was fully elucidated as 6,8- dimethoxy-7-prenyloxycoumarin. This represents the first report of a coumarin from that endemic genus. In another study the alkaloids in three species of Zanthoxylum, Z. davyi (Verdoorn) Waterm., Z. thorneroftii (Verdoorn) Waterm. and Z. humile (E .A. Bruce) Waterm . , were investigated. Chelerythrine, nitidine, (-) -α-N-methylcanadine, (+)-laurifoline and (+)-magnoflorine were isolated and characterized in the stem and root bark of Z. davyi, while the root bark of Z. thorneroftii contained skimmianine and decarine in addition to the alkaloids present in Z. davyi. Skimmianine, decarine, N-norchelerythrine, chelerythrine, (-)-α-N-methylcanadinc, candicine and tembetarine were identified in the root bark of Z. humile. The chemotaxonomic significance of these alkaloids occurring in the South African taxa in relation to other African Zanthoxylum taxa, is discussed. Several non-alkaloids (lupeol, β-sitosterol and (-)-sesamin) were also isolated and characterized in Z. davyi and Z. humile. Horizontal cellulose column chromatography and low pressure liquid chromatography have been applied to the separation of quaternary alkaloids
- Full Text:
- Date Issued: 1979
- Authors: Finkelstein, Nathan
- Date: 1979
- Subjects: Zanthoxylum Rutaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3725 , http://hdl.handle.net/10962/d1001460
- Description: Selected species of two South African rutaceous genera, Agathosma Willd. and Zanthoxylum L., were phytochemically studied. Two species of the former genus, A. puberula (Steud.) Fourc . and A. elavisepala R. A. Dyer, yielded a novel O-prenylcoumarin, puberul in, the structure of which was fully elucidated as 6,8- dimethoxy-7-prenyloxycoumarin. This represents the first report of a coumarin from that endemic genus. In another study the alkaloids in three species of Zanthoxylum, Z. davyi (Verdoorn) Waterm., Z. thorneroftii (Verdoorn) Waterm. and Z. humile (E .A. Bruce) Waterm . , were investigated. Chelerythrine, nitidine, (-) -α-N-methylcanadine, (+)-laurifoline and (+)-magnoflorine were isolated and characterized in the stem and root bark of Z. davyi, while the root bark of Z. thorneroftii contained skimmianine and decarine in addition to the alkaloids present in Z. davyi. Skimmianine, decarine, N-norchelerythrine, chelerythrine, (-)-α-N-methylcanadinc, candicine and tembetarine were identified in the root bark of Z. humile. The chemotaxonomic significance of these alkaloids occurring in the South African taxa in relation to other African Zanthoxylum taxa, is discussed. Several non-alkaloids (lupeol, β-sitosterol and (-)-sesamin) were also isolated and characterized in Z. davyi and Z. humile. Horizontal cellulose column chromatography and low pressure liquid chromatography have been applied to the separation of quaternary alkaloids
- Full Text:
- Date Issued: 1979
The South African shipping question, 1886-1914
- Authors: Solomon, Vivian
- Date: 1979
- Subjects: Shipping conferences -- History Shipping -- South Africa -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1039 , http://hdl.handle.net/10962/d1004667
- Description: From Preface: For the best part of a generation the "Shipping Question" was a talking-point in South Africa; yet today it is completely forgotten, and the name of its leading actor is virtually unknown. Scant reference to the controversy will be found in economic- or other histories; in the rare cases where it is alluded to, the treatment is superficial. This study seeks to fill that gap. At the outset it is advisable to define the scope of the work. It is not a history of the South African shipping trade in the pre-1914 era: shiplovers have had that ground amply covered by Marischal Murray, and indeed are unlikely to find in the following pages much to their taste. Neither is it an economic analysis of shipping conferences: there is a growing body of work on that subject, and this study does not seek to add to it. Nor is it a business history: it does not probe the structure, the management or the profitability of shipping enterprise in the period concerned. A full-scale discussion of these latter topics would be a major undertaking in its own right, nor is it at all certain that the necessary materials are accessible or even extant. In short, the study is concerned with the origins, the course and the outcome of the "Shipping Question" of the period 1886-1914. Documentation for a controversy that was essentially mercantile in its origins and its first dimensions might be thought to be patchy and sparse; but it is gratifying to record that a substantial volume of material has been uncovered. The newspapers and periodicals of the time, especially in the period before the Boer War, devoted much more attention to shipping than has since been usual; The British and South African Export Gazette, South Africa, The African Review, and the London edition of The Cape Argus have been of particular value. In that era, again, the Chambers of Commerce occupied a more prominent position in their communities than they seem to do now, and their meetings were reported at length, often to the extent of several columns of newsprint; these reports have been of great assistance. It is fortunate, moreover, that the papers of two of the leading protagonists on the South African side have survived: the Garlick Papers and the Jagger Papers, now housed in the University of Cape Town Libraries; these, while perhaps not as full as might have been hoped, have shed a good deal of light on mercantile thinking and strategy. If the controversy had been confined to the mercantile sector, however, it would scarcely justify detailed investigation. It entered also into the sphere of government and politics and it came to assume an Imperial dimension; and in these aspects it is pleasingly well documented in official primary sources. The papers of prominent public figures, furthermore, have yielded some valuable insights and, in some cases, the documents that rightfully belong in official repositories! The minutes of one of the corporate bodies to the dispute - the South African Merchants' Committee in London - are still extant, and they have been of great use in supplementing the (sometimes condensed) versions of the Committee's proceedings that are available from newspaper- and other sources. While disappointingly attenuated in some areas, the records of the Union-Castle Line have been alike fascinating and indispensable. The papers of Percy Molteno, a member of the Line's management and one of the leading actors in the second part of this study, form a valuable supplement to the records. One cause for regret has been the absence of primary sources emanating from the other shipping lines involved in the controversy. The Union- Castle Line was the dominant partner in the trade, and will therefore occupy the centre of the stage; but its colleagues' records would have been useful in perhaps correcting undue emphases or false perspectives.
- Full Text:
- Date Issued: 1979
- Authors: Solomon, Vivian
- Date: 1979
- Subjects: Shipping conferences -- History Shipping -- South Africa -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1039 , http://hdl.handle.net/10962/d1004667
- Description: From Preface: For the best part of a generation the "Shipping Question" was a talking-point in South Africa; yet today it is completely forgotten, and the name of its leading actor is virtually unknown. Scant reference to the controversy will be found in economic- or other histories; in the rare cases where it is alluded to, the treatment is superficial. This study seeks to fill that gap. At the outset it is advisable to define the scope of the work. It is not a history of the South African shipping trade in the pre-1914 era: shiplovers have had that ground amply covered by Marischal Murray, and indeed are unlikely to find in the following pages much to their taste. Neither is it an economic analysis of shipping conferences: there is a growing body of work on that subject, and this study does not seek to add to it. Nor is it a business history: it does not probe the structure, the management or the profitability of shipping enterprise in the period concerned. A full-scale discussion of these latter topics would be a major undertaking in its own right, nor is it at all certain that the necessary materials are accessible or even extant. In short, the study is concerned with the origins, the course and the outcome of the "Shipping Question" of the period 1886-1914. Documentation for a controversy that was essentially mercantile in its origins and its first dimensions might be thought to be patchy and sparse; but it is gratifying to record that a substantial volume of material has been uncovered. The newspapers and periodicals of the time, especially in the period before the Boer War, devoted much more attention to shipping than has since been usual; The British and South African Export Gazette, South Africa, The African Review, and the London edition of The Cape Argus have been of particular value. In that era, again, the Chambers of Commerce occupied a more prominent position in their communities than they seem to do now, and their meetings were reported at length, often to the extent of several columns of newsprint; these reports have been of great assistance. It is fortunate, moreover, that the papers of two of the leading protagonists on the South African side have survived: the Garlick Papers and the Jagger Papers, now housed in the University of Cape Town Libraries; these, while perhaps not as full as might have been hoped, have shed a good deal of light on mercantile thinking and strategy. If the controversy had been confined to the mercantile sector, however, it would scarcely justify detailed investigation. It entered also into the sphere of government and politics and it came to assume an Imperial dimension; and in these aspects it is pleasingly well documented in official primary sources. The papers of prominent public figures, furthermore, have yielded some valuable insights and, in some cases, the documents that rightfully belong in official repositories! The minutes of one of the corporate bodies to the dispute - the South African Merchants' Committee in London - are still extant, and they have been of great use in supplementing the (sometimes condensed) versions of the Committee's proceedings that are available from newspaper- and other sources. While disappointingly attenuated in some areas, the records of the Union-Castle Line have been alike fascinating and indispensable. The papers of Percy Molteno, a member of the Line's management and one of the leading actors in the second part of this study, form a valuable supplement to the records. One cause for regret has been the absence of primary sources emanating from the other shipping lines involved in the controversy. The Union- Castle Line was the dominant partner in the trade, and will therefore occupy the centre of the stage; but its colleagues' records would have been useful in perhaps correcting undue emphases or false perspectives.
- Full Text:
- Date Issued: 1979
Genetic and bacteriophage studies on Bacteroides thetaiotaomicron and related anaerobic strains
- Authors: Burt, Sharon Joy
- Date: 1978
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20972 , http://hdl.handle.net/10962/5753
- Description: Gram-negative obligately anaerobic bacilli were isolated from faeces on selective media. R plasmid transfer was investigated in mating experiments between 30 anaerobes and between the anaerobes and known donor and recipient E. coli strains. The transfer of R plasmids from E.coli to B.fragilis, Bacteroides spp., Fusobacterium spp. and other faecal obligate anaerobic bacteria was possible after heat treatment of the recipients at 50°C. The anaerobic exconjugants were unstable and were not able to retransfer the ampr marker. A bacteriophage, B1 , specific for the anaerobe B.thetaiotaomicron, was isolated and characterised. The properties of the phage included a variable burst size and the production of many defective phage particles without tails which were not viable. The B.thetaiotaomicron host was able to establish a phage carrier state with B1 phage. Phenol-extracted phage DNA could transfect ca2+-treated B.thetaiotaomicron cells and transfection was not limited to a particular stage in the growth cycle. An obligatory step in the transfection procedure was a 33-fold dilution in broth, allowing replication of the infected cells. Prolonged incubation of treated cells with DNA prior to dilution in broth resulted in a large decrease in phage titre. The application of this transfection system to the development of a transformation system was not successful . Conventional transformation procedures did not yield transformants, and it was not possible to transduce B.thetaiotaomicron with B1 phage. The B.thetaiotaomicron strain used was distinguished by the formation of two distinct morphological variants. Each morphological type gave rise to the other at the same frequency. Environmental conditions other than elevated temperature, had no effect on the segregation frequency. The grey colony variant was not capsulated and was sensitive to B1 phage, whereas the white colony type was encapsulated and was phage-resistant. Another feature of the B.thetaiotaomicron strain was the low incidence of mutants. A second survey of the occurrence of R plasmids in aerobic coliforms from a remote area of the Transkei and from an urban area, was undertaken. An increase in transferable antibiotic resistance was found over the last three years. It can be concluded that this was a result of the use of antibiotics among the human population, since there are no veterinary services in the area and the addition of antibiotics to animal feeds is not practised.
- Full Text:
- Date Issued: 1978
- Authors: Burt, Sharon Joy
- Date: 1978
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20972 , http://hdl.handle.net/10962/5753
- Description: Gram-negative obligately anaerobic bacilli were isolated from faeces on selective media. R plasmid transfer was investigated in mating experiments between 30 anaerobes and between the anaerobes and known donor and recipient E. coli strains. The transfer of R plasmids from E.coli to B.fragilis, Bacteroides spp., Fusobacterium spp. and other faecal obligate anaerobic bacteria was possible after heat treatment of the recipients at 50°C. The anaerobic exconjugants were unstable and were not able to retransfer the ampr marker. A bacteriophage, B1 , specific for the anaerobe B.thetaiotaomicron, was isolated and characterised. The properties of the phage included a variable burst size and the production of many defective phage particles without tails which were not viable. The B.thetaiotaomicron host was able to establish a phage carrier state with B1 phage. Phenol-extracted phage DNA could transfect ca2+-treated B.thetaiotaomicron cells and transfection was not limited to a particular stage in the growth cycle. An obligatory step in the transfection procedure was a 33-fold dilution in broth, allowing replication of the infected cells. Prolonged incubation of treated cells with DNA prior to dilution in broth resulted in a large decrease in phage titre. The application of this transfection system to the development of a transformation system was not successful . Conventional transformation procedures did not yield transformants, and it was not possible to transduce B.thetaiotaomicron with B1 phage. The B.thetaiotaomicron strain used was distinguished by the formation of two distinct morphological variants. Each morphological type gave rise to the other at the same frequency. Environmental conditions other than elevated temperature, had no effect on the segregation frequency. The grey colony variant was not capsulated and was sensitive to B1 phage, whereas the white colony type was encapsulated and was phage-resistant. Another feature of the B.thetaiotaomicron strain was the low incidence of mutants. A second survey of the occurrence of R plasmids in aerobic coliforms from a remote area of the Transkei and from an urban area, was undertaken. An increase in transferable antibiotic resistance was found over the last three years. It can be concluded that this was a result of the use of antibiotics among the human population, since there are no veterinary services in the area and the addition of antibiotics to animal feeds is not practised.
- Full Text:
- Date Issued: 1978
Heterotrophic carbon dioxide fixation by Euglena
- Authors: Peak, Jennifer Grace
- Date: 1978
- Subjects: Euglena
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5824 , http://hdl.handle.net/10962/d1007650
- Description: Heterotrophic (dark, non-photosynthetic) carbon dioxide fixation was measured in the phytoflagellate Euglena gracilis. Variation in heterotrophic carbon dioxide fixation depends on the phase of batch growth and the mode of nutrition. A sharp increase in heterotrophic carbon dioxide fixation occurs during the mid- to late-logarithmic growth periods in Euglena growing photoautotrophically (with carbon dioxide as carbon source, light as energy source) and heterotrophically (in the dark with glucose as sole carbon and energy source). Cells growing heterotrophically with acetate or ethanol as sole carbon source do not increase their heterotrophic carbon dioxide fixation during the growth cycle. Addition of acetate to cultures of Euglena causes a reduction in dark carbon dioxide fixation. The results are consistent with the hypothesis that heterotrophic carbon dioxide fixation in Euglena functions in anaplerotic replenishment of the tricarboxylic acid cycle. The regulation of these changes in heterotrophic carbon dioxide fixation was shown to be controlled by exogenous ammonium in a complex fashion. Ammonium stimulates heterotrophic carbon dioxide fixation after a period of ammonium deprivation. The kinetics of the regulatory effects of the ammonium ion on dark carbon dioxide fixation are presented. A survey into the activities of carboxylating enzymes from both autotrophically and heterotrophically grown Euglena was conducted. The heterotrophic cultures were supplied with either glucose or acetate as substrate. PEP carboxykinase (E.C.4.1.1.38) and (E.C.4.1.1.49) could not be detected in any of the cultures tested. A trace amount of PEP carboxykinase (E.C.4.1.1.32) is present in the acetate grown cells only and a trace amount of pyruvate carboxylase (E.C.6.4.1.1.) is present in the glucose grown cells only. Malate enzyme (E.C.1.1.1.40), PEP carboxylase (E.C.4.1.1.31) and acetylcoenzyme A carboxylase (E.C.6.4.1.2) are present in all cells tested. Ammonium stimulation causes a small increase in specific activity of all the enzymes except acetyl-CoA carboxylase. The largest increase occurs in PEP carboxylase, but the increase is not sufficient to account for observed increases in whole cell dark carbon dioxide fixation after ammonium stimulation. Two isoenzymes of PEP carboxylase were purified from each other from both ammonium stimulated and non-stimulated cells. There are no significant differences between elution profiles of isoenzymes from ammonium stimulated and control cells. There are no significant differences between elution profiles of isoenzymes from autotrophic and heterotrophic cells. The kinetics of the regulation of the two isoenzymes by malate, citrate, succinate and 3-phosphoglycerate are presented. The products of heterotrophic carbon dioxide fixation by ammonium stimulated and control cells were identified and measured by chromatography. Ammonium stimulates the biosynthesis of glutamine, glycine, serine and alanine.
- Full Text:
- Date Issued: 1978
- Authors: Peak, Jennifer Grace
- Date: 1978
- Subjects: Euglena
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5824 , http://hdl.handle.net/10962/d1007650
- Description: Heterotrophic (dark, non-photosynthetic) carbon dioxide fixation was measured in the phytoflagellate Euglena gracilis. Variation in heterotrophic carbon dioxide fixation depends on the phase of batch growth and the mode of nutrition. A sharp increase in heterotrophic carbon dioxide fixation occurs during the mid- to late-logarithmic growth periods in Euglena growing photoautotrophically (with carbon dioxide as carbon source, light as energy source) and heterotrophically (in the dark with glucose as sole carbon and energy source). Cells growing heterotrophically with acetate or ethanol as sole carbon source do not increase their heterotrophic carbon dioxide fixation during the growth cycle. Addition of acetate to cultures of Euglena causes a reduction in dark carbon dioxide fixation. The results are consistent with the hypothesis that heterotrophic carbon dioxide fixation in Euglena functions in anaplerotic replenishment of the tricarboxylic acid cycle. The regulation of these changes in heterotrophic carbon dioxide fixation was shown to be controlled by exogenous ammonium in a complex fashion. Ammonium stimulates heterotrophic carbon dioxide fixation after a period of ammonium deprivation. The kinetics of the regulatory effects of the ammonium ion on dark carbon dioxide fixation are presented. A survey into the activities of carboxylating enzymes from both autotrophically and heterotrophically grown Euglena was conducted. The heterotrophic cultures were supplied with either glucose or acetate as substrate. PEP carboxykinase (E.C.4.1.1.38) and (E.C.4.1.1.49) could not be detected in any of the cultures tested. A trace amount of PEP carboxykinase (E.C.4.1.1.32) is present in the acetate grown cells only and a trace amount of pyruvate carboxylase (E.C.6.4.1.1.) is present in the glucose grown cells only. Malate enzyme (E.C.1.1.1.40), PEP carboxylase (E.C.4.1.1.31) and acetylcoenzyme A carboxylase (E.C.6.4.1.2) are present in all cells tested. Ammonium stimulation causes a small increase in specific activity of all the enzymes except acetyl-CoA carboxylase. The largest increase occurs in PEP carboxylase, but the increase is not sufficient to account for observed increases in whole cell dark carbon dioxide fixation after ammonium stimulation. Two isoenzymes of PEP carboxylase were purified from each other from both ammonium stimulated and non-stimulated cells. There are no significant differences between elution profiles of isoenzymes from ammonium stimulated and control cells. There are no significant differences between elution profiles of isoenzymes from autotrophic and heterotrophic cells. The kinetics of the regulation of the two isoenzymes by malate, citrate, succinate and 3-phosphoglycerate are presented. The products of heterotrophic carbon dioxide fixation by ammonium stimulated and control cells were identified and measured by chromatography. Ammonium stimulates the biosynthesis of glutamine, glycine, serine and alanine.
- Full Text:
- Date Issued: 1978
Some principles of communicating effectively through press advertisements with Blacks
- Authors: Koekemoer, Ludi
- Date: 1978
- Subjects: Advertising, Newspaper -- South Africa , Black people and mass media -- South Africa , Mass media -- South Africa , Mass media and culture -- South Africa , Communication in marketing -- South Africa , Communication -- Social aspects -- South Africa , Press and politics -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:837 , http://hdl.handle.net/10962/d1013407
- Description: [Introduction] An investigation of relevant literature reveals numerous studies on the principles of effective advertising communications. These studies are based on work done overseas and may not apply to Blacks in South Africa. Pioneer advertising research into the Black market has been conducted in recent years by the University of South Africa's Bureau of Market Research (BM). The resultant data obtained indicated that communicating to the Black market should be treated separately from communicating to Whites in South Africa and further research is required on the effectiveness of advertising communications aimed at Blacks. This study was designed to supplement the research conducted by the Bureau of Market Research rather than to validate these findings.
- Full Text:
- Date Issued: 1978
- Authors: Koekemoer, Ludi
- Date: 1978
- Subjects: Advertising, Newspaper -- South Africa , Black people and mass media -- South Africa , Mass media -- South Africa , Mass media and culture -- South Africa , Communication in marketing -- South Africa , Communication -- Social aspects -- South Africa , Press and politics -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:837 , http://hdl.handle.net/10962/d1013407
- Description: [Introduction] An investigation of relevant literature reveals numerous studies on the principles of effective advertising communications. These studies are based on work done overseas and may not apply to Blacks in South Africa. Pioneer advertising research into the Black market has been conducted in recent years by the University of South Africa's Bureau of Market Research (BM). The resultant data obtained indicated that communicating to the Black market should be treated separately from communicating to Whites in South Africa and further research is required on the effectiveness of advertising communications aimed at Blacks. This study was designed to supplement the research conducted by the Bureau of Market Research rather than to validate these findings.
- Full Text:
- Date Issued: 1978
The anatomy of the triassic theropod Syntarsus rhodesiensis (Saurischia : Podokesauridae) and a consideration of its biology
- Authors: Raath, M A
- Date: 1978
- Subjects: Reptiles, Fossil Dinosaurs Paleontology -- Triassic , Dinosaurs , Fossils , Reptiles , Palaeontology , Triassic period
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5601 , http://hdl.handle.net/10962/d1002051
- Description: The osteology of the Upper Triassic podokesaurid Syntarsus rhodesiensis is described, based on a series of 30+ individuals representing all skeletal elements, recovered since the description of the holotype (Raath, 1969). A brief account of the geology of the finds is given, with an attempt at a reconstruction of the palaaoenvironment. The excellence of preservation of the bones has permitted an attempt at the restoration of soft tissues including the brain, cranial nerves, main cranial blood vessels and the musculature of the jaws, neck and limbs. Histological sections of limb bones have shown that the compact bone was highly vascular, and this, together with the structure of the brain, palaeoenvironmental considerations, social behaviour and group structure, leads to the conclusion that Syntarsus was an endothermic homeotherm inhabiting a hot arid region at the end of the Triassic, with a social organisation into "flocks" in which females predominated numerically. Clear evidence of sexual dimorphism is presented. Syntarsus is reconstructed as a bipedal, saltatorial predator which differs in subtle, but probably generically significant, characteristics from the closely related North American genus, Coelophysis. Its anatomy characterises it as a medium-sized agile animal with a highly kinetic skull; incipiently opposable pollex in the raptorial manus; highly cursorial hindlimb; and with features in the dentition and hallux which suggest a grooming function. It is concluded that the Triassic coelurosaurian stock provided an advanced and well adapted base from which the successful coelurosaur radiation into the later Mesozoic sprang, and that this stock was physiologically pre-adapted for the emergence of the avian (and possibly the pterosaur) lineages in the Jurassic
- Full Text:
- Date Issued: 1978
- Authors: Raath, M A
- Date: 1978
- Subjects: Reptiles, Fossil Dinosaurs Paleontology -- Triassic , Dinosaurs , Fossils , Reptiles , Palaeontology , Triassic period
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5601 , http://hdl.handle.net/10962/d1002051
- Description: The osteology of the Upper Triassic podokesaurid Syntarsus rhodesiensis is described, based on a series of 30+ individuals representing all skeletal elements, recovered since the description of the holotype (Raath, 1969). A brief account of the geology of the finds is given, with an attempt at a reconstruction of the palaaoenvironment. The excellence of preservation of the bones has permitted an attempt at the restoration of soft tissues including the brain, cranial nerves, main cranial blood vessels and the musculature of the jaws, neck and limbs. Histological sections of limb bones have shown that the compact bone was highly vascular, and this, together with the structure of the brain, palaeoenvironmental considerations, social behaviour and group structure, leads to the conclusion that Syntarsus was an endothermic homeotherm inhabiting a hot arid region at the end of the Triassic, with a social organisation into "flocks" in which females predominated numerically. Clear evidence of sexual dimorphism is presented. Syntarsus is reconstructed as a bipedal, saltatorial predator which differs in subtle, but probably generically significant, characteristics from the closely related North American genus, Coelophysis. Its anatomy characterises it as a medium-sized agile animal with a highly kinetic skull; incipiently opposable pollex in the raptorial manus; highly cursorial hindlimb; and with features in the dentition and hallux which suggest a grooming function. It is concluded that the Triassic coelurosaurian stock provided an advanced and well adapted base from which the successful coelurosaur radiation into the later Mesozoic sprang, and that this stock was physiologically pre-adapted for the emergence of the avian (and possibly the pterosaur) lineages in the Jurassic
- Full Text:
- Date Issued: 1978
The decision-making process in a rural community in Lesotho
- Authors: Perry, J G, 1942-
- Date: 1978
- Subjects: Decision making -- Lesotho Sotho (African people) -- Social life and customs Local government -- Lesotho Land tenure -- Lesotho Thatched roofs -- Lesotho Grasses -- Lesotho Law -- Lesotho Courts -- Lesotho Community power -- Lesotho Civic leaders -- Lesotho Community life -- Lesotho Lesotho -- Social conditions Lesotho -- Rural conditions Lesotho -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2111 , http://hdl.handle.net/10962/d1007635
- Description: From Introduction: Lesotho is a small, mountainous country entirely surrounded by South Africa. The stark nature of its terrain and topography present harsh options to its inhabitants. Much of the country is mountainous, better suited to the keeping of stock than to agriculture. The lowlands, where the soils are more amenable to the plough, are scarred and cut by dongas. The soil is overworked and overcrowded and Lesotho does not grow enough to feed its people who depend on migrancy as a viable alternative to the limited resources of their own land. They stream from the country to seek wage employment in South Africa, for Lesotho has minimal industrial development and cannot provide jobs for her people. The civil service absorbs some of the educated elite, as does teaching, but the majority must sell their sweat in South Africa's service.
- Full Text:
- Date Issued: 1978
- Authors: Perry, J G, 1942-
- Date: 1978
- Subjects: Decision making -- Lesotho Sotho (African people) -- Social life and customs Local government -- Lesotho Land tenure -- Lesotho Thatched roofs -- Lesotho Grasses -- Lesotho Law -- Lesotho Courts -- Lesotho Community power -- Lesotho Civic leaders -- Lesotho Community life -- Lesotho Lesotho -- Social conditions Lesotho -- Rural conditions Lesotho -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2111 , http://hdl.handle.net/10962/d1007635
- Description: From Introduction: Lesotho is a small, mountainous country entirely surrounded by South Africa. The stark nature of its terrain and topography present harsh options to its inhabitants. Much of the country is mountainous, better suited to the keeping of stock than to agriculture. The lowlands, where the soils are more amenable to the plough, are scarred and cut by dongas. The soil is overworked and overcrowded and Lesotho does not grow enough to feed its people who depend on migrancy as a viable alternative to the limited resources of their own land. They stream from the country to seek wage employment in South Africa, for Lesotho has minimal industrial development and cannot provide jobs for her people. The civil service absorbs some of the educated elite, as does teaching, but the majority must sell their sweat in South Africa's service.
- Full Text:
- Date Issued: 1978
A cross-cultural study of interpersonal distance and orientation schemata
- Authors: Edwards, David J A
- Date: 1977
- Subjects: Personal space -- Testing Orientation (Psychology) Cross-cultural studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3206 , http://hdl.handle.net/10962/d1011743
- Description: Expectations about interpersonal distance during social encounters (distance schemata) and body orientation (orientation schemata) were investigated among White English-speakers and Xhosa groups which included illiterate traditionalists (Reds), poorly educated urban dwellers, and highly literate students and nurses. In a series of six experiments a doll placement task was used in which subjects represented dyadic encounters by placing pairs of standing dolls. For each situation represented the responses of each group of subjects were summarised in the form of a profile which showed the mean of the distance and three angle measures (IPOS profile). Independent variables included culture of subject, type of situation represented (friendly encounter, quarrel, accusation and denial, request) and the sex, age or relationship of the persons represented. In the culminating experiment (Experiment 6), females from three Xhosa groups (Reds or XR, poorly educated urban or XU, and urban nurses or XN) made twenty-three placements. In some respects the schemata of the four groups were very similar, while in others both distance and orientation schemata were a function of cultural group. The experiments allowed an assessment of the validity of the doll placement method to be made, and results were discussed in terms of the effects on interpersonal distance and body orientation of cultural norms concerning the showing of respect and the nature and strength of the emotions present in the various types of situation. It was concluded that with cultural movement away from the traditionalist pattern the schemata of the urban Xhosa showed a transition towards those found among the Whites in some respects. However, while the schemata of the XN group showed features of both those of the XR and White groups, those of the XU group showed features found in neither which seemed to reflect the insecurity of the cultural milieu of the urban poor.
- Full Text:
- Date Issued: 1977
- Authors: Edwards, David J A
- Date: 1977
- Subjects: Personal space -- Testing Orientation (Psychology) Cross-cultural studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3206 , http://hdl.handle.net/10962/d1011743
- Description: Expectations about interpersonal distance during social encounters (distance schemata) and body orientation (orientation schemata) were investigated among White English-speakers and Xhosa groups which included illiterate traditionalists (Reds), poorly educated urban dwellers, and highly literate students and nurses. In a series of six experiments a doll placement task was used in which subjects represented dyadic encounters by placing pairs of standing dolls. For each situation represented the responses of each group of subjects were summarised in the form of a profile which showed the mean of the distance and three angle measures (IPOS profile). Independent variables included culture of subject, type of situation represented (friendly encounter, quarrel, accusation and denial, request) and the sex, age or relationship of the persons represented. In the culminating experiment (Experiment 6), females from three Xhosa groups (Reds or XR, poorly educated urban or XU, and urban nurses or XN) made twenty-three placements. In some respects the schemata of the four groups were very similar, while in others both distance and orientation schemata were a function of cultural group. The experiments allowed an assessment of the validity of the doll placement method to be made, and results were discussed in terms of the effects on interpersonal distance and body orientation of cultural norms concerning the showing of respect and the nature and strength of the emotions present in the various types of situation. It was concluded that with cultural movement away from the traditionalist pattern the schemata of the urban Xhosa showed a transition towards those found among the Whites in some respects. However, while the schemata of the XN group showed features of both those of the XR and White groups, those of the XU group showed features found in neither which seemed to reflect the insecurity of the cultural milieu of the urban poor.
- Full Text:
- Date Issued: 1977
A linguistic account of quantifiers in English and their place in the development of some modern approaches to syntax and semantics
- Authors: Aldridge, Maurice Vincent
- Date: 1977
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20966 , http://hdl.handle.net/10962/5707
- Description: From Introduction: I should make it clear from the outset that I have no intention of trying to construct a calculus for the quantificational system of English as a natural language. My interests are purely linguistic with special emphasis on that part of the discipline traditionally known as semantics. Thus, although I offer a miniature survey of the development of quantificational studies in Philosophy in Chapter One, and have frequent recourse, in other charters, to observations made by philosophers, especially Quine, I make no attempt whatever to emulate the logicians by constructing such things as rules of inference. I have also tried to avoid symbolic representations except in those cases in which they show up aspects of semantic structure very clearly, and where I have symbolised, I have alternated between the systems of Quine and Peano-Russell, selection in each instance being determined by judgements regarding clarity.
- Full Text:
- Date Issued: 1977
- Authors: Aldridge, Maurice Vincent
- Date: 1977
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20966 , http://hdl.handle.net/10962/5707
- Description: From Introduction: I should make it clear from the outset that I have no intention of trying to construct a calculus for the quantificational system of English as a natural language. My interests are purely linguistic with special emphasis on that part of the discipline traditionally known as semantics. Thus, although I offer a miniature survey of the development of quantificational studies in Philosophy in Chapter One, and have frequent recourse, in other charters, to observations made by philosophers, especially Quine, I make no attempt whatever to emulate the logicians by constructing such things as rules of inference. I have also tried to avoid symbolic representations except in those cases in which they show up aspects of semantic structure very clearly, and where I have symbolised, I have alternated between the systems of Quine and Peano-Russell, selection in each instance being determined by judgements regarding clarity.
- Full Text:
- Date Issued: 1977
An investigation of the relationship between acculturation, n achievement and n affiliation in Owambo
- Authors: Steyn, Daniël Marthinus
- Date: 1977
- Subjects: Ovambo (African people) , Acculturation -- Namibia , Achievement motivation , Affiliation (Psychology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3241 , http://hdl.handle.net/10962/d1013295
- Description: The contents of this thesis were mainly determined by the traditional methodological requirements for a thesis of this nature. However a need was felt to include a somewhat expanded survey of the interrelationship between anthropology and psychology. This "need" developed during a review of the above-mentioned interrelationship especially when we found that the historical interaction between these two disciplines had never been followed from the earliest times to the present. Furthermore, although different writers have treated different aspects of this interaction, not one could be found that had treated all the different angles of the relationship. Thus although it is a well known fact that there is a prominent relationship between these two disciplines this was found to be quite inadequately documented. Furthermore, it is usually discussed from either a psychological or an anthropological viewpoint. The hazy view of the interrelationship between these two disciplines is naturally a frustrating situation for any researcher in this field - especially one who would prefer to have a view of the position of his research within the wider panorama of research surrounding it. Intro., p. 1.
- Full Text:
- Date Issued: 1977
- Authors: Steyn, Daniël Marthinus
- Date: 1977
- Subjects: Ovambo (African people) , Acculturation -- Namibia , Achievement motivation , Affiliation (Psychology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3241 , http://hdl.handle.net/10962/d1013295
- Description: The contents of this thesis were mainly determined by the traditional methodological requirements for a thesis of this nature. However a need was felt to include a somewhat expanded survey of the interrelationship between anthropology and psychology. This "need" developed during a review of the above-mentioned interrelationship especially when we found that the historical interaction between these two disciplines had never been followed from the earliest times to the present. Furthermore, although different writers have treated different aspects of this interaction, not one could be found that had treated all the different angles of the relationship. Thus although it is a well known fact that there is a prominent relationship between these two disciplines this was found to be quite inadequately documented. Furthermore, it is usually discussed from either a psychological or an anthropological viewpoint. The hazy view of the interrelationship between these two disciplines is naturally a frustrating situation for any researcher in this field - especially one who would prefer to have a view of the position of his research within the wider panorama of research surrounding it. Intro., p. 1.
- Full Text:
- Date Issued: 1977
Colour vision of the citrus psylla Trioza erytreae (Del Guercio) (Homoptera: Psyllidae) in relation to alightment colour preferences
- Authors: Urban, Alan Joseph
- Date: 1977
- Subjects: Trioza , Homoptera , Jumping plant-lice , Color vision
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5885 , http://hdl.handle.net/10962/d1013286
- Description: The colour vision of adult citrus psylla, Trioza erytreae, was investigated in the laboratory using the behavioural parameters: alightment and walking. Light green flushing leaves (under which the nymphs develop) were significantly preferred, visually, to dark green mature leaves for alightment. Diffuse reflectance spectroscopy showed (when expressed in the parameters of human colour vision) that flush has a very slightly longer dominant wavelength, and roughly double the reflectance and purity. Alightrnent frequency correlated almost equally well with "purity" (as noted by Moericke, 1952 et seq., in "yellow-sensitive" aphids) as with the aphidological colour parameter "long/short ratio" developed by Kennedy et al. (1961). Elucidation of the mechanism underlying the citrus psylla's alightment colour preference was initially attempted with a printed spectrum and several paint series of measured spectral characteristics. It was clear that T.erytreae belongs to the "yellow-sensitive" group of Homoptera, but it was impossible to distinguish which pararneter(s) of colour the psyllids were responding to. Phototactic (walking) response to the individual parameters of colour was therefore measured using a monochromator. The phototactic action spectrum (against wavelength) was tri-modal, with peaks in the yellow-green (YG), blue (B), and ultra= violet (UV). Rate of phototaxis was not influenced by bandwidth (roughly equivalent to purity), but was proportional to intensity (roughly equivalent to reflectance). To investigate the influence of the above three wavelength regions on alightment, use was made of a very simple flight chamber incorporating a target of coloured light. Yellow-green and UV light both independently stimulated alightment . Their effect was additive. Different thresholds indicated distinct YG and UV receptor systems. Blue light alone did not stimulate alightment, and was strongly alightment-inhibitory in combination both with YG and with UV light. On the basis of the above physiological/behavioural findings, a new alightment formula was drawn up for describing the hamopteran's apparent manner of alightment determining integration of surface reflectance. The flush preference and alightment distributions on the series of artificial surfaces were found to correlate slightly more accurately, on average, as well as more consistently, with the new formula than with previously-available colour parameters. These findings are placed in perspective to the literature, and their possible economic relevance is discussed.
- Full Text:
- Date Issued: 1977
- Authors: Urban, Alan Joseph
- Date: 1977
- Subjects: Trioza , Homoptera , Jumping plant-lice , Color vision
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5885 , http://hdl.handle.net/10962/d1013286
- Description: The colour vision of adult citrus psylla, Trioza erytreae, was investigated in the laboratory using the behavioural parameters: alightment and walking. Light green flushing leaves (under which the nymphs develop) were significantly preferred, visually, to dark green mature leaves for alightment. Diffuse reflectance spectroscopy showed (when expressed in the parameters of human colour vision) that flush has a very slightly longer dominant wavelength, and roughly double the reflectance and purity. Alightrnent frequency correlated almost equally well with "purity" (as noted by Moericke, 1952 et seq., in "yellow-sensitive" aphids) as with the aphidological colour parameter "long/short ratio" developed by Kennedy et al. (1961). Elucidation of the mechanism underlying the citrus psylla's alightment colour preference was initially attempted with a printed spectrum and several paint series of measured spectral characteristics. It was clear that T.erytreae belongs to the "yellow-sensitive" group of Homoptera, but it was impossible to distinguish which pararneter(s) of colour the psyllids were responding to. Phototactic (walking) response to the individual parameters of colour was therefore measured using a monochromator. The phototactic action spectrum (against wavelength) was tri-modal, with peaks in the yellow-green (YG), blue (B), and ultra= violet (UV). Rate of phototaxis was not influenced by bandwidth (roughly equivalent to purity), but was proportional to intensity (roughly equivalent to reflectance). To investigate the influence of the above three wavelength regions on alightment, use was made of a very simple flight chamber incorporating a target of coloured light. Yellow-green and UV light both independently stimulated alightment . Their effect was additive. Different thresholds indicated distinct YG and UV receptor systems. Blue light alone did not stimulate alightment, and was strongly alightment-inhibitory in combination both with YG and with UV light. On the basis of the above physiological/behavioural findings, a new alightment formula was drawn up for describing the hamopteran's apparent manner of alightment determining integration of surface reflectance. The flush preference and alightment distributions on the series of artificial surfaces were found to correlate slightly more accurately, on average, as well as more consistently, with the new formula than with previously-available colour parameters. These findings are placed in perspective to the literature, and their possible economic relevance is discussed.
- Full Text:
- Date Issued: 1977
Conscientious objection and the concept of worship
- Authors: Moulder, James Edward
- Date: 1977
- Subjects: Conscientious objectors -- Law and legislation -- South Africa , Conscientious objectors -- South Africa , Conscientious objection , Conscientious objection -- Religious aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2749 , http://hdl.handle.net/10962/d1013555
- Description: [Preface] " ... the focus of this inquiry is limited to some of the connections between conscientious objection in South Africa and the worship and imitation of Christ. More specifically, at the most general level this essay is an attempt to explore six questions: What kind of conscientious objection does South African law allow? Why are some conscientious objectors only conscientious noncombatants? Why are some Christians conscientious noncombatants? Is it appropriate to worship Christ? Does Romans 13 undermine conscientious noncompliance? And is there a prescription for servile compliance? These are, however, not the only questions which are raised in this essay. Nor are they the only questions which can and need to be asked. But they are the questions which interest me. In addition, they have not received as much attention as they deserve".
- Full Text:
- Date Issued: 1977
- Authors: Moulder, James Edward
- Date: 1977
- Subjects: Conscientious objectors -- Law and legislation -- South Africa , Conscientious objectors -- South Africa , Conscientious objection , Conscientious objection -- Religious aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2749 , http://hdl.handle.net/10962/d1013555
- Description: [Preface] " ... the focus of this inquiry is limited to some of the connections between conscientious objection in South Africa and the worship and imitation of Christ. More specifically, at the most general level this essay is an attempt to explore six questions: What kind of conscientious objection does South African law allow? Why are some conscientious objectors only conscientious noncombatants? Why are some Christians conscientious noncombatants? Is it appropriate to worship Christ? Does Romans 13 undermine conscientious noncompliance? And is there a prescription for servile compliance? These are, however, not the only questions which are raised in this essay. Nor are they the only questions which can and need to be asked. But they are the questions which interest me. In addition, they have not received as much attention as they deserve".
- Full Text:
- Date Issued: 1977
Examination of the theological education of Africans in the Presbyterian, Methodist, Congregational and Anglican churches in South Africa from 1860 to 1960
- Authors: Gqubule, T Simon N
- Date: 1977
- Subjects: Theological -- Study and teaching Theological seminaries -- South Africa Theology -- Study and teaching -- Protestant churches
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1254 , http://hdl.handle.net/10962/d1012082
- Description: This is in many ways a limited study. The first limitation is that only four denominations, the Anglican, Congregational, Methodist, Presbyterian, are considered and nothing is said about the work of the Moravians, Lutherans, Roman Catholics and the Dutch Reformed Churches in the field of theological education. The second limitation is that it is a study of theological education as distinct from general, industrial and other forms of education. All the forms of theological education considered here were run at missionary institutions that offered other forms of education and prepared their students for public government examinations with certain government conditions to be met. Moreover, a certain standard of general education was required before candidates were admitted to the theological course. Therefore, theological education was constantly dependent upon and was influenced by secular education and government regulations concerning secular education. For that reason the first chapter is a very brief survey of White Education in the Cape and African education in all four provinces from the beginning to 1915, the year before Fort Hare opened its doors to students seeking 'higher' education. The second chapter discusses the educational programme of Lovedale because Lovedale generally determined the whole of African education in the Cape. When Lovedale and the Methodists transferred their training to the South African Native College at Fort Hare, theological students had to abide by educational and other regulations of the university College. Chapters III and IV deal with the Methodist theological schools and the courses followed at Fort Hare. The third limitation of this study is that it is a study of the theological education of Africans, which category includes Coloureds and Indians because in the four churches under review they were trained together with Africans. In all churches under review here the theological education of whites was done in an unsatisfactory and ad hoc way. Many men were ordained without a satisfactory theological education. They were given some training by their superintendents, bishops or other men appointed to do the job in addition to their own normal duties. A few were sent overseas and many went through some arrangement within this country. St Paul's Theological College for Anglicans was opened in 1902. A start was made with the training of white Methodist Candidates for the ministry in the buildings of the Wesleyan High School for Girls in Grahamstown, in July 1928, under the Rev. James Pendlebury, B.A. (a supernumerary). Dr. William Flint who started the Methodist College as Principal, at Bollihope, Cape Town, in 1929, was seventy-five years of age when he opened the new Sbllege. From 1948 white theological students of the Methodist, Presbyterian and Congregational Churches have been trained at Livingstone House, Rhodes University, Grahamstown. .The final limitation is that this study ends at the close of 1960 and thus omits some of the exciting developments in theological education that have taken place since then. These limitations and demarcations were, however, necessary in order to focus attention on a small area where the main problems could be seen clearly, unencumbered by lesser issues. Where the training was run on denominational lines, it seemed necessary wherever possible to give a chapter to each denomination, and to attempt to pull the threads together in a concluding chapter.
- Full Text:
- Date Issued: 1977
- Authors: Gqubule, T Simon N
- Date: 1977
- Subjects: Theological -- Study and teaching Theological seminaries -- South Africa Theology -- Study and teaching -- Protestant churches
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1254 , http://hdl.handle.net/10962/d1012082
- Description: This is in many ways a limited study. The first limitation is that only four denominations, the Anglican, Congregational, Methodist, Presbyterian, are considered and nothing is said about the work of the Moravians, Lutherans, Roman Catholics and the Dutch Reformed Churches in the field of theological education. The second limitation is that it is a study of theological education as distinct from general, industrial and other forms of education. All the forms of theological education considered here were run at missionary institutions that offered other forms of education and prepared their students for public government examinations with certain government conditions to be met. Moreover, a certain standard of general education was required before candidates were admitted to the theological course. Therefore, theological education was constantly dependent upon and was influenced by secular education and government regulations concerning secular education. For that reason the first chapter is a very brief survey of White Education in the Cape and African education in all four provinces from the beginning to 1915, the year before Fort Hare opened its doors to students seeking 'higher' education. The second chapter discusses the educational programme of Lovedale because Lovedale generally determined the whole of African education in the Cape. When Lovedale and the Methodists transferred their training to the South African Native College at Fort Hare, theological students had to abide by educational and other regulations of the university College. Chapters III and IV deal with the Methodist theological schools and the courses followed at Fort Hare. The third limitation of this study is that it is a study of the theological education of Africans, which category includes Coloureds and Indians because in the four churches under review they were trained together with Africans. In all churches under review here the theological education of whites was done in an unsatisfactory and ad hoc way. Many men were ordained without a satisfactory theological education. They were given some training by their superintendents, bishops or other men appointed to do the job in addition to their own normal duties. A few were sent overseas and many went through some arrangement within this country. St Paul's Theological College for Anglicans was opened in 1902. A start was made with the training of white Methodist Candidates for the ministry in the buildings of the Wesleyan High School for Girls in Grahamstown, in July 1928, under the Rev. James Pendlebury, B.A. (a supernumerary). Dr. William Flint who started the Methodist College as Principal, at Bollihope, Cape Town, in 1929, was seventy-five years of age when he opened the new Sbllege. From 1948 white theological students of the Methodist, Presbyterian and Congregational Churches have been trained at Livingstone House, Rhodes University, Grahamstown. .The final limitation is that this study ends at the close of 1960 and thus omits some of the exciting developments in theological education that have taken place since then. These limitations and demarcations were, however, necessary in order to focus attention on a small area where the main problems could be seen clearly, unencumbered by lesser issues. Where the training was run on denominational lines, it seemed necessary wherever possible to give a chapter to each denomination, and to attempt to pull the threads together in a concluding chapter.
- Full Text:
- Date Issued: 1977
Feeding ecology of the cichlid fish Sarotherodon Mossambicus in Lake Sibaya, KwaZulu
- Authors: Bowen, Stephen H
- Date: 1977
- Subjects: Cichlids -- Ecology , Fishes -- Ecology -- South Africa -- KwaZulu-Natal -- Sibaya, Lake
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5837 , http://hdl.handle.net/10962/d1009688 , Cichlids -- Ecology , Fishes -- Ecology -- South Africa -- KwaZulu-Natal -- Sibaya, Lake
- Description: The feeding of the cichlid fish Sarotherodon mossambicus in Lake Sibaya, KwaZulu, was studied in relation to various biotic and abiotic features of the l ake environment from January, 1973 to July, 1975. The primary goal of the study was to determine the cause of stunting and poor condition of adults in this population. Juvenile and adult S. mossambicus feed on a mixture of detritus, bacteria and diatoms that occurs as a flocculent layer on sand substrates throughout the lake. Concentrated gastric acid, commonly at pH values of 1.5 and lower, lyses diatoms and bacteria which are subsequently digested in the intestine. This is the first report of digestion of bacteria by a fish, and the nutritional significance of the finding is discussed. Juveniles feed predominantly on shallow sand terraces found along the margin of much of the lake, while adults usually feed in offshore waters at depths of 3 m and greater. Benthic floc from feeding areas of juveniles and adults have similar concentrations of organic matter, total carbohydrate, soluble carbohydrate and calories, but differ markedly in respect to diatom and protein concentration. Diatom concentrations are generally high in terrace floc but are consistently low in floc from deep water. Protein concentration of benthic floc decreases with increasing depth from 0 - 5 m. Partial correlation analysis shows that protein and diatom concentrations have no correlation independent. of their common relationship to depth, and the evidence implicates detrital bacteria as the primary source of protein in benthic floc. Probable causes of the observed distributions of diatoms and protein are discussed. The protein content of benthic floc profoundly influences its nutritional value. A comparison with available data on animal nutrition shows that the ratio of digestible protein to digestible energy in floc in the shallows is high enough that this food resource would be expected to support good growth, but the ratio for deep water floc is so low that it would be expected to result in conspicuous malnutrition. Thus, inadequate dietary protein is identified as the principal cause of stunting and poor condition of adult S· mossambicus in Lake Sibaya; It is argued that the ratio of digestible protein to digestible calories can be expected to determine the food value of particulate organic matter that includes amorphous detritus in other ecosystems. Despite stunting and poor condition of adults, S. mossambicus are abundant in Lake Sibaya. The precocious breeding of this population is discussed as an adaptation that allows it to maximize reproductive output given the limited resources available to adults. Juvenile S. mossambicus perform daily movements from deep water onto the terraces where they feed and then back into deep water. During periods of relatively low lake level when terrace waters were usually less than 1.5 m deep (1-73 to 1-74), juveniles were present on the terrace throughout daylight hours. At relatively high lake levels (7-74 to 8-75), juveniles were present on the terraces for only about five hours following sunset. Periods of heavy wave action interrupt feeding activity and result in reduced numbers of fish in terrace waters. The possible roles of predator avoidance and temperature in determination of daily feeding behavior are discussed. Daily energy assimilation by juveniles, estimated by a field technique, is approximately 115 cal per g fish dry weight.
- Full Text:
- Date Issued: 1977
- Authors: Bowen, Stephen H
- Date: 1977
- Subjects: Cichlids -- Ecology , Fishes -- Ecology -- South Africa -- KwaZulu-Natal -- Sibaya, Lake
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5837 , http://hdl.handle.net/10962/d1009688 , Cichlids -- Ecology , Fishes -- Ecology -- South Africa -- KwaZulu-Natal -- Sibaya, Lake
- Description: The feeding of the cichlid fish Sarotherodon mossambicus in Lake Sibaya, KwaZulu, was studied in relation to various biotic and abiotic features of the l ake environment from January, 1973 to July, 1975. The primary goal of the study was to determine the cause of stunting and poor condition of adults in this population. Juvenile and adult S. mossambicus feed on a mixture of detritus, bacteria and diatoms that occurs as a flocculent layer on sand substrates throughout the lake. Concentrated gastric acid, commonly at pH values of 1.5 and lower, lyses diatoms and bacteria which are subsequently digested in the intestine. This is the first report of digestion of bacteria by a fish, and the nutritional significance of the finding is discussed. Juveniles feed predominantly on shallow sand terraces found along the margin of much of the lake, while adults usually feed in offshore waters at depths of 3 m and greater. Benthic floc from feeding areas of juveniles and adults have similar concentrations of organic matter, total carbohydrate, soluble carbohydrate and calories, but differ markedly in respect to diatom and protein concentration. Diatom concentrations are generally high in terrace floc but are consistently low in floc from deep water. Protein concentration of benthic floc decreases with increasing depth from 0 - 5 m. Partial correlation analysis shows that protein and diatom concentrations have no correlation independent. of their common relationship to depth, and the evidence implicates detrital bacteria as the primary source of protein in benthic floc. Probable causes of the observed distributions of diatoms and protein are discussed. The protein content of benthic floc profoundly influences its nutritional value. A comparison with available data on animal nutrition shows that the ratio of digestible protein to digestible energy in floc in the shallows is high enough that this food resource would be expected to support good growth, but the ratio for deep water floc is so low that it would be expected to result in conspicuous malnutrition. Thus, inadequate dietary protein is identified as the principal cause of stunting and poor condition of adult S· mossambicus in Lake Sibaya; It is argued that the ratio of digestible protein to digestible calories can be expected to determine the food value of particulate organic matter that includes amorphous detritus in other ecosystems. Despite stunting and poor condition of adults, S. mossambicus are abundant in Lake Sibaya. The precocious breeding of this population is discussed as an adaptation that allows it to maximize reproductive output given the limited resources available to adults. Juvenile S. mossambicus perform daily movements from deep water onto the terraces where they feed and then back into deep water. During periods of relatively low lake level when terrace waters were usually less than 1.5 m deep (1-73 to 1-74), juveniles were present on the terrace throughout daylight hours. At relatively high lake levels (7-74 to 8-75), juveniles were present on the terraces for only about five hours following sunset. Periods of heavy wave action interrupt feeding activity and result in reduced numbers of fish in terrace waters. The possible roles of predator avoidance and temperature in determination of daily feeding behavior are discussed. Daily energy assimilation by juveniles, estimated by a field technique, is approximately 115 cal per g fish dry weight.
- Full Text:
- Date Issued: 1977
Pitch learning and the implications for music education
- Authors: Byrd, Audrey S
- Date: 1977
- Subjects: Musical pitch -- Instruction and study
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2627 , http://hdl.handle.net/10962/d1001867
- Description: A study of pitch learning must outline first the procedures involved in such learning and then identify specific factors appearing to influence the learning of pitch. Once identified, each factor can then be evaluated by controlled experiment before confirming its influence. Since it is what is heard and perceived that is learnt, I have started with the process of Hearing and Perceiving, for as Arnold Abramovitz, Senior Lecturer in Psychology at Cape Town says, “the reception, processing and interpretation of acoustic symbols constitutes some of the most elusive and complex phenomena to attempt to examine, gauge and measure, due partly to the transient, ephemeral nature of sound itself.”
- Full Text:
- Date Issued: 1977
- Authors: Byrd, Audrey S
- Date: 1977
- Subjects: Musical pitch -- Instruction and study
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2627 , http://hdl.handle.net/10962/d1001867
- Description: A study of pitch learning must outline first the procedures involved in such learning and then identify specific factors appearing to influence the learning of pitch. Once identified, each factor can then be evaluated by controlled experiment before confirming its influence. Since it is what is heard and perceived that is learnt, I have started with the process of Hearing and Perceiving, for as Arnold Abramovitz, Senior Lecturer in Psychology at Cape Town says, “the reception, processing and interpretation of acoustic symbols constitutes some of the most elusive and complex phenomena to attempt to examine, gauge and measure, due partly to the transient, ephemeral nature of sound itself.”
- Full Text:
- Date Issued: 1977
Pitch learning and the implications for music education
- Authors: Byrd, Audrey S
- Date: 1977
- Subjects: Musical pitch -- Instruction and study
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2675 , http://hdl.handle.net/10962/d1007403
- Description: From introduction: A study of pitch learning must outlina first the procedures involved in such learning ar~d then identify specific factors appearing to influence the learning of pitch. Once identified, each factor can then be evaluated by controlled experiment before confirming its influence. Since it is \'lhat is heard and perceived that is learnt, I have started with the process of Hearing and Perceiving, for as Arnold Abramovitz, Senior Lecturer in Psychology at Cape Town says, "the reception, processing and interpretation of acoustic symbols constitutes some of the most elusive and complex phenomena to attempt to examine, gauge and measure, due partly to the transient, ephemeral nature of sound itself."
- Full Text:
- Date Issued: 1977
- Authors: Byrd, Audrey S
- Date: 1977
- Subjects: Musical pitch -- Instruction and study
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2675 , http://hdl.handle.net/10962/d1007403
- Description: From introduction: A study of pitch learning must outlina first the procedures involved in such learning ar~d then identify specific factors appearing to influence the learning of pitch. Once identified, each factor can then be evaluated by controlled experiment before confirming its influence. Since it is \'lhat is heard and perceived that is learnt, I have started with the process of Hearing and Perceiving, for as Arnold Abramovitz, Senior Lecturer in Psychology at Cape Town says, "the reception, processing and interpretation of acoustic symbols constitutes some of the most elusive and complex phenomena to attempt to examine, gauge and measure, due partly to the transient, ephemeral nature of sound itself."
- Full Text:
- Date Issued: 1977
Studies on the completely mixed activated sludge treatment of fellmongery and tannery lime-sulphide effluents
- Authors: Rawlings, Douglas Eric
- Date: 1977
- Subjects: Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purificiation -- Biological treatment , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4112 , http://hdl.handle.net/10962/d1013052
- Description: Industries producing highly polluted waste waters are having to purify their effluents to meet with ever increasing requirements laid down by water authorities. The South African Water Act of 1956 has prescribed a very high standard to which waste waters must conform before discharge into a South African water course. Enforcement of these standards falls under the jurisdiction of government authorities such as the Department of Water Affairs. Similarly, municipalities and other local authorities set standards with which trade effluents must comply before discharge into public sewers for treatment in a municipal sewage works. These local authorities are empowered to recover from the trader the additional costs incurred in treating trade effluents. Costs are usually levied in respect of volume, oxygen demand, settleable solids and the production of secondary sludge. In recent years, these standards have been enforced to an extent where the survival of several industries has become dependant on whether these industries are able to purify or dispose of their effluents in a manner acceptable to the water authorities. Chap. 1, p. 1.
- Full Text:
- Date Issued: 1977
- Authors: Rawlings, Douglas Eric
- Date: 1977
- Subjects: Tanneries -- Waste disposal , Sewage sludge -- South Africa -- Management , Sewage -- Purificiation -- Biological treatment , Water quality management -- South Africa , Water -- Purification -- Biological treatment -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4112 , http://hdl.handle.net/10962/d1013052
- Description: Industries producing highly polluted waste waters are having to purify their effluents to meet with ever increasing requirements laid down by water authorities. The South African Water Act of 1956 has prescribed a very high standard to which waste waters must conform before discharge into a South African water course. Enforcement of these standards falls under the jurisdiction of government authorities such as the Department of Water Affairs. Similarly, municipalities and other local authorities set standards with which trade effluents must comply before discharge into public sewers for treatment in a municipal sewage works. These local authorities are empowered to recover from the trader the additional costs incurred in treating trade effluents. Costs are usually levied in respect of volume, oxygen demand, settleable solids and the production of secondary sludge. In recent years, these standards have been enforced to an extent where the survival of several industries has become dependant on whether these industries are able to purify or dispose of their effluents in a manner acceptable to the water authorities. Chap. 1, p. 1.
- Full Text:
- Date Issued: 1977
The biology of Clarias Gariepinus (Burchell, 1822) in Lake Sibaya, Kwazulu, with emphasis on its role as a predator
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
The polysaccharides of Opuntia ficus-indica (L.) Mill. and Opuntia aurantiaca Lindl.
- Authors: McGarvie, Donald
- Date: 1977
- Subjects: Polysaccharides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4438 , http://hdl.handle.net/10962/d1007597
- Description: The partially acetylated acidic mucilage isolated from the cactus Opuntia ficus-indica consists of a highly branched molecule containing D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 2.9:6.6:3.8:1.3 : 1.0. A partial hydrolysis study led to the isolation of fourteen oligosaccharides and a degraded polysaccharide. Periodate oxidation of the degraded polysaccharide and methylation analysis of the degraded and reduced degraded polysaccharides led to the proposal of a structure for the degraded polysaccharide consisting of a chain of alternating α-l,4-D-galactopyranosyluronic acid and β-1,2-Lrhamnopyranosyl units with branches consisting of short chains of β-1,6-D-galactopyranosyl units Iinked to C-3 of the rhamnose residues. An insight into the nature of the peripheral side-chains was obtained by methylation studies of the oligosaccharides and the native polysaccharide. The majority of the side-chains are terminated by D-xylopyranosyl and L-arabinofuranosyl units while there is a small proportion of D-galactopyranosyl end-groups. The remaining units of the peripheral chains consists of mainly 1,3- and 1,5-1 inked L-arabinofuranosyl units. The acidic polysaccharide isolated from the jointed cactus Opuntia aurantiaca contains D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 5.9:5 .5:3.4: 1. 2:1.0 . A partial hydrolysis study revealed a similar series of galactose containing oligosaccharides as was identified from the mucilage of Opuntia ficus-indica. The degraded polysaccharide isolated from the partial hydrolysate was methylated and a possible structure proposed for the repeating unit. Methylation studies of the native polysaccharide indicated a polysaccharide with a more complex structure than that for the mucilage of Opuntia ficus-indica.
- Full Text:
- Date Issued: 1977
- Authors: McGarvie, Donald
- Date: 1977
- Subjects: Polysaccharides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4438 , http://hdl.handle.net/10962/d1007597
- Description: The partially acetylated acidic mucilage isolated from the cactus Opuntia ficus-indica consists of a highly branched molecule containing D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 2.9:6.6:3.8:1.3 : 1.0. A partial hydrolysis study led to the isolation of fourteen oligosaccharides and a degraded polysaccharide. Periodate oxidation of the degraded polysaccharide and methylation analysis of the degraded and reduced degraded polysaccharides led to the proposal of a structure for the degraded polysaccharide consisting of a chain of alternating α-l,4-D-galactopyranosyluronic acid and β-1,2-Lrhamnopyranosyl units with branches consisting of short chains of β-1,6-D-galactopyranosyl units Iinked to C-3 of the rhamnose residues. An insight into the nature of the peripheral side-chains was obtained by methylation studies of the oligosaccharides and the native polysaccharide. The majority of the side-chains are terminated by D-xylopyranosyl and L-arabinofuranosyl units while there is a small proportion of D-galactopyranosyl end-groups. The remaining units of the peripheral chains consists of mainly 1,3- and 1,5-1 inked L-arabinofuranosyl units. The acidic polysaccharide isolated from the jointed cactus Opuntia aurantiaca contains D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 5.9:5 .5:3.4: 1. 2:1.0 . A partial hydrolysis study revealed a similar series of galactose containing oligosaccharides as was identified from the mucilage of Opuntia ficus-indica. The degraded polysaccharide isolated from the partial hydrolysate was methylated and a possible structure proposed for the repeating unit. Methylation studies of the native polysaccharide indicated a polysaccharide with a more complex structure than that for the mucilage of Opuntia ficus-indica.
- Full Text:
- Date Issued: 1977
5-hydroxytryptamine and sexual behaviour in rhesus monkeys
- Authors: Gradwell, Peter Bertram
- Date: 1976
- Subjects: Rhesus monkey -- Behavior Sexual behavior in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3210 , http://hdl.handle.net/10962/d1012086
- Description: Selective inhibition of 5-hydroxytryptamine by parachlorophenylalanine (PCPA) is able to restore sexual receptivity in female rhesus monkeys made unreceptive by bilateral adrenalectomy. PCPA in the doses used reduces the levels of 5-hydroxyindoleacetic acid (5HIAA) in the cerebrospinal fluid to 40 per cent of the normal oestradioltreated condition. Both the increased sexual receptivity and the lowered 5HIAA levels "in the CSF are in turn reversed by 5-hydroxytryptophal (5HTP), the irrmediate precursor of 5HT and the substance whose synthesis is inhibited by PCPA. 5HTP on its own reduces sexual receptivity and increases 5HIAA levels in the CSF of ovariectomised, oestradiol-treated (but otherwise intact) female rhesus monkeys. A substance other than an adrenal androgen has therefore been shown to restore sexual receptivity in adrenalectomised female monkeys . Testosterone propionate and oestradiol benzoate both lower the turnover rates of 5HT in the brains of ovariectomised female monkeys, as measured by the 2 hour probenecid test. Taken together, these findings suggest that adrenal androgens could act on specific sites in the female monkey brain via 5HT-containing neural systems, to control (or at least influence) sexual receptivity. All the results of administering oestradiol to ovariectomised monkeys in these experiments are consistent with the established roles of this hormone in female sexual attractiveness and in the gonadotrophin- controlling systems of the hypothalamo-hypophyseal axis. In contrast to these findings on 5HT and sexual receptivity in female monkeys, no clear role for 5HT- containing neural systems could be demonstrated in the grooming, aggressive or social behaviours of female monkeys. No clear role for 5HT could be demonstrated in the refractory period following ejaculation in male monkeys , or when testosterone replacement is given to castrated male monkeys.
- Full Text:
- Date Issued: 1976
- Authors: Gradwell, Peter Bertram
- Date: 1976
- Subjects: Rhesus monkey -- Behavior Sexual behavior in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3210 , http://hdl.handle.net/10962/d1012086
- Description: Selective inhibition of 5-hydroxytryptamine by parachlorophenylalanine (PCPA) is able to restore sexual receptivity in female rhesus monkeys made unreceptive by bilateral adrenalectomy. PCPA in the doses used reduces the levels of 5-hydroxyindoleacetic acid (5HIAA) in the cerebrospinal fluid to 40 per cent of the normal oestradioltreated condition. Both the increased sexual receptivity and the lowered 5HIAA levels "in the CSF are in turn reversed by 5-hydroxytryptophal (5HTP), the irrmediate precursor of 5HT and the substance whose synthesis is inhibited by PCPA. 5HTP on its own reduces sexual receptivity and increases 5HIAA levels in the CSF of ovariectomised, oestradiol-treated (but otherwise intact) female rhesus monkeys. A substance other than an adrenal androgen has therefore been shown to restore sexual receptivity in adrenalectomised female monkeys . Testosterone propionate and oestradiol benzoate both lower the turnover rates of 5HT in the brains of ovariectomised female monkeys, as measured by the 2 hour probenecid test. Taken together, these findings suggest that adrenal androgens could act on specific sites in the female monkey brain via 5HT-containing neural systems, to control (or at least influence) sexual receptivity. All the results of administering oestradiol to ovariectomised monkeys in these experiments are consistent with the established roles of this hormone in female sexual attractiveness and in the gonadotrophin- controlling systems of the hypothalamo-hypophyseal axis. In contrast to these findings on 5HT and sexual receptivity in female monkeys, no clear role for 5HT- containing neural systems could be demonstrated in the grooming, aggressive or social behaviours of female monkeys. No clear role for 5HT could be demonstrated in the refractory period following ejaculation in male monkeys , or when testosterone replacement is given to castrated male monkeys.
- Full Text:
- Date Issued: 1976