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:
- 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.
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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:
- 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:
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:
- 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.
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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:
- 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:
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:
- 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:
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