"Complexes of carbohydrates with magnesium-ions" : "the isolation of an oligosaccharide containing L-galactose from the polysaccharide of Aeodes orbitosa" : "horizontal cellulose colum chromatography of sugars"
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
A contribution to the biology of Pseudodiaptomus hessei (Mrázek) (Copepoda : Calanoida) in Lake Sibaya, South Africa
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974
A contribution to the limnology of Swartvlei: the effect of physico-chemical factors upon primary and secondary production in the pelagic zone
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
A study of the burrowing sandprawn Callianassa kraussi Stebbing (Crustacea - Decapoda - Thalassinidea)
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
Genetic studies on collagenolytic achromobacter strains and their bacteriophages
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
Social criteria in the drama of Molìère
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
The council of advice at the Cape of Good Hope, 1825-1834: a study in colonial government
- Authors: Donaldson, Margaret E
- Date: 1974
- Subjects: South Africa -- History -- To 1836 Great Britain -- Colonies -- Administration Cape of Good Hope (South Africa) -- History -- 1795-1872
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2603 , http://hdl.handle.net/10962/d1011220
- Description: The Council of Advice first emerged as a constitutional device for colonial rule in colonies captured by Britain during the wars against France between 1793 and 1814. The search for some new form of government for colonies of conquest had been necessitated by the difficulty generally experienced in assimilating formerly foreign colonies into the traditional British pattern of representation. Experience in Quebec between 1764 and 1791 had led to the gradual recognition of conciliar government as a workable substitute to bridge the gap between military rule and the grant of representative institutions. Between 1794 when a Council of Advice was first introduced in the island of San Domingo, and 1825, when the Cape of Good Hope was granted a council of this type, the composition, function and scope of such councils was gradually defined and elaborated. There was a continual interplay of precedent and example from one colony to another, facilitated by the growth of the Colonial Office in London during the early decades of the 19th Century. Councils of Advice were also introduced into some a-typical colonies of settlement, notably New South Wales, where the particular circumstances of the colony gave rise to the further development of the conciliar pattern of government, influenced by the practical experience in Quebec prior to 1791. Thus the Council of Advice at the Cape of Good Hope from 1825-1834 was but one example of an instrument of government which was being widely used in the British empire, and which was still developing in form and function during the period under consideration. The Council of Advice at the Cape reflects this fluidity. The composition of the council was altered on several occasions during the nine years of its existence; the degree of independence allowed to council members was a question which arose on several occasions, especially in relation to discussion of policy decisions taken in London; moreover, the council met at the discretion of the governor and four different men held this office during the period 1825-34, each with his own individual idea of the function and value of a council of advice. Preface, p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Donaldson, Margaret E
- Date: 1974
- Subjects: South Africa -- History -- To 1836 Great Britain -- Colonies -- Administration Cape of Good Hope (South Africa) -- History -- 1795-1872
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2603 , http://hdl.handle.net/10962/d1011220
- Description: The Council of Advice first emerged as a constitutional device for colonial rule in colonies captured by Britain during the wars against France between 1793 and 1814. The search for some new form of government for colonies of conquest had been necessitated by the difficulty generally experienced in assimilating formerly foreign colonies into the traditional British pattern of representation. Experience in Quebec between 1764 and 1791 had led to the gradual recognition of conciliar government as a workable substitute to bridge the gap between military rule and the grant of representative institutions. Between 1794 when a Council of Advice was first introduced in the island of San Domingo, and 1825, when the Cape of Good Hope was granted a council of this type, the composition, function and scope of such councils was gradually defined and elaborated. There was a continual interplay of precedent and example from one colony to another, facilitated by the growth of the Colonial Office in London during the early decades of the 19th Century. Councils of Advice were also introduced into some a-typical colonies of settlement, notably New South Wales, where the particular circumstances of the colony gave rise to the further development of the conciliar pattern of government, influenced by the practical experience in Quebec prior to 1791. Thus the Council of Advice at the Cape of Good Hope from 1825-1834 was but one example of an instrument of government which was being widely used in the British empire, and which was still developing in form and function during the period under consideration. The Council of Advice at the Cape reflects this fluidity. The composition of the council was altered on several occasions during the nine years of its existence; the degree of independence allowed to council members was a question which arose on several occasions, especially in relation to discussion of policy decisions taken in London; moreover, the council met at the discretion of the governor and four different men held this office during the period 1825-34, each with his own individual idea of the function and value of a council of advice. Preface, p. 1-2.
- Full Text:
- Date Issued: 1974
The ecology of juvenile Rhabdosargus holubi (Steinachner) (Teleostei : Sparidae)
- Authors: Blaber, Stephen J M
- Date: 1974
- Subjects: Osteichthyes Fishes -- Breeding Fish populations Fish culture -- South Africa Estuaries -- South Africa -- Eastern Cape Aquatic ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5672 , http://hdl.handle.net/10962/d1005357
- Description: INTRODUCTION: Estuaries have received considerable attention from biologists in southern Africa in the past thirty years. Professor J.H. Day and the Zoology Department of the University of Cape Town have undertaken ecological surveys of a large number of estuaries of a variety of types, laying the important groundwork for more detailed studies of single species or problems. Their studies showed that the fish populations of southern African estuaries consist mainly of marine species. Why and when these species enter or leave the estuaries and whether they grow or breed in them were not established. The only relatively detailed study of a fish in southern African estuaries was that of Talbot (1955) who investigated aspects of the growth, feeding and reproduction of Rhabdosargus globiceps (Cuvier). No quantitative information has been published on any of the fish species, perhaps due to the difficulty of obtaining such data; results such as population estimates, mortality rates and growth rates are particularly unreliable when the area being investigated is in direct contact with the sea. Studies relating to even a single species of fish are hampered by immigration and emigration between estuary and sea, which make the population continuously variable. The larger estuaries are also difficult to sample adequately, especially with regard to netting, except perhaps on a very large scale using expensive commercial equipment. Along the southern African coast many of the smaller estuaries with a limited catchment area are cut off from the sea for most of the year due to erratic rainfall and longshore drift of sand. These closed or 'blind' estuaries of south eastern Africa, of which there are at least thirty in the eastern Cape Province, provide excellent areas for studying estuarine fish populations which enter when the estuary is open to the sea, but become isolated once it closes. These fish which become cut off in closed estuaries are subject to a new series of conditions. They are exposed to the wider temperature and salinity fluctuations of an estuary and they are forced to utilise the food resources of the estuary. Additionally they may be subjected to predation from piscivorous birds, and those predatory fish which are also cut off in the estuary. These factors will affect the size, mortality, and growth rates of a fish population. Since the fish are isolated no recruitment from the sea can take place, and any increase in numbers would have to come from breeding within the estuary. It is inevitable that the most numerous species should receive attention first. Rhabdosargus holubi (Steindachner) (Synonomy : Sargus holubi Stndr, Austrosparus tricuspidens Smith, Rhabdosargus tricuspidens (Smith))(Plate 1) is one of the most abundant fish in the estuaries of the eastern Cape Province. According to Smith (1965) it is endemic to southern Africa, occurring from the Cape to Zululand, being most common between Mossel Bay and East London. It is largely replaced by Rhabdosargus sarba (Forskal) in the north of its range and by Rhabdosargus globiceps (Cuvier) in the south. Commonly called the 'flatty' or silver bream it is considered only as being of nuisance value by fishermen, seldom exceeding 30 cm in length. In this study the ecology of R.holubi was examined in relation to the closed West Kleinemond estuary which is a small 'blind' estuary typical of those found along the eastern Cape coast. The growth, mortality and population size of R.holubi in this estuary were investigated and linked where possible with predation and detailed studies into the tolerances, food, and feeding of the species. It was not known at the commencement of the study whether breeding could occur in estuaries, although Smith (1965) stated that R.holubi does breed in estuaries. During the course of the sampling programme in the West Kleinemond estuary, measurements of the growth and population structure of two other species of fish were recorded for comparison with R.holubi: the sparid Lithognathus lithognathus (Cuvier) (White Steenbras) and the piscivorous carangid Hypacanthas amia (L.) (Leervis or garrick). Laboratory studies on R.holubi were possible due to the fact that large numbers of this species could be caught in eastern Cape estuaries and transported to Grahamstown, where they could be maintained in captivity for up to four months in recirculating seawater aquaria. During the course of the study over 2000 fish were kept in captivity at different times for a variety of experiments. Another 2500 were preserved for gut analyses and lipid determinations, while over 5000 were captured, examined and released in the field.
- Full Text:
- Date Issued: 1974
- Authors: Blaber, Stephen J M
- Date: 1974
- Subjects: Osteichthyes Fishes -- Breeding Fish populations Fish culture -- South Africa Estuaries -- South Africa -- Eastern Cape Aquatic ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5672 , http://hdl.handle.net/10962/d1005357
- Description: INTRODUCTION: Estuaries have received considerable attention from biologists in southern Africa in the past thirty years. Professor J.H. Day and the Zoology Department of the University of Cape Town have undertaken ecological surveys of a large number of estuaries of a variety of types, laying the important groundwork for more detailed studies of single species or problems. Their studies showed that the fish populations of southern African estuaries consist mainly of marine species. Why and when these species enter or leave the estuaries and whether they grow or breed in them were not established. The only relatively detailed study of a fish in southern African estuaries was that of Talbot (1955) who investigated aspects of the growth, feeding and reproduction of Rhabdosargus globiceps (Cuvier). No quantitative information has been published on any of the fish species, perhaps due to the difficulty of obtaining such data; results such as population estimates, mortality rates and growth rates are particularly unreliable when the area being investigated is in direct contact with the sea. Studies relating to even a single species of fish are hampered by immigration and emigration between estuary and sea, which make the population continuously variable. The larger estuaries are also difficult to sample adequately, especially with regard to netting, except perhaps on a very large scale using expensive commercial equipment. Along the southern African coast many of the smaller estuaries with a limited catchment area are cut off from the sea for most of the year due to erratic rainfall and longshore drift of sand. These closed or 'blind' estuaries of south eastern Africa, of which there are at least thirty in the eastern Cape Province, provide excellent areas for studying estuarine fish populations which enter when the estuary is open to the sea, but become isolated once it closes. These fish which become cut off in closed estuaries are subject to a new series of conditions. They are exposed to the wider temperature and salinity fluctuations of an estuary and they are forced to utilise the food resources of the estuary. Additionally they may be subjected to predation from piscivorous birds, and those predatory fish which are also cut off in the estuary. These factors will affect the size, mortality, and growth rates of a fish population. Since the fish are isolated no recruitment from the sea can take place, and any increase in numbers would have to come from breeding within the estuary. It is inevitable that the most numerous species should receive attention first. Rhabdosargus holubi (Steindachner) (Synonomy : Sargus holubi Stndr, Austrosparus tricuspidens Smith, Rhabdosargus tricuspidens (Smith))(Plate 1) is one of the most abundant fish in the estuaries of the eastern Cape Province. According to Smith (1965) it is endemic to southern Africa, occurring from the Cape to Zululand, being most common between Mossel Bay and East London. It is largely replaced by Rhabdosargus sarba (Forskal) in the north of its range and by Rhabdosargus globiceps (Cuvier) in the south. Commonly called the 'flatty' or silver bream it is considered only as being of nuisance value by fishermen, seldom exceeding 30 cm in length. In this study the ecology of R.holubi was examined in relation to the closed West Kleinemond estuary which is a small 'blind' estuary typical of those found along the eastern Cape coast. The growth, mortality and population size of R.holubi in this estuary were investigated and linked where possible with predation and detailed studies into the tolerances, food, and feeding of the species. It was not known at the commencement of the study whether breeding could occur in estuaries, although Smith (1965) stated that R.holubi does breed in estuaries. During the course of the sampling programme in the West Kleinemond estuary, measurements of the growth and population structure of two other species of fish were recorded for comparison with R.holubi: the sparid Lithognathus lithognathus (Cuvier) (White Steenbras) and the piscivorous carangid Hypacanthas amia (L.) (Leervis or garrick). Laboratory studies on R.holubi were possible due to the fact that large numbers of this species could be caught in eastern Cape estuaries and transported to Grahamstown, where they could be maintained in captivity for up to four months in recirculating seawater aquaria. During the course of the study over 2000 fish were kept in captivity at different times for a variety of experiments. Another 2500 were preserved for gut analyses and lipid determinations, while over 5000 were captured, examined and released in the field.
- Full Text:
- Date Issued: 1974
A contribution to the understanding of the ethology of the cichlids of Southern Africa
- Authors: Ribbink, Anthony J
- Date: 1975
- Subjects: Cichlids -- Africa, Southern , Fishes -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5889 , http://hdl.handle.net/10962/d1013369
- Description: Allopatric populations of Pseudocrenilabrus philander were found to differ in male breeding coloration. These colours are described and attention is drawn to the possibility that male coloration might prevent population hybridisation. Behaviour of the allopatric populations was studied in the laboratory. The execution of behaviour patterns of the various populations was found to be indistinguishable, and very similar to that of Haplochromis. Behaviour of P. philander was recorded in three morphologically different natural water bodies. Diurnal activities were found to follow a set rhythm. Though P. philander was shown to have adapted to a variety of habitats they retained their behavioural Components in an unchanged form. Field and laboratory observations are used to propose a behavioural mechanism for the natural regulation of population density. Although aggression between conspecific territorial Sarot herodon mossambicus habituated so that neighbours could live close to one another, it was found that P.philander are intolerant of their neighbours and are consequently forced apart. Though the execution of behaviour patterns was apparently identical for all populations of P. philander, field observations indicated that the frequency of performance differed. An experimental procedure was established to quantitatively compare the behaviour of various populations. As a result of comparative and choice chamber investigations, it is suggested that one of the four populations of P. philander would be unlikely to hybridise with the others if they were to become sympatric. These popUlations would be kept apart because of colour and behavioural differences. Differences of egg-size, fry-size, developmental and interbrood periods were also found, providing further evidence of incipient speciation. Evolutionary divergence of the allopatric populations of P. philander is discussed against a background of geological and geographical evidence. Consideration is given to the role of male coloration, ethological barriers and the importance of ethological differences to taxonomy. Behavioural evidence suggests that P. philander has closer affinities with the haplochromids than was initially realised. It is concluded that the clinal populations of P. philander should not be taxonomically separated, and it is argued that it would be premature to give the Kuruman population an elevated taxonomic status.
- Full Text:
- Date Issued: 1975
- Authors: Ribbink, Anthony J
- Date: 1975
- Subjects: Cichlids -- Africa, Southern , Fishes -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5889 , http://hdl.handle.net/10962/d1013369
- Description: Allopatric populations of Pseudocrenilabrus philander were found to differ in male breeding coloration. These colours are described and attention is drawn to the possibility that male coloration might prevent population hybridisation. Behaviour of the allopatric populations was studied in the laboratory. The execution of behaviour patterns of the various populations was found to be indistinguishable, and very similar to that of Haplochromis. Behaviour of P. philander was recorded in three morphologically different natural water bodies. Diurnal activities were found to follow a set rhythm. Though P. philander was shown to have adapted to a variety of habitats they retained their behavioural Components in an unchanged form. Field and laboratory observations are used to propose a behavioural mechanism for the natural regulation of population density. Although aggression between conspecific territorial Sarot herodon mossambicus habituated so that neighbours could live close to one another, it was found that P.philander are intolerant of their neighbours and are consequently forced apart. Though the execution of behaviour patterns was apparently identical for all populations of P. philander, field observations indicated that the frequency of performance differed. An experimental procedure was established to quantitatively compare the behaviour of various populations. As a result of comparative and choice chamber investigations, it is suggested that one of the four populations of P. philander would be unlikely to hybridise with the others if they were to become sympatric. These popUlations would be kept apart because of colour and behavioural differences. Differences of egg-size, fry-size, developmental and interbrood periods were also found, providing further evidence of incipient speciation. Evolutionary divergence of the allopatric populations of P. philander is discussed against a background of geological and geographical evidence. Consideration is given to the role of male coloration, ethological barriers and the importance of ethological differences to taxonomy. Behavioural evidence suggests that P. philander has closer affinities with the haplochromids than was initially realised. It is concluded that the clinal populations of P. philander should not be taxonomically separated, and it is argued that it would be premature to give the Kuruman population an elevated taxonomic status.
- Full Text:
- Date Issued: 1975
A dielectric and spectroscopic study of molecular association in solutions of alcohols
- Authors: Campbell, Colin
- Date: 1975
- Subjects: Alcohols , Dielectrics , Spectrum analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4454 , http://hdl.handle.net/10962/d1010424
- Description: This study is concerned with the association characteristics of solutions of alcohols in some non-polar solvents. The permittivities at 2 MHz and 25°C for solutions of the straight chain octanols in cyclohexane, carbon tetrachloride and benzene have been examined over the entire solute concentration range, with particular attention -1 being paid to the range below 0.1 molℓ⁻¹ By applying the Kirkwood- Fröhlich equation to these data, the apparent dipole moments of the alcohols as a function of concentration have been evaluated. These concentration dependencies have been correlated with infrared absorption results on the same systems to provide information on the sizes and configurations of the proposed hydrogen bonded multimers. It is concluded that, at very low solute concentrations, the alcohol molecules exist as monomers; but with increasing concentration, two types of hydrogen bonded multimers are formed, the first (at low concentrations) being of high dipole moment and the second (at higher concentrations) being of low dipole moment. At high concentrations, the molecules associate to form a three-dimensional network. Attempts have been made to determine equilibrium parameters for molecular models which are consistent with the qualitative understanding of the association behaviour. These parameters were obtained by applying least-squares, curve-fitting techniques to the low concentration permittivity data. A similar investigation has been conducted on solutions of 2,3,4-trimethyl-3-pentanol in the same solvents. The steric hindrance around the hydroxyl group of this alcohol modifies the association behaviour so that a three-dimensional network does not form at high solute concentrations. Proton magnetic resonance chemical shifts for the hydroxyl proton of this alcohol in carbon tetrachloride solutions have been measured. Attempts have also been made to determine equilibrium parameters which describe formation of the hydrogen bonded multimers. To extend this study to include solutes other than octanols, similar experiments have been conducted on solutions of t-butanol in hexadecane, a system which has recently been investigated by other workers using different experimental techniques. The association behaviour of this system is qualitatively similar to that of the straight-chain octanols. The combination of permittivity and infrared measurements, although proving extremely powerful in interpreting the association characteristics of dilute alcohol solutions, is less adequate at high solute concentrations. Attention was therefore directed towards dielectric relaxation and viscosity studies to investigate concentrated solutions. The relaxation times at 20°C of the low frequency dispersion have been measured for solutions of 1-propanol, 1-butanol, 1-hexanol, 1-octanol and 1-decanol in cyclohexane using time domain reflectometry techniques. Similar measurements have also been made on solutions of 1-butanol and 1-octanol in carbon tetrachloride and in benzene. The concentration dependence of the viscosities of certain of these systems has also been examined in an independent study. The ratio of the dielectric relaxation time to the viscosity, the "reduced relaxation time", is qualitatively similar for each system studied. This similarity leads to an explanation of the molecular process responsible for the low frequency dispersion in terms of the proximity of the hydroxyl groups in concentrated alcohol solutions and the fraction of the groups which are not involved in hydrogen bonding.
- Full Text:
- Date Issued: 1975
- Authors: Campbell, Colin
- Date: 1975
- Subjects: Alcohols , Dielectrics , Spectrum analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4454 , http://hdl.handle.net/10962/d1010424
- Description: This study is concerned with the association characteristics of solutions of alcohols in some non-polar solvents. The permittivities at 2 MHz and 25°C for solutions of the straight chain octanols in cyclohexane, carbon tetrachloride and benzene have been examined over the entire solute concentration range, with particular attention -1 being paid to the range below 0.1 molℓ⁻¹ By applying the Kirkwood- Fröhlich equation to these data, the apparent dipole moments of the alcohols as a function of concentration have been evaluated. These concentration dependencies have been correlated with infrared absorption results on the same systems to provide information on the sizes and configurations of the proposed hydrogen bonded multimers. It is concluded that, at very low solute concentrations, the alcohol molecules exist as monomers; but with increasing concentration, two types of hydrogen bonded multimers are formed, the first (at low concentrations) being of high dipole moment and the second (at higher concentrations) being of low dipole moment. At high concentrations, the molecules associate to form a three-dimensional network. Attempts have been made to determine equilibrium parameters for molecular models which are consistent with the qualitative understanding of the association behaviour. These parameters were obtained by applying least-squares, curve-fitting techniques to the low concentration permittivity data. A similar investigation has been conducted on solutions of 2,3,4-trimethyl-3-pentanol in the same solvents. The steric hindrance around the hydroxyl group of this alcohol modifies the association behaviour so that a three-dimensional network does not form at high solute concentrations. Proton magnetic resonance chemical shifts for the hydroxyl proton of this alcohol in carbon tetrachloride solutions have been measured. Attempts have also been made to determine equilibrium parameters which describe formation of the hydrogen bonded multimers. To extend this study to include solutes other than octanols, similar experiments have been conducted on solutions of t-butanol in hexadecane, a system which has recently been investigated by other workers using different experimental techniques. The association behaviour of this system is qualitatively similar to that of the straight-chain octanols. The combination of permittivity and infrared measurements, although proving extremely powerful in interpreting the association characteristics of dilute alcohol solutions, is less adequate at high solute concentrations. Attention was therefore directed towards dielectric relaxation and viscosity studies to investigate concentrated solutions. The relaxation times at 20°C of the low frequency dispersion have been measured for solutions of 1-propanol, 1-butanol, 1-hexanol, 1-octanol and 1-decanol in cyclohexane using time domain reflectometry techniques. Similar measurements have also been made on solutions of 1-butanol and 1-octanol in carbon tetrachloride and in benzene. The concentration dependence of the viscosities of certain of these systems has also been examined in an independent study. The ratio of the dielectric relaxation time to the viscosity, the "reduced relaxation time", is qualitatively similar for each system studied. This similarity leads to an explanation of the molecular process responsible for the low frequency dispersion in terms of the proximity of the hydroxyl groups in concentrated alcohol solutions and the fraction of the groups which are not involved in hydrogen bonding.
- Full Text:
- Date Issued: 1975
Accident liability and primary process thinking : a study in ego psychology
- Authors: Nell, Oelrich
- Date: 1975
- Subjects: Automobile drivers -- Psychology , Ego (Psychology) , Traffic safety -- South Africa -- Psychological aspects , Liability for traffic accidents -- South Africa , Traffic accidents -- South Africa -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3220 , http://hdl.handle.net/10962/d1012950
- Description: Serious efforts must be made to combat the high accident rate on the roads in the Republic of South Africa. The same spirit which exists in the field of medicine when there are evidences that an epidemic is beginning to take its toll, must come into being amongst those who are concerned with traffic and its problems. The public itself needs to become more aware of road safety. Many associations and institutions have been created to assist with the inculcation of the road safety ideal. The National Road Safety Council, which creates opportunities for investigation into aspects of road safety must continue to expand its sphere of influence. The research project contained on the following pages represents an attempt to contribute to the human factor in traffic safety, particularly by making a closer study of the driver of the motor vehicle. The writer is concerned with the carnage that is caused by road accidents. His previous study of personality and particularly of the projective techniques of assessment has prompted a consideration of the problem.
- Full Text:
- Date Issued: 1975
- Authors: Nell, Oelrich
- Date: 1975
- Subjects: Automobile drivers -- Psychology , Ego (Psychology) , Traffic safety -- South Africa -- Psychological aspects , Liability for traffic accidents -- South Africa , Traffic accidents -- South Africa -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3220 , http://hdl.handle.net/10962/d1012950
- Description: Serious efforts must be made to combat the high accident rate on the roads in the Republic of South Africa. The same spirit which exists in the field of medicine when there are evidences that an epidemic is beginning to take its toll, must come into being amongst those who are concerned with traffic and its problems. The public itself needs to become more aware of road safety. Many associations and institutions have been created to assist with the inculcation of the road safety ideal. The National Road Safety Council, which creates opportunities for investigation into aspects of road safety must continue to expand its sphere of influence. The research project contained on the following pages represents an attempt to contribute to the human factor in traffic safety, particularly by making a closer study of the driver of the motor vehicle. The writer is concerned with the carnage that is caused by road accidents. His previous study of personality and particularly of the projective techniques of assessment has prompted a consideration of the problem.
- Full Text:
- Date Issued: 1975
From Frontier to Midlands : a history of the Graaff-Reinet district, 1786-1910
- Authors: Smith, Kenneth Wyndham
- Date: 1975
- Subjects: Graaff-Reinet (South Africa) -- History , South Africa -- Economic conditions -- History , South Africa -- Politics and government -- History , Frontier and pioneer life -- Graaff-Reinet
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2615 , http://hdl.handle.net/10962/d1013242
- Description: The study of local history in South Africa is still in its infancy and has not been accorded the same recognition as elsewhere. There is no convenient manual to guide the would-be local historian of the Cape. There are few models that provide an insight into the main problems encountered by the local historian of a Cape community. In such local histories as exist, attention has been focussed predominantly on the foundation and physical growth of towns, the naming of streets, the establishment of schools and hospitals. Many of these accounts were written for publicity purposes or to commemorate the founding of towns. Although there is no history of the Dutch Reformed Church in Graaff-Reinet, the history of local congregations of the Dutch Reformed Church has generally been well covered in the form of Gedenkboeke and other studies. These frequently have a particular relevance as many towns such as Burgersdorp and Colesberg were founded as a result of the initiative of the church. Preface.
- Full Text:
- Date Issued: 1975
- Authors: Smith, Kenneth Wyndham
- Date: 1975
- Subjects: Graaff-Reinet (South Africa) -- History , South Africa -- Economic conditions -- History , South Africa -- Politics and government -- History , Frontier and pioneer life -- Graaff-Reinet
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2615 , http://hdl.handle.net/10962/d1013242
- Description: The study of local history in South Africa is still in its infancy and has not been accorded the same recognition as elsewhere. There is no convenient manual to guide the would-be local historian of the Cape. There are few models that provide an insight into the main problems encountered by the local historian of a Cape community. In such local histories as exist, attention has been focussed predominantly on the foundation and physical growth of towns, the naming of streets, the establishment of schools and hospitals. Many of these accounts were written for publicity purposes or to commemorate the founding of towns. Although there is no history of the Dutch Reformed Church in Graaff-Reinet, the history of local congregations of the Dutch Reformed Church has generally been well covered in the form of Gedenkboeke and other studies. These frequently have a particular relevance as many towns such as Burgersdorp and Colesberg were founded as a result of the initiative of the church. Preface.
- Full Text:
- Date Issued: 1975
Interactions between steroidal anti-inflammatory agents and collagen
- Authors: Kanfer, Isadore
- Date: 1975
- Subjects: Anti-inflammatory agents Collagen
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3849 , http://hdl.handle.net/10962/d1012620
- Description: Much research has been done on the formation of fibrils from solutions of soluble collagen in vitro in order to gain some knowledge of the mechanisms which may occur in vivo. The in vitro formation of fibres from solutions of collagen has been shown to be extremely sensitive to the nature of the solution environment and the presence of added chemical compounds, and thus constitutes an interesting system for the study of collagen-small molecule inter actions. The present study is concerned with the effects of various corticosteroid drugs, used medicinally as anti-inflammatory agents, on collagen in solution. As these corticosteroids are administered to reduce inflammation in conditions such as rheumatoid arthritis and a host of other pathological conditions in which collagen is implicated, this work has been undertaken in order to establish and charac teri ze any binding mechanisms which may be involved. Furthermore, the corticosteroid drugs available commercially in pure form as the free base or as the water-soluble ester salts offer an interesting range of structural and stereochemical variants for the study of their reaction with a complex and biologically important protein molecule such as collagen. A great deal of research on drug- protein interactions (Goldstein, 1949; Meyer and Guttman, 1968a) and more specifically, steroid-protein interactions have been reported over the years (Daughaday, 1959; Sandberg et al., 1966; Villee and Engel, 1961; Westphal , 1971). Comprehensive reports, however, on steroid-collagen interactions in vitro are conspicuously absent from modern scientific literature although relatively superficial accounts have been published (Menczel and Maibach, 1972; Eik-Nes et al., 1954). Although work involving the above has appeared relating specifically to the effects of steroids on collagen biosynthesis both in vivo and in vitro there have been minimal accounts of steroid-collagen interactions tailored to characterize the binding at the molecular level. The effect of corticosteroids on the metabolism of connective tissue has also received special attention (Asboe-Hansen, 1959; Kivirikko, 1953; Nakagawa and Tsurufuji, 1972). Recently, Uitto et al. (1972) reported the effects of several anti-inflammatory corticosteroids on collagen biosynthesis in vitro, whilst Aalto and Kulonen (1972) reported the effects of several antirheumatic drugs on the synthesis of collagen and other proteins in vitro. The interactions between collagen and certain drugs has also been briefly reviewed (Chvapil, 1967). Much data also exists on the binding of a wide range of small molecules and ions with serum albumin (Steinhardt and Reynolds, 1969; Scatchard, 1949; Klotz, 1950). Serum albumin, being specialized for a very general transport function and apparently designed for the purpose of combining with a large range of small molecules, has a proportion of possible reactive sites 'buried' within the molecule itself because of its folded conformation. In addition, serum albumin shows a high degree of cooperative binding in contrast to collagen. The latter molecule, with its larger molecular size and weight is specialized for a biologically structural function and has a higher proportion of possible reactive sites which appear relatively more accessible to ligands. A study of the interactions between corticosteroids and collagen thus provides the opportunity to investigate a protein which is very different from the much studied serum albumin. Because of the limited information available regarding the interaction of steroid drugs and collagen at the molecular level, studies of this nature are relevant to the understanding of the mode of action of steroid compounds which are such an important group of therapeutic substances used in modern medicine.
- Full Text:
- Date Issued: 1975
- Authors: Kanfer, Isadore
- Date: 1975
- Subjects: Anti-inflammatory agents Collagen
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3849 , http://hdl.handle.net/10962/d1012620
- Description: Much research has been done on the formation of fibrils from solutions of soluble collagen in vitro in order to gain some knowledge of the mechanisms which may occur in vivo. The in vitro formation of fibres from solutions of collagen has been shown to be extremely sensitive to the nature of the solution environment and the presence of added chemical compounds, and thus constitutes an interesting system for the study of collagen-small molecule inter actions. The present study is concerned with the effects of various corticosteroid drugs, used medicinally as anti-inflammatory agents, on collagen in solution. As these corticosteroids are administered to reduce inflammation in conditions such as rheumatoid arthritis and a host of other pathological conditions in which collagen is implicated, this work has been undertaken in order to establish and charac teri ze any binding mechanisms which may be involved. Furthermore, the corticosteroid drugs available commercially in pure form as the free base or as the water-soluble ester salts offer an interesting range of structural and stereochemical variants for the study of their reaction with a complex and biologically important protein molecule such as collagen. A great deal of research on drug- protein interactions (Goldstein, 1949; Meyer and Guttman, 1968a) and more specifically, steroid-protein interactions have been reported over the years (Daughaday, 1959; Sandberg et al., 1966; Villee and Engel, 1961; Westphal , 1971). Comprehensive reports, however, on steroid-collagen interactions in vitro are conspicuously absent from modern scientific literature although relatively superficial accounts have been published (Menczel and Maibach, 1972; Eik-Nes et al., 1954). Although work involving the above has appeared relating specifically to the effects of steroids on collagen biosynthesis both in vivo and in vitro there have been minimal accounts of steroid-collagen interactions tailored to characterize the binding at the molecular level. The effect of corticosteroids on the metabolism of connective tissue has also received special attention (Asboe-Hansen, 1959; Kivirikko, 1953; Nakagawa and Tsurufuji, 1972). Recently, Uitto et al. (1972) reported the effects of several anti-inflammatory corticosteroids on collagen biosynthesis in vitro, whilst Aalto and Kulonen (1972) reported the effects of several antirheumatic drugs on the synthesis of collagen and other proteins in vitro. The interactions between collagen and certain drugs has also been briefly reviewed (Chvapil, 1967). Much data also exists on the binding of a wide range of small molecules and ions with serum albumin (Steinhardt and Reynolds, 1969; Scatchard, 1949; Klotz, 1950). Serum albumin, being specialized for a very general transport function and apparently designed for the purpose of combining with a large range of small molecules, has a proportion of possible reactive sites 'buried' within the molecule itself because of its folded conformation. In addition, serum albumin shows a high degree of cooperative binding in contrast to collagen. The latter molecule, with its larger molecular size and weight is specialized for a biologically structural function and has a higher proportion of possible reactive sites which appear relatively more accessible to ligands. A study of the interactions between corticosteroids and collagen thus provides the opportunity to investigate a protein which is very different from the much studied serum albumin. Because of the limited information available regarding the interaction of steroid drugs and collagen at the molecular level, studies of this nature are relevant to the understanding of the mode of action of steroid compounds which are such an important group of therapeutic substances used in modern medicine.
- Full Text:
- Date Issued: 1975
Paradoks as poësie: 'n ondersoek na enkele aspekte van die poësie van Breyten Breytenbach
- Authors: Van der Merwe, Anna Maria
- Date: 1975
- Subjects: Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3636 , http://hdl.handle.net/10962/d1013302
- Full Text:
- Date Issued: 1975
- Authors: Van der Merwe, Anna Maria
- Date: 1975
- Subjects: Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3636 , http://hdl.handle.net/10962/d1013302
- Full Text:
- Date Issued: 1975
Studies on achromobacter iophagus and other collagenolytic hide bacteria
- Authors: Welton, Richard Leslie
- Date: 1975
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21099 , http://hdl.handle.net/10962/6367
- Description: From Introduction: Collagenases are enzymes capable of specifically attacking the native collagen helix under non-denaturing conditions at physiological conditions of pH, temperature and salt concentration. They are active only on collagen or its breakdown products and are without effect on any other fibrous or globular protein. In the laboratory, collagenases are used in investigations of the biosynthesis of collagen and for structural and immunochemical studies of collagens and collagen-like proteins; also they are proving their worth as agents for facilitating tissue transplantation and for cell-dispersion in tissue cultures . Established clinical applications of collagenases include the treatment of burns and dermal lesions; in addition they are being evaluated as agents for the removal of undesirable tissues such as herniated intervertebral discs and the sloughs resulting from cryogenic or cauterizing procedures. Moreover, as human collagenases are implicated in various pathological disorders involving connective tissue degradation, the roles played by these collagenases are being investigated in the hope of finding ways to arrest, control or treat the diseases.
- Full Text:
- Date Issued: 1975
- Authors: Welton, Richard Leslie
- Date: 1975
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21099 , http://hdl.handle.net/10962/6367
- Description: From Introduction: Collagenases are enzymes capable of specifically attacking the native collagen helix under non-denaturing conditions at physiological conditions of pH, temperature and salt concentration. They are active only on collagen or its breakdown products and are without effect on any other fibrous or globular protein. In the laboratory, collagenases are used in investigations of the biosynthesis of collagen and for structural and immunochemical studies of collagens and collagen-like proteins; also they are proving their worth as agents for facilitating tissue transplantation and for cell-dispersion in tissue cultures . Established clinical applications of collagenases include the treatment of burns and dermal lesions; in addition they are being evaluated as agents for the removal of undesirable tissues such as herniated intervertebral discs and the sloughs resulting from cryogenic or cauterizing procedures. Moreover, as human collagenases are implicated in various pathological disorders involving connective tissue degradation, the roles played by these collagenases are being investigated in the hope of finding ways to arrest, control or treat the diseases.
- Full Text:
- Date Issued: 1975
Studies on the biology and ecology of Amblyomma Herbraem Koch, 1844 and other tick species (Ixodidae) of the Eastern Cape
- Authors: Norval, R A I
- Date: 1975
- Subjects: Ticks -- South Africa -- Eastern Cape , Ixodidae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5871 , http://hdl.handle.net/10962/d1012968
- Description: Tick borne diseases of livestock are among the most important factors which have retarded economic development in many parts of Africa. Modification of the environment due to the expansion of agriculture into previously undeveloped areas, together with the introduction of livestock, has disturbed the natural balance which existed between ticks and indigenous hosts. Many tick species have adapted to domestic stock, and in some instances have spread over large areas which were previously uninfested. A number of tick species which are parasitic on domestic stock, eg. Amblyomma hebraeum Koch, 1844, Boophilus decoloratus (Koch, 1844), Rhipicephalus evertsi Neumann, 1897 and Rhipicephalus appendiculatus Netunann, 1901, are vectors of pathogenic micro-organisms. Unlike indigenous hosts however, domestic stock have no innate immunity to tickborne diseases. Intro., p. 1.
- Full Text:
- Date Issued: 1975
- Authors: Norval, R A I
- Date: 1975
- Subjects: Ticks -- South Africa -- Eastern Cape , Ixodidae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5871 , http://hdl.handle.net/10962/d1012968
- Description: Tick borne diseases of livestock are among the most important factors which have retarded economic development in many parts of Africa. Modification of the environment due to the expansion of agriculture into previously undeveloped areas, together with the introduction of livestock, has disturbed the natural balance which existed between ticks and indigenous hosts. Many tick species have adapted to domestic stock, and in some instances have spread over large areas which were previously uninfested. A number of tick species which are parasitic on domestic stock, eg. Amblyomma hebraeum Koch, 1844, Boophilus decoloratus (Koch, 1844), Rhipicephalus evertsi Neumann, 1897 and Rhipicephalus appendiculatus Netunann, 1901, are vectors of pathogenic micro-organisms. Unlike indigenous hosts however, domestic stock have no innate immunity to tickborne diseases. Intro., p. 1.
- Full Text:
- Date Issued: 1975
The African press in South Africa
- Authors: St Leger, Frederick York
- Date: 1975
- Subjects: Press -- South Africa -- History Ethnic press -- South Africa -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3328 , http://hdl.handle.net/10962/d1003116
- Description: In a plural society, riven by deep conflict, as is South Africa, where however the Press retains a considerable measure of freedom to contribute to the political process it is the political role which is of the greatest significance rather than, for example, the reflection by the Press of social values or the internal organisation of the Press as a social system. Although it is, of course, hardly possible completely to ignore these other aspects in any institutional study.
- Full Text:
- Date Issued: 1975
- Authors: St Leger, Frederick York
- Date: 1975
- Subjects: Press -- South Africa -- History Ethnic press -- South Africa -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3328 , http://hdl.handle.net/10962/d1003116
- Description: In a plural society, riven by deep conflict, as is South Africa, where however the Press retains a considerable measure of freedom to contribute to the political process it is the political role which is of the greatest significance rather than, for example, the reflection by the Press of social values or the internal organisation of the Press as a social system. Although it is, of course, hardly possible completely to ignore these other aspects in any institutional study.
- Full Text:
- Date Issued: 1975
The population dynamics of an indigenous Psyllid Acizzia Russellae (Homoptera: Psyllidae )with special reference to the influence of the host plant Acacia Karroo
- Authors: Webb, John Warren
- Date: 1975
- Subjects: Homoptera , Jumping plant-lice , Insect populations , Insects -- Ecology , Acacia -- Karroo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5894 , http://hdl.handle.net/10962/d1013415
- Description: The biology and ecology of an indigenous, non-pest insect on an indigenous host plant were investigated. The study includes a taxonomic description of this new species, an account of its general biology, monitoring of the seasonal fluctuations in numbers of the psyllid and its hymenopterous parasitoids, and a study of various aspects of the host plant, including nitrogen levels, water stress, leaf hardness, and the effect of cutting, in relation to spatial and temporal differences in insect population numbers. Natural enemies, inter- and intra-specific competition had very little determining influence on the population numbers of the psyllid. Temperature and humidity had little direct effect, but may have influenced the population dynamics via its effects on the host plant. Seasonal patterns in psyllid numbers followed fluctuations in nitrogen levels; statistically valid correlations were obtained between leaf nitrogen and psyllid numbers on individual trees at various times. These findings were supported by the results of preliminary laboratory experiments employing different fertilizer treatments. No effect of water stress or leaf hardness was clearly discerned. Cutting of trees altered the characteristics of the subsequent regenerative growth so as to allow massive psyllid infestations to develop, thus showing the tremendous importance of the host plant in determining population levels in this insect. Preliminary investigations of the nature and mechanism of this effect were conducted, and its significance is discussed. The relevance of these findings to modern concepts of regulation in insect populations and to principles of pest management is discussed.
- Full Text:
- Date Issued: 1975
- Authors: Webb, John Warren
- Date: 1975
- Subjects: Homoptera , Jumping plant-lice , Insect populations , Insects -- Ecology , Acacia -- Karroo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5894 , http://hdl.handle.net/10962/d1013415
- Description: The biology and ecology of an indigenous, non-pest insect on an indigenous host plant were investigated. The study includes a taxonomic description of this new species, an account of its general biology, monitoring of the seasonal fluctuations in numbers of the psyllid and its hymenopterous parasitoids, and a study of various aspects of the host plant, including nitrogen levels, water stress, leaf hardness, and the effect of cutting, in relation to spatial and temporal differences in insect population numbers. Natural enemies, inter- and intra-specific competition had very little determining influence on the population numbers of the psyllid. Temperature and humidity had little direct effect, but may have influenced the population dynamics via its effects on the host plant. Seasonal patterns in psyllid numbers followed fluctuations in nitrogen levels; statistically valid correlations were obtained between leaf nitrogen and psyllid numbers on individual trees at various times. These findings were supported by the results of preliminary laboratory experiments employing different fertilizer treatments. No effect of water stress or leaf hardness was clearly discerned. Cutting of trees altered the characteristics of the subsequent regenerative growth so as to allow massive psyllid infestations to develop, thus showing the tremendous importance of the host plant in determining population levels in this insect. Preliminary investigations of the nature and mechanism of this effect were conducted, and its significance is discussed. The relevance of these findings to modern concepts of regulation in insect populations and to principles of pest management is discussed.
- Full Text:
- Date Issued: 1975
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