Politics, latent and overt, in Hill of Fools
- Authors: Wright, Laurence
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:7064 , http://hdl.handle.net/10962/d1007430
- Description: [From the text]: R. L. Peteni’s novel Hill of Fools (1976) is a work that benefits greatly when Collingwood’s maxim is observed. The author’s family history and the circumstances surrounding the book’s publication add a dimension of political and social meaning which its surface deliberately occludes. Perhaps more importantly, while the story can readily be enjoyed, the quality of sensibility behind the work is not readily accessed without understanding some of the socio-political background.
- Full Text:
- Date Issued: 2004
Science after a century at Rhodes University
- Authors: Woods, D R
- Date: 2004
- Language: English
- Type: Article , text
- Identifier: vital:7123 , http://hdl.handle.net/10962/d1006584
- Description: Rhodes Centenary issue , The small University of Rhodes (6142 students), in the rural city of Grahamstown, was established in 1904 as a result of a £50 000 grant from the Rhodes Trust in Oxford. It grew out of St Andrew’s College, which provided the first four professors and 41 students. The first paper from Rhodes in the South African Journal of Science (then called the Report of the South African Association for the Advancement of Science) was by Selmar Schonland, one of the university’s founding fathers. Entitled: ‘Biological and ethnological observations on a trip to the N.E. Kalahari’, it appeared in 1904. The following pages provide a glimpse into the growth and achievements of various departments in the faculties of Science and Pharmacy and associated institutes a century after the university was born.
- Full Text:
- Date Issued: 2004
Recent African derivation of Chrysomya putoria from C. chloropyga and mitochondrial DNA paraphyly of cytochrome oxidase subunit one in blowflies of forensic importance
- Authors: Wells, J D , Lunt, N , Villet, Martin H
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6888 , http://hdl.handle.net/10962/d1011648
- Description: Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.
- Full Text:
- Date Issued: 2004
Mechanisms generating biological diversity in the genus Platypleura Amyot & Serville, 1843 (Hemiptera: Cicadidae) in southern Africa: implications of a preliminary molecular phylogeny
- Authors: Villet, Martin He , Barker, Nigel P , Lunt, N
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6554 , http://hdl.handle.net/10962/d1006012
- Description: Truly understanding biological diversity requires a move from descriptive studies to mechanistic interpretations based on comparative biology and a thorough recognition of the natural history of the focal organisms. A useful step in such comparative studies is the generation of a phylogeny, so that one can assess the phylogenetic independence of the focal taxa and trace the evolutionary significance of their characteristics. As a preliminary to such studies on the platypleurine cicada genus Platypleura, we sequenced 498 bases of the cytochrome oxidase I (COI) gene from thirteen African species. To circumvent problems with outgroup selection, we also included sequences from representatives of the platypleurine genera Brevisiana, Capcicada, Munza, Oxypleura, Severiana, and Systophlochius, all of the subtribe Platypleuriti, and two species of the genus Ugada, of the subtribe Hainanosemiiti. The resulting phylogenies support the synonymization of the monotypic genus Systophlochius with the widespread, speciose genus Platypleura; confirm the placement of Platypleura sp. 7 in that genus; and confirm the independence of Capcicada and Platypleura. Although the preliminary phylogeny lacks strong support at many nodes, it suggests that three radiations of Platypleura have occurred in southern Africa and that there was progressive southward speciation of these radiations. A novel modification of the ancestral area analysis further suggests that the group has an ancestral association with acacias but there were five independent speciation events associated with host- switching. These insights can be summarized by a general hypothesis that the mechanisms underlying platypleurine biodiversity in southern Africa involve two ancient vicariance events and subsequent speciation by vicariance, switching of plant associations, and changes of habitat preferences. We offer this example to illustrate how analysis of preliminary data can help to generate hypotheticodeductive research hypotheses, to provoke interest in testing these hypotheses, and to illustrate the utility of phylogenies beyond systematics.
- Full Text:
- Date Issued: 2004
Phenomenology in education : a case study in educational leadership
- Authors: Van der Mescht, Hennie
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6101 , http://hdl.handle.net/10962/d1008665
- Description: [From the introduction]: Overheard during tea at an Education Faculty research design course: “Phenomenology produces interesting and surprising results, but it’s just too much work …” The speaker was a prospective Masters student who had decided against “phenomenological” research, presumably because “it’s just too much work”. Having been deeply involved in phenomenological research myself for some years, I could identify with his reservation. But his first statement is of course equally true: phenomenological research does indeed produce “interesting and surprising results”, as many of my students have found. I should at the outset describe what I mean by phenomenological research more carefully, since, as Schweitzer (2002) has recently pointed out, there is certainly more than one meaning out there. The kind of research I am referring to is not the kind frequently featured in this journal, which Schweitzer (2002) describes as “Husserlian”, but another kind, which he describes as “‘what’s it like for them’ type of studies”. In this paper I present a case for the latter, and consider its appropriateness to the field of education. I argue that this approach to phenomenological research (which Schweitzer refers to as empirical) is a potentially powerful way of making sense of education practitioners’ (and learners’) sense-making, and can lead to startling new insights into the uniquely complex processes of learning, teaching and educational managing and leading.
- Full Text:
- Date Issued: 2004
Western Alumna inspiring catalyst
- Authors: University of Western Ontario
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7172 , http://hdl.handle.net/10962/d1006078 , Nyokong, Tebello
- Description: University of Western Ontario President's Report 2004
- Full Text:
Livelihood benefits from the local level commercialization of savanna resources: a case study of the new and expanding trade in marula (Sclerocarya birrea) beer in Bushbuckridge, South Africa
- Authors: Shackleton, Sheona E
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6649 , http://hdl.handle.net/10962/d1007060
- Description: In the face of economic hardship and poverty, rural people in South Africa and globally are increasingly turning to the natural resource base to generate income. One product that has recently entered into local commercial markets is a traditional alcoholic beverage brewed from the fruits of Sclerocarya birrea (marula), commonly known as marula beer. It was rarely traded in the past due to customary taboos prohibiting its sale. In Bushbuckridge, Limpopo province, rural women have been selling marula beer in the business centres of the district and along the roadside since 1998. A survey of these markets was undertaken in 2002, to discover the commercialization process involved, from raw material harvesting to marketing, and to assess the importance of the trade for household livelihoods and poverty alleviation. Fifty-one traders were interviewed, who indicated that the sale of marula beer provides a vital source of income to several hundred households from amongst the poorest sector of the Bushbuckridge community. Of particular importance were the low barriers of entry to the trade, as the resource is abundant and freely accessible and there are few costs to produce marula beer. Incomes earned were modest, averaging a net R500 per season, and highly seasonal, but came at a critical point in the household calendar, after the festive season and when cash was required for the new school year. Income bridging, livelihood diversification, and the provision of a safety net for the poorest members of society are some of the key benefits of the beer trade.
- Full Text:
- Date Issued: 2004
The importance of non-timber forest products in rural livelihood security and as safety nets: a review of evidence from South Africa
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6650 , http://hdl.handle.net/10962/d1007061
- Description: We review and synthesize recent South African work that examines the role and importance of non-timber forest products (NTFPs) in the daily lives of rural people in South Africa. The most commonly used such products are wild spinaches, fuelwood, wooden utensils edible fruits, grass hand-brushes, and twig hand-brushes, used by 85% or more of households. More than half the households investigated also make use of edible insects, wood for construction, bushmeat, wild honey and reeds for weaving. Individual households may exploit dozens of animal and plant species. The range in annual, direct-use values is large, from less than R1000 per household per year to over R12 000. The value to rural households is manifest through a daily net function which represents a cost saving to the families involved and to the state, as well as through an emergency net, which serves as an insurance in times of misfortune, such as drought, disease, and unexpected economic hardship. The emergency net function has hardly been quantified in South Africa and internationally. Ad hoc trade in NTFPs is a common emergency net, which in some instances evolves into a permanent way of life. Financial returns from trade are variable, depending on resource type and hours worked, but are typically low. Despite the small cash incomes from trade, they provide an important contribution that complement the diverse livelihood strategies within a household, especially for the poorer sectors of rural society. Moreover, there are non-financial benefits of NTFP trade that are commonly overlooked.
- Full Text:
- Date Issued: 2004
An indirect method to assess the energy expenditure of manual labourers in situ
- Authors: Scott, Patricia A , Christie, Candice J
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6742 , http://hdl.handle.net/10962/d1008390
- Description: The aim of ergonomics is to identify any incompatibility between worker capabilities and the demands of their job. It is therefore desirable that in a developing country such as South Africa we have some basic, yet valid and usable means of measuring worker responses to physically demanding manual tasks. Extensive ergonomic research has been conducted in the controlled environment of laboratories around the globe, but only a limited number of investigations have been conducted in the workplace. This is due to the impossibility of controlling the extraneous factors such as the environment and changing workloads while assessing worker responses, plus the impracticality of using hi-tech equipment under difficult conditions on unsophisticated workers. The likelihood of obtaining ‘natural’ responses thereby is low. The focus of this study was to establish a less invasive means of assessing the physiological responses (specifically energy expenditure) of manual labourers working in the field. Twenty-three forestry stackers were assessed. Heart-rate responses were recorded during a full shift, after which the workers participated in a submaximal incremental step test. Subjects were fitted with a gas analyser, and heart rate and oxygen consumption responses were measured throughout the 12-min test. These data were used to establish a regression equation based on the relationship between heart rate and oxygen consumption (r² = 0.49; r = 0.69). Using this equation (y=0.26x – 6.42), one can measure heart rate in the field and predict the energy cost of manual tasks.
- Full Text:
- Date Issued: 2004
Endothermy in African Platypleurine Cicadas: the influence of body size and habitat (Hemiptera: Cicadidae)
- Authors: Sanborn, Allen F , Villet, Martin H , Phillips, P K
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6925 , http://hdl.handle.net/10962/d1011912
- Description: The platypleurine cicadas have a wide distribution across Africa and southern Asia. We investigate endothermy as a thermoregulatory strategy in 11 South African species from five genera, with comparisons to the lone ectothermic platypleurine we found, in an attempt to ascertain any influence that habitat and/or body size have on the expression of endothermy in the platypleurine cicadas. Field measurements of body temperature (Tb) show that these animals regulate Tb through endogenous heat production. Heat production in the laboratory elevated Tb to the same range as in animals active in the field. Maximum Tb measured during calling activity when there was no access to solar radiation ranged from 13.2° to 22.3°C above ambient temperature in the five species measured. The mean Tb during activity without access to solar radiation did not differ from the mean Tb during diurnal activity. All platypleurines exhibit a unique behavior for cicadas while warming endogenously, a temperature- dependent telescoping pulsation of the abdomen that probably functions in ventilation. Platypleurines generally call from trunks and branches within the canopy and appear to rely on endothermy even when the sun is available to elevate Tb, in contrast to the facultative endothermy exhibited by New World endothermic species. The two exceptions to this generalization we found within the platypleurines are Platypleura wahlbergi and Albanycada albigera, which were the smallest species studied. The small size of P. wahlbergi appears to have altered their thermoregulatory strategy to one of facultative endothermy, whereby they use the sun when it is available to facilitate increases in Tb. Albanycada albigera is the only ectothermic platypleurine we found. The habitat and host plant association of A. albigera appear to have influenced the choice of ectothermy as a thermoregulatory strategy, as the species possesses the metabolic machinery to elevate to the Tb range observed in the endothermic species. Therefore, size and habitat appear to influence the expression of thermoregulatory strategies in African platypleurine cicadas.
- Full Text:
- Date Issued: 2004
Evolution of Labeo victorianus predates the Pleistocene desiccation of Lake Victoria: evidence from mitochondrial DNA sequence variation
- Authors: Rutaisire, Justus , Booth, Anthony J , Masembe, C , Nyakaana, S , Muwanika, V B
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6762 , http://hdl.handle.net/10962/d1007924
- Description: Geological data show that Lake Victoria dried out some 15 000 years ago. These data suggest that the entire faunal diversity within the lake has evolved since this time. However, mitochondrial DNA sequence diversity in the endemic cyprinid fish, Labeo victorianus, was high (24 haplotypes in 38 individuals; percentage sequence divergence of 0.74%), suggesting that the evolution of this species predates this Late Pleistocene climatological event. This finding is consistent with what has been reported earlier for cichlid fishes in the lake.
- Full Text:
- Date Issued: 2004
A fuzzy classification technique for predicting species' distributions: applications using invasive alien plants and indigenous insects
- Authors: Robertson, Mark P , Villet, Martin H , Palmer, Anthony R
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6897 , http://hdl.handle.net/10962/d1011659 , http://dx.doi.org/10.1111/j.1366-9516.2004.00108.x
- Description: A new predictive modelling technique called the fuzzy envelope model (FEM) is introduced. The technique can be used to predict potential distributions of organisms using presence-only locality records and a set of environmental predictor variables. FEM uses fuzzy logic to classify a set of predictor variable maps based on the values associated with presence records and combines the results to produce a potential distribution map for a target species. This technique represents several refinements of the envelope approach used in the BIOCLIM modelling package. These refinements are related to the way in which FEMs deal with uncertainty, the way in which this uncertainty is represented in the resultant potential distribution maps, and the way that these maps can be interpreted and applied. To illustrate its potential use in biogeographical studies, FEM was applied to predicting the potential distribution of three invasive alien plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.), and three native cicada species (Capicada decora Germar, Platypleura deusta Thun. and P. capensis L.) in South Africa, Lesotho and Swaziland. These models were quantitatively compared with models produced by means of the algorithm used in the BIOCLIM modelling package, which is referred to as a crisp envelope model (the CEM design). The average performance of models of the FEM design was consistently higher than those of the CEM design. There were significant differences in model performance among species but there was no significant interaction between model design and species. The average maximum kappa value ranged from 0.70 to 0.90 for FEM design and from 0.57 to 0.89 for the CEM design, which can be described as 'good' to 'excellent' using published ranges of agreement for the kappa statistic. This technique can be used to predict species' potential distributions that could be used for identifying regions at risk from invasion by alien species. These predictions could also be used in conservation planning in the case of native species.
- Full Text:
- Date Issued: 2004
Quantification of the photosynthetic performance of phosphorus-deficient Sorghum by means of chlorophyll-a fluorescence kinetics
- Authors: Ripley, Bradley S , Redfern, S P , Dames, Joanna F
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6456 , http://hdl.handle.net/10962/d1004464
- Description: Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 μmol mol^(–1)) or low (5 μmol mol^(–1)) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PI_ABS_); plants with increased PI_ABS_ manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.
- Full Text:
- Date Issued: 2004
Making sense of science through two languages: a South African case study
- Authors: Probyn, Margie J
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:7025 , http://hdl.handle.net/10962/d1007209
- Description: Mzamo Senior Secondary School (not its real name) looks like any typical township school in South Africa: modern face-brick classroom blocks which conceal a serious lack of resources, material and human. Under apartheid the disparities in spending on white and African students meant hugely different teaching and learning contexts - including infrastructure, teacher training, pupil: teacher ratios and teaching materials. Today, 10 years into the new democracy and despite government’s efforts to equalize spending, the historic inequalities persist. The school is surrounded by township houses and shacks that reflect the high poverty levels in the Eastern Cape Province. Students at schools like this face an additional but less obvious problem – that of the language medium. Although in the Eastern Cape, Xhosa is the home language of 83,8% of the population and English speakers comprise only 3.7%, the official language medium in schools is English from the beginning of Grade 4 in the majority of schools. South Africa is a multilingual country with 11 official languages recognized in the Constitution of 1996 – 9 indigenous languages and the two colonial languages, English and Afrikaans.
- Full Text:
- Date Issued: 2004
Evidence for Archaean lamprophyre from the Kaapvaal Craton, South Africa
- Authors: Prevec, S A , Anhaeusser, C R , Poujol, M
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6739 , http://hdl.handle.net/10962/d1007555
- Description: A suite of mafic dykes occurs as a late component in a wellcharacterized trondhjemite–tonalite–diorite–granodiorite assemblage in the Johannesburg Dome of the central Kaapvaal Craton, southern Africa. The dykes have been subdivided into two sets, based on their orientation, and major and trace element geochemistry. Set 1 dykes are characterized by elevated SiO2, Al2O3 and TiO2, and particularly by enriched LILE and HSFE (e.g. Zr > 200 ppm, Nb > 20 ppm, Ba > 300 ppm), higher than in any of the accompanying felsic rocks. REE and trace element values for Set 1 dykes are similar to those for calc-alkaline lamprophyres. The Set 2 dykes have similar trace element distributions, but are significantly less enriched in general, and are broadly tholeiitic in composition, with enriched MgO (>11 wt. percentage) indicative of an olivine–phyric tholeiitic basaltic protolith. Field relationships and available U–Pb zircon geochronology indicate that the dykes are contemporaneous with components of the trondhjemitic host rocks, and with late granodiorites. The geochemical, geochronological and field petrological setting indicates partial melting of basaltic and eclogitic lithosphere at c. 3120 Myr ago in the basal Kaapvaal Craton, and subsequent emplacement into pre-existing c. 3430 Myr tonalitic to dioritic crust.
- Full Text:
- Date Issued: 2004
Pollination biology of Bergeranthus multiceps (Aizoaceae) with preliminary observations of repeated flower opening and closure
- Authors: Peter, Craig I , Dold, Anthony P , Barker, Nigel P , Ripley, Bradley S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6529 , http://hdl.handle.net/10962/d1005970
- Description: Little is known about pollination of the Aizoaceae (Mesembryanthemaceae). There are sparse reports of generalist pollination in the family by a variety of insects (predominantly bees). Furthermore, most species are self-incompatible in cultivation. In this study, observations were made on two populations of Bergeranthus multiceps (Salm-Dyck) Schwantes growing in the Eastern Cape province of South Africa. Insects visiting the flowers were collected and examined for pollen. While 79 individual insects (in 24 genera representing 14 families and four orders) were collected visiting the flowers, the majority (43 individuals) were female Allodapula variegata bees (Apidae, subfamily Xylocopinae, tribe Allodapini)collecting pollen. All other bee visitors were also female, suggesting pollen collection as the primary activity at the flowers. The protandrous flowers were found to be self-incompatible, pointing to the importance of bee-mediated xenogamy in this species. The flowers of B. multiceps are bright yellow in the human visual spectrum. In addition, the petals of this species reflect ultraviolet light. In contrast, the yellow anthers absorb UV. Flower opening and closing is common in the Aizoaceae. Interestingly, in B. multiceps flowers open at about 15:30 and remain open for approximately three hours before closing again in the late afternoon. These afternoon flower opening events were found to be closely correlated to ambient temperatures above 23°C, relative humidity lower than 50% and vapour pressure deficit below 1.05 kPa measured from as early as 09:00 on the days when flowers opened.
- Full Text:
- Date Issued: 2004
The development of a toxicity database using freshwater macroinvertebrates, and its application to the protection of South African water resources
- Authors: Palmer, Carolyn G , Muller, Wilhelmine J , Gordon, Andrew K , Scherman, Patricia A , Davies-Coleman, Heather D , Pakhomova, L , de Kock, E
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:7073 , http://hdl.handle.net/10962/d1009528
- Description: There is a growing international trend towards the protection of freshwater resources from pollution by imposing instream guidelines and specified waste-discharge conditions. Current methods for devising freshwater quality guidelines are based on species sensitivity distributions (SSDs) that are used to identify pollutant concentrations, ensuring the protection of a modelled percentage of species (95% protection is a common goal). SSDs are derived from the toxicity test results of as many taxa as possible for each polluting substance. Waste-discharge licences can be for single substances, specified in terms of chemical concentrations, and derived in conjunction with instream guidelines; or for complex mixtures, specified in terms of toxic units. In both cases toxicity test results are the core data used. The emphasis on SSDs calls into question the species constituting the test populations. It is likely that SSDs based in part on the responses of local organisms will achieve superior site-specific ecological protection. Until the early 1990s, there were very few data on the tolerances of South African freshwater organisms. In the intervening decade, the Unilever Centre for Environmental Water Quality at Rhodes University has developed a toxicity database that, to date, records the responses of 21 South African freshwater taxa to 26 single-substance pollutants or mixtures. This is the most comprehensive database of South African toxicity responses available and has been used in the drawing up of methods and guidelines to protect water resources. This paper aims to make these data available and to describe applications of the data using selected case studies.
- Full Text:
- Date Issued: 2004
Economic feasibility of an experimental octopus fishery in South Africa
- Authors: Oosthuizen, Ané
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6760 , http://hdl.handle.net/10962/d1007773
- Description: Octopus vulgaris was identified as a new marine resource to be commercially exploited through an experimental fishery. A recent policy on developing fisheries in South Africa emphasizes the importance of investigating the economic feasibility of a fishery as part of its management framework. The study reported here generated baseline information necessary in the design of the experimental fishery, giving guidelines as to which vessels, fishing gear and markets would be most feasible. The proposed fishery, gear and vessel type, fishing techniques and expected catch rates are described, the results of market research are outlined, and the cost of fishing is estimated. The potential business should consist of small and medium-sized vessels deploying unbaited pots attached to long lines. The longline pot fishery could be economically feasible, provided a 30 percent catch in 6600 pots/month is attained. Only existing, debt-free vessels should be used. The minimum catch per unit effort (CPUE) for various fishing operation scenarios was calculated to determine economic feasibility. This is an estimated minimum CPUE, based on assumptions that cannot be confirmed until the fishery starts. Furthermore, this economic analysis also needs to be assessed by stakeholders with experience of fishery operations , Rhodes Centenary issue of: South African Journal of Science.
- Full Text:
- Date Issued: 2004
Genetic analysis of the Octopus vulgaris population on the coast of South Africa
- Authors: Oosthuizen, Ané , Jiwaji, Meesbah , Shaw, Paul W
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6761 , http://hdl.handle.net/10962/d1007922
- Description: This study on Octopus vulgaris focused on the COIII gene region of mitochondrial DNA. Sequences from 21 samples from the Eastern Cape, and 14 samples from the Western Cape, were compared to determine whether different populations exist along the South African coast. A 380-bp segment of the COIII region of mtDNA was amplified using the polymerase chain reaction with specific designed primers. Phylogenetic inference was made using maximum parsimony (MP), maximum likelihood (ML), and distance based methods. All sequences conformed to a single haplotype. Lack of variation within and between east and west coast samples precluded further population genetic analysis. The sequence obtained in this study was also compared with other sequences lodged in the Genbank database. Phylogenetically, the South African O. vulgaris is closely related to O. vulgaris from Senegal (0.67% divergence) and the Mediterranean (1.51% divergence). Within the Mediterranean group, O. vulgaris from South Africa displayed less sequence divergence from Senegalese and Mediterranean individuals than O. vulgaris from Venezuela (3.85%) and Taiwan (3.87%). These data do not, therefore, refute the hypothesis of a single O. vulgaris genetic population around the coast.
- Full Text:
- Date Issued: 2004
Effects of substituents and solvents on the photochemical properties of zinc phthalocyanine complexes and their protonated derivatives
- Authors: Ogunsipe, Abimbola Olukayode , Nyokong, Tebello
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6585 , http://hdl.handle.net/10962/d1004161
- Description: Zinc phthalocyanine derivatives containing various ring substituents and axial ligands were studied with respect to the effect of substituents on protonation. Aggregation resulted in failure of some of the ZnPc derivatives to protonate. In fact addition of protonating agents to aggregated ZnPc derivatives resulted in increase in aggregation followed by slow degradation. Axial ligands were lost on protonation. Photobleaching, fluorescence and singlet oxygen quantum yields of the protonated derivatives were compared with those of the unprotonated derivatives. In all cases protonation decreases the singlet oxygen and fluorescence quantum yields. However, photobleaching quantum yields decreased (i.e. stability increased) for the protonated derivatives except when axial ligands were present, where protonation resulted in decrease in stability.
- Full Text:
- Date Issued: 2004