Analysis of transcription factor binding specificity using ChIP-seq data.
- Authors: Kibet, Caleb Kipkurui
- Date: 2014
- Subjects: Transcription factors , Chronic myeloid leukemia , Antioncogenes , Cancer cells -- Growth -- Regulation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4115 , http://hdl.handle.net/10962/d1013131
- Description: Transcription factors (TFs) are key regulators of gene expression whose failure has been implicated in many diseases, including cancer. They bind at various sites at different specificity depending on the prevailing cellular conditions, disease, development stage or environmental conditions of the cell. TF binding specificity is how well a TF distinguishes functional sites from potential non-functional sites to form a useful regulatory network. Owing to its role in diseases, various techniques have been used to determine TF binding specificity in vitro and in vivo, including chromatin immuno-precipitation followed by massively parallel sequencing (ChIP-seq). ChIP-seq is an in vivo technique that considers how the chromatin landscape affects TF binding. Motif enrichment analysis (MEA) tools are used to identify motifs that are over-represented in ChIP-seq peak regions. One such tool, CentriMo, finds over-represented motifs at the center since peak calling software are biased to declaring binding regions centered at the TF binding site. In this study, we investigate the use of CentriMo and other MEA tools to determine the difference in motif enrichment attributed presence of Chronic Myeloid leukemia (CML)), treatment with Interferon (IFN) and Dexamethasone (DEX) compared to control based on Fisher’s exact test; using uniform peaks ChIP-seq data generated by the ENCODE consortium. CentriMo proved to be capable. We observed differential motif enrichment of TFs with tumor promoter activity: YY1, CEBPA, Egr1, Cmyc family, Gata1 and JunD in K562 while Stat1, Irf1, and Runx1 in Gm12878. Enrichment of CTCF in Gm12878 with YY1 as the immuno-precipitated (ChIP-ed) factor and the presence of significant spacing (SpaMo analysis) of CTCF and YY1 in Gm12878 but not in K562 could show that CTCF, as a repressor, helps in maintaining the required YY1 level in a normal cell line. IFN might reduce Cmyc and the Jun family of TFs binding via the repressive action of CTCF and E2f2. We also show that the concentration of DEX treatment affects motif enrichment with 50nm being an optimum concentration for Gr binding by maintaining open chromatin via AP1 TF. This study has demonstrated the usefulness of CentriMo for TF binding specificity analysis.
- Full Text:
- Date Issued: 2014
The demography, spatial ecology and reproductive success of the black rhinoceros, Diceros bicornis, in Hluhluwe-iMfolozi Park, Kwazulu-Natal, South Africa
- Authors: Nhleko, Zoliswa Nombulelo
- Date: 2014
- Subjects: Hluhluwe-iMfolozi Park (South Africa) , Black rhinoceros -- South Africa -- Hluhluwe , Animal populations -- South Africa -- Hluhluwe , Spatial ecology -- South Africa -- Hluhluwe , Black rhinoceros -- Reproduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5849 , http://hdl.handle.net/10962/d1011825 , Hluhluwe-iMfolozi Park (South Africa) , Black rhinoceros -- South Africa -- Hluhluwe , Animal populations -- South Africa -- Hluhluwe , Spatial ecology -- South Africa -- Hluhluwe , Black rhinoceros -- Reproduction
- Description: Black rhinoceroses (Diceros bicornis) are endangered; there are only ~5000 individuals remaining worldwide. Consequently, black rhinos are managed as a metapopulation in southern Africa. This means that even though several sub-populations of black rhinos are geographically separated, they are managed as a single population. This is achieved by interchanging genetic material between the sub-populations. The main aim of the metapopulation management approach is to increase black rhino numbers in the sub-region. The Rhino Management Group (RMG), formed in 1989, was tasked with setting scientifically defensible demographic targets for the remaining black rhino sub-populations in southern Africa. In the same year, the RMG set fecundity rate at 25% and stated that each black rhino sub-population should achieve a minimum growth rate of 5% per year. The black rhino population in the Hluhluwe-iMfolozi Park (HiP), KwaZulu-Natal, South Africa, is of international importance as it has historically been a significant donor population for the translocation of black rhinos to establish new subpopulations elsewhere in the sub-region. However, the black rhino population at HiP is performing poorly in terms of reproductive success. My study was initiated to assess the reproductive life-histories of the black rhino population at HiP and to determine whether the population was meeting the demographic targets set by the RMG. I also wished to assess the use of space by black rhinos in HiP as a potential explanation for the observed reproductive output. Detailed life-history information for known black rhinos (n = 120) was used to investigate reproductive success between 1998 and 2012. The mean age at sexual maturity (ASM) was determined as 12 years, which is higher than the ASM found in black rhino populations that are considered to be performing poorly (ASM = ~ 7 years). The intercalving interval (ICI) was three years, nine months; this was also longer than the ICI of most black rhino populations. Further, the 2012 black rhino population at HiP had a growth rate of 6.4%, and the population comprised 60% adults, 23% sub-adults and 13% juveniles. Such demographics are usually observed in stable populations and it is possible that poor habitat quality could be resulting in the delayed ASM and longer ICI’s at HiP. In addition, 5% of the population is removed annually as part of the Black Rhino Range Expansion Program (BRREP) to establish new sub-populations. This could also be negatively influencing the reproductive performance of the HiP population. To determine the home range and habitat use of black rhinos at HiP, field data from 13 individual adult black rhinos (n = 9 females and 4 males) over a two-year period (2011-2012) were analyzed. Black rhino female home ranges were slightly smaller (15.4 ± 12.9 km²) than the home ranges of males (23.3 ±14.0 km²) and both sexes utilized similar habitats in the centre of the park. In addition, both the male and female black rhinos were found closer to rivers and drainage lines than expected. However, the assessment of black rhino space use in HiP was limited by a small sample size, making inferences of the impact of space use on reproductive success difficult. Nevertheless, my study suggests that food availability likely influences the location and sizes of black rhino home ranges at HiP. I believe that my study forms the first step in understanding the factors that influence the reproductive success and habitat use patterns of the current black rhino population at HiP. The information produced by my study should enable park management to identify future research to be conducted at HiP, which will yield more robust data for making informed black rhino management decisions at HiP and elsewhere.
- Full Text:
- Date Issued: 2014
Bluetooth audio and video streaming on the J2ME platform
- Authors: Sahd, Curtis Lee
- Date: 2011 , 2010-09-09
- Subjects: Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4633 , http://hdl.handle.net/10962/d1006521 , Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Description: With the increase in bandwidth, more widespread distribution of media, and increased capability of mobile devices, multimedia streaming has not only become feasible, but more economical in terms of space occupied by the media file and the costs involved in attaining it. Although much attention has been paid to peer to peer media streaming over the Internet using HTTP and RTSP, little research has focussed on the use of the Bluetooth protocol for streaming audio and video between mobile devices. This project investigates the feasibility of Bluetooth as a protocol for audio and video streaming between mobile phones using the J2ME platform, through the analysis of Bluetooth protocols, media formats, optimum packet sizes, and the effects of distance on transfer speed. A comparison was made between RFCOMM and L2CAP to determine which protocol could support the fastest transfer speed between two mobile devices. The L2CAP protocol proved to be the most suitable, providing average transfer rates of 136.17 KBps. Using this protocol a second experiment was undertaken to determine the most suitable media format for streaming in terms of: file size, bandwidth usage, quality, and ease of implementation. Out of the eight media formats investigated, the MP3 format provided the smallest file size, smallest bandwidth usage, best quality and highest ease of implementation. Another experiment was conducted to determine the optimum packet size for transfer between devices. A tradeoff was found between packet size and the quality of the sound file, with highest transfer rates being recorded with the MTU size of 668 bytes (136.58 KBps). The class of Bluetooth transmitter typically used in mobile devices (class 2) is considered a weak signal and is adversely affected by distance. As such, the final investigation that was undertaken was aimed at determining the effects of distance on audio streaming and playback. As can be expected, when devices were situated close to each other, the transfer speeds obtained were higher than when devices were far apart. Readings were taken at varying distances (1-15 metres), with erratic transfer speeds observed from 7 metres onwards. This research showed that audio streaming on the J2ME platform is feasible, however using the currently available class of Bluetooth transmitter, video streaming is not feasible. Video files were only playable once the entire media file had been transferred.
- Full Text:
- Date Issued: 2011
Studies in South African marine molluscan chemistry
- Authors: Bromley, Candice Leigh
- Date: 2011
- Subjects: Mollusks -- South Africa , Marine invertebrates -- South Africa , Marine metabolites -- South Africa , Chemical oceanography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4356 , http://hdl.handle.net/10962/d1005021
- Description: This thesis investigates the variability occurring in the secondary metabolites produced by three South African marine molluscs. Chapter Two discusses the isolation and spectroscopic structure elucidation of the metabolites isolated from two Siphonaria species. The re-investigation of Siphonaria capensis yielded siphonarienfuranone (2.2) as the only common polypropionate isolated from both the 1998 and 2009 collections of S. capensis from the same areas suggesting possible seasonal or genetic variation in polypropionate production. The sterol cholest-7-en-3,5,7- triol (2.33) was also isolated form the 2009 collection of S. capensis and this is the first time this compound has been isolated from a Siphonaria species. The second species, Siphonaria oculus is closely related to S. capensis and the investigation into the former’s secondary metaboliteproduction revealed 2.2 as a major metabolite suggesting an inter-species overlap in polypropionate production. Three new polypropionate metabolites, 2.35, 2.36 and 2.37 were also isolated from S. oculus. An unsuccessful attempt was made to establish the absolute configuration of 2.37 using the modified Mosher’s method and the limited amount of 2.37 available prevented any further attempts at resolving the absolute configuration of this compound. The 1H NMR analysis of the defensive mucus collected directly from S. oculus revealed the presence of the acyclic polypropionate 2.37 as a minor metabolite. The absence of characteristic signals for the furanone containing compounds 2.2, 2.35 and 2.36, might suggest that these compounds cyclise from a hypothetical acyclic precursor (2.38) during standard work up of bulk acetone extracts of Siphonaria species. Chapter Three discusses the re-isolation and spectroscopic structure elucidation of the metabolites isolated from the nudibranch, Leminda millecra. Three known natural products, millecrone A (3.1), 8-hydroxycalamenene (3.6) and cubebenone (3.8) were re-isolated from our 2010 collection of L. millecra, as well as the new minor metabolite 8-acetoxycalamenene (3.16). The cytotoxic prenylated toluquinones and toluhydroquinones (3.9-3.15) initially isolated from the 1998 collection of L. millecra were not found in the 2010 collection supporting the hypothesis that these compounds may be of fungal origin. L. millecra clearly shows variability in the compounds sequestered by this species with millecrone A (3.1) being the only common metabolite in the three investigations of L. millecra to date. An unsuccessful attempt was made to establish the absolute configuration of 3.1, 3.6 and 3.8 through initial LAH reduction of the ketone moiety contained in 3.1 and 3.8 and esterification of the resultant diastereomeric alcohol mixtures and the phenol functionality in 3.6 with (1S)-camphanic chloride. Crystallisation of the (S)- camphanate esters of 3.6 and 3.8 for X-ray analysis were unsuccessful, while the unexpected conjugate addition of a hydride in 3.1 resulted in complex diastereomeric mixtures which could not be separated by HPLC.
- Full Text:
- Date Issued: 2011
The impact of angling on smallmouth and largemouth yellowfish, labeobarbus aeneus and labeobarbus kimberleyensis, in Lake Gariep, South Africa
- Authors: Ellender, Bruce Robert
- Date: 2009
- Subjects: Barbus aeneus , Largemouth bass , Labeobarbus , Fishing -- South Africa -- Gariep Dam
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5289 , http://hdl.handle.net/10962/d1005133 , Barbus aeneus , Largemouth bass , Labeobarbus , Fishing -- South Africa -- Gariep Dam
- Description: A large sportfishery that targets both smallmouth (Labeobarbus aeneus) and largemouth (Labeobarbus kimberleyensis) yellowfish exists in South Africa. Both species have high conservation priority, and no assessments documenting the effect of angling on L. aeneus and L. kimberleyensis have been undertaken. The overall aim of this study was to provide an assessment of the impact of angling on L. aeneus and L. kimberleyensis. The specific objectives of this study were to characterise the sectors utilising Lake Gariep, document catch, effort and total catch for the fishery as well as the locality specific biology of L. aeneus and L. kimberleyensis. The study was undertaken on Lake Gariep, South Africa's largest impoundment, situated on the Orange River system in central South Africa. Subsistence fishers were the dominant user group, constituting 60 % of the fishery, the remainder constituted recreational anglers. Angler catches were dominated by carp (Cyprinus carpio; 74 %), followed by mudfish (Labeo capensis; 13 %) and smallmouth yellowfish (8 %). Catches of largemouth yellowfish contributed < 0.5 % to the total catch. The relative abundance of species by weight differed by area (χ² test of independence: χ² = 182, df = 4, p ≤ 0.05). On any sampling day time fished was the best predictor for differences in probability of capture (PC) (Wald X²(1) = 7.169, p = 0.007). The probability of capturing L. aeneus differed significantly between month (Wald X²(5) = 20.690, p = 0.000) and region (Wald X²(3) = 46.755, p = 0.000). The single best predictor of differences in log abundance and non-zero CPUE was region (Factorial ANOVA p ≤ 0.05). Mean CPUE ranged from 0.21 ± 0.06 kg. man⁻¹.hr⁻¹ to 0.82 ± 0.11 kg. man⁻¹.hr⁻¹ in the OV region and 0.42 ± 0.10 kg. man⁻¹.hr⁻¹ to 1.17 ± 0.24 kg. man⁻¹.hr⁻¹ in the GD region. Angler effort was higher in OV than in GD and ranged from 17 ± 3 anglers/day to 45 ± 9 anglers/day and 6 ± 1 anglers/day to 41 ± 8 anglers/day, respectively. Total catch was higher in the GD 46.0 [95 % CI = 15:102.6] t. period⁻¹ than the OV region 40.0 [95 % CI = 13.9:89.6] t. period⁻¹. The total catch from the Lake Gariep fishery between March and December 2007 was estimated to be 86.0 [95 % CI = 40.4:154.8] t. period⁻¹. Age and growth was determined using whole otoliths. The growth of L. aeneus was best described by the von Bertalanffy growth model as Lt = 481.80 (1- e⁻°·²²⁽t⁺°·⁶¹⁾). Gonadal development for L. aeneus was seasonal, with the gonadosomatic index peaking in January, revealing a distinct spawning season. The length at 50 % maturity for female L. aeneus was attained at a fork length of 354.7 mm. Natural mortality (M) was estimated at 0.55 year⁻¹. The growth of L. kimberleyensis was described by the von Bertalanffy growth model as Lt = 763.22 (1- e⁻°·¹¹⁽t⁺°·⁶³⁾). Only 6 mature female and 15 mature male L. kimberleyensis were recorded during the study period. The smallest mature female was a 390 mm FL stage four female and the earliest recorded mature male was a 337 mm FL, ripe running male. Natural mortality (M) was estimated at 0.08 year⁻¹ for L. kimberleyensis. Per recruit analysis indicated that current fishing mortality reduces the L. aeneus spawner biomass by 7 %, which is considered negligible. Labeobarbus kimberleyensis forms an insignificant proportion of anglers catches and stock status is currently considered pristine.
- Full Text:
- Date Issued: 2009
An exploratory study of the experiences of black teenage mothers
- Authors: Mpetshwa, Nomonde
- Date: 2001 , 2012-06-20
- Subjects: Teenage pregnancy , Teenage pregnancy -- South Africa -- Eastern Cape , Black teenage mothers -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:704 , http://hdl.handle.net/10962/d1006470 , Teenage pregnancy , Teenage pregnancy -- South Africa -- Eastern Cape , Black teenage mothers -- South Africa -- Eastern Cape
- Description: An exploratory descriptive design was used to explore the experiences of a sample of black teenage mothers of Libode, Ngqeleni and Port St Johns. A St Barnabas Hospital birth record register was used to select seven Xhosa speaking black teenage mothers, with children under a year old who have kept their children and are staying with their extended families. Qualitative interview was used to collect data from the abovementioned respondents. The data one want to use may not feasibly be available in any other form, so that asking people for their accounts, talking and listening to them, may be the only way to get at what you are interested in (Mason 1998:39). Qualitative interview was therefore used to collect data from the abovementioned respondents. Qualitative interview according to Mason (1998:38) involve one to one interaction as in this study, or a larger group, and it carries more advantages in data collection compared to other research tools. Some interesting information, which drew the researcher's attention, was gathered. Information such as the reaction by family members, community and its structures, and peers including teenage fathers, made the research more challenging. The anger showed by brothers of one of respondents raised the researcher's curiosity. Another interesting piece of information that was gathered was the negative reaction by the church. The researcher had no idea that the church can negatively involve itself in community affairs, but one of the respondents reported to have been encouraged by one of the church members to go on with her studies despite her pregnancy. The same applied to some schools, where pregnant teenagers were not allowed to continue schooling, while in other schools the same situation was allowed. The major findings were that, respondents have forfeited some of their favorite hobbies such as extra mural school activities, teenage activities and their lives have been negatively affected by their teenage motherhood in areas such as education, family relations, peer relations including their boyfriends and community. Again lack of support by people close to these young mothers including different professionals has also been identified. It has also transpired during this study that, teenagers can indeed be good mothers, but socioeconomic stress and lack of social support often prevent them from giving their babies a reasonable start in life. Amongst the recommendations made undertaking a bigger study has been suggested
- Full Text:
- Date Issued: 2001
The influence of a methylated-β-Cyclodextrin on the solubility and photostability of midazolam in aqueous solution
- Authors: Lebete, Mosimotsana Leah
- Date: 2001 , 2013-04-26
- Subjects: Midazolam -- Solubility
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3823 , http://hdl.handle.net/10962/d1005923 , Midazolam -- Solubility
- Description: Midazolam, used clinically as an anticonvulsant, anxiolytic, muscle relaxant and sedative is a photolabile imidazo-benzodiazepine which is marketed under the trade names Dormicum® and Hypnovel® as tablets and injectables. Because of an aqueous solubility of < 0.1 mg/ml above pH 4, the preparation of aqueous dosage formulations near physiological pH, requires a solubilizer. The aim of this study was thus to prepare a 10 mg/ml midazolam aqueous solution for topical application using randomly-methylated-pcyclodextrin (RAMEB), considered to be a suitable candidate as a solubilizer because of its absorption enhancing properties, and to investigate its effect on both the solubility and the photostability of midazolam. Solubility studies of midazolam (excess of 15 mg/ml) in the presence of 0, 5,10,20, 30% m/v of RAMEB at pH 5.0 and pH 5.8 (phosphate buffer) were undertaken and the results analyzed using a UV method validated for linearity, accuracy, precision and specificity. A stability-indicating HPLC method was developed and validated (precision and accuracy, linearity, range, limit of quantitation, specificity, robustness and ruggedness) for application to kinetic photostability studies and the identification of photodegradants by LC-MS. Forced degradation studies were carried out at concentrations of 0.5 mg/ml of midazolam instead of the target concentration of 10 mg/ml because of the acceleratory effect of the decreased concentration on the rate of photodegradation. The solutions of midazolam with and without RAMEB were irradiated at 550 W/m² for 12 hrs in order to degrade the drug to ± 10% of the original concentration. The UV method proved to be valid in terms of linearity with a correlation coefficient of 0.9998, precise and accurate, and specific for the determination of midazolam in the presence of RAMEB. The results of the phase solubility studies indicated that desired solubility of 10 mg/ml was achieved with 30% m/v RAMEB at pH 5.0. RAMEB slightly decreased the photostability of midazolam, the rate constants being 0.137 and 0.154 hr⁻¹ in the absence and presence of RAMEB, respectively. LC-MS analysis revealed that one of the major photoproducts in the presence and absence of RAMEB was N-desalkylflurazepam, a starting material in the synthesis of midazolam. RAMEB inhibited formation of some photoproducts and introduced two new photoproducts, a dimer and an addition product. The difference in the nature of these photoproducts formed may be attributed to the ability of RAMEB to provide conformational control and to stabilize free radicals. Although RAMEB improved the solubility of midazolam to the target concentration, photostability is decreased with the presence of different photoproducts. These studies have however provided information on the overall photostability of midazolam, the identity of its photodegradants and the photodegradation pathway in the presence and absence of RAMEB, and may be used for further method development and validation for the analysis of aqueous dosage forms containing RAMEB as a solubilizer. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2001
Virtual sculpting : an investigation of directly manipulated free-form deformation in a virtual environment
- Authors: Gain, James Edward
- Date: 1996
- Subjects: Computer simulation , Computer graphics , Virtual reality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4660 , http://hdl.handle.net/10962/d1006661 , Computer simulation , Computer graphics , Virtual reality
- Description: This thesis presents a Virtual Sculpting system, which addresses the problem of Free-Form Solid Modelling. The disparate elements of a Polygon-Mesh representation, a Directly Manipulated Free-Form Deformation sculpting tool, and a Virtual Environment are drawn into a cohesive whole under the mantle of a clay-sculpting metaphor. This enables a user to mould and manipulate a synthetic solid interactively as if it were composed of malleable clay. The focus of this study is on the interactivity, intuitivity and versatility of such a system. To this end, a range of improvements is investigated which significantly enhances the efficiency and correctness of Directly Manipulated Free-Form Deformation, both separately and as a seamless component of the Virtual Sculpting system.
- Full Text:
- Date Issued: 1996
The geology of the Welkom Goldfield with special reference to the "A", "B" and Beatrix Reefs
- Authors: Dwyer, Gordon Bransby
- Date: 1993
- Subjects: Gold mines and mining -- South Africa -- Free State , Gold ores -- Geology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4963 , http://hdl.handle.net/10962/d1005575 , Gold mines and mining -- South Africa -- Free State , Gold ores -- Geology -- South Africa
- Description: The first Witwatersrand gold deposits in the Orange Free State were discovered under younger cover rocks in the 1930's with the aid of drilling and geophysics. The Welkom gold deposits are found in the sedimentary rock sequences of the Central Rand Group, which represent unconformity bounded genetic packages. The structural configuration of the goldfield is one of a north to south trending synform that is split near it's axis by the De Bron and Homestead faults. The "B" Reef is a highly variable, erratically mineralised reef that lies on an unconformity at the base of the Spes Bona Formation. The "A" Reef Zone consists of several placers 1 including the "Reworked BPM" 1 the Witpan, the Uitsig, the Hanging Wall Grits and the Upper "A" Reef. The Beatrix Reef lies at the base of the Eldorado Formation on an unconformity surface overlying the Virginia Formation in the southern part of the Welkom Goldfield. The origin of gold in the Witwatersrand basin can be classified into the modified placer theory, the syngenetic theory and the epigenetic theory. From the distribution of basin edge unconformities it can be deduced that the Welkom fan depository was tectonically active on the western, southern and eastern margins during sedimentation. Palaeocurrent studies indicate that sediment was transported predominantly from the south and west. It is thought that the "B", "A" and Beatrix Reefs were all deposited in a braided stream environment. A multidisciplinary approach to ore evaluation of Witwatersrand deposits is considered to be the best method, where sedimentology, geostatistics and structural geology are used.
- Full Text:
- Date Issued: 1993
The stock identification of the Cape horse mackerel, Trachurus trachurus capensis (Pisces: Carangidae)
- Authors: Naish, Kerry-Ann
- Date: 1990
- Subjects: Carangidae -- Identification , Trachurus trachurus -- Identification , Carangidae -- South Africa , Trachurus trachurus -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5320 , http://hdl.handle.net/10962/d1005165 , Carangidae -- Identification , Trachurus trachurus -- Identification , Carangidae -- South Africa , Trachurus trachurus -- South Africa
- Description: Three stocks of the Cape horse mackerel, Trachurus trachurus capensis, have been recognised in the ICSEAF convention region off southern Africa (Figure 1) on the basis of catch distribution and biological analyses. They were identified as being off Namibia (ICSEAF Divisions 1 . 3 and 1.4), off the West Coast of South Africa (Div. 1.6) and off the South Coast (Div. 2.1 and 2.2). Recently, speculation as to the accuracy of the classification of the South African populations has arisen. The aim of this study was to determine the number of stocks In Divisions 1.6, 2.1 and 2.2, using methodology which assessed the spatial and temporal nature and the phenotypic and genotypic characteristics of the species. The distribution of horse mackerel was evaluated by studying the trends in catch data and length frequency distributions obtained from the demersal industry during 1986 to 1988 and from the demersal biomass cruises in 1987 and 1988. Adult fish, found in Div. 2.1 and 2.2, probably migrated; during the months in which horse mackerel were expected to spawn, CPUE values were higher over the central Agulhas Bank than in the east of the study region. During the quiescent period, catches and numbers were higher in the latter region. Juvenile horse mackerel were found in the nursery areas utilised by pelagic fish and it is likely that they were transported northward from the Agulhas Bank. A decrease in biomass of individuals in Div. 1.5 indicated a separation between a northern and a southern population. Analyses of the phenotype, or epigenetic characters, of horse mackerel were used as a further test of stock integrity. Monthly samples were drawn from Div. 1.6, 2.1 and 2.2 during May 1988 to June, 1989. Comparisons for the values obtained from growth, length-at-50%-maturity and the season of otolith ring formation from each region showed no significant variation in the phenotype. Morphometric analysis proved inconclusive. Monthly gonadosomatic indices show that fish south of the Orange River share the same spawning season. Reports from the literature show that horse mackerel in the latter region differ from those of northern Namibia in spawning season, age-at-50%-maturity and season of otolith ring formation. The genetic structure of the populations of horse mackerel was evaluated by means of a restriction enzyme analysis of the Mitochondrial DNA of 37 fish collected from Divisions 1.4, 1.5, 1.6, 2.1 and 2.2. Two composite genotypes of horse mackerel were found; one belonging to fish in Div. 1.4 and one to fish in Div. 1.6, 2.1 and 2.2. The genetic distance between the two genotypes, 0.07, was the expected distance between two populations at a subspecies level. Fish in Div. 1.5 consisted of both genotypes and may be a region of mixing between the two populations. The interpretation of results was cautioned; prevlous work has shown that the migration of a small number of individuals between two stocks can be expected to maintain a low variation between the populations. In concluding, it was recommended that the horse mackerel be managed as two stocks, one in Div. 1.3 and 1.4 and one in Div. 1.6, 2.1 and 2.2
- Full Text:
- Date Issued: 1990
The nature of a self
- Authors: Le Chat, Gavin John
- Date: 1978 , 2013-10-17
- Subjects: Self , Identity (Philosophical concept) , Dualism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2737 , http://hdl.handle.net/10962/d1006916 , Self , Identity (Philosophical concept) , Dualism
- Description: The purpose of this thesis is to demonstrate just what kind of entity a self or person is (p. 1). , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
A 22 GHz radio telescope
- Authors: Mutch, Laurence Ian
- Date: 1976
- Subjects: Radio telescopes , Paraboloid , Radio astronomy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5532 , http://hdl.handle.net/10962/d1012919
- Description: This thesis reports on the design, construction, testing and operation of the spectral line and continuum receivers built for the 22 GHz Radio Telescope. First results from 'the telescope were obtained and have been analysed to give an estimate of system efficiency. Tests have been performed on the front end and in particular on the 22 GHz mixer in order to determine the minimum detectable temperature. The Sun, Moon and major planets are sources suitable for antenna alignment and consequently a literature survey of emission at 22 GHz from elements of the Solar system has been made.
- Full Text:
- Date Issued: 1976