Effect of grazing systems on growth performance, carcass characteristic, meat quality of beef cattle and economic performance of the enterprise
- Authors: Dayimani, Siyavuya
- Date: 2019
- Subjects: Grazing -- Environmental aspects Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17294 , vital:40873
- Description: Under conditions of adaptive Holistic Management™, we tested whether rotational grazing approaches such as holistic planned grazing (HPG) and four-camp grazing (FCG) influence growth, carcass and meat quality attributes of beef steers compared to continuous, seasonlong (SLG) grazing. Thirty steers (250 ±19.56 kg, 16-17-month-old) were randomly assigned to SLG, HPG and FCG systems (10 steers/ treatment) at a private farm in Cedarville, Eastern Cape Province, South Africa where grazing was managed using an adaptive approach involving inter alia planned grazing charts, seasonal movement of cattle, and supplemental feeding. The steers were slaughtered at 40-41 months for carcass measurements and longissimus et lumborum was sampled for meat quality analyses. All the grazing systems had comparable live weights and average daily gain. All the investigated carcass attributes were also similar across grazing treatments (P > 0.05). Meat from steers on the SLG system had higher (P<0.05) drip loss, protein and fat contents and lower (P <0.05) shear force, moisture and ash contents than the two rotational grazing approaches (HPG and FCG). The HPG had higher (P < 0.05) total running and capital costs compared to SLG and FCG grazing systems. The SLG system had greater (P ≤ 0.05) gross and net income compared to FCG and HPG systems, respectively. Overall, all the grazing systems had comparable growth performance, carcass characteristics and meat quality but rotational grazing systems had lower gross income relative to the SLG grazing system.
- Full Text:
- Authors: Dayimani, Siyavuya
- Date: 2019
- Subjects: Grazing -- Environmental aspects Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17294 , vital:40873
- Description: Under conditions of adaptive Holistic Management™, we tested whether rotational grazing approaches such as holistic planned grazing (HPG) and four-camp grazing (FCG) influence growth, carcass and meat quality attributes of beef steers compared to continuous, seasonlong (SLG) grazing. Thirty steers (250 ±19.56 kg, 16-17-month-old) were randomly assigned to SLG, HPG and FCG systems (10 steers/ treatment) at a private farm in Cedarville, Eastern Cape Province, South Africa where grazing was managed using an adaptive approach involving inter alia planned grazing charts, seasonal movement of cattle, and supplemental feeding. The steers were slaughtered at 40-41 months for carcass measurements and longissimus et lumborum was sampled for meat quality analyses. All the grazing systems had comparable live weights and average daily gain. All the investigated carcass attributes were also similar across grazing treatments (P > 0.05). Meat from steers on the SLG system had higher (P<0.05) drip loss, protein and fat contents and lower (P <0.05) shear force, moisture and ash contents than the two rotational grazing approaches (HPG and FCG). The HPG had higher (P < 0.05) total running and capital costs compared to SLG and FCG grazing systems. The SLG system had greater (P ≤ 0.05) gross and net income compared to FCG and HPG systems, respectively. Overall, all the grazing systems had comparable growth performance, carcass characteristics and meat quality but rotational grazing systems had lower gross income relative to the SLG grazing system.
- Full Text:
Students’ perceived experiences of a flipped classroom at a traditional South African university in comparison to the traditional classroom
- Authors: Cilliers, Liezel
- Date: 2019
- Subjects: Teaching -- trends Flipped classrooms
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10353/15881 , vital:40545
- Description: The purpose of this study was to explore students’ perceived experiences of flipped classrooms at a traditional South African university in comparison to the traditional classroom. Universities across the world are confronted with a variety of problems. One of these challenges include the massification of higher education as more students now have access to universities resulting in larger class sizes and lower through put rates. Universities have traditionally made use of the face-to-face model of lectures and tutorials as a passive mode of course instruction and delivery. However, due to the massification of higher education, it has become very difficult for lecturers to communicate and collaborate with students. One of the ways that lecturers have attempted to overcome the problem of massification is to make use of technology to increase the delivery of course content. When lectures are made available online while the traditional class time is used to build conceptual understanding and cognitive skills among students, the approach is known as ‘flipping’ the classroom. Several studies have shown that this type of active classroom approach can perform better than traditional lectures when learning outcomes are compared. There is also a very limited body of knowledge available regarding students’ perceived experiences of flipped classrooms at traditional South African universities. The theoretical frameworks guiding this study are the Activity Theory and Constructivism, whilst a pragmatic paradigm was employed. The flipped classroom was used in one course of the Management and Commerce Faculty at a traditional university in South Africa. The study was divided into three cycles: The first cycle involved 4 weeks of traditional lectures, the second cycle of 4 weeks introduced blended learning into the course, while the third cycle of 4 weeks changed the content delivery method to a flipped classroom. At the end of each cycle a formal evaluation through focus groups interviews (with 10 students per cycle) and a questionnaire (that was administered to the class) was conducted to inform the next cycle. Throughout the research process, the researcher also kept detailed field notes to as an account of the planning, execution and reflection for each class. The researcher also observed the behavior of the students during the various research cycles to provide a ‘snapshot’ of the classes. The results of the study suggest that students prefer the use of the flipped classroom is it enables them to communicate with their peers and the lecturer, and providing them with opportunities to better understand learning content through discussions and reasoning, rather than the means of receiving information. Barriers that were identified included difficulty with learning strategies and technical assistance when students needed assistance. However, students were positive about both the use of the flipped classroom as opposed to the use of the traditional classroom.
- Full Text:
- Authors: Cilliers, Liezel
- Date: 2019
- Subjects: Teaching -- trends Flipped classrooms
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10353/15881 , vital:40545
- Description: The purpose of this study was to explore students’ perceived experiences of flipped classrooms at a traditional South African university in comparison to the traditional classroom. Universities across the world are confronted with a variety of problems. One of these challenges include the massification of higher education as more students now have access to universities resulting in larger class sizes and lower through put rates. Universities have traditionally made use of the face-to-face model of lectures and tutorials as a passive mode of course instruction and delivery. However, due to the massification of higher education, it has become very difficult for lecturers to communicate and collaborate with students. One of the ways that lecturers have attempted to overcome the problem of massification is to make use of technology to increase the delivery of course content. When lectures are made available online while the traditional class time is used to build conceptual understanding and cognitive skills among students, the approach is known as ‘flipping’ the classroom. Several studies have shown that this type of active classroom approach can perform better than traditional lectures when learning outcomes are compared. There is also a very limited body of knowledge available regarding students’ perceived experiences of flipped classrooms at traditional South African universities. The theoretical frameworks guiding this study are the Activity Theory and Constructivism, whilst a pragmatic paradigm was employed. The flipped classroom was used in one course of the Management and Commerce Faculty at a traditional university in South Africa. The study was divided into three cycles: The first cycle involved 4 weeks of traditional lectures, the second cycle of 4 weeks introduced blended learning into the course, while the third cycle of 4 weeks changed the content delivery method to a flipped classroom. At the end of each cycle a formal evaluation through focus groups interviews (with 10 students per cycle) and a questionnaire (that was administered to the class) was conducted to inform the next cycle. Throughout the research process, the researcher also kept detailed field notes to as an account of the planning, execution and reflection for each class. The researcher also observed the behavior of the students during the various research cycles to provide a ‘snapshot’ of the classes. The results of the study suggest that students prefer the use of the flipped classroom is it enables them to communicate with their peers and the lecturer, and providing them with opportunities to better understand learning content through discussions and reasoning, rather than the means of receiving information. Barriers that were identified included difficulty with learning strategies and technical assistance when students needed assistance. However, students were positive about both the use of the flipped classroom as opposed to the use of the traditional classroom.
- Full Text:
The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla under farm conditions
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
Synthesis, characterization and photophysical studies of RU(II)bipyridyl-dithiocarbamate complexes as sensitizers for dye sensitized solar cells
- Authors: Fudo, Zintle
- Date: 2018
- Subjects: Dye-sensitized solar cells Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6168 , vital:29498
- Description: The depletion of fossil fuels and the increasing energy demand for energy has led to the search for better and improved technologies with special focus renewable energy, especially solar cells. The first generation solar cells based on silicon are expensive, hence dye sensitized solar cells come in as a better alternative as these solar cells are environmental friendly, they have moderately good conversion efficiency and they are relatively cheap to produce. Dithiocarbamate ligands have been widely used in many research fields, as these are versatile ligands. Coordination of dithiocarbamates with metals such as ruthenium has produced high conversion efficiency and have the ability to extend the MLCT absorptions, and this can further extend their wavelength. In this study five dithiocarbamate sodium salt ligands were prepared and were coded as FL1= Aniline, FL2= p- toluidine, FL3= p- anisidine, FL4=dibenzyl, FL5=diphenyl. These ligands were used to synthesize Ru(II) metal complexes which were formulated as [Ru(FLx)(dcbpy)(NCS)] and [Ru(FLx)2(dcbpy)] where FLx is the dithiocarbamate ligand and dcbpy is 2,2-bipyridine-4,4’-dicarboxylic acid and the complexes were coded as FCx. The synthesized compounds were characterized using techniques such as the melting point, molar conductivity, FT-IR and NMR spectroscopy. For spectroelectrochemical studies of the metal complexes, techniques such as UV-Vis and photoluminescence spectroscopy were carried out. Furthermore, redox properties of the complexes were analyzed using cyclic and square wave voltammetry. The FT-IR displayed all the expected peaks of interest both in the dithiocarbamate ligands and in the metal complexes. The electronic spectra confirmed the successful coordination of ligand to the metal centre, the electronic spectra of the complexes also confirmed the six coordinate octahedral geometry of the complexes. The complexes exhibited some photoluminescence properties that are suitable for dye sensitization. The cyclic voltammogram of the complexes displayed more reduction potentials that could be attributed to the π-conjugation in the ligands incorporated during synthesis. The square wave voltammogram of the complexes is in agreement with the results obtained in cyclic voltammetry.
- Full Text:
- Authors: Fudo, Zintle
- Date: 2018
- Subjects: Dye-sensitized solar cells Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6168 , vital:29498
- Description: The depletion of fossil fuels and the increasing energy demand for energy has led to the search for better and improved technologies with special focus renewable energy, especially solar cells. The first generation solar cells based on silicon are expensive, hence dye sensitized solar cells come in as a better alternative as these solar cells are environmental friendly, they have moderately good conversion efficiency and they are relatively cheap to produce. Dithiocarbamate ligands have been widely used in many research fields, as these are versatile ligands. Coordination of dithiocarbamates with metals such as ruthenium has produced high conversion efficiency and have the ability to extend the MLCT absorptions, and this can further extend their wavelength. In this study five dithiocarbamate sodium salt ligands were prepared and were coded as FL1= Aniline, FL2= p- toluidine, FL3= p- anisidine, FL4=dibenzyl, FL5=diphenyl. These ligands were used to synthesize Ru(II) metal complexes which were formulated as [Ru(FLx)(dcbpy)(NCS)] and [Ru(FLx)2(dcbpy)] where FLx is the dithiocarbamate ligand and dcbpy is 2,2-bipyridine-4,4’-dicarboxylic acid and the complexes were coded as FCx. The synthesized compounds were characterized using techniques such as the melting point, molar conductivity, FT-IR and NMR spectroscopy. For spectroelectrochemical studies of the metal complexes, techniques such as UV-Vis and photoluminescence spectroscopy were carried out. Furthermore, redox properties of the complexes were analyzed using cyclic and square wave voltammetry. The FT-IR displayed all the expected peaks of interest both in the dithiocarbamate ligands and in the metal complexes. The electronic spectra confirmed the successful coordination of ligand to the metal centre, the electronic spectra of the complexes also confirmed the six coordinate octahedral geometry of the complexes. The complexes exhibited some photoluminescence properties that are suitable for dye sensitization. The cyclic voltammogram of the complexes displayed more reduction potentials that could be attributed to the π-conjugation in the ligands incorporated during synthesis. The square wave voltammogram of the complexes is in agreement with the results obtained in cyclic voltammetry.
- Full Text:
An investigation of the contribution of street vending on livelihoods : case of street vendors in Nkonkobe Municipality
- Authors: Dube, Thulani
- Date: 2017
- Subjects: Street vendors -- South Africa -- Eastern Cape Street vendors -- South Africa -- Eastern Cape -- Economic conditions Vending stands -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/6068 , vital:29488
- Description: The informal sector thrives in a context of high unemployment, underemployment, poverty, gender inequality and precarious work. It plays a significant role in such circumstances, especially in income generation and in contributing to the livelihood of those engaged in it. The study investigated the contribution of street vending to the livelihood of street vendors in Nkonkobe Municipality. The aim of the study was to investigate whether street vending has the potential to sustain the lives of those engaged in it. In order to reach its objectives, the study employed a qualitative research approach whereby a non-probability sampling design in the form of a purposive sampling method was adopted and considered appropriate for this study. In terms of data collection, the study made use of structured questionnaires as a data collection method whereby questionnaires were administered and distributed to 40 street venders. The Upper Bound Poverty Line (UBPL) was used as a measurement to assess whether the participants’ incomes were above the poverty datum line in order to determine the sector’s contribution to the traders’ livelihood. From this study, it was found that street vending has both positive and negative impacts with regard to the success and profit-earning potential of these traders. Thus, the study concluded that street vending is a vital community development tool and a major source of livelihood as it plays a very important socio-economic role in Nkonkobe and in South Africa in general. The sector provides a livelihood for a huge population mainly comprised of the poor and other impoverished groups of society.
- Full Text:
- Authors: Dube, Thulani
- Date: 2017
- Subjects: Street vendors -- South Africa -- Eastern Cape Street vendors -- South Africa -- Eastern Cape -- Economic conditions Vending stands -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/6068 , vital:29488
- Description: The informal sector thrives in a context of high unemployment, underemployment, poverty, gender inequality and precarious work. It plays a significant role in such circumstances, especially in income generation and in contributing to the livelihood of those engaged in it. The study investigated the contribution of street vending to the livelihood of street vendors in Nkonkobe Municipality. The aim of the study was to investigate whether street vending has the potential to sustain the lives of those engaged in it. In order to reach its objectives, the study employed a qualitative research approach whereby a non-probability sampling design in the form of a purposive sampling method was adopted and considered appropriate for this study. In terms of data collection, the study made use of structured questionnaires as a data collection method whereby questionnaires were administered and distributed to 40 street venders. The Upper Bound Poverty Line (UBPL) was used as a measurement to assess whether the participants’ incomes were above the poverty datum line in order to determine the sector’s contribution to the traders’ livelihood. From this study, it was found that street vending has both positive and negative impacts with regard to the success and profit-earning potential of these traders. Thus, the study concluded that street vending is a vital community development tool and a major source of livelihood as it plays a very important socio-economic role in Nkonkobe and in South Africa in general. The sector provides a livelihood for a huge population mainly comprised of the poor and other impoverished groups of society.
- Full Text:
Differential regulation of wheat (Triticum aestivum) callose synthases during Russian wheat aphid (diuraphis noxia)infestation
- Authors: Ngwenya, Nompilo
- Date: 2017
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8100 , vital:31522
- Description: Plant production serves as the primary food source for all living beings and is continuously being affected by many biotic and abiotic factors. Wheat, one of the most consumed cereal crops in the world and the second most cultivated crop after maize in South Africa, is continuously being affected by Russian wheat aphid (RWA) since 1978. To counteract the effect of this aphid, the first resistant wheat cultivar was developed in 1984 in South Africa containing the Dn1 resistance gene. However, the mechanism of action of the resistance is still not fully understood to date. The feeding of the RWA on the wheat induces callose deposition especially in susceptible wheat cultivars, linking the β-1.3-polysaccharide (callose) to the resistance mechanism. Callose is synthesized by callose synthases, also known as glucan synthase-like genes (GSL). Not much is known about the mechanism of action of callose synthases or how they are regulated in response to the RWA. Bioinformatics tools, such as those available at NCBI, were used to identify the wheat callose synthases genes. The proteins encoded by the identified wheat callose synthases genes, were then analyzed for conserved domain motifs using the MEME suite and InterproScan, sequence similarities using ClustaL Omega and transmembrane domains using HMMTOP and ProtCamp. These were then compared with those of the already characterized Arabidopsis callose synthase proteins in an attempt to identify the wheat callose synthase(s) that responds to aphid feeding. Further bioinformatics studies were carried out to identify the presence of biotic stress associated cis-acting regulatory elements found in the 1.5 kbp upstream region of the start codon of the Arabidopsis callose synthase genes. Eight partial wheat callose synthase sequences were identified and two of these (TaGSL2 and TaGSL22) showed high similarities to the AtGSL5, which is up-regulated in response to aphid feeding in Arabidopsis. Six of the wheat callose synthase genes were mediated to code for the functional callose synthases proteins: TaGSL3, 8, 12, 19, 22 and 23, and analyzed for conserved protein motifs. Based on the sequence similarities and conserved protein domains, TaGSL2 and TaGSL22 were found to be the most similar to AtGSL5 and most likely to respond to RWA infestation. Cis-acting regulatory element analyses confirmed the possibility of TaGSL22 being responsible for callose deposition in wheat as biotic stress associated cis-acting regulatory elements, Box W1, TC- rich element and W- box were all found in the 1.5 kbp upstream of the TaGSL22 coding region. Callose was quantified in both susceptible and resistant wheat cultivars using the aniline blue fluorescence method. When infested with RWA-SA1, the susceptible wheat cultivar (Tugela) deposited significantly higher amounts of callose, compared to the resistant wheat cultivar (Tugela DN), which deposited little, to no callose with respect to the control samples. Transcription analysis, of the TaGSL2 and TaGSL22 in RWA-SA2 infested Tugela and Tugela DN wheat cultivars, was performed using real time polymerase chain reaction (qPCR). Both TaGSL2 and TaGSL22 genes were up-regulated in Tugela and Tugela DN wheat cultivars in response to RWA-SA2 infestation, with TaGSL22 being more expressed than TaGSL2 in both cultivars, indicating that RWA-SA2 is able to overcome the resistance of Tugela DN and cause callose deposition. However, significantly higher expression of both genes was still observed in the susceptible, Tugela wheat cultivar. This study therefore confirms that callose deposition is associated with RWA-SA1 feeding, only in the susceptible wheat cultivar, Tugela and not the resistant cultivar, Tugela DN. However, during RWA-SA2 feeding, two of the eight identified callose synthases in wheat, are up-regulated in response to RWA-SA2 feeding, in both the resistant and susceptible wheat cultivars with higher levels observed in the susceptible wheat cultivar when compared to the resistant wheat cultivar. TaGSL2 and TaGSL22 are therefore implicated in the callose deposition observed in the susceptible and resistant wheat cultivars, after RWA-SA2 infestation. Further studies are required to confirm the differential regulation of the two wheat callose synthases proteins during RWA infestation and their possible role in the resistance mechanism of the resistant wheat cultivar, Tugela DN.
- Full Text:
- Authors: Ngwenya, Nompilo
- Date: 2017
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8100 , vital:31522
- Description: Plant production serves as the primary food source for all living beings and is continuously being affected by many biotic and abiotic factors. Wheat, one of the most consumed cereal crops in the world and the second most cultivated crop after maize in South Africa, is continuously being affected by Russian wheat aphid (RWA) since 1978. To counteract the effect of this aphid, the first resistant wheat cultivar was developed in 1984 in South Africa containing the Dn1 resistance gene. However, the mechanism of action of the resistance is still not fully understood to date. The feeding of the RWA on the wheat induces callose deposition especially in susceptible wheat cultivars, linking the β-1.3-polysaccharide (callose) to the resistance mechanism. Callose is synthesized by callose synthases, also known as glucan synthase-like genes (GSL). Not much is known about the mechanism of action of callose synthases or how they are regulated in response to the RWA. Bioinformatics tools, such as those available at NCBI, were used to identify the wheat callose synthases genes. The proteins encoded by the identified wheat callose synthases genes, were then analyzed for conserved domain motifs using the MEME suite and InterproScan, sequence similarities using ClustaL Omega and transmembrane domains using HMMTOP and ProtCamp. These were then compared with those of the already characterized Arabidopsis callose synthase proteins in an attempt to identify the wheat callose synthase(s) that responds to aphid feeding. Further bioinformatics studies were carried out to identify the presence of biotic stress associated cis-acting regulatory elements found in the 1.5 kbp upstream region of the start codon of the Arabidopsis callose synthase genes. Eight partial wheat callose synthase sequences were identified and two of these (TaGSL2 and TaGSL22) showed high similarities to the AtGSL5, which is up-regulated in response to aphid feeding in Arabidopsis. Six of the wheat callose synthase genes were mediated to code for the functional callose synthases proteins: TaGSL3, 8, 12, 19, 22 and 23, and analyzed for conserved protein motifs. Based on the sequence similarities and conserved protein domains, TaGSL2 and TaGSL22 were found to be the most similar to AtGSL5 and most likely to respond to RWA infestation. Cis-acting regulatory element analyses confirmed the possibility of TaGSL22 being responsible for callose deposition in wheat as biotic stress associated cis-acting regulatory elements, Box W1, TC- rich element and W- box were all found in the 1.5 kbp upstream of the TaGSL22 coding region. Callose was quantified in both susceptible and resistant wheat cultivars using the aniline blue fluorescence method. When infested with RWA-SA1, the susceptible wheat cultivar (Tugela) deposited significantly higher amounts of callose, compared to the resistant wheat cultivar (Tugela DN), which deposited little, to no callose with respect to the control samples. Transcription analysis, of the TaGSL2 and TaGSL22 in RWA-SA2 infested Tugela and Tugela DN wheat cultivars, was performed using real time polymerase chain reaction (qPCR). Both TaGSL2 and TaGSL22 genes were up-regulated in Tugela and Tugela DN wheat cultivars in response to RWA-SA2 infestation, with TaGSL22 being more expressed than TaGSL2 in both cultivars, indicating that RWA-SA2 is able to overcome the resistance of Tugela DN and cause callose deposition. However, significantly higher expression of both genes was still observed in the susceptible, Tugela wheat cultivar. This study therefore confirms that callose deposition is associated with RWA-SA1 feeding, only in the susceptible wheat cultivar, Tugela and not the resistant cultivar, Tugela DN. However, during RWA-SA2 feeding, two of the eight identified callose synthases in wheat, are up-regulated in response to RWA-SA2 feeding, in both the resistant and susceptible wheat cultivars with higher levels observed in the susceptible wheat cultivar when compared to the resistant wheat cultivar. TaGSL2 and TaGSL22 are therefore implicated in the callose deposition observed in the susceptible and resistant wheat cultivars, after RWA-SA2 infestation. Further studies are required to confirm the differential regulation of the two wheat callose synthases proteins during RWA infestation and their possible role in the resistance mechanism of the resistant wheat cultivar, Tugela DN.
- Full Text:
Species composition and seasonal population dynamics of free-living and engorged cattle ticks in three agro-ecological zones of the Eastern Cape Province, South Africa
- Authors: Yawa, Mandla
- Date: 2017
- Subjects: Ticks Boophilus microplus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9067 , vital:34224
- Description: This study was conducted to determine species composition and seasonal population dynamics of free-living and engorged cattle ticks in three agro-ecological zones (Bedford dry grassland, Kowie thicket and Bisho thornveld) of the Eastern Cape Province, South Africa. The occurrence of ticks on cattle was studied monthly from April 2016 and March 2017. Tick collections were performed on 360 selected cattle in each agro-ecological zones. During tick collections, 10 randomly selected cattle were sampled at each locality and more attention was given to African blue tick and the presence of Asian blue tick. A half body tick collection was performed from cattle and visible ticks were collected by means of fine-forceps after the animals had been restrained. Body regions that were examined includes the ear, head, neck, chest, abdomen, flank, front and hind leg and feet, tail, and peri-anal region. At each locality, six replicate drags of 100 m, approximately 50 m apart, were performed to collect ticks from vegetation. All ticks collected per cattle and from vegetation were stored in labelled sample tubes containing 70percent ethanol, subsequently counted and identified to genus and species level using a standard stereomicroscope. A total of 31425 ticks belonging to ten species were collected during the study. Rhipicephalus (Boophilus) decoloratus, was the most observed tick species (32.50percent), all other ticks like R. evertsi evertsi (18.84percent), R. appendiculatus (17.26percent), A. hebraeum (16.27percent), R. simus (7.69percent) were also commonly collected. Ixodes pilosus (3.84percent), H. rufipes (3.46percent), R. follis (0.08percent) together with Haemaphysalis silacea (0.02percent) were sporadic infestation. Haemaphysalis elliptica (0.04percent) was only found on the vegetation. No H. rufipes was collected in the thicket vegetation. Agro-ecological zones differ significantly (P<0.05) in tick species and distribution. Significantly more R. (B.) decoloratus were collected in thicket during summer compared to thornveld and dry grassland regions (P<0.05). Free-living ticks were widely distributed across different seasons but with of R. (B.) decoloratus larvae were significantly higher (P<0.05) in thornveld region during the spring season. In conclusion, agro-ecological differences and seasonal variations had an influence on ticks abundance and distribution. From this study, it is of interest to note the absence of R. (B.) microplus, whose trend to invade new areas previously colonised by R. (B.) decoloratus has been observed in Africa. In conclusion, agro-ecological differences and seasonal variations had an influence on ticks abundance and distribution. The aforementioned absence of R. (B.) microplus in this study highlights the importance of further research as this tick invades new areas previously colonised by R. (B.) decoloratus in the continent.
- Full Text:
- Authors: Yawa, Mandla
- Date: 2017
- Subjects: Ticks Boophilus microplus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9067 , vital:34224
- Description: This study was conducted to determine species composition and seasonal population dynamics of free-living and engorged cattle ticks in three agro-ecological zones (Bedford dry grassland, Kowie thicket and Bisho thornveld) of the Eastern Cape Province, South Africa. The occurrence of ticks on cattle was studied monthly from April 2016 and March 2017. Tick collections were performed on 360 selected cattle in each agro-ecological zones. During tick collections, 10 randomly selected cattle were sampled at each locality and more attention was given to African blue tick and the presence of Asian blue tick. A half body tick collection was performed from cattle and visible ticks were collected by means of fine-forceps after the animals had been restrained. Body regions that were examined includes the ear, head, neck, chest, abdomen, flank, front and hind leg and feet, tail, and peri-anal region. At each locality, six replicate drags of 100 m, approximately 50 m apart, were performed to collect ticks from vegetation. All ticks collected per cattle and from vegetation were stored in labelled sample tubes containing 70percent ethanol, subsequently counted and identified to genus and species level using a standard stereomicroscope. A total of 31425 ticks belonging to ten species were collected during the study. Rhipicephalus (Boophilus) decoloratus, was the most observed tick species (32.50percent), all other ticks like R. evertsi evertsi (18.84percent), R. appendiculatus (17.26percent), A. hebraeum (16.27percent), R. simus (7.69percent) were also commonly collected. Ixodes pilosus (3.84percent), H. rufipes (3.46percent), R. follis (0.08percent) together with Haemaphysalis silacea (0.02percent) were sporadic infestation. Haemaphysalis elliptica (0.04percent) was only found on the vegetation. No H. rufipes was collected in the thicket vegetation. Agro-ecological zones differ significantly (P<0.05) in tick species and distribution. Significantly more R. (B.) decoloratus were collected in thicket during summer compared to thornveld and dry grassland regions (P<0.05). Free-living ticks were widely distributed across different seasons but with of R. (B.) decoloratus larvae were significantly higher (P<0.05) in thornveld region during the spring season. In conclusion, agro-ecological differences and seasonal variations had an influence on ticks abundance and distribution. From this study, it is of interest to note the absence of R. (B.) microplus, whose trend to invade new areas previously colonised by R. (B.) decoloratus has been observed in Africa. In conclusion, agro-ecological differences and seasonal variations had an influence on ticks abundance and distribution. The aforementioned absence of R. (B.) microplus in this study highlights the importance of further research as this tick invades new areas previously colonised by R. (B.) decoloratus in the continent.
- Full Text:
The experiences of young adults raised in single-parent families in the Raymond Mhlaba Local Municipality, Eastern Cape, South Africa
- Authors: Makoni, Mavis
- Date: 2017
- Subjects: Single-parent families , Children of single parents Young adults
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/5292 , vital:29184
- Description: Although the single-parent family is becoming an increasingly common family structure, it is associated with a great many hardships. Owing to the heavy responsibilities which fall on single parents, most fail to meet all of the needs of their children, particularly with respect to the financial needs which are entailed by providing educational necessities, safe, stable and permanent accommodation, adequate food and nutrition and healthcare. This study adopted the parental loss perspective, the economic hardship perspective and the interparental conflict perspective in investigating the experiences of young adults who were raised in single-parent families. A qualitative approach was adopted to conduct the research and data was collected from 26 male and female participants between the ages of 22 and 39 years who resided within the Raymond Mhlaba Local Municipality. The researcher sought permission to conduct this study from all the community leaders including the councillors and chiefs, thereby acquiring the first referrals. The study made use of purposive sampling and snowballing to select the research sample. The data was collected by using semi-structured interviews and focus group discussions and analysed through the use of thematic analysis. The principal findings of the study indicate that although children who are raised in single-parent homes can attain high levels of education and have solid functional relationships in later life, a lack of finance and active parental involvement in their educational activities and social lives can serve to limit their development. As single-mother households face more economic hardships than any other family structures, financial assistance from both the government and their communities would undoubtedly increase the likelihood of children in single-mother families attaining their true academic potential. In addition, free counselling services would also help children who are forced to live under these circumstances overcome the emotional burden which inevitably accompanies either losing or being separated from one parent.
- Full Text:
- Authors: Makoni, Mavis
- Date: 2017
- Subjects: Single-parent families , Children of single parents Young adults
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/5292 , vital:29184
- Description: Although the single-parent family is becoming an increasingly common family structure, it is associated with a great many hardships. Owing to the heavy responsibilities which fall on single parents, most fail to meet all of the needs of their children, particularly with respect to the financial needs which are entailed by providing educational necessities, safe, stable and permanent accommodation, adequate food and nutrition and healthcare. This study adopted the parental loss perspective, the economic hardship perspective and the interparental conflict perspective in investigating the experiences of young adults who were raised in single-parent families. A qualitative approach was adopted to conduct the research and data was collected from 26 male and female participants between the ages of 22 and 39 years who resided within the Raymond Mhlaba Local Municipality. The researcher sought permission to conduct this study from all the community leaders including the councillors and chiefs, thereby acquiring the first referrals. The study made use of purposive sampling and snowballing to select the research sample. The data was collected by using semi-structured interviews and focus group discussions and analysed through the use of thematic analysis. The principal findings of the study indicate that although children who are raised in single-parent homes can attain high levels of education and have solid functional relationships in later life, a lack of finance and active parental involvement in their educational activities and social lives can serve to limit their development. As single-mother households face more economic hardships than any other family structures, financial assistance from both the government and their communities would undoubtedly increase the likelihood of children in single-mother families attaining their true academic potential. In addition, free counselling services would also help children who are forced to live under these circumstances overcome the emotional burden which inevitably accompanies either losing or being separated from one parent.
- Full Text:
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