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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Plasticity of Primary Metabolism in Parasitic Orobanchaceae

Clermont, Kristen Renee 20 November 2018 (has links)
Parasitic weeds of the family Orobanchaceae attach to the roots of host plants via haustoria capable of drawing nutrients from host vascular tissue. Species in this family span the spectrum of host nutrient dependency, allowing comparisons that provide insight into parasite adaptation. A key aspect of this is the relationship between parasite metabolism and the metabolite profile of its host. To what extent does the metabolite profile of the parasite depend on that of the host? Do parasites that differ in host-dependency also differ in their metabolism or do they use common metabolic strategies? These questions were addressed using comparative profiling of primary metabolites to gain insight into carbon and nitrogen assimilation by the obligate holoparasite Phelipanche aegyptiaca and the facultative hemiparasite Triphysaria versicolor. First, metabolite profiles of these parasites and their hosts were compared during the key life stages before and after haustorial attachment. Second, the impact of specific variations in host metabolism was analyzed for P. aegyptiaca growing on Arabidopsis thaliana hosts that had mutations in amino acid metabolism but otherwise identical genetic backgrounds. Comparison of P. aegyptiaca and T. versicolor metabolite profiles identified substantial differences in the stages spanning the transition from pre-haustorial development through post-haustorial feeding. Each parasite species is distinct from the other and from their hosts. For parasites growing on host lines that differ in amino acid content, the size of P. aegyptiaca tubercles decreased when grown on the aap6 mutant line, which has decreased levels of asparagine in the phloem sap compared to the wild type. However, altered amino acid levels in other lines did not impact P. aegyptiaca growth, indicating that this parasite has ability to compensate for variation in host metabolic composition. This research highlights the importance of aspartate and asparagine to early post-attachment metabolism in both P. aegyptiaca and T. versicolor and through host deficiencies possibly associated with decreased growth in P. aegyptiaca. Overall, this work provides insights both into the metabolism of parasitic plants and lays the foundation for the development of new metabolism-based control strategies. / Ph. D. / Parasitic weeds of the plant family Orobanchaceae attach to the roots of host plants via haustoria. Parasite haustoria embed into the host plant and are capable of drawing nutrients from host vascular tissue. Species in this family span the spectrum of the extent to which a parasitic plant may depend on its host for nutrients. This allows comparisons that provide insight into the ways in which parasites adapt. A key aspect of this is the relationship between the metabolite profile of the parasite and the metabolite profile of the host. To what extent does the metabolite profile of the parasite depend on that of the host? Do parasites that differ in host-dependency also differ in their metabolism or do they use common metabolic strategies? These questions were addressed using comparative profiling of primary metabolites to gain insight into carbon and nitrogen assimilation by the obligate parasite Phelipanche aegyptiaca (which cannot perform photosynthesis) and the facultative parasite Triphysaria versicolor (which can perform photosynthesis). First, metabolite profiles of these parasites and their hosts were compared during the key life stages before and after haustorial attachment. Second, the impact of specific variations in host metabolism was analyzed for P. aegyptiaca growing on Arabidopsis thaliana hosts. These hosts had mutations in enzymes related to amino acid metabolism but otherwise identical genetic backgrounds. Comparison of P. aegyptiaca and T. versicolor metabolite profiles identified substantial differences in the stages spanning the transition from pre-haustorial development through post-haustorial feeding. Each parasite species is distinct from the other and from their hosts. For parasites growing on host lines that differ in amino acid content, the size of P. aegyptiaca tubercles decreased when grown on the aap6 mutant line, which has decreased levels of asparagine in the phloem sap compared to the wild type. However, altered amino acid levels in other lines did not impact P. aegyptiaca growth, indicating that this parasite has ability to compensate for variation in host metabolic composition. Overall, this work provides insights both into the metabolism of parasitic plants and lays the foundation for the development of new metabolism-based control strategies.
202

Genius Loci---Vertical Temple Design

Zhao, Yuxuan 22 February 2019 (has links)
China is a high speed developing country during the past 40 years. However, when China became better and better, there were a lot of issues being left, such as boomed populations, urban village emerging, social media issues and lack of human spirit. All of these issues occurred in the modern urban context, which made the "Loci Genius" lose. So how could architects reconstruct and conserve the "Genius Loci." I try to build the temple for people in the high dense city, which help people to find and think for themselves, to keep peaceful. I believe people and space could build the journey to the pilgrimage. The Buddha joss will not be made in the temple, but be established in every visitor's mind finally. / Master of Architecture
203

Planar Magnetic Integration and Parasitic Effects for a 3 KW Bi-directional DC/DC Converter

Ferrell, Jeremy 03 September 2002 (has links)
Over the recent years many people have been trying to reduce the size and weight of magnetic components and thus the overall system [ 19 ]. One attempt at this is to increase the switching frequency of the system. However, this attempt has its limitations due to increased device switching losses. Device limitations usually confine this frequency to lower value than is desired. An effective approach, reducing the size and weight is to use the planar magnetics for possible integration with the power circuit and thus eliminating the associated interconnections. Planar magnetics uses the printed circuit board as the windings. This will allow the magnetic component to be implemented into the circuit. The integration of the magnetic components and power circuit will decrease the number of connections, reduce the height, and ensure the parasitic repeatability. Having external connections can cause problems in the system. In this case the system must carry a large amount of current. The connections can cause heating from resistance and inductance of the connection. The planar approach also will decrease the height of the system. This is because the planar magnetic cores have a higher surface area with a decreased height. This can reduce the height of the system by 25 %- 50 % [ 19 ]. The parasitic repeatability is also a very important factor. In many cases the typology relies on the parasitic elements for energy storage. Since, the parasitic elements are mainly a result from the geometry of the system; and the planar system has the windings made from the printed circuit board, the parasitic elements will be very consistent through the manufacturing process. For topologies that rely on the parasitic elements for soft switching, the planar design can incorporate parasitic elements with the leakage components for the soft-switching requirement. This thesis redefines the conventional term of leakage inductance as the sum of a set of lumped parasitic inductances and the transformer leakage inductance for the integrated planar magnetics and inverter power circuitry. For the conventional non-integrated transformer, either planar or non-planar, the leakage inductance is defined between two terminals of the transformer. However, for the integrated planar magnetics, the new lumped parasitic and leakage inductance should include the inverter switch and dc bus interconnections. The transformer was first designed using a closed-form solution for a known geometry with different copper thickness. The calculated leakage inductance was then verified with finite element analysis and the impedance analyzer measurement. It was found that the theoretical calculation and the finite element analysis results agreed very well, but the measurement was more than one order of magnitude higher. This prompted the study of interconnect parasitics. With geometrical structure and proper termination and lumping, a set of parasitic inductances were defined, and the results were verified with measurements of both impedance analyzer and phase-shifted modulated full-bridge inverter testing. In addition to parasitic inductance analysis, the flux distribution and associated thermal performance of the planar structure were also studied with finite element analysis. The resulting plots of flux distribution and temperature profile indicate the key locations of mechanical mounting and heat sinking. Overall the thesis covers essential design considerations in electrical, mechanical, and thermal aspects for the planar magnetics integration. / Master of Science
204

Determining the effect of polluted mine water on the ecosystem health of a karstic cave environment in the Witwatersrand Basin / Gerhard Cornelis du Preez

Du Preez, Gerhard Cornelis January 2014 (has links)
The Wonderfontein Cave is located within the Witwatersrand Basin (Gauteng province, South Africa) and is associated with the river banks of the Wonderfontein Spruit. This cave system has for many years been subjected to the influx of polluted mine water. Since subterranean environments remain poorly studied, it is unknown what the effect of this might be on the associated ecosystem. Furthermore, water that enters the Wonderfontein Cave poses a severe health threat as it drains into the underlying aquifer, which is abstracted for human and animal use. The general aim of this study was to determine the extent of metal pollution (enrichment), as well as to study the toxicity hazard potential of the soils and sediments associated with the Wonderfontein Cave. The objectives of this study were to (1) quantify the extent of anthropogenic metal pollution of water, soils and sediments associated with the Wonderfontein Cave (2) and assessing the toxicity hazard potential of these substrates; (3) determining whether nematode taxa and C. gariepinus individuals represent isolated communities and a population within the Wonderfontein Cave, respectively; (4) measuring the effect of mining-associated pollutants on the soil and sediment health of the Wonderfontein Cave by making use of nematodes to serve as bioindicators; (5) evaluating and comparing biomarker responses to metal bioaccumulation in C. gariepinus populations associated with the Wonderfontein Cave and epigean (surface) environments and lastly (6) comparing the results of the above identified assessments over both a temporal and spatial scale. Sampling was undertaken during April (1st sampling interval) and September (2nd sampling interval) 2013, which respectively represented the end of the high and low flow periods. Also, sampling of the subterranean (Wonderfontein Cave) and associated surface (Wonderfontein Spruit) environments were undertaken. The findings of this study suggested that especially the sediments associated with the Wonderfontein Cave have been subjected to severe nickel, copper, zinc, cobalt, aluminium, cadmium, lead and uranium enrichment. Also, the concentrations of many of the studied metals exceeded the respective water, soil and sediment environmental quality guidelines. Thus, also taking into consideration that most of the sediments were classified as being toxic, a severe threat is posed to the health of the associated biota. Although 60 nematode genera were identified from soil and sediments samples collected from the respective sampling sites associated with the Wonderfontein Cave and Spruit, it was concluded that most of these genera were likely only temporary residents of the subterranean environment. Even though plant-parasitic and nonparasitic nematodes were present, most of the collected soil and sediment samples were dominated by bacterivores (non-parasitic nematodes). Zero genetic divergence was recorded between the C. gariepinus populations associated with the Wonderfontein Cave and Stoffels Dam (Wonderfontein Spruit). However, significant temporal and spatial variation was observed in some bioaccumulated metals and biomarker responses within and between the respective C. gariepinus populations. Furthermore, the metal bioaccumulation levels present in both these fish populations pose a substantial threat to human health and are thus not fit for consumption. Also, no significant fish condition differences were observed between the C. gariepinus populations associated with the Wonderfontein Cave and Spruit. This study served as an initiative to create awareness and promote the conservation of Africa’s karst landscapes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
205

Determining the effect of polluted mine water on the ecosystem health of a karstic cave environment in the Witwatersrand Basin / Gerhard Cornelis du Preez

Du Preez, Gerhard Cornelis January 2014 (has links)
The Wonderfontein Cave is located within the Witwatersrand Basin (Gauteng province, South Africa) and is associated with the river banks of the Wonderfontein Spruit. This cave system has for many years been subjected to the influx of polluted mine water. Since subterranean environments remain poorly studied, it is unknown what the effect of this might be on the associated ecosystem. Furthermore, water that enters the Wonderfontein Cave poses a severe health threat as it drains into the underlying aquifer, which is abstracted for human and animal use. The general aim of this study was to determine the extent of metal pollution (enrichment), as well as to study the toxicity hazard potential of the soils and sediments associated with the Wonderfontein Cave. The objectives of this study were to (1) quantify the extent of anthropogenic metal pollution of water, soils and sediments associated with the Wonderfontein Cave (2) and assessing the toxicity hazard potential of these substrates; (3) determining whether nematode taxa and C. gariepinus individuals represent isolated communities and a population within the Wonderfontein Cave, respectively; (4) measuring the effect of mining-associated pollutants on the soil and sediment health of the Wonderfontein Cave by making use of nematodes to serve as bioindicators; (5) evaluating and comparing biomarker responses to metal bioaccumulation in C. gariepinus populations associated with the Wonderfontein Cave and epigean (surface) environments and lastly (6) comparing the results of the above identified assessments over both a temporal and spatial scale. Sampling was undertaken during April (1st sampling interval) and September (2nd sampling interval) 2013, which respectively represented the end of the high and low flow periods. Also, sampling of the subterranean (Wonderfontein Cave) and associated surface (Wonderfontein Spruit) environments were undertaken. The findings of this study suggested that especially the sediments associated with the Wonderfontein Cave have been subjected to severe nickel, copper, zinc, cobalt, aluminium, cadmium, lead and uranium enrichment. Also, the concentrations of many of the studied metals exceeded the respective water, soil and sediment environmental quality guidelines. Thus, also taking into consideration that most of the sediments were classified as being toxic, a severe threat is posed to the health of the associated biota. Although 60 nematode genera were identified from soil and sediments samples collected from the respective sampling sites associated with the Wonderfontein Cave and Spruit, it was concluded that most of these genera were likely only temporary residents of the subterranean environment. Even though plant-parasitic and nonparasitic nematodes were present, most of the collected soil and sediment samples were dominated by bacterivores (non-parasitic nematodes). Zero genetic divergence was recorded between the C. gariepinus populations associated with the Wonderfontein Cave and Stoffels Dam (Wonderfontein Spruit). However, significant temporal and spatial variation was observed in some bioaccumulated metals and biomarker responses within and between the respective C. gariepinus populations. Furthermore, the metal bioaccumulation levels present in both these fish populations pose a substantial threat to human health and are thus not fit for consumption. Also, no significant fish condition differences were observed between the C. gariepinus populations associated with the Wonderfontein Cave and Spruit. This study served as an initiative to create awareness and promote the conservation of Africa’s karst landscapes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
206

Bioassay-guided phytochemical study of indigenous medicinal plants of Ethiopia

Gutu, Ketema Tolossa January 2018 (has links)
In many developing countries, farmers and pastoralists still rely on their indigenous knowledge, practices and locally available plants to control nematode parasitic infections, both in livestock and humans. The overall aim of my thesis was to undertake bioassay-guided phyto-chemical study of extracts and their constituents from Ethiopian anti-parasitic plants used by healers to control gastrointestinal nematode parasites in livestock to validate their ethno-medicinal use and to characterise and identify their active ingredients. As a first experiment (Chapter Three), four types of crude extracts (water, 70% methyl-alcohol, absolute methanol and acetone) of four indigenous Ethiopian medicinal plants (Adenia species, Cissus ruspolii, Ipomoea eriocarpa and Euphorbia thymifolia) were screened against Teladorsagia circumcincta egg hatching in vitro, not only as a first step to validate the traditional healers claim but also to choose the most promising plant extract(s) for further phyto-chemical studies. The egg hatching inhibition (EHI) test results revealed that the anti-parasitic properties of these plants depended on plant species, dose, and solvent polarity. The water extracts of both C. ruspolii and Adenia sp. exhibited largest, up to 100% EHI but also larval migration inhibition activities, and were selected for further studies. The second experiment (Chapter Four) assessed the nature of active constituents in these extracts by physico-chemical methods. It was observed that the major constituents of both plant extracts responsible for the EHI activities are likely highly polar, water-soluble, small and moderately heat-labile molecules. The third and fourth experiments (Chapters Five and Six) consisted of separating Cissus ruspolii and Adenia sp. water extracts into discrete fractions by gel-permeation chromatography, EHI tests of Bio-Gel P-2 fractions followed by thin layer chromatography (TLC) profiling of these fractions to detect separated spots (in day light, under UV-light or after staining with various staining reagents) and also to see how elution patterns of separated spots affected by column parameters. The EHI tests on the fractions obtained revealed that the active constituents of C. ruspolii and Adenia sp. water crude extracts were eluted into few fractions based on their molecular sizes. The TLC profilings of these fractions identified spot patterns of active and inactive fractions, which allowed pooling of active constituents based on their EHI and TLC profiling into three pools for each plant. The fifth experiment (Chapter Seven) was to isolate and purify compounds from these pools using various preparative planar and column chromatographic methods. Sequential applications of column chromatography followed by preparative thin layer chromatography isolated and purified five active compounds from C. ruspolii and two active compounds from Adenia sp. The sixth experiment (Chapter Eight) was to characterize and propose/elucidate structures of compounds from the active fractions using chromatographic, analytical and spectroscopic methods. In this regard, the structures of two oleanane type triterpenoid saponins isolated from one of active fractions of Adenia sp. were proposed based on their mass spectrometry (MS) and nuclear magnetic resonance (NMR) data with support of compounds property, TLC and literature. Similar outcomes for C. ruspolii were not achieved due to lack of sufficient sample to run 13C-nuclear magnetic resonance spectroscopy and distortionless enhancement by polarization transfer (DEPT), contamination of some purified compounds with ill-characterised substance from the preparative TLC matrix and in some cases mass spectrometry (MS) and nuclear magnetic resonance (NMR) data did not support each other. The last experiment (Chapter Nine) was to assess anthelmintic efficacy and safety of C. ruspolii and Adenia sp. crude water extracts in Heligmosomoides bakeri infected mice. This in vivo test revealed that both plant extracts exhibited significant reduction in worm burdens and worm egg excretion, with moderate effects on haematology and organ weights at tolerated dosages. In conclusion, both in vitro and in vivo data revealed that Adenia sp. and C. ruspolii have anthelmintic properties, thus validating traditional healer claims and supporting ethno-medicinal use. The bioassay-guided phytochemical study resulted in the isolation of a number of active compounds from these plants, for some of which a structure has been proposed.
207

Epidemiology of human intestinal parasites in Qwa-Qwa, South Africa.

Mosala, Thabang Innocentia. January 1995 (has links)
This study investigated the prevalences and intensity of intestinal parasites and aspects of their epidemiology among children in the Qwa-Qwa region of the eastern Free St~te. Faecal samples of 1180 children differing socio-economic status from nine schools at altitudes varying from 1660m to 2200m were examined quantitatively by means of the formol-ether sedimentation technique. Socio-economic, and demographic characteristics for the communities served by the schools were obtained from the literature and from a questionnaire. The study showed that, the area supports a markedly low diversity of parasite infections, and at lower intensities, than low altitude areas such as the coastal plain of KwaZulu-Natal and Eastern Cape, the Northern Province, Mpumalanga and the Western Cape. The intestinal parasite fauna affecting children in Qwa-Qwa is dominated by protozoans with only few helminths and no hookworm or bilharzia. The results indicated that factors which influence the transmission of intestinal parasites in Qwa-Qwa appear to be related primarily to social, economic and cultural aspects of the peoples' lifestyles. Climatic factors were not found important. There was a significant seasonal effect on the intensities of all parasite infection, except two protozoans, Entamoeba coli and Endolimax nana. Water source, electricity, house-type and quality of meat were found to be the important socio-economic factors that influenced parasite transmission. These relationships were investigated by fitting logistic regression and generalized linear mixed models. By documenting human parasitism (above 1700m) this study provided an endpoint to the altitudinal transect conducted in 1993 in KwaZulu-Natal by Appleton and Gouws (in press). Public health authorities and Primary Health Care personnel should find this study useful when designing and implementing nutrition and parasite control. Severe ascariasis has been reported from the study area. It will help focus PHC activities in Qwa-Qwa and in the wider context of Free State Province by demonstrating the value of proper personal and environmental hygiene in the home, thereby forming the basis for intestinal parasite control at the community level. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.
208

A Neural Network Based System to Recognize, Detect and Locate Sealworm Parasitic Infestations on Cod Fish Fillet Images / Neural Network System to Recognize Parasites on Fish Images

Aryee, Emmanuel 04 1900 (has links)
In this project, an investigation of a neural network based system is used to examine the following: a) the possibility and practicability of analysing and recognising parasites/sealworms on a parasite/sealworm infested cod fish images, b) the most efficient but robust way of presenting data to the neural network for efficient training and generalisation. The basic problem is to automate the sorting of sealworm infested cod fish from good normal cod fish using a neural network based system. The generalised back propagation supervised learning algorithm is used and both steepest descent and conjugate gradient methods are investigated. Various data representation schemes in unprocessed and processed formats before presentation for training of the neural network, are also examined. Finally the level of recognition achieved by the neural network when presented with the cod fish images is computed. Thus in this project an attempt is made to analyse and find the best components for solving the basic problem and then use this information to develop a neural network based system to recognise, detect and locate parasite/sealworms on cod fish images. / Thesis / Master of Science (MSc)
209

Ecology of Fungus-Farming by Termites : Fungal Population Genetics and Defensive Mechanism of Termites against the Parasitic Fungus Pseudoxylaria

Katariya, Lakshya January 2017 (has links) (PDF)
All living organisms require food for growth and survival. Heterotrophs depend on autotrophs such as green plants which can synthesize their own food unlike heterotrophic animals. Among heterotrophs, only humans and some insects have the remarkable ability to cultivate crops for food. While humans cultivate plants, three insect lineages—ants, termites, and beetles—cultivate fungi inside their nests in obligate mutualistic exo-symbioses. Interestingly, just like human agriculture, insect fungus farms are also threatened by weeds and pests, e.g. the farms of fungus-growing termites which cultivate Termitomyces fungi can be overgrown by weeds such as the parasitic fungus Pseudoxylaria. Studies on ant and beetle fungus-farming systems have uncovered the important role of chemicals and behaviour in helping these insects to protect their crops from parasitic fungi. On the other hand, studies on the termite system till now, have only revealed the presence of antifungal compounds and actinobacteria which are largely non-specific and inhibitory to the mutualistic crop fungi. Antifungal behavioural mechanisms, if present, are yet to be discovered. Therefore, this thesis focuses on different anti-Pseudoxylaria mechanisms employed by fungus-growing termites, viz. role of nest abiotic factors, mechanism of fungal recognition by termite hosts, behavioural response of termite to Pseudoxylaria presence and coupling of this behaviour to anti-Pseudoxylaria activity. The present thesis has been divided into six chapters. CHAPTER 1 gives a brief literature review on fungus-farming insects and the different mechanisms which insects employ in order to keep their fungal farms safe from growth of parasitic fungi with specific reference to fungus-growing termites. The obligate mutualistic interaction between termites and the Termitomyces fungus is 19–49 My-old and is, therefore, a very ancient agriculture system. The mutualistic fungus is cultivated on partially digested plant matter called fungus comb inside the nest and harvested by termites for nutrition. At the same time, the weedy fungal parasite Pseudoxylaria can compete with the mutualistic fungus for nutrition leading to negative effects on the fungal farms. Termite hosts are believed to use abiotic factors, antibiotics and hygienic behaviours to keep their fungal gardens free from parasitic fungi such as Pseudoxylaria. However, the actual mechanisms used by termites against parasitic fungi are unclear. Unravelling the proximate mechanisms used in fungal cultivar protection is central to understanding the evolutionary stability of these farming mutualisms. CHAPTER 2 examines the diversity and population genetic structure of Termitomyces and Pseudoxylaria strains associated with the fungus-growing termite Odontotermes obesus. Genetic diversity of cultivar and parasite could have important implications for the stability of the mutualistic interaction, e.g. genetic clonality arising from monoculture is generally thought to make populations more prone to infection by parasites. Using molecular phylogenetic tools, within-nest genetic homogeneity was found in Termitomyces species but not in Pseudoxylaria species. Lower OTU but higher genotypic diversity (within the most abundant OTU) was found in the genus Termitomyces compared to Pseudoxylaria. Additionally, population genetics methods suggested a sexual population structure for Termitomyces and clonal propagation for Pseudoxylaria species. This is the first study to investigate the population genetics of the symbiotic fungi associated with the termite genus Odontotermes or any other termite species from India. In CHAPTER 3, the effect of nest micro-environment alone on the growth of the parasitic fungus Pseudoxylaria was examined. For this, seasonal changes in nest xiii temperature and CO2 were recorded and in situ and ex situ growth experiments were performed on Pseudoxylaria. The monthly pattern of mound temperatures was found to be similar to the outside—cycling from highs in summer to lows in winter—but characterised by dampened variation compared to high daily fluctuations outside. Moreover, the mound CO2 levels were found to be orders of magnitude above atmospheric levels and, unlike the outside, were characterised by daily and monthly fluctuations. With in situ experiments during summer and winter, the effect of these dissimilar conditions—inside and outside mounds—was examined on Pseudoxylaria growth. The growth of the parasite was found to be greater inside than outside the mound. Following this, the growth of different parasite isolates under controlled ex situ conditions was examined—spanning the variation in environmental conditions that mounds exhibit daily and seasonally. High CO2 levels decreased parasitic fungal growth in general but temperature had an isolate-dependent effect. Taken together, these results suggested that the parasite is adapted to survive in the mound. However, mound environmental conditions still seemed to exert a negative effect on parasite growth, even if they cannot inhibit Pseudoxylaria completely. These results shed light on the possible new role of termite-engineered structures in impacting parasitic fungus ecology, independent of any direct role of termites in suppressing parasite growth. This is the first study to investigate the effect of abiotic factors on Pseudoxylaria growth. In CHAPTER 4, whether termites can differentiate between Termitomyces and Pseudoxylaria was investigated. In a novel, laboratory-based choice assay, termites displayed a differential response towards the two fungi by burying the Pseudoxylaria with agar. Also, termites were found to be able to differentiate between the fungi using olfactory cues, i.e. smell, alone, for this task. The mutualistic and parasitic fungi were found to emit unique volatile bouquets which could help termites to distinguish between them. This is important because, whether termites use antifungal compounds or hygienic behaviours, it is crucial that they are able to differentiate between the parasitic and mutualistic fungi so that they can selectively use antifungal mechanisms—whether chemical or behavioural—against Pseudoxylaria. This is of special significance because, many actinobacteria and anti-Pseudoxylaria compounds isolated from this system till now, lack specificity and inhibit the mutualistic Termitomyces as well. Also, fungal grooming and weeding behaviours as displayed by fungus-growing ants have not yet been reported in termites. This is the first study to show that termites have the behavioural capacity to differentiate between the mutualistic and parasitic fungi in an ecologically relevant setting. In CHAPTER 5, whether the burying of Pseudoxylaria could affect its growth was investigated. It was found that termites can utilise agar, glass beads and soil for deposition over the offered fungal plugs but the use of agar and glass beads did not inhibit Pseudoxylaria growth effectively. On the other hand, soil deposition was found to decrease growth of both Pseudoxylaria and Termitomyces fungi post-burial. However, Pseudoxylaria was found to be affected more strongly than Termitomyces. Further, hypoxia acting alone seemed to decrease only Pseudoxylaria survival without any apparent effect on Termitomyces. Therefore, hypoxia induced by soil deposition may be the reason behind the decrease in Pseudoxylaria survival. However, presence of antifungal compounds can not be ruled out and they may be selectively applied in larger quantities on Pseudoxylaria with soil deposition. This study demonstrates an anti-Pseudoxylaria activity of this insect behaviour, unique to termites among fungus-farming insects, to the presence of the parasitic fungus. CHAPTER 6 concludes the findings of this thesis and suggests a working model for the mechanism of growth suppression of Pseudoxylaria inside a termite nest. In particular, focus is on the important role of abiotic factors when combined with termite behaviour in the apparent absence of Pseudoxylaria from termite nests. These results not only shed new light on how the ecology of these fungi is affected by their termite host but also reveal the mechanistic bases that may contribute fundamentally to the evolutionary stability of this ancient mutualism.
210

PARASITIC OPERATIONS:  TO INHABIT A CADAVER

Tolis, Benjamin January 2020 (has links)
My project takes place in Athens, address Lagoumitzi 15. The plan is to undertake and give life to the huge skeleton-like unfinished structure there. I transform the "skeleton" to a center for urban art, street art. My ambition is for the buidling to become the epicentre for street art in Athens. Since I am designing the building for a non-conformist group of people, graffiti artists, I choose to approach the project by trying to mimic the parasitic art form that is graffiti, in architecture. I wanted the building to radiate the same energy as the artform it is devoted to, and its intended users. The method I am working with is a parasitic method originally by Andrew Benjamin.

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