Dissertations / Theses on the topic 'Fungal'
To see the other types of publications on this topic, follow the link: Fungal.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Fungal.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
LIU, Qi. "The link between Fungal nutrition and Fungal Phenotype." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12035.
Full textAbstract:
Carbon and nitrogen are key macro-nutrients affecting growth and fitness particularly in heterotrophic organisms. A considerable body of evidence suggests that many organisms including mammals, insects and slime moulds have a target intake that is optimal in the sense of maximising growth or ecological fitness. In nutritionally heterogeneous environments, these organisms show an ability to regulate the intake of carbon (C) and nitrogen (N) compounds by selecting different food types to reach the target ratio. This is now a major focus of research in diet-related chronic disease in humans including obesity. Fungi are one of the most important components of the terrestrial ecosystem, and play a key role in nutrient cycling, structural genesis, water infiltration and carbon storage in soil. The manner in which the fungal phenotype emerges in response to the complex nutritional environment of soil is fundamental to the persistence of these functions across space and time. We explore the extent to which the fungal phenotype can be understood in terms of a target ratio of C: N. We used the fungus Mucor mucedo as the model species, and studies its growth in different nutrient regimes by varying the C: N ratio, and including both organic and inorganic sources of nitrogen. There is evidence for a target C: N ratio in a homogeneous environment, although growth rate remains high over a relatively broad range in the ratio by comparison with other organisms. We attribute this to the capacity of fungi to recycle and translocate internal sources of nutrients to regions of high demand. In a heterogeneous environment, we provide evidence that this is the case, although nitrogen is more readily translocated than carbon in this species. In this study, a comparison of growth rate for different C: N ratios and nutrient concentrations indicates efficiency, the amplitude of the oscillations is a measure of stability. This provides an important constraint for our understanding of underlying regulatory pathways linking C and N to growth. A hyphal-level II model for fungal growth is developed to study the consequences of our findings for the emergence of the fungal phenotype, and is used to generate new hypotheses for future testing. Finally, a metabolic model is constructed that synthesises existing knowledge of carbon and nitrogen pathways in cells. We built two versions of this network model corresponding to the case of organic and inorganic sources of nitrogen respectively. Both models reproduced oscillatory growth observed in the laboratory experiments and, consistent with observation, the amplitude of the oscillations is positively correlated with the C: N ratio only for the inorganic N version of the model. A peak C: N ratio for fungal growth is also only predicted for inorganic sources of N, as we saw in the observed behaviour. The networks we built for this project may be highly conserved across the kingdom of life, therefore the models may be broadly applicable with certain modifications.
2
Hart, Rodney S. (Rodney Sebastian). "Physical interactions of filamentous fungal spores and unicellular fungi." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/17371.
Full textAbstract:
Thesis (MSc)--University of Stellenbosch, 2006.ENGLISH ABSTRACT: It is known that many hyphomycetous fungi are dispersed by wind, water and insects. However, very little is known about how these fungi may differ from each other regarding their ability to be disseminated by different environmental vectors. Consequently, to obtain an indication of the primary means of spore dispersal employed by representatives of the genera Acremonium, Aspergillus and Penicillium, isolated from soil and indoor environments, we monitored spore liberation of cultures representing these genera in an airflow cell. The experimental data obtained, of plate counts conducted of the air at the outlet of the airflow cell, were subjected to an appropriate analysis of variance (ANOVA), using SAS statistical software. Intraspecific differences occurred regarding aerial spore release. Under humid conditions, however, Penicillium species were more successful in releasing their spores than Aspergillus and the Acremonium strain. Under desiccated conditions the Aspergillus took longer to release their spores than representatives of Acremonium and Penicillium. The taxa that were investigated did not differ from each other regarding the release of spores in physiological salt solution (PSS). Although not proven, indications are that water may act as an important dispersion agent for these fungi, because washing of cultures with PSS resulted in all cases in an immediate massive release of colony forming units. Subsequently, using standard plate count techniques, conidial adhesion of the fungi mentioned above to synthetic membranes, leaf cuttings and insect exoskeletons differing in hydrophobicity and electrostatic charge were investigated. We found that the different genera showed different adhesion profiles for the series of test surfaces, indicating differences in physico-chemical characteristics of the fungal spore surfaces. In general, the Penicillium strains showed a greater ability to adhere to the test surfaces, than the aspergilli, while the representative of Acremonium showed the least adherence. No significant difference in the percentage spore adhesion was found between hydrophobic and hydrophilic materials. Furthermore, evidence was uncovered supporting the contention that, under dry conditions, electrostatic surface charges play a role in the adherence of fungal spores to surfaces, because adherence was positively correlated (Correlation coefficient = 0.70898, p = 0.001) to positive electrostatic charges on the lamellar surfaces. In the next part of the study, standard plate count methods were used to determine the relative adhesion of the above mentioned hyphomycetous fungi, as well as a polyphyletic group of yeasts, to the test surfaces submerged in 10 mM sodium phosphate buffer (pH 7.0). As was found with the experiments with the dry surfaces, both intraspecific and intergenus differences were uncovered. Overall, the fungi adhered better to hydrophilic surfaces than to hydrophobic surfaces. This indicated that the fungal surfaces were covered with relatively hydrophilic compounds such as carbohydrates. Subsequently, it was demonstrated that all the fungi adhered to plasma membrane glycoprotein coated polystyrene and the presence of fungal carbohydrates on the surfaces of the fungal propagules was confirmed using epi-fluorescence microscopy. Differences in the strategy of the fungal genera to release their airborne spores, as well as differences in their adhesion profiles for the series of test materials, may be indicative of a unique environmental niche for each genus. In future, this phenomenon should be investigated further.
AFRIKAANSE OPSOMMING: Hifomisete fungi is daarvoor bekend om te versprei deur middel van wind, water, en insek vektore. Maar nietemin, daar is bykans geen kennis m.b.t. hoe hierdie fungi van mekaar verskil t.o.v. hul vermoë om versprei te word deur omgewings vektore nie. Gevolglik was spoorvrystelling van kulture, verteenwoordigend van die genera Acremonium, Aspergillus en Penicillium gemoniteer om ‘n aanduiding te kry van primêre wyse van spoorverspreiding waardeur verteenwoordigers van die onderskeie genera ingespan word. Eksperimentele data ingewin, vanaf plaat tellings wat uitgevoer was op lug afkomstig vanuit die uitlaat-klep van die lugvloei kapsule, was onderwerp aan ‘n toepaslike analise van afwyking (ANOVA), deur gebruik te maak van ‘n SAS statistiese pakket. Intraspesie verskille is waargeneem t.o.v. lug spoorvrystelling. Desnieteenstaande was Penicillium meer suksesvol onder vogtige kondisies t.o.v. spoorvrystelling in vergelyking met Aspergillus en die Acremonium stam. Onder droë kondisies het verteenwoordigers van Aspergillus langer geneem om hul spore vry te stel as verteenwoordigers van onderskeidelik, Penicillium en Acremonium. Geen verskille was waargeneem m.b.t. spoorvrystelling in fisiologiese soutoplossing (FSO) tussen die verskillende filogenetiese stamme nie. Alhoewel dit nie bewys is nie, wil dit voorkom asof water as belangrike verspreidingsagent van die betrokke fungi dien, aangesien die spoel van kulture met FSO tot ‘n oombliklike enorme vrystelling van kolonie-vormende eenhede gelei het. Gevolglik, deur gebruik te maak van standaard plaattellings tegnieke, was spoor aanhegting van bogenoemde fungi aan sintetiese membrane, blaar snitte en insek eksoskelette wat verskil in terme van hidrofobisiteit en elektriese lading, ondersoek. Daar was gevind dat die aanhegtingsprofiele m.b.t. hierdie reeks toetsoppervlaktes van die verskillende genera verskil, wat op sigself ‘n aanduiding was van verskille in fisieschemiese eienskappe van die swamspoor oppervlaktes. Penicillium stamme het ‘n hoër aanhegtings vermoë aan die toetsoppervlaktes getoon as die aspergilli, terwyl die verteenwoordiger van Acremonium die laagste aanhegting getoon het. Geen betekenisvolle verskille i.t.v. persentasie spoor aanhegting was gevind tussen hidrofobiese en hidrofiliese oppervlakte nie. Daarbenewens was die argument dat spoorvrystelling onder droë kondisies beïnvloed word deur elektrostatiese oppervlak ladings, bevestig deur ons bevindinge, want aanhegting het positief gekoreleer (Korrelasie koëffisient = 0.70898, p = 0.001) met positiewe ladings op die oppervlaktes. ‘n Standaard plaattellingstegniek was aangewend in die volgende fasset van die studie om die relatiewe aanhegting van bogenoemde hifomisete fungi, sowel as ‘n polifilitiese groep giste aan die toetsoppervlaktes, gedompel in 10 mM natrium fosfaat buffer (pH 7.0) vas te stel. Intraspesie en intragenus verskille was weereens waargeneem, net soos in die geval van die eksperimente met die droë oppervlakte. In die algemeen het die swamme baie beter geheg aan hidrofiliese oppervlaktes in vergelyking met hidrofobiese oppervlakte. Dit was ‘n aanduiding dat die swamspoor oppervlaktes bedek was met relatiewe hidrofiliese verbindings bv. koolhidrate. Verder was daar bewys dat alle swamme ingesluit in hierdie studie die vermoë het om plasmamembraan glikoproteïn bedekte polistireen te bind, en gevolglik was die teenwoordigheid van van koolhidrate op die swamspore bevestig m.b.v epi-fluoresensie mikroskopie. Verskille in die strategie van swamme om spore in die lug vry te stel, sowel as verskille in die aanhegtingsprofiele vir ‘n reeks toetsmateriale, mag net ‘n aanduiding wees van ‘n unieke omgewings nis vir elke genus wat in hierdie studie ondersoek is. Hierdie verskynsel moet dus in die nabye toekoms nagevors word.
3
Marcet, Houben Marina. "Fungal phylogenomics.A global analysis of fungal genomes and their evolution." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8685.
Full textAbstract:
Fungi is the eukaryotic group with a largest amount of completely sequenced species and therefore it is particularly well suited for comparative genomics analyses. A species tree is often an important part of phylogenomics analysis. Concern about its reliability led us to design several methods by which we could identify nodes in the species tree that were poorly supported by a whole phylome. We determined that the species tree was mostly well supported but some nodes showed large discrepancies to most genes.
These results could partly be attributed to evolutionary events that result in topological changes in gene trees. Our analyses have shown that HGT plays an important role in fungal evolution. Gene duplications followed by differential loss are also often the cause of incongruence. The OXPHOS pathway, despite being formed by multi-protein complexes, has been affected by this process at similar levels than the rest of the genome.
Els fongs són el grup d'espècies eucariotes amb un major nombre de genomes completament seqüenciats. Per això són un grup ideal on aplicar tècniques filogenòmiques.
L'arbre de les espècies és un punt clau en molts anàlisis filogenòmics i com a tal necessitem saber si és fiable. Hem dissenyat diferents mesures que aprofiten la informació d'un filoma per identificar aquells punts en l'arbre de les especies que no estan ben suportats. Les discrepàncies que hem trobat poden ser degudes a successos evolutius (transferència horitzontal, duplicacions,...). Hem demostrat que la transferència horitzontal juga un paper important en l'evolució de fongs. També hem estudiat els efectes de duplicacions en l'evolució de la via metabòlica de la fosforilació oxidativa.
Podem concloure que l'arbre de les especies és majoritàriament robust, però que necessitem ser capaços d'identificar nodes subjectes a variacions. Successos evolutius poden ser la causa de les discrepàncies observades en els arbres gènics.
4
Pereira, Tatiana Araujo. "Purificação e caracterização de enzimas envolvidas na bioluminescência de fungos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-12042018-105954/.
Full textAbstract:
Esta tese descreve estudos realizados na tentativa de purificar e caracterizar enzimas envolvidas na BL de fungos, além de trabalhos conduzidos a fim de investigar o mecanismo da bioluminescência de fungos. Inicialmente, tentou-se isolar as duas enzimas supostamente responsáveis pala reação bioluminescente em fungos. Parâmetros de atividade ótima (pH e temperatura) e comportamento cinético foram investigados. Todavia, com a descoberta de que a luciferina fúngica é o derivado hidroxilado da hispidina (3-hidróxihispidina), novas estratégias foram abordadas. Os esforços se concentraram na purificação da luciferase, visto que a hidroxilase não faz parte do sistema bioluminescente de fungos. Avaliação da interação da luciferase fúngica com a luciferina ou derivados dela sugeriram comportamento relativamente promíscuo da enzima. Os resultados indicaram que a reação luciferina-luciferase é favorecida em meio básico (pH ~8), a ~20 °C. Ensaios com 18O2 revelaram que a inserção de oxigênio na molécula de luciferina produz um intermediário cuja descarboxilação gera a oxiluciferina. Paralelamente, a síntese da hispidina in vitro a partir de ácido cafeico na presença de malonil-CoA e de extrato de micélios bioluminescentes resultou na emissão de luz, confirmando que a luciferina é reciclada no processo.This work describes studies performed to purify and characterize enzymes responsible for the fungal bioluminescence. Also, it shows important data that contributes to understand the mechanism for bioluminescence reaction in fungi. First, we tried to isolate two enzymes suspected of being involved on fungal bioluminescence. Optimum activity parameters (pH and temperature) and kinetic behavior were investigated. However, the discovery that fungal luciferin is the hispidin derivative 3-hydroxyhispidin demanded adaptations in the project. First of all, concentrates efforts to luciferase purification was priority, since hydroxylase is not part of the bioluminescent system of fungi. Studies on the luciferase interaction with different substrates showed some promiscuity for the enzyme. The results indicated higher intensity of light from luciferin-luciferase reaction in alkaline solutions (pH ~ 8) at ~ 20 °C. The reaction in medium with 18O2 revealed that insertion of oxygen into the luciferin structure produces an intermediate whose decarboxylation generates oxyluciferin. In parallel, the in vitro synthesis of hispidin using caffeic acid and malonyl-CoA with the mycelium extract resulted in the emission of light, confirming that luciferin is recycled in the process.
5
Leal, Sixto M. Jr. "Fungal Keratitis: Immune Recognition, Neutrophil-Hyphae Interactions and Fungal Anti-Oxidative Defenses." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1339081455.
Full text
6
McAleese, Thomas James. "Interactions of fungal hyphae." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356898.
Full text
7
Auer, Nadja. "Fungal degradation of nitrocellulose." Thesis, University of Westminster, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251569.
Full text
8
Donovan, Tessa May. "Biosynthesis of fungal melanin." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/13689.
Full text
9
Simpson, T. J. "Biosynthesis of fungal metabolites." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/11389.
Full text
10
Grassano, Stacie. "Whey-Based Fungal Microfactories for In Situ Production of Entomopathogenic Fungi." ScholarWorks @ UVM, 2008. http://scholarworks.uvm.edu/graddis/92.
Full textAbstract:
The eastern hemlock is a late-successional conifer species that is valued for its ecological functions, recreational importance, aesthetic beauty, and economic value. The hemlock woolly adelgid (HWA, Adelges tsugae Annand, Homoptera: Adelgidae) is an invasive aphid-like insect from Asia that is causing serious damage to the eastern and Carolina hemlock. HWA was first introduced to the Eastern United States to Virginia in the 1950’s and has since moved along the east coast from Georgia to Maine. It can kill a healthy tree in three to seven years depending on many environmental factors. Native predators have not been successful in reducing damage to hemlock trees or limiting the spread of HWA. Chemical, cultural, and biological control efforts have been implemented in states with high populations of HWA. Chemical applications are costly and current formulations are difficult to apply in large stands and in forested areas. Salvage cutting is a method to control the spread of adelgid and recover some economic value of the wood. Predatory beetles native to Asia, where HWA is present but not a severe problem, have been researched, reared, and released into infested stands in the Eastern United States. Their success for management of HWA has been difficult to ascertain. The entomopathogenic fungus Lecanicillium muscarium ((Petch) Zares & Gams) is another biological control agent with potential to manage and suppress adelgid populations. L. muscarium (Mycotal™ technical powder, Koppert Biological Systems) plus the nutritive base sweet whey, may promote conidia production without contact with a host and this means of increasing conidia is called a whey-based fungal microfactory. The whey would act as a nutritive substrate for fungi sprayed into hemlock forests. Formulation droplets deposited on hemlock needles should support fungal growth and serve as tiny factories for conidia production. Microfactory production was characterized in different combinations of sweet whey (0, 5, 10, and 15%) and conidia concentration (1 x 106, 1 x 107, and 1 x 108 conidia/ml) applied to lids of Petri dishes. A dramatic 42- and 29-fold increase in conidia production occurred with the addition of 10% sweet whey to 1 x 106 and 1 x 107 conidia/ml, respectively. Increasing whey concentration increased the number of conidia that were recovered. Conidia production was also obtained on hemlock foliage, with similar trends in influence of conidia and whey concentration. The hemlock branches also contained HWA and their mortality was evaluated. Adelgid mortality was highest in formulations containing sweet whey, but whey had an independent effect on mortality. Several antimicrobials were evaluated for compatibility with L. muscarium in the microfactory formulation. Nisin did not inhibit conidia production. The addition of antimicrobials to the whey-based formulations may limit the competition between the fungus and other microbes present in the spray tank and on foliage. Whey-based fungal microfactory technology is intended to facilitate multiplication of fungi in the natural environment. Transferring a portion of fungal massproduction into the treatment environment could reduce application costs and increase the feasibility of using fungi for biological control of HWA and other pest species.
11
Oses-Ruiz, Miriam. "Signalling circuitry controlling fungal virulence in the rice blast fungus Magnaporthe oryzae." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/16968.
Full textAbstract:
Rice blast disease is caused by the filamentous ascomycete fungus Magnaporthe oryzae and is the most destructive disease of cultivated rice. The pathogen elaborates a specialized infection structure called the appressorium. The morphological and physiological transitions that lead to appressorium formation of M. oryzae are stimulated through perception of environmental signals and are tightly regulated by cell cycle checkpoints. External stimuli are internalized by a variety of intracellular MAP kinase signaling pathways, and the major pathway regulating appressorium morphogenesis and plant infection is the Pmk1 MAP kinase signaling pathway. The central kinase, Pmk1, is required for appressorium morphogenesis and the homeobox and C2/H2 Zn-finger domain transcription factor, called Mst12, is required for appressorium formation and tissue invasion. The Mst12 null mutant is able to form melanised appressoria, but it is non-pathogenic. To understand the mechanism of appressorium morphogenesis and penetration peg formation, genome-wide comparative transcriptional profiling analysis was performed for the Δpmk1 and Δmst12 mutant using RNA-seq and HiSeq 2000 sequencing. This thesis reports the identification of gene sets regulated by the Pmk1 signalling pathway and defines the sub-set of these genes regulated by Mst12. I show that a hierarchy of transcription factors is likely to operate downstream of Pmk1 to regulate the main processes required for appressorium morphogenesis and plant infection. I also report the role of Mst12 in cytoskeletal re-organisation and show that it is necessary for septin-dependent F-actin polymerisation at the base on the appressorium prior to plant infection. This is consistent with the major transcriptional changes observed by RNA-seq. The thesis also reports experiments that strongly suggest that appressorium mediated plant penetration is regulated by an S-phase checkpoint which operates independently of the conventional DNA damage and repair response, and the Cds1 and Chk1 checkpoint kinases. Transcriptional profiling results are consistent with the S-phase checkpoint operating downstream of the Pmk1 MAP kinase signalling pathway. An integrated model for the operation of the Pmk1/Mst12 signalling pathways and the hierarchical control of appressorium morphogenesis in the rice blast fungus is presented.
12
Aryan, Fatemah Ali. "Immunology of the emerging human fungal pathogens Rhizopus oryzae and Pseudallescheria boydii." Thesis, University of Exeter, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603475.
Full text
13
Hagen, Ethan D. "A Macrofungal Survey of the Baker Property, Athens County, Ohio." Ohio University Honors Tutorial College / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1309220666.
Full text
14
Kobayashi, Motoo. "Fungal cell wall synthesis inhibitors, FR207944 and FR227244, produced by filamentous fungi." Kyoto University, 2005. http://hdl.handle.net/2433/144992.
Full textAbstract:
Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第11673号
論農博第2556号
新制||農||912(附属図書館)
学位論文||H17||N4056(農学部図書室)
23486
UT51-2005-D591
(主査)教授 加藤 暢夫, 教授 清水 昌, 教授 宮川 恒
学位規則第4条第2項該当
15
Jenkins, Tim A. "Fungal biological control of Hieracium." Thesis, University of Canterbury. Microbiology, 1995. http://hdl.handle.net/10092/4841.
Full textAbstract:
Hieracium species are a severe weed problem in the high country native tussock grasslands of New Zealand. This thesis reports on the potential for fungal biological control of Hieracium, in particular with a rust pathogen, Puccinia hieracii var. piloselloidarum. Isolates of Hieracium rust were collected from throughout Northern, Central and
Southern Europe, and the British Isles. One thousand four hundred and twenty four
isolates were screened on New Zealand Hieracium pilosella to identify the most
infective strains for potential use as biological control agents. The rust isolates most
pathogenic to New Zealand H. pilosella, were from the south of Ireland. They had a
shorter latent period and higher infectivity compared to other isolates. One isolate
infected representatives of all New Zealand H. pilosella sites as well as H. praealtum
and H. x stoloniflorum.
Hieracium rust was common throughout Europe with large seasonal fluctuations.
Most dissemination, infection and effect was seen in a main peak in spring and a
secondary peak in autumn. The rust could survive through winter conditions within
host tissue allowing rapid re-establishment of symptoms during occasional periods of
suitable milder weather and, eventually, with the onset of spring. In an intensive field
study of one Edinburgh area, the level of rust infection on patches of H. pilosella was
found to be affected by several site factors, particularly the density of patches.
The infection process of Hieracium rust was studied. Spore germination was fastest
in the dark and occurred over a wide range of temperatures. Inoculations of hosts was
either on to detached leaves kept on water agar or on to whole rosettes. Infection of
detached leaves was generally higher than on whole rosettes and may allow a wider
host range of subgenus Pilosella taxa. Infection rarely occurred on all inoculated
plants. This was attributed in part to the effect of host condition. A genetic resistance
component of the non-susceptibility remains possible although one rust isolate was
able to infect representatives of all identified genotypes of New Zealand H. pilosella.
The variation present in New Zealand Hieracium species was investigated by
chromosome analysis and isozyme electrophoresis. H. pilosella from 34 collections
throughout New Zealand were predominantly pentaploid with a hexaploid found in
just one population; the pentaploids included variants, according to electrophoresis
results and morphological characters.
Hieracium rust showed potential as a biological control agent. The rust significantly
affected the growth of H. pilosella and displayed strict host-specificity, with no hosts
outside the subgenus Pilosella.
Powdery mildew, Erysiphe cichoracearum, is common and very pathogenic on
Hieracium spp. throughout Europe. However, Hieracium powdery mildew grew on
two New Zealand endemic species, Embergeria grandi/olia and Kirkianella novaezelandiae.
Several other Hieracium pathogens were noted but their potential for
biological control requires further investigation.
16
Pegg, N. A. "Synthesis of natural fungal pigments." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380151.
Full text
17
Lakkireddy, Gopalkrishna. "Immunomodulatory properties of fungal polysaccarides." Thesis, University of Westminster, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433715.
Full text
18
Walsh, Maura Stephanie. "Cloning fungal polyketide synthase genes." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333957.
Full text
19
Vandegrift, Andrew. "Ecological Roles of Fungal Endophytes." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20401.
Full textAbstract:
Endophytic fungi live within tissues of plant hosts without causing symptoms of disease. These fungi are broadly split into the taxonomically and ecologically cohesive Clavicipitaceous endophytes, which infect grasses, and the taxonomically diverse non-Clavicipitaceous endophytes, which are found in nearly all plants and have diverse ecological strategies. My dissertation has two sections: Section A investigates the intersection of Clavicipitaceous endophyte ecology with other ecological theory, including invasion ecology (Chapter II) and community ecology and climate change (Chapter III); Section B investigates the ecology of one group of non-Clavicipitaceous endophytes, the Xylariaceae, using a culture-based study in Ecuador (Chapter IV) and a next-generation sequencing based endophyte survey in Taiwan (Chapter V). Section B is centered on testing the Foraging Ascomycete (FA) hypothesis—the idea that some decomposer fungi may adapt an endophytic lifestyle to escape limitations in primary substrate in both time and space.
In Chapter II, I utilized a host-specific Epichloë endophyte present ubiquitously in the European native range of the Pacific Northwest (PNW) invasive grass Brachypodium sylvaticum to test theories of invasion. In Chapter III, I examined the grass Agrostis capillaris in the context of a climate manipulation experiment in prairies in the PNW to elucidate patterns of interaction between multiple symbionts (Epichloë endophytes, dark septate root endophytes, and arbuscular mycorrhizal fungi) within single hosts across climatic variation.
In Chapter IV, I began to test the FA hypothesis by examining spatial relationships of Xylaria endophytic fungi in the forest canopy with Xylaria decomposer fungi on the forest floor in a remote Ecuadorian cloud forest. In Chapter V, I build on the results from the previous study, using a novel technique to examine spatial ecology of the Xylariaceae, pairing traditional mycological collection with the preparation of a next-generation sequencing metabarcode library of endophytes over a much greater area.
This dissertation includes previously published and unpublished coauthored material.
20
Trollope, Kim Mary. "Engineering a fungal β-fructofuranosidase." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96757.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2015.ENGLISH ABSTRACT: β-fructofuranosidases are hydrolytic enzymes that act on sucrose to yield the products glucose and fructose. Under high substrate conditions these enzymes display fructosyltransferase activity which results in the synthesis of fructooligosaccharides (FOS). Some enzymes display higher propensities for FOS synthesis than others, with the determinants of this activity remaining unclear. The consumption of FOS produces a prebiotic effect that positively alters the composition of the colonic microflora, and as a result is linked to improved human and animal health. The increased demand for FOS has necessitated the industrial production of these nutraceuticals. In enzymatic sucrose biotransformation processes operating at high substrate loading and temperatures between 50 and 60°C, β-fructofuranosidase activity is negatively influenced by glucose product inhibition and thermal instability. The aim of this study was therefore to engineer the Aspergillus japonicus β-fructofuranosidase, FopA, to improve a FOS synthesis bioprocess. A dual approach was employed to engineer FopA so as to increase the probability of obtaining an improved enzyme variant(s). A random mutagenesis approach was applied to harness the potential of the randomness of introduced mutations as precise structural knowledge of the enzyme regions involved in the phenotypic presentation of product inhibition, specific activity and thermal stability was unavailable. A semi-rational approach afforded the additional opportunity to reduce the number of variants to be screened, yet theoretically increased the functional content of the library. This study details the development of a method to rapidly quantify FOS using Fourier transform mid infrared attenuated total reflectance spectroscopy and multivariate data analysis. The method offers improvements over conventionally used high performance liquid chromatography in terms of reduced sample analysis times and the absence of toxic waste products. This is the first report on the direct screening of an enzyme variant library for FOS synthesis to identify improved variants and will significantly support future engineering of β-fructofuranosidases using random mutagenesis approaches. The random mutagenesis approach yielded a variant displaying limited relief from glucose inhibition. At the peak difference in performance, the variant produced 28% more FOS from the same amount of sucrose, when compared to the parent. The semi-rational approach, using a combined crystal structure and evolutionary-guided approach, yielded a four amino acid combination variant displaying improved specific activity and thermostability that was able to reduce the time to completion of an industrial-like FOS synthesis reaction by 26%. The positive outcome of the semi-rational approach showed that engineering loops regions in an enzyme is a feasible strategy to improve both specific activity and thermostability, most probably due to the modification of enzyme structural flexibility. A bioinformatic tool that enables the identification of β-fructofuranosidases displaying high-level FOS synthesis from protein sequence alone was also developed during the study. These investigations revealed conserved sequence motifs characteristic of enzymes displaying low- and high-level FOS synthesis and a structural loop, unique to the latter group, that were readily applicable identifiers of FOS synthesis capacity. The tool presented may also be useful to improve the understanding of the structure-function relationships of β-fructofuranosidases by facilitating the identification of variations in groups of enzymes that have been functionally sub-classified.
AFRIKAANSE OPSOMMING: β-fruktofuranosidases is hidrolitiese ensieme wat op sukrose inwerk en glukose en fruktose as produkte vorm. Onder toestande met hoë substraatkondisies vertoon hierdie ensieme fruktosieltransferase-aktiwiteit wat tot die sintese van frukto-oligosakkariede (FOS) lei. Sommige ensieme neig na ʼn hoër FOS-sintese as ander, maar die bepalende faktore vir hierdie aktiwiteit is nog onbekend. Die verbruik van FOS veroorsaak ʼn prebiotiese effek wat die samestelling van kolon mikroflora positief beïnvloed en met verhoogde mens- en dieregesondheid verbind word. Die verhoogde aanvraag vir FOS het die industriële produksie van hierdie nutraseutiese middel genoodsaak. Tydens ensiemgedrewe sukrose-biotransformasieprosesse by hoë substraatladings en temperature tussen 50 en 60 °C, word β-fruktofuranosidase-aktiwiteit negatief deur glukose produkonderdrukking en termiese onstabiliteit beïnvloed. Die doel van hierdie studie was dus om die Aspergillus japonicus β-fruktofuranosidase, FopA, vir ʼn verbeterde FOS-sintese bioproses te manipuleer. ʼn Tweeledige benadering is vir FopA manipulasie gevolg om die waarskynlikheid van verbeterde variant(e) te verhoog. ʼn Lukrake mutagenese benadering, wat die potensiaal van ingevoegde mutasie ewekansigheid inspan, is in die lig van onvoldoende akkurate kennis van die strukturele gedeeltes betrokke by produkinhibisie-, spesifieke aktiwiteit- en termiese stabiliteit fenotipes gevolg. Die toepassing van ʼn semi-rasionele benadering het ook geleentheid vir die sifting van ʼn kleiner variantbibioloteek geskep, terwyl die funksionele inhoud teoreties verhoog word. Die studie beskryf die ontwikkeling van ʼn metode vir die vinnige kwantifisering van FOS, gebaseer op Fourier transform middel infrarooi geattenueerde totale refleksie spektroskopie en meerveranderlike data-analise. Dit is die eerste melding van ʼn direkte sifting van ʼn ensiemvariantversameling vir FOS-sintese om verbeterde variante te identifiseer, en kan die toekomstige manipulasie van β-fruktofuranosidases deur middel van lukrake mutagenese-benaderings beduidend ondersteun. Die lukrake mutagenese-benadering het ʼn variant met beperkte opheffing van glukose-onderdrukking gelewer. By die punt waar die prestasie die meeste verskil, het die variant 28% meer FOS vanaf dieselfde hoeveelheid sukrose geproduseer in vergelyking met die ouer-ensiem. Die semi-rasionele benadering, gegrond op ʼn kombinasie van kristalstruktuur en evolusionêre-geleide benaderings, het ʼn vier-aminosuurkombinasie variant met hoër spesifieke aktiwiteit en termostabiliteit gelewer wat die voltooiingstyd van ʼn tipiese industriële FOS sintesereaksie met 26% kon verkort. Die positiewe uitkoms van die semi-rasionele benadering het aangedui dat manipulasie van die lusgedeeltes in ʼn ensiem ʼn lewensvatbare strategie is om beide spesifieke aktiwiteit en termostabiliteit te verbeter, moontlik as gevolg van wysigings in die buigsaamheid van die ensiemstruktuur. ʼn Bioïnformatika-hulpmiddel vir die identifikasie van β-fruktofuranosidases met hoë vlakke van FOS-sintese op grond van proteïenvolgordes is ook tydens die studie ontwikkel. Motiewe met gekonserveerde volgordes kenmerkend van lae- en hoë-vlak FOS-produserende ensieme en ʼn strukturele lus, uniek tot die laasgenoemde groep, is tydens die ondersoek onthul wat as maklike identifiseerders van FOS-sintesekapasiteit kan dien. Die voorgestelde hulpmiddel kan ook nuttig wees om die struktuur-funksie-verwantskap van β-fruktofuranosidases beter te verstaan deur die identifikasie van variasie in ensiemgroepe wat funksioneel gesubklassifiseer is.
21
Bahri-Esfahani, Jaleh. "Fungal transformation of phosphate minerals." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/944bbfa4-4899-429c-be2b-b057d2d10773.
Full text
22
Al-Taie, Ali Hussein Shuaa. "Continuum models for fungal growth." Thesis, University of Dundee, 2011. https://discovery.dundee.ac.uk/en/studentTheses/9b2c14ff-c012-4541-a6ea-3ab0fea38e50.
Full textAbstract:
Fungi generally exist as unicellular organisms (yeasts) or in a vegetative state in which a mycelium, i.e. an interconnected network of tubes (hyphae) is formed. The mycelium can operate over a very large range of scales (each hypha is only a few microns in diameter, yet mycelia can be kilometres across). Fungi are of fundamental importance to many natural processes: certain species have major roles in decomposition and nutrient cycling in the soil; some form vital links with plant roots allowing nutrient transfer. Other species are essential to industrial processes: citric acid production for use in soft drinks; brewing and baking; treatment of industrial effluent and ground toxins. Unfortunately, certain species can cause devastating damage to crops, serious disease in humans or can damage building materials. In this thesis we constructed new models for the development of fungal mycelia. At this scale, partial differential equations representing the interaction of biomass with the underlying substrate is the appropriate choice. Models are essentially based on those derived by Davidson and co workers (see e.g. Boswell et al.(2007)). These models are of a complex mathematical structure, comprising both parabolic and hyperbolic parts. Thus, their analytic and numerical properties are nontrivial. The objectives of this thesis are to: (i) obtain a solid understanding of the physiology of growth and function and the varying mathematical techniques used in model construction. (ii) revisit existing models to reinterpret the various model components in a simple form. (iii) construct models to compare the growth dynamics of different phenotype for new species to see if these "scale " appropriately.
23
Tuch, Brian B. "Evolution of fungal transcription circuits." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3297786.
Full text
24
Ling, Wood-hay Ian, and 凌活希. "ITS sequencing for identification of pathogenic fungi and discovery ofa novel fungal species." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50713164.
Full textAbstract:
Eleven fungal strains were received from the clinical microbiology laboratory collection of Queen Mary Hospital and Pamela Youde Nethersole Eastern Hospital in Hong Kong from 2010-2011. The collection comprised of ten ascomycetes and one zygomycete. They were identified down to the genus level based on the morphological criteria. Internal transcribed spacer (ITS), beta-tubulin, actin and 28S gene sequencing were used for genotypic characterization. The ITS sequences of four of the strains demonstrate <3%-base difference to a single fungal species. They were species of the genus, Acremonium, Aspergillus, Cladophialophora and Ochroconis respectively. Five strains belonging to the genus, Trichophyton, Monascus, Mucor, Arthrinium and Acremonium could not be identified to the species level due to low interspecies heterogeneity. The tubulin gene was used for two of the strains. The tubulin sequence of a strain of Phaeoacremonium was identified to the species level with 0%-base difference. The ITS, partial beta-actin and 28S rDNA genes were sequenced for a strain of Exophiala. They showed a distinct cluster, mostly closely related to, but distinct from, Exophiala xenobiotica, Exophiala jeanselmei and Exophiala oligosperma. The genotypic characteristics suggest the strain to be a novel species of Exophiala. More genotypic and phenotypic characterization are required to described this strain of Exophiala.published_or_final_version
Microbiology
Master
Master of Research in Medicine
25
Kshirsagar, Anandini S. "Phytotoxins of Rosellinia necatrix prill." Thesis, Liverpool John Moores University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343187.
Full text
26
Balkan, Mehmet Ali. "Sex-Specific Fungal Communities of the Dioicous Moss Ceratodon purpureus." PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/2658.
Full textAbstract:
Mosses display a number of hallmark life history traits that influence their ecology at the population and community level. The long lived separation of sexes observed in the haploid gametophyte (dioicy) is one such feature of particular importance, as it is observed in the majority of bryophytes and creates intraspecific specialization of male and female individuals.
The prevalence of sexually dimorphic mosses raises the possibility of sex-specific interactions with fungi as observed in some vascular plants. Here I investigated how moss sex shapes fungal communities associated with gametophytic tissues of the ubiquitous moss, Ceratodon purpureus. Using greenhouse populations of C. purpureus grown in a common garden, I examined fungal community structure and overall abundance of fungal biomass associated with male and female individuals from multiple populations. I hypothesized that individual mosses would harbor unique fungal communities based on their sex, and that overall fungal biomass associated with host tissues would differ significantly due to differences in morphological and physiological characteristics between the sexes. I found that fungal community composition and overall abundance (i.e. biomass) differ between male and female individuals of C. purpureus, and that sex-specific patterns are retained across individuals from three different populations. This work provides a first glance at how genetically based sexual systems in early land plants influence affiliated fungal community composition.
27
Naranjo, Ortiz Miguel Ángel 1989. "Non-vertical genomics in fungal evolution." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/666037.
Full textAbstract:
Non-vertical genomic events, which include horizontal gene transfer (HGT) and hybridization, are widely studied evolutionary processes in certain groups. HGT is particularly well known for prokaryotic organisms, while studies on hybridization started centuries ago for plants and animals. However, these phenomena are often overlooked when studying the evolution of other eukaryotic groups. Fungi, in particular, offer a privileged framework to study these kind of events, since the tractability of their genomes have made them target of hundreds of sequencing projects. This thesis reviews current knowledge on fungal diversity and evolutionary processes, with emphasis on the role of HGT and hybridization. We present an study on HGT of D-amino acid metabolic enzymes across eukaryotes, a novel computational framework for the study of hybrid genomes and other genomic anomalies, and a series of phylogenomic studies aimed to pinpoint possible ancient polyploidy events in fungi. Our findings expand current knowledge on non-vertical fungal evolution at different evolutionary and genomic scales, providing a multi-disciplinary perspective.Los eventos genómicos no verticales, que incluyen transferencia horizontal de genes (THG) e hibridación, han sido estudiados ampliamente en determinados grupos. THG es particularmente bien conocida para organismos prokariotas, mientras que los estudios sobre hibridación comenzaron en plantas y animales hace ya siglos. Sin embargo, estos fenómenos han sido a menudo ignorados a la hora de estudiar la evolución de otros grupos de eukariotas. Los hongos, en particular, ofrecen un sistema privilegiado en el que estudiar este tipo de eventos, puesto que la tractabilidad de sus genomas les ha llevado a ser objeto de cientos de proyectos de secuenciación. La presente tesis incluye una revisión del conocimiento actual acerca de la diversidad y procesos evolutivos, con énfasis en el papel de la THG y la hibridación. Presentamos un estudio acerca de THG de enzimas del metabolismo de D-amino ácidos en eukariotas, una nueva herramienta computacional para el estudio de genomas híbridos y otras anomalías genómicas, y una serie de estudios filogenómicos con la intención de identificar posibles eventos de paleopoliploidización en hongos. Nuestros resultados exapanden el conocimiento actual acerca de la evolución no vertical en hongos a diferentes escalas evolutivas y genómicas, proporcionando una perspectiva mulidisciplinar.
28
Bareich, David C. Wright Gerard D. "Fungal aspartate kinase mechanism and inhibition /." *McMaster only, 2003.
Find full text
29
Lanternier, Fanny. "Invasive fungal infections and CARD9 deficiency." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05T082.
Full textAbstract:
Les infections fongiques invasives, sont des infections sévères grevées d’une lourde mortalité. Elles sont actuellement un problème majeur de santé publique et leur incidence augmente. Les candidémies représentent la quatrième cause d’infection hématogène nosocomiale aux Etats-Unis, les cryptococcoses sont responsables de 600 000 décès chaque année en Afrique et l’aspergillose invasive infecte 10% des patients transplantés de cellules souches. La mortalité de ces infections reste élevée avec des taux de mortalité de 50, 15 et 40% respectivement. L’augmentation de leur incidence est due à l’accroissement des populations immunodéprimées à risque de développer des infections fongiques en raison de l’augmentation des thérapeutiques immunosuppressives et de l’allongement de la durée de vie des patients immunodéprimés. Les infections fongiques invasives surviennent chez des patients immunodéprimés, majoritairement dans un contexte d’immunodépression acquise (neutropénie, chimiothérapie, greffe de cellules souches périphériques ou transplantation d’organe solide, diabète, infection par le virus de l’immunodéficience humaine), mais également secondairement à un déficit immunitaire héréditaire (granulomatose septique chronique, déficit immunitaire combiné, neutropénie congénitale, défaut de l’axe IFNγ-IL12). Cependant certains patients développent des infections fongiques invasives sans immunodépression ou facteurs de risques identifiés. Nous avons donc émis l’hypothèse que ces infections avaient possiblement une origine génétique non identifiée. Au cours de ma thèse, j’ai étudié une cohorte de patients présentant des infections fongiques invasives sans facteur favorisant identifié afin de rechercher une étiologie génétique à ces infections. Le premier groupe de patients que j’ai étudié présentait une dermatophytose invasive ou dermatophytose profonde sans immunodépression. Contrairement à la dermatophytose superficielle, en général bénigne et fréquente dans la population générale; la dermatophytose profonde est une infection rare, invasive et sévère, dans laquelle les dermatophytes (qui sont des champignons filamenteux) envahissent les tissus dermiques et hypodermiques, les ganglions et parfois les organes profonds. Les patients que j’ai étudié étaient tous originaires d’Afrique du Nord, pour la plupart issus de familles consanguines, dont certains avec des cas multiples. Ces observations suggéraient une origine génétique de la dermatophytose profonde avec une hérédité probablement récessive. Au cours de ma thèse, j’ai étudié les caractéristiques cliniques, immunologiques et génétiques de 18 patients atteints d’une dermatophytose profonde, issus de neuf familles Marocaines, Algériennes, Tunisiennes ou Egyptiennes. En parallèle, j’ai étudié des patients ayant présenté des infections fongiques avec localisations cérébrales. L’une de ces patients a présenté des abcès cérébraux suite à une infection disséminée à Exophiala dermatitidis et trois patients ont développé des infections du système nerveux central à Candida spp.. Les infections invasives à Exophiala dermatitidis sont des infections rares, avec de fréquentes atteintes du système nerveux central, survenant majoritairement chez des patients sans déficit immunitaire identifié suggérant l’existence d’une origine génétique probable méconnue chez ces patients. Les candidoses invasives surviennent habituellement chez des patients neutropéniques, ayant récemment subi une intervention chirurgicale ou étant porteurs d’un cathéter intraveineux. Parmi les candidoses invasives, les localisations au système nerveux central sont rares, et classiquement rapportées chez des nouveau-nés prématurés ou suite à une intervention neurochirurgicale. J’ai par ailleurs étudié une patiente ayant développé des infections invasives des tissus sous-cutanés et des adénopathies dues à un champignon filamenteux. (...)Invasive fungal diseases are a major health problem as they are severe infections complicated with high mortality rates and with rising incidence. Invasive fungal diseases occur mainly in patients with acquired immunodeficiencies, but also with primary immunodeficiencies (chronic granulomatous disease, defect in IFN-ϒ/IL-12 axis, congenital neutropenia). However, few patients develop invasive fungal disease without known risk factor. We therefore hypothesized that these infections probably have an unidentified genetic etiology. I studied a cohort of patients who developed invasive fungal diseases without risk factors and searched for a genetic etiology to their infections. The first group of patients presented with deep dermatophytosis without known immunodeficiency. Deep dermatophytosis is a rare, invasive and severe infection where dermatophytes invade dermis, hypodermis, lymph nodes and sometimes deep organs. I could study clinical, immunological and genetic characteristics of 18 patients from nine families who presented deep dermatophytosis. I also studied patients who developed central nervous system (CNS) fungal infections; one patient with CNS Exophiala dermatitidis infection and three patients with CNS Candida spp. infection. Invasive E. dermatitidis infections are rare, with frequent CNS location, mainly reported in patients without known immunodeficiencies, suggesting a potential unknown genetic etiology in these patients. CNS candidiasis are also rare infections usually occuring in preterm neonates or following neurosurgery. Based on literature data previously reporting a large consanguineous Iranian family with CARD9 deficiency that developed chronic mucocutaneous and central nervous system candidiasis; according to candidate gene approach, I sequenced CARD9 in all patients. CARD9 is an adaptor protein expressed by myeloid cells that signals downstream Dectin-1 and Dectin2 that are the main Pattern Recognotion Receptor implicated in antifungal immunity. I identified in all studied patients homozygous CARD9 mutations. Among 18 patients with deep dermatophytosis, 16 had homozygous nonsense Q289X and two homozygous missense R101C mutation in CARD9. I identified R18W, R35Q and R70W homozygous missense mutations in the patients who developed E. dermatitidis and two patients who developed CNS candidiasis, respectively. Transmission was autosomal recessive for all patients, except for the one with E. dermatitidis infection who had an uniparental disomy. In contrast with controls, CARD9 expression is abolished in Q289X, reduced in R70W and normal in R18W patients’ myeloid cells. CARD9 deficient patients whole blood and dendritic cells display a selective response defect to Candida albicans and Saccharomyces cerevisiae ; with IL-6 and TNF-α production impairment after Candida albicans and Saccharomyces cerevisiae stimulation. This defect can explain elective fungal susceptibility of CARD9 deficient patients to invasive fungal infections. This work evidenced that CARD9 deficiency was the main genetic etiology of deep dermatophytosis. It also could evidence that CARD9 deficiency is associated with Exophiala dermatitidis and Candida spp. CNS infections. This susceptibility is associated with proinflammatory cytokines defect by dendritic cells and whole blood to fungal agents. Various fungal clinical phenotypes in CARD9 deficient patients assess CARD9 central role in skin and central nervous system antifungal immunity
30
Williams, Katherine. "Genetic manipulation of fungal secondary metabolism." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535469.
Full text
31
蔡婉華 and Yuen-wah Choi. "The fungal diversity of Brucea javanica." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B3122586X.
Full text
32
Strong, Neil. "Fungal deterioration of sawn softwood lumber." Thesis, University of Portsmouth, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285528.
Full textAbstract:
The colonisation of freshly sawn Corsican pine lumber by sapstain and mould fungi was investigated at a sawmill in Hampshire, UK. Three repeat trials encompassing the different seasons of the year were carried out over two years. Results show that fungal colonisation of sawn lumber is dependent on the effect of time of year. Sawlogs were stored for different intervals up to 16 weeks before conversion to boards. Boards were then stored for up to 12 weeks after milling and sampled every 4 weeks to determine the effect of timber ageing on fungal colonisation up to 28 weeks after felling. The metabolic activity of wood cells over the period after felling of the original tree was also measured. It was evident that the defacement of boards reached maximum levels after 12 weeks exposure irrespective of seasonal influences. Initial levels of fungal growth on lumber were reduced if the boards were milled from logs stored for a period prior to conversion. Investigations into the metabolic activity of the wood cells revealed significant levels of respiration taking place up to 28 weeks after felling of the original tree including 12 weeks post-conversion into boards. Boards were used to make a nested stack arrangement allowing plastic tanks top be placed in the centre. The tanks contained a sub-sample of the full-size boards in order to investigate insect activity and effects of gammairradiation. A total of 115 insect species representing 16 of the 34 British orders were collected during the trials. Seventy-two percent of these insects were collected from within the stacks of lumber and investigations using sealed tanks containing boards showed that the insects could influence the fungal colonisation of sawn lumber. Despite the relatively short length of the trials, a succession of insect colonisation from fungivores through to predators and detritivores was recorded. Boards, which were sterilised by gamma-irradiation, were preferentially colonised by mould fungi and subsequent internal staining was confined to the outer surface. Trials with short-length billets allowed the wood-colonising ability of selected sapstain fungi to be investigated under controlled conditions following sterilisation by gamma-irradiation or autoclaving, and storage at 30°C and 20°C. Lesion formation in gamma-irradiated tissue was solely due to the fungus potentially conditioning the wood for colonisation. Colonisation studies also revealed that different fungi exhibit different strategies enabling them to infect timber. Pathogenic species demonstrated a relatively fast initial growth rate to establish themselves before triggering any host anti-fungal responses in the wood. The characteristic lesions created in the billets were investigated using light and electron microscopy to reveal hyphal invasion and or/ wood cell modifications. Respiratory activity of the lesions was elucidated using radioactively labelled glucose allowing the metabolic pathways to be ascertained and demonstrated that wood tissue in the apparently healthy regions adjacent to the lesions reacted as if infected. Future work considers the possibility of biocontrol, using insects in combination with gamma-irradiation of sawn lumber and also further investigations into the reaction zones produced by the fungus growing in the wood.
33
Dickinson, J. M. "The chemistry of fungal biocontrol agents." Thesis, University of Sussex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267277.
Full text
34
Smith, Helen K. "Biosynthesis of the fungal metabolite tenellin." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4524/.
Full textAbstract:
This thesis concerns the biosynthesis of tenellin, a bright yellow secondary metabolite of the fungus Beauveria bassiana. Several putative intermediates have been synthesised and feeding experiments performed in order to provide some insight into the biosynthetic pathway. Tenellin was originally thought to be formed from the condensation of phenylalanine and a polyketide moiety, however recent studies have now shown that tyrosine is the more direct amino acid precursor. The biosynthesis is proposed to occur by rearrangement of tyrosine to 3-amino-2-(4-hydroxy)-phenylpropionic acid, in a similar manner to the rearrangement observed in alkaloid biosynthesis. The synthesis of this β- amino acid is described and the subsequent incorporation study using labelled material discussed. The result argues against the intermediacy of this compound in the biosynthesis of tenellin. Consequently, it is proposed that the biosynthesis of tenellin does not include the rearrangement of tyrosine, but instead proceeds via a five membered teframic acid, which is considered to undergo rearrangement and ring expansion to generate the pyridone ring of tenellin. The putative acyl tetramic acid precursor is synthesised and administered to cultures of Beauveria bassiana. Preliminary (^2)H NMR spectra indicate a possible incorporation and that the tetramic acid has a role in tenellin biosynthesis. Further analysis by HPLC and LCMS is described. The biosynthetic origin of H-6 of tenellin has never been established. Several experiments, including the synthesis of [2-(^2)H]-tyrosine, are described, but the origin of this proton remains unclear.
35
Ramalho, M. T. "Properties of fungal 3-carboxymuconate cyclases." Thesis, University of Kent, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377945.
Full text
36
Harley, Kate. "Investigating fungal tetraketide synthase gene clusters." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432732.
Full text
37
Lakay, Francisco Martin. "Fungal enzymes as animal feed additives." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52280.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2001.ENGLISH ABSTRACT: The use of fungal enzymes as ruminant feed digestibility enhancers was investigated. Currently, ruminants may not digest 38 to 80 % of fibrous forages' content. A renewed interest in the potential of feed enzymes for ruminants was prompted by the high costs of livestock production, together with the availability of newer enzyme preparations. Direct application of enzyme preparations can improve in vitro dry matter (DM) and neutral detergent fibre (NDF) degradation, indicating that direct-fed fibrolytic enzymes may be effective in enhancing in vivo digestion of forages. Two commercial enzyme products, Fibrozyme and Celluclast, and fungal extracellular enzyme extracts from Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, and Thermomyces lanuginosus were evaluated for enhancing in vitro feed digestibility. Fibrozyme addition to both wheat straw and lucerne hay did not improve their in vitro digestibilities, even after a two hour pre-incubation period. The four fungal enzyme extracts did not enhance wheat straw's digestibility, but marginal increases were evident for lucerne hay. Celluclast addition resulted in marginal increases in the digestibility of both oat hay and oat silage, with no enhanced effect on lucerne hay and NaOH-treated wheat straw. No relationship could be found between the level of enzyme activity and the degree of feed digestion in the in vitro assay. Enzyme hydrolysis with Celluclast, in the absence of rumen fluid, gave more conclusive results. All the feed samples tested showed a positive response to Celluclast addition, even the less digestible feeds, namely sugarcane bagasse and wheat straw. In vitro results show that the assays were unsuccessful, because almost all of the experiments conducted showed inconclusive results. Alternative feed evaluation assays, which include the in vivo, in sacco and in situ methods of analysis, as well as gas production measurement and in vitro analysis with the DAISyII system, should be evaluated. A more detailed study of feed digestibility should be motivated by determining which feeds are hydrolysable, their chemical composition, i.e. how accessible the feeds are, and also evaluation of feed mixtures. The enzyme supplements also need to be evaluated for optimum temperature and pH, as well as the compilation of enzyme cocktails.
AFRIKAANSE OPSOMMING: Die gebruik van swamensieme om die verteerbaarheid van herkouervoere te verhoog, is ondersoek. Tussen 38 en 80 % van veselagtige voere se inhoud is tans onverteerbaar. 'n Hernieude belangstelling in die potensiaal van voerensieme vir herkouers word deur die hoë koste van veeproduksie, asook die beskikbaarheid van nuwe ensiempreparate gedryf Direkte byvoeging van ensiempreparate kan die in vitro droëmateriaal (DM) en neutrale onoplosbare vesel (NOV) vertering verbeter, wat daarop dui dat fibrolitiese ensieme wat direk gevoer word, effektief mag wees tydens die in vivo vertering van voer. Twee kommersiële ensiemprodukte, Fibrozyme en Celluclast, en die vier ekstrasellulêre ensieme van vier swamme, naamlik Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, en Thermomyces lanuginosus is vir hul vermoë om die in vitro verteerbaarheid van voere te verbeter getoets. Byvoeging van Fibrozyme by beide koringstrooi en lusernhooi het geen verbetering in hulonderskeie in vitro verteerbaarheid tot gevolg gehad nie, selfs nie eens na 'n twee uur vooraf inkubasieperiode nie. Koringstrooi se verteerbaarheid is nie verbeter deur die byvoeging van die vier swam-ensiempreparate nie, maar 'n minimale verbetering is wel waargeneem in die verteerbaarheid van lusernhooi. Byvoeging van Celluclast het 'n minimale verbetering in beide hawerhooi en hawerkuilvoer se verteerbaarheid tot gevolg gehad, maar geen effek op lusernhooi of NaOH-behandelde koringstrooi se verteerbaarheid nie. Geen verwantskap is tussen die vlak van ensiemaktiwiteit en die mate van vertering tydens die in vitro toets gevind nie. Ensiematiese afbraak met Celluclast, in die afwesigheid van rumenvloeistof, het meer konkrete resultate gelewer. Al die voermonsters het 'n positiewe respons op die byvoeging van Celluclast getoon, selfs ook die minder verteerbare voere, nl. suikerrietbagasse en koringstrooi. In die wyer konteks was die resulate van die in vitro verteringstoetse egter onbeduidend as gevolg van groot variasie in die metings. Alternatiewe voerontledingstoetse, wat moontlik beter resultate mag lewer, sluit in in vivo, in sacco en in situ analises, asook die meting van gasproduksie en in vitro analise met die DAISyII sisteem. 'n Meer uitgebreide studie van voerverteerbaarheid wat die bepaling van die afbraak van voere, hul chemiese samestelling, met ander woorde toeganklikheid van voere, en die ondersoek van voermengsels behels, behoort aandag te geniet. Die ensiemmengsels behoort ook ten opsigte van samestelling, optimum temperatuur en pH ondersoek teword.
38
Stenzel, Desmond John Francis. "Biosynthesis of some polyketide fungal metabolites." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/13006.
Full text
39
Elcombe, Suzanne E. "The innate response to fungal infection." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/bd524bb3-6273-4ea3-9faa-7ef7092755d3.
Full textAbstract:
In the healthy individual fungal infections are relatively benign, however in the rapidly increasing population of immunosuppressed patients fungal infections have become an increasing cause of morbidity and mortality. In the response to fungal pathogens, the innate immune system recognises a series of specific PAMPs via the Dectin-1 and TLR2 receptors, ultimately resulting in pro and anti-inflammatory cytokine production. Following Dectin-1 activation, I show that blocking SYK activity with SYK inhibitor II prevents MAPK and NF?B signalling, causing a reduction in both pro and antiinflammatory cytokine production. However, the clinically used inhibitor R406 (fostamatinib), which has been described as a SYK inhibitor, does not block these signalling pathways downstream of Dectin-1 activation, but is able to abolish cytokine production. As R406 has these effects in response to not only Dectin-1 ligand stimulation, but also TLR2 and TLR4 stimulation, it is likely that these events are the result of an off target effect of R406, and not a result of SYK inhibition. In line with this, R406 was found to inhibit multiple kinases in an in vitro kinase screening panel. To investigate signalling further downstream of Dectin-1, I attempted to elicit the kinase responsible for ERK1/2 activation. For most stimuli, Raf-1 activates MEK1/2 which activates ERK1/2, however in response to TLR signalling the kinase Tpl2 is required to activate MEK1/2. I show that the kinase responsible for ERK1/2 activation downstream of Dectin-1 is not Tpl2, but is an unidentified off target effect of the Tpl2 small molecule inhibitor SHN681. MSK1 and 2 have previously been shown to be important in limiting inflammatory cytokine production by macrophages in response to the TLR4 agonist LPS. This is in large part due to the ability of MSKs to regulate the production of the anti-inflammatory cytokine IL-10. In this thesis I show that MSKs are activated in macrophages by fungal ligands, including the Dectin-1 specific agonists curdlan and depleted zymosan, via the ERK1/2 and p38a MAPK pathways. Further, I show that although MSKs regulate Dectin-1 induced IL-10 transcription, this does not significantly affect pro-inflammatory cytokine production. This is in direct contrast to the inhibition of these pro-inflammatory cytokine that we see post LPS stimulation. Investigating further, I show that although IL-10 secreted in response to zymosan is unable to suppress pro-inflammatory cytokine production, it is still able to promote STAT3 phosphorylation. I suggest that Gfi1 is involved as I show that LPS can induce high levels of Gfi1 expression, whereas zymosan does not induce Gfi1. One possible explanation would be that without Gfi1 to inhibit PIAS3, PIAS3 is binding the activated STAT3 and not allowing it to bind to DNA. This would result in STAT3 being unable to function, and hence no repression of proinflammatory cytokine expression would occur, regardless of the level of IL-10 present. Finally, I show that activation of Dectin-1 in a SYK dependent fashion resulted in macrophage switching to a regulatory macrophage phenotype. As regulatory macrophages are thought of as essentially anti-inflammatory, this may help explain why many people suffer commensal fungal infections that can persist for long periods of time without developing the classical inflammatory signs of infection.
40
Mazinga, I. P. "Fungal infection in HIV-positive patients." Thesis, Видавництво СумДУ, 2012. http://essuir.sumdu.edu.ua/handle/123456789/27524.
Full text
41
Zhang, Xing. "Exploring fungal virulence using C. elegans." Thesis, Aix-Marseille, 2020. http://theses.univ-amu.fr.lama.univ-amu.fr/200924_ZHANG_406xehco6dvggp718z420kj_TH.pdf.
Full textAbstract:
Parmi les candidats figuraient plusieurs entérotoxines thermolabiles, une famille de protéines qui est élargie dans le génome de D. coniospora par rapport à d'autres champignons pathogènes. Nous nous sommes concentrés sur 3 (DcEntA-C). L'expression de DcEntA et de DcEntB, mais pas de DcEntC, rendait les vers malades et plus sensibles à l'infection. Normalement, l'infection par D. coniospora provoque l'induction de l'expression de gènes codant des peptides antimicrobiens des familles nlp et cnc. Il est intéressant de noter que l'expression de la seule entérotoxine DcEntA a bloqué la transcription des gènes nlp et cnc. DcEntA a agi en inhibant la translocation nucléaire du facteur de transcription STAT STA-2, nécessaire à l'expression des gènes de défense. Nous avons démontré que cet effet était spécifique car DcEntA a induit une forte expression d'un gène inductible par une infection indépendante de STA-2. En revanche, les vers exprimant l'entérotoxine DcEntB présentaient une élévation de l'expression de nlp-29 dépendante de STA-2. DcEntB est localisé au niveau du nucléole et affecte la taille et la morphologie du nucléole. La base moléculaire de ces différences et l'importance relative de ces facteurs au cours de l'infection ont été étudiées en détail. Notre résultat révélé la complexité des stratégies de virulence fongique. Globalement, en disséquant le mode d'action des différents facteurs de virulence, cette étude nous a permis de mieux comprendre la pathogénie fongique et la course évolutive entre l'hôte et l'agent pathogèneAmong the candidates were several heat-labile enterotoxins, a protein family that is expanded in the genome of D. coniospora compared to other pathogenic fungi. We focused on 3 (DcEntA-C). Expression of DcEntA and DcEntB, but not DcEntC made worms sick and more susceptible to infection. Normally, D. coniospora infection provokes the induction of expression of antimicrobial peptide genes of the nlp and cnc families. Interestingly, expression of the single enterotoxin DcEntA blocked the transcription of both nlp and cnc genes. DcEntA acted by inhibiting the nuclear translocation of the STAT transcriptional factor STA-2, required for defence gene expression. We demonstrated that this effect was specific as DcEntA induced high expression of a STA-2-independent infection-inducible gene. In contrast, worms expressing the enterotoxin DcEntB exhibited a STA-2 dependent elevation of nlp-29 expression. DcEntB was localized to the nucleolus and affected nucleolus size and morphology. The molecular basis of these differences and the relative importance of these factors during infection was explored in detail. Our result revealed the complexity of fungal virulence strategies. Overall, by dissecting the mode of action of different virulence factors, this study allowed us to understand better fungal pathogenesis and the evolutionary arms race between host and pathogen
42
Sheth-Ughade, Parita. "Immunological responses to fungal epitope peptides." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/immunological-responses-to-fungal-epitope-peptides(1f8234cb-77e4-4577-a6ba-e57d502048a4).html.
Full textAbstract:
Introduction: Fungi are common aeroallergens responsible for at least 3% – 10% of allergic diseases worldwide, with the proportion hugely variable in different populations. Treatment is complicated by viable nature and disease causing ability of the allergen and is often only palliative. Thus, this study aimed to serve as a pilot investigation to design novel anti-allergy therapeutics to cure allergy at the molecular level. It investigates the effect of wild type fungal peptides and corresponding variant peptides on allergy associated immunological responses – cellular and cytokine based – to use such variant peptides to cause the delicate shift from an allergic to a normal immune response. Further, the study explores the role of bioinformatics in investigating allergy and designing novel therapeutics. Methods: This study used ProPred, a bioinformatics software, to predict wild type peptides from selected allergens of Aspergillus fumigatus and Alternata alternaria for a target population. These were then modified to generate single amino acid variants. Both these peptide sets were tested to compare the cellular and cytokine patterns they generated in sensitised (n = 3) and healthy volunteers (n = 3) to check for anti-allergy responses that may be exerted by certain variants. The recruited population was also subjected to skin prick testing (SPT, n = 46) to check for co-sensitisations patterns and HLA typing (n = 40) to evaluate ProPred accuracy for peptide prediction. This study also attempted an in silico search for unknown Penicillium chrysogenum allergens by comparing known Penicillium and A. fumigatus allergens to identify probable agents of co-sensitization. Results: Of the wild type and variant peptides tested in this study, one variant peptide – peptide 1.1v from Asp f 2 – was successfully identified to change the cellular and cytokine profile to promote an anti-allergic response when compared to its corresponding wild type form (1.1o). This candidate is a good target for further investigation for use in peptide immunotherapy. Further, 8 shared allergens between A. fumigatus and P. chrysogenum were identified that may possibly be agents of co-sensitization between these species. SPT results indicated maximum subject co-sensitization between A. fumigatus and Candida albicans and P. chrysogenum. HLA typing results demonstrated the efficiency of ProPred to be 96.29%, thus implying that bioinformatics can effectively be used to study allergy in this novel manner. Conclusion: This study has demonstrated that variant peptides with a single amino acid change can cause the delicate shift from an allergic to a healthy immune response in sensitised subjects. This approach – in combination with other allergy associated factors such as epitope specificity for HLA types and inherent co-sensitization patterns in a population – can effectively be used to design peptide candidates for immunotherapy to target allergy at the molecular level. With promising results obtained in this pilot study, this approach guarantees further investigation in immunotherapy. This study has also demonstrated that bioinformatics can be effectively used to design and execute allergy studies in a targeted and inexpensive manner.
43
Choi, Yuen-wah. "The fungal diversity of Brucea javanica /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2505904x.
Full text
44
Lo, Victor. "Hydrophobins: Biological application of fungal proteins." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18961.
Full textAbstract:
Hydrophobin protiens are unique to the fungal kingdome and have evolved to function in different roles during the growth and development of filamentous fungi. Due to the unique properties of these proteins to self-assemble into amphipathic monolayers at hydrophobic:hydrophlic interfaces, they can be found as biosurfactants, protective coatings and as primers to enhance surface adhesion. In recent decades there has been a significant development towards the applying these proteins to a range of different research fields, from food technology and surface coatings to drug delivery devices. However, the understanding of the mechanism in which these proteins undergo self-assemble at the interface is still lacking. In this project, I have combined high resolution imagaing techniques, such as AFM, TEM and TEM tomography to compare the substructure of different Class I hydrophobin rodlet films, and using colometric kinetic assays to delineate a model for the assembly mechanisms at the interface. With the information, I was able to reveal that the exposure of hydrophobin proteins to the surface interface is a determining factor. By altering the surface interface with additives, such as ethanol, it was possible to manipulate the hydrophobin film structure and physioproperties. This knowledge was used to successfully formulate a nanosupsension of hydrophobin with hydrophobic compounds, such as curcumin and Amphotericin B. This research project lays the foundation for the future development and refinement of hydrophobin-based technologies.
45
Arnold, Anne Elizabeth. "Neotropical fungal endophytes: Diversity and ecology." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/289841.
Full textAbstract:
Fungal endophytes associated with leaves of woody plants are thought to be diverse and abundant, especially in tropical forests. However, associations of endophytes with tropical woody angiosperms have not been characterized in detail. In this dissertation, I assess: (1) the scale of endophyte biodiversity in a tropical forest; (2) ecological, temporal, and host-mediated factors influencing endophyte abundance in leaves of tropical trees; (3) utility of endophyte morphospecies as functional taxonomic units; and (4) the nature of endophyte-host interactions. To characterize endophyte biodiversity, I measured endophyte richness in asymptomatic leaves of two distantly related, but co-occurring, host species in lowland forest in central Panama. I found that endophytes are highly diverse within leaves, plants, and host species, and that they demonstrate both host preference and spatial heterogeneity. To determine factors influencing abundance of tropical endophytes, I assessed effects of inoculum abundance, duration of exposure to inoculum, phylogenetic position of host, and leaf traits (e.g., chemical and structural defenses) on rates of endophyte infection. I found that endophyte abundance is sensitive to inoculum abundance in the short term, but to duration of exposure over the long term. In turn, inoculum abundance is sensitive to canopy cover, time of day, and time since precipitation. Generally, neither leaf traits nor phylogenetic position of hosts is related to rates of endophyte infection: endophytes occur with consistently high abundance and diversity among representatives of 14 orders of angiosperms. To assess utility of morphospecies as taxonomic units, I compared diversity and taxonomic composition among morphospecies of endophytes as delineated using several criteria, and among species as inferred using nrDNA data. I found that conservatively designated morphospecies can approximate species boundaries as defined by nrDNA data for diverse Ascomycota. Finally, I examined effects of endophytes on (1) minimum leaf conductance, a measure of water loss from leaves under drought conditions; and (2) leaf mortality and necrosis in the presence of a foliar pathogen for a focal host. I found that endophytes may cost their hosts by increasing water loss under conditions of severe drought, but that they also may play an important role in host defense against pathogens.
46
Gorton, Rebecca Louise. "Molecular diagnosis of invasive fungal disease." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10047377/.
Full textAbstract:
BACKGROUND: Invasive fungal infections (IFI) are opportunistic infections caused by yeast or filamentous fungi, typically presenting in immunocompromised patients (haemato-oncology, intensive care, HIV, solid organ transplant settings). This research aims to comprehensively evaluate molecular diagnostics to address the current shortfall in IFI diagnosis and, where appropriate, embed molecular methods into routine clinical service. METHODS: Molecular methodologies, including PCR, MALDI-TOF MS and PNA-FISH, were evaluated on clinical sample cohorts from the Royal Free Hospital NHS Foundation Trust. Each method was critically appraised for: statistical performance, clinical utility and suitability for service adoption. RESULTS: MALDI-TOF MS improved yeast agar culture identification, demonstrating 97.4% (185/190) concordance with ITS rRNA sequencing, and time to identification was significantly reduced (p < 0.01, 24 hrs. v’s 15 mins). Lower identification rates of 66% (33/50) were observed when applying MALDI-TOF MS directly to blood culture for yeast identification. In contrast PNA-FISH identified 98.5% (93/96, CI: 91.2, 98.9) of yeasts direct from blood culture within 30 minutes. Using PCP PCR a 60% (3/5) increase in the detection of PCP from BAL in non-HIV patients was demonstrated compared with GMS staining. Overall sensitivity was 100% (95% CI: 56.6, 100) and specificity was 97.9% (95% CI: 88.9, 99.6) for the diagnosis of PCP. Aspergillus PCR demonstrated a sensitivity of 100% (95% CI: 34.2, 100) and specificity of 93.8% (95% CI: 86.4, 97.3) for the diagnosis of IA but a low PPV of 28.6% (95% CI: 8.2, 64.1). CONCLUSIONS: Molecular diagnostic assays can improve the diagnosis of IFI through improved accuracy of identification and increased detection of fungal pathogens from specimens. Results must be interpreted alongside clinical presentation, as false positivity occurs utilising highly sensitive molecular assays. Dual biomarker strategies may improve the performance of molecular diagnostics but the associated impact on healthcare economics must also be considered.
47
Ricks, Kevin Daniel. "Biotic Filtering in Endophytic Fungal Communities." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6871.
Full textAbstract:
Plants can be colonized by complex communities of endophytic fungi. This thesis presents two studies, both of which investigate biotic filtering in endophytic fungal communities. Chapter 1. Endophytic fungi can be acquired horizontally via propagules produced in the environment such as in plant litters of various species. Given that litters from different plant species harbor distinct endophytic fungal communities and that endophytic fungi may be dispersal-limited, the structure of the endophytic fungal community of a given plant may be determined by proximity to particular inoculum sources. Community assembly may also be affected by biotic filtering by the plant. Therefore, a plant may be able to select particular fungal taxa from among the available pool. In that case, the structure of the endophytic fungal community in the plant could be somewhat independent of the structure of the inoculum community. We tested the hypothesis that biotic filtering of endophytic fungal communities occurs in Bromus tectorum by exposing it to a variety of inoculum sources including litters from several co-occurring plant species. The inoculum sources differed significantly from each other in the structures of the communities of endophytic fungi they harbored. We characterized the structures of the resulting leaf and root endophytic fungal communities in Bromus tectorum using high-throughput sequencing. All tested inoculum sources successfully produced complex communities of endophytic fungi in Bromus tectorum. There was significantly more variation in the structures of the communities of endophytic fungi among the inoculum sources than in the resultant endophytic fungal communities in the leaves and roots of Bromus tectorum. These results suggest that biotic filtering by Bromus tectorum played a significant role in the assembly of the endophytic fungal communities in tissues of Bromus tectorum. Because endophytic fungi influence plant fitness, it is reasonable to expect there to be selective pressure to develop a uniform, desirable endophytic fungal community even from disparate inoculum sources via a process known as biotic filtering. Chapter 2. Frequently one finds that different plant species harbor communities that are distinct. However, the nature of this interspecific variation is not clear. We characterized the endophytic fungal communities in six plant species from the eastern Great Basin in central Utah. Four of the species are arbuscular mycorrhizal (two in the Poaceae and two in the Asteraceae), while the other two species are nonmycorrhizal (one in the Brassicaceae and one in the Amaranthaceae). Our evidence suggests that both host mycorrhizal status and phylogenic relatedness independently influence endophytic fungal community structure.
48
Lahore, S. "¿SYNTHETIC STUDIES TOWARDS BIOACTIVE FUNGAL METABOLITES¿." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/229905.
Full textAbstract:
The problem of the development of new pesticides is very urgent, mainly because of the appearance of pest forms resistant to permitted pesticides and for the strict requirements in terms of their safety for people and the environment. Small molecules produced in biological contexts have been, and still are, a large reservoir of new biologically active substances, which can become scaffolds for the discovery of new agrochemicals.
The aim of this PhD work was to synthesize naturally occurring potentially antifungal and herbicidal compounds and to test their biological activity.
Efforts mainly focused towards the total synthesis of Bulgarein, a fungal metabolite produced by the fungus Bulgaria inquinans. Bulgarein possesses a benzo[j]fluoranthene skeleton, that can be found in a number of polyketide-derived fungal metabolites endowed with significant biological activity, in particular inhibition of Topoisomerase I. As no attempt to synthesize any of these compounds has been reported in literature so far, a synthetic sequence to the benzo[j]fluoranthene nucleus has been developed. Crucial steps for our strategy include a Suzuki coupling followed by a McMurry ring closure. The approach is modular and rapid and can be utilized to synthesize natural products, biologically active analogues or building blocks for the preparation of materials. Following this strategy, the first total synthesis of the recently isolated natural product benzo[j]fluoranthene-4,9-diol was carried out. Efforts were made to adapt the sequence for the synthesis of Bulgarein and other variously substituted compounds with this skeleton.
As a second topic in this research, attention was dedicated to another natural compound, Farinomalein A, a structurally rather simple maleimide isolated in 2009 from the entomopathogenic fungus Paecilomyces farinosus. Farinomalein shows potent inhibition of Phytophthora sojae, a plant pathogen that every year causes enormous damage to soybean crops. Recently, three new farinomalein derivatives (Farinomalein C, D & E) were isolated from an endophyte from the mangrove plant Avicennia marina, growing in Oman.
Due to the interesting antifungal activity of this class of compounds, a practical synthesis of farinomalein A was developed, which may have value in the large-scale preparation of the natural compound. Starting from farinomalein A, all the three derivatives were successfully synthesized . The antifungal activity of the derivatives was evaluated against Cladosporium cladosporioides and other pathogenic fungi.
An approach to the synthesis of Ascaulitoxin, a phytotoxic metabolite produced by the fungus Ascochyta caulina, was also developed.
49
OTTAVIANO, EMERENZIANA. "TACKLING BIOFILM-RELATED OPPORTUNISTIC FUNGAL INFECTIONS." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/807858.
Full textAbstract:
More than 1.5 million people/year die for a biofilm-related fungal
infection. The ability to develop biofilms is widespread among
human opportunistic pathogens, among them fungi. Biofilms are a
community of microorganisms with the ability to attach to surfaces
biotic or abiotic, surrounded by a self-produced extracellular
polymeric matrix. The pathogen clearance and the general
overcoming of the infection are complicated by biofilm presence as
it confers tolerance to antimicrobial treatments. Compromised or
altered immune response and an inflammatory milieu can
exacerbate the pathogenesis and prolong the resolution of the
infection. Candida albicans, between yeasts, and Aspergillus
fumigatus between molds, are pathobionts considered the most
common agents of opportunistic fungi mediated. In our study we
assessed different strategies to eradicate biofilms and counteract
biofilm-related infections, targeting both pathogens and host
immune response. We investigated the efficacy of urinary fractions
after cranberry extract intake by healthy volunteers against C.
albicans biofilm. By mass spectrometry analyses, we identified two
metabolites picking in the most active urine fractions, 5-(3′,4′-
dihydroxy phenyl)-γ-valerolactone and 4-hydroxybenzoic acid,
which revealed a strong inhibitory effect on C. albicans adhesion
and biofilm formation. Both compounds were also able to
downregulate the expression of key genes involved in early phases
of biofilm formation. Due to the spread of the use of catheters or
prostheses in the medical field, the possibility to develop
biomaterials with biofilm inhibitory activity could represent a good
10
strategy to control nosocomial infections. We thus investigated
newly synthesized hydrogels and demonstrated their ability to
prevent C. albicans growth.
To target both pathogen virulence and host immune response, we
conducted two different studies, the first on C. albicans systemic
candidiasis and the second on A. fumigatus infection in cystic
fibrosis patients.
We investigated the possible dual action of pilocarpine, a
muscarinic receptor agonist, in vitro and in vivo using the model
host Galleria mellonella. Pilocarpine showed a direct effect in
inhibiting C. albicans biofilm biomass and metabolic activity, and its
administration to infected larvae increased larval survival. Because
of the different behavior of pilocarpine compared to acetylcholine in
the modulation of larva immune response, we concluded that the
antifungal activity of pilocarpine might rely on muscarinic-like
receptor activation on C. albicans, whereas the strong
immunomodulatory effect of acetylcholine (but not of pilocarpine)
might imply the engagement of nicotinic receptors. A similar
approach, aimed at targeting both infection and inflammation, was
used to investigate A. fumigatus persistence in CF patient lungs.
Indeed, CF monocytes are characterized by altered intracellular
lipid accumulation, that compromise pathogen clearance, and the
infection resolution. We demonstrated that the treatment of patient
monocytes with Myriocin, by inhibiting the synthesis of sphingolipids
and hampering CF inflammation, ameliorate the A. fumigatus
conidia internalization and clearance. On the host side, Myriocin
11
was able to reduce the over expression of genes encoding for proinflammatory
cytokines and at the same time to increase the
expression of gene encoding for pathogen recognizing receptors,
crucial for its clearance.
Our results indicate that, despite we are still far from clinical
practice, exploring alternative anti-biofilm strategies could pave the
way to new target discovery and to integrated approaches able to
promote the infection resolution.
50
Nguyen, Hai. "Taxonomy, Phylogeny and Genomics of the Wallemiomycetes and a Newly Discovered Class of Extremophilic Fungi." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32386.
Full textAbstract:
New species of fungi that belong to the class Wallemiomycetes and related lineages were discovered and characterized. The Wallemiomycetes includes species of brown moulds from the genus Wallemia. Further study was warranted for Wallemia sebi because of its ubiquity in the human indoor environments and its potential roles in food spoilage, human allergy and disease. A survey of Wallemia in house dust was conducted. Sequencing of DNA and application of the genealogical concordance phylogenetic species recognition (GCPSR) led to recognition of four species within the W. sebi species complex (WSSC) and served as the foundation for phenotypic assessment and the formal description of three new species called W. mellicola, W. canadensis and W. tropicalis. A survey of heat resistant fungi in soils coincidentally resulted in the discovery of a new lineage of fungi related to Wallemia. This new lineage included a previously described monotypic genus Basidioascus and a new sister genus given the name Geminibasidium. A part of the morphological life cycle of these fungi was documented where two new basidial types were discovered, followed by the description of three new species called B. magus, G. donsium and G. hirsutum. Further studies on the sexuality and origins of the species B. undulatus were carried out with genome sequencing, genome analysis, confocal microscopy and electron microscopy. These results led to the creation of a new class of fungi called the Geminibasidiomycetes, which are distantly related to the Wallemiomycetes. Solving the WSSC, circumscribing a new class of fungi called Geminibasidiomycetes and characterizing the species of Geminibasidiomycetes on a taxonomic and genomic level are my original contributions to scientific knowledge.