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1
Johansson, Per. "Effects of habitat conditions and disturbance on lichen diversity : studies on lichen communities in nemoral, boreal and grassland ecosystems /." Uppsala : Dept. of Conservation Biology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200606.pdf.
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Candotto, Carniel Fabio. "Meccanismi di risposta di simbionti lichenici allo stress foto-ossidativo." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/10139.
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2012/2013I licheni, una simbiosi mutualistica tra un fungo (il micobionte), generalmente un ascomicete, e una o più popolazioni di alghe e/o cianobatteri (il fotobionte) sono considerati forme di vita estremofile in quanto da disidratati possono resistere a condizioni ambientali molto difficili come elevati irraggiamenti solari, scarsa disponibilità d'acqua e di nutrienti e dosi elevate di inquinanti aerodiffusi. Tali fattori di stress tuttavia inducono una sovrapproduzione a livello cellulare di specie reattive dell'ossigeno (ROS), che se eccede le difese antiossidanti genera stress ossidativo. L'accumulo delle ROS è un fenomeno molto pericoloso perché porta al danneggiamento di importanti macromolecole come lipidi, proteine e DNA ed in casi estremi può condurre anche alla morte cellulare. Sebbene gli effetti dello stress foto-ossidativo nei licheni siano già stati studiati, in questo dottorato di ricerca si è voluto approfondire alcuni aspetti ancora poco chiari relativi alla resistenza dei fotobionti a questo stress e alla resistenza dei licheni allo stress ossidativo indotto dalla presenza di elevate concentrazioni di inquinanti fotochimici come l'ozono (O3). Sul primo filone di ricerca sono stati condotti due studi. Nel primo ci si è focalizzati sugli effetti dello stress foto-ossidativo su parametri fisiologici di vitalità (ChlaF) e di produzione di ROS in un fotobionte lichenico e nella sua controparte lichenizzata. Ciò è stato ottenuto sottoponendo colture axeniche del fotobionte Trebouxia sp. e lobi del lichene Parmotrema perlatum da cui è stato isolato il fotobionte, a diverse combinazioni di umidità relativa e intensità luminose per periodi di tempo crescenti. L'obiettivo di questo studio è stato quello di approfondire le conoscenze sui benefici indotti dalla lichenizzazione nella resistenza al disseccamento e al concomitante stress foto-ossidativo. Il secondo studio invece, strettamente connesso al primo, è focalizzato sulla variazione di espressione genica dell'intero trascrittoma del fotobionte Trebouxia gelatinosa, isolato dal lichene Flavoparmelia caperata (L.) Hale, indotta da eventi di disidratazione e reidratazione. Con questo studio si è voluto individuare ed analizzare i meccanismi molecolari alla base della tolleranza di questo organismo al disseccamento e al concomitante stress fotoossidativo. Sul secondo filone di ricerca invece è stato condotto uno studio sulle risposte fisiologiche, citologiche e biochimiche del lichene Flavoparmelia caperata (L.) Hale sottoposto a fumigazioni con O3 e mantenuto a diversi regimi di idratazione e di umidità relativa ambientale. L'obiettivo di questo studio è stato quello di verificare se la tolleranza di questo lichene allo stress ossidativo derivante dall'esposizione all'O3 dipende da una strategia O3-avoidant, imputabile alla sua inattività metabolica durante le ore della giornata in cui si verifica il picco dell'O3, oppure da una O3-tolerant, dovuta invece alla presenza di un cospicuo ed efficace corredo di difese antiossidanti. Il primo studio ha dimostrato che il fotobionte algale al di fuori della simbiosi è in grado di resistere a livelli elevati di stress foto-ossidativo anche per periodi molto lunghi. Tuttavia è stato confermato che la simbiosi adduce benefici importanti come l'aumento della capacità di estinzione dell'energia accumulata dalle clorofille attraverso meccanismi non fotochimici e un ridotto effetto ossidativo indotto dal disseccamento. Questi risultati ci hanno permesso di sfatare l'ormai consolidata idea che i fotobionti algali, in particolare quelli del genere Trebouxia, siano particolarmente delicati e incapaci di tollerare autonomamente (al di fuori della simbiosi) fattori di stress abiotici come quelli che intervengono durante il disseccamento. Dai risultati del secondo studio è emerso che il fotobionte T. gelatinosa per far fronte alle importanti alterazioni dovute alla perdita d'acqua, si affida soprattutto a meccanismi che intervengono durante la fase di reidratazione. I più importanti coinvolgono molecole di riparazione “chaperone”, e. g. “Heath Shock Proteins”, e proteine della famiglia “Desiccation Related Proteins”, la cui funzione è ancora sconosciuta, ma visto l'elevato numero, la loro diversità intraspecifica e la sensibilità ai cambi di contenuto idrico, sembrano giocare un ruolo molto importante. Paradossalmente invece non sono state osservate alterazioni nell'espressione di geni collegati alle difese antiossidanti, che è sempre rimasta a livelli costitutivi. Ciò è stato interpretato come una strategia che permette all'organismo di avere sempre a disposizione mRNA per la neo-sintesi di nuovi enzimi coinvolti nelle difese antiossidanti. Infine nell'ultimo studio è stata riconfermata l'elevata resistenza del lichene F. caperata allo stress ossidativo derivato dall'esposizione all'O3 in quanto alla concentrazione utilizzata, ovvero il massimo registrato nell'ambiente alle nostre latitudini, non è stato osservato alcun effetto sulla vitalità nonostante sia stata osservata una notevole produzione di ROS. L'effetto ossidativo dell'O3 infatti è stato controbilanciato dalle difese antiossidanti le quali si sono mostrate altamente sensibili all'esposizione ed efficaci anche a bassi contenuti idrici. Lo stress ossidativo derivante da fattori abiotici di origine naturali e antropica dunque sembra essere gestito efficacemente sia dai licheni che dai loro fotobionti isolati, grazie ad efficienti difese antiossidanti e all'intervento di meccanismi di riparazione del danno.
XXVI Ciclo
1983
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Denoeud-Valdeyron, Marie-Laure. "Les lichens, bioindicateurs de pollution atmospherique : application aux alentours de l'usine roquette a lestrem." Lille 2, 1992. http://www.theses.fr/1992LIL2P020.
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MATHEY, ANNICK. "De in situ lichenum investigatione de l'analyse in situ des lichens." Paris 6, 1987. http://www.theses.fr/1987PA066744.
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Le but de l'etude est de montrer, a partir d'exemples qu'il est possible de reunir des informations sur une plante (morphologie, anatomie, chimie et ecologie) sans creation d'artefact et de remplacer des donnees subjectives par des donnees mesurables, c'est-a-dire reproductibles. Les lichens constituent un modele biologique
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Chu, Fung Joanna. "Ecology of supralittoral lichens on Hong Kong rocky shores /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18735526.
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Nguyen, Thi Thu Tram. "Screening of mycosporine-like compounds in the dermatocarpon genus : phytochemical study of the lichen dermatocarpon luridum (WITH.) J.R Laundon." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S177/document.
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Un criblage phytochimique à partir de quatre lichens saxicoles hydrophiles du genre Dermatocarpon a mis en évidence la présence inattendue de composés de type mycosporines dans ces chlorolichens. Leur présence a été confirmée dans des échantillons historiques d'herbiers couvrant une période de plus de 170 ans. Leur teneur était comprise entre 0,1 et 1,4 mg/g de lichen sec. Trois mycosporines ont été isolées de Dermatocarpon luridum collecté en Bretagne sur des rochers d'eau vive: deux mycosporines natives, la mycosporine glutaminol et la mycosporine glutamicol ainsi qu'un artéfact d'isolement, l'ester éthylique de la mycosporine glutamicol. Leurs propriétés physico-chimiques incluant le calcul de leur pKa ont été déterminées. L'étude phytochimique a également conduit à l'isolement de sept autres composés dont un acide aminé non protéique, un dipeptide et un céramide identifiés pour la première fois dans un lichen et le cérévistérol jusqu'ici non décrit dans D. luridum. Les activités cytotoxiques et photoprotectrives des composés disponibles en quantité suffisante ont été évaluées. Le cérévistérol a montré une cytotoxicité modérée sur huit lignées cellulaires contrairement aux cinq autres composés. Les propriétés photoprotectrices et activités antioxydantes de l'ester éthylique de la mycosporine glutamicol et d'un extrait aqueux semi-purifié de D. miniatum présentent un intérêt pour un possible développement comme actif solaireA screening of mycosporine-like compounds in four hydrophilic Dermatocarpon lichen species has highlighted the unexpected occurrence of such metabolites in chlorolichens. These compounds were confirmed and quantified in historical herbarium samples (15-50 mg) even more than 170 years old. Total mycosporine contents ranged from 0.1 to 1.4 mg/g of dry lichens. Two genuine mycosporines (mycosporine glutaminol and the more stable mycosporine glutamicol) with an artifact mycosporine glutamicol ethyl ester were isolated from Dermatocarpon luridum collected in a breton river. Their physico-chemical properties were also determined including pKa. The phytochemical studies led to the isolation of seven additional compounds in which a non-protein amino acid, a dipeptide and a ceramide were identified for the first time in lichens and cerevisterol for the first time in D. luridum. Compounds obtained in suitable quantity were evaluated for their cytotoxic and photoprotective properties. Except a moderate cytotoxicity of cerevisterol, the five tested compounds were not found toxic on the eight cell lines. Photoprotective properties of the mycosporine glutamicol ethyl ester and a semi-purified aqueous extract of Dermatocarpon miniatum along with some antioxidant activities are promising to develop new sunscreens
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Cooper, Susan Mary. "Genital lichen planus." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432941.
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Caldiz, Mayra S. "Diversity and growth of epiphytic macrolichens in northwestern Patagonian Nothofagus forests /." Alnarp : Swedish University of Agricultural Sciences, 2005. http://diss-epsilon.slu.se/archive/00000831/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005.Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts, three co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks appendix.
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Högnabba, Filip. "Phylogenetic studies of cyanobacterial lichens /." Helsinki : Yliopistopaino, 2007. http://ethesis.helsinki.fi.
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Roullier, Catherine. "Recherche de mycosporines et de dérivés aminés lichéniques d’intérêt pour les cancers photoinduits : étude phytochimique d’un lichen marin : Lichina pygmaea (Lightf.) C. Agardh." Rennes 1, 2010. http://www.theses.fr/2010REN1S085.
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Suite à l’augmentation croissante des cancers de la peau, la recherche de nouvelles solutions thérapeutiques (et préventives) est nécessaire. Les lichens sont une source prometteuse de métabolites secondaires. Dans un premier temps, un criblage de différents lichens à cyanobactéries a permis de mettre en évidence la présence de composés de type mycosporine dans plusieurs d’entre elles et notamment d’une structure nouvellement décrite. La mycosporine sérinol a pu ensuite être isolée en quantité à partir d’un lichen marin Lichina pygmaea. Son étude phytochimique plus poussée a conduit à l’isolement de nouveaux dérivés aminés, comme la pygméine dont l’accès à des analogues de synthèse a permis de confirmer son identification. La plupart des composés obtenus en quantité suffisante ont été évalués pour leurs capacités photoprotectrice et à visée anticancéreuse. Quelques composés ont montré une activité intéressante et pourraient être de bons candidats dans la protection des cancers photoinduitsAs cutaneous cancers are increasing, research of new therapeutic solutions is necessary and the lichens are a promising source of secondary metabolites. Initially, a screening of various lichens containing cyanobacteria has highlighted the presence of mycosporine-like compounds in several of them, including a newly described structure. Then, mycosporine serinol has been isolated quantitatively from a marine lichen Lichina pygmaea. Further phytochemical studies led to the isolation of new amino derivatives, like pygmeine which has been synthetized along with analogues. Most of the compounds obtained in suitable quantity were evaluated for their photoprotective properties and in anti-cancer targeted tests. Some compounds showed interesting activity and could be good candidates in the protection of photoinduced skin cancers
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Sumner, Robert Walker 1975. "Pattern formation in lichen." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86757.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 73-76).
by Robert Walker Sumner.
S.M.
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Girard, François. "Remise en production des pessières à lichens de la forêt boréale commerciale : nutrition et croissance de plants d'épinette noire trois ans après traitements de préparation de terrain /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2004. http://theses.uqac.ca.
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Carter, Nick. "Bioprotection explored : lichens on limestone." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396154.
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Hogan, Erika. "Nitrogen-phosphorus relationships in lichens." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10906/.
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Nitrogen enrichment promotes phosphomonoesterase (PME) activity in the common heathland lichen Cladonia portentosa. This is associated with a marked increase in thallus N:P mass ratio and significant up-regulation of inorganic phosphate uptake capacity, evidencing a shift from N-limited to P-limited growth. Phosphomonoesterase activity in C. portentosa responds rapidly to change in N deposition load, with a significant increase in activity recorded within 6 months of transplantation from a low-N to high-N site. The location of PME activity in C. portentosa was revealed using a fluorescent marker and was found to be concentrated on both the outer and inner surfaces of the hollow ‘tube-like’ thallus branches. Activity appeared to be associated exclusively with the mycobiont and was located within the hyphal-lumina, consistent with a membrane bound ecto-enzyme. High PME activity in axenic mycobiont cultures of C. portentosa provided further evidence of a fungal location and confirmed that rates of activity in this lichen are amongst the highest reported for any other plant/fungal system in the literature. Different classes of phosphatases were assayed in a range of N2-fixing and non-N2-fixing lichens in an oligotrophic subarctic environment. No relationship was found between the capacities for nitrogenase and PME activities. Maximum rates of PME activity were recorded in fruticose mat-forming lichens which capture nutrients predominantly from atmospheric deposits. 5´ nucleotide phosphodiesterase activity was readily detected in N2-fixing lichens and was particularly high in rhizine-rich regions of foliose terricolous lichen thalli, consistent with the utilisation of organic phosphates from soil and litter sources.
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McDaid, Ann. "Chemical characterisation of Irish lichens." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282253.
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Salix, Jessie Lynn. "Lichens and their distribution in Lewis and Clark Caverns State Park." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/salix/SalixJ04.pdf.
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Sangvichien, Ek. "Studies on tropical lichen mycobionts." Thesis, Liverpool John Moores University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431284.
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Harries, Matthew. "The immunopathobiology of lichen planopilaris." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/the-immunopathobiology-of-lichen-planopilaris(a72b5c46-fcfd-46c8-a30a-715720233f59).html.
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Introduction: The hair follicle bulge has recently been added to a growing list of human tissue compartments that exhibit a complex combination of immunosuppressive mechanisms, termed immune privilege (IP), which appear to restrict immune mediated injury in specific locations. As epithelial hair follicle stem cells (eHFSC) reside in the hair follicle bulge region it is conceivable that these IP mechanisms protect this vital compartment from immune-mediated damage, thereby ensuring the ongoing growth and cyclic regeneration of the hair follicle. Lichen planopilaris (and variants) are inflammatory hair disorders that result in hair follicle destruction and permanent alopecia. Growing evidence suggests that eHFSC destruction is a key factor in the permanent follicle loss seen in these conditions, and that IP collapse may predispose these cells to immune mediated injury. Aims: The overall aim of this project was to generate immunohistomorphometric, gene profiling, and limited functional evidence to probe the 'bulge immune privilege collapse' hypothesis in a carefully selected model disease for inflammation-induced epithelial stem cell death, lichen planopilaris (LPP). Methods: Adult patients with LPP (or variant frontal fibrosing alopecia) were recruited. Biopsies from lesional and non-lesional scalp skin were performed and either snap frozen in liquid nitrogen, fixed in formalin for paraffin embedding or transferred immediately for hair follicle organ culture. Both frozen and paraffin embedded tissue was processed for immunohistochemistry (IHC) analysis using various immune privilege, hair bulge (eHFSC) and immune cell markers. Cultured samples were supplemented with various chemicals know to influence hair follicle immune privilege with analysis performed using IHC. Further, additional paired lesional and non-lesional samples were sectioned horizontally for laser capture microdissection of bulge cells. Following extraction of RNA, reverse transcription and amplification of cDNA from these selected bulge cells; gene expression profiling was performed comparing lesional with non-lesional samples. Selected, differentially regulated genes were validated using IHC and quantitative real-time PCR. Results: Bulge IP collapse is present in active LPP, as suggested by increased expression of MHC class I, β2microglobulin and MHC class II, along with reduced expression of the locally produced immunosuppressant TGFβ2, at both the gene and protein level. Microarray pathway analysis supports these data with the antigen processing canonical pathway being prominently enriched. Cell mediated immune responses are prominent in active disease, suggested by significantly increased numbers of activated and cytotoxic T-cells infiltrating the bulge epithelium, along with greater numbers of mast cells and macrophages in the peri-follicular connective tissue sheath. Bulge cell eHFSC loss is suggested by loss of bulge cell markers (e.g. keratin 15) on IHC, microarray and qPCR, and supported by microarray analysis showing virtually global loss of recognised bulge eHFSC signatures. Hair follicle organ culture experiments confirm bulge IP collapse in a separate cohort of patients, and demonstrate that the pro-inflammatory cytokine, interferon-γ can further collapse IP in the bulge epithelium of cultured hair follicles. Conclusion: These data identify collapse of immune privilege in bulge cells in active LPP, and identify prominent cell-mediated immune responses and loss of eHFSC signatures in active disease. The pro-inflammatory cytokine, interferon-γ also appears to play a prominent role in IP collapse and contributes to immune cell trafficking into affected tissue. Future study is required to ascertain triggering factors of IP collapse and pursue other identified candidates from gene expression analysis.
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Lee, Andrew. "Management of Vulval Lichen Sclerosus." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/26469.
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Vulval lichen sclerosus (VLS) is an inflammatory skin condition which affects mostly females over the age of 50, but can occur at any age, including childhood. It is symptomatic in most with the potential to cause itch, pain, inflammation, difficulty urinating, constipation and psychological distress. The typical clinical features are of a well defined white sclerotic plaque with an atrophied wrinkled surface, often with purpura and excoriation. The typical areas involved include the vulva, perineum and perianal area but it can also affect the clitoris, vaginal introitus, and other internal structures of the vagina. Unlike most skin conditions it can also result in permanent scarring and loss of normal vaginal structure with significant impact on quality of life. Furthermore it carries a 2-6% risk of malignant squamous cell cancer of the vulva.
Topical corticosteroids are effective as a first-line treatment in achieving remission of acutely active vulval lichen sclerosus with well-documented evidence to support this. However VLS is a chronic and often lifetime condition for many women and there has historically been a lack of clear evidence for the best approach for long term management. Long term management is important as even after achieving remission, the disease can wax and wane and has a tendency to recur without ongoing treatment. There is well documented knowledge on how to achieve remission, but little long-term data or established guidelines on the best approach once remission was achieved or indeed if it was required at all. Previous standards of care revolved around symptomatic management, not maintenance treatment of what is a chronic condition.
The key elements of the research to be presented in this thesis demonstrates the importance of treatment being continued on a regular maintenance regime in order to reduce the risk of malignant transformation, reduce further scarring and to sustain improvement in quality of life.
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Halonen, P. (Pekka). "Studies on the lichen genus Usnea in East Fennoscandia and Pasific North America." Doctoral thesis, Oulun yliopisto, 2000. http://urn.fi/urn:isbn:9514255240.
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Abstract
The shrubby Usnea species of East Fennoscandia and the whole known Usnea flora of British Columbia were studied. Furthermore, the status and distribution of Usnea hirta and U. longissima, which have divergent habitat requirements and distribution patterns, were surveyd in East Fennoscandia. The two species also occur in British Columbia and their chemistry, ecology and distribution were compared in the two study areas. The nomenclature and taxonomy of U. hirta were also revised.
Nine shrubby Usnea species were documented from East Fennoscandia and 25 species and species groups were recorded from British Columbia (when U. fulvoreagens and U. pacificana are included as distinct species). U. chaetophora, U. diplotypus and U. nidulans s. lat. were reported as new to North America, whereas U. esperantiana and U. rigida s. lat. were documented for the first time for Canada, and U. ceratina and U. rubicunda are new to British Columbia. U. pacificana was described as a new species from the Pacific Canada and the United States and U. wasmuthii was reported from the states of Washington and Oregon as new to North America. Several taxa were recognized as synonyms and lectotypified in our studies.
In total, 21 secondary medullary substances or compound groups were found in the East Fennoscandian and 24 in the British Columbia Usnea species. Salazinic acid is the most common substance in both areas. New chemotypes were found in three shrubby Usnea species in East Fennoscandia and in six taxa in British Columbia. Differences in the chemistry of some species were found when comparing the East Fennoscandian and British Columbia specimens, e.g., in U. hirta and U. longissima.
All the East Fennoscandian Usnea species studied have a relatively southern distribution or they are infrequent in northern regions, while most of the surveyed North American species have more or less maritime distribution. All these Usneae are primarily epiphytes and the majority of them prefer well-lit and moist sites.
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Prather, Hannah Marie. "Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3615.
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Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of threats to ecosystems. Largely, human-related impacts on biodiversity will hold consequences for larger ecological processes and research looking into human impacts on sensitive epiphytic lichen and moss communities is an emerging area of research. While seemingly small, lichen and moss communities exist on nearly every terrestrial ecosystem on Earth and contribute to whole-system processes (e.g. hydrology, mineral cycling, food web energetics) worldwide. To further examine human impacts on epiphytic communities, I conducted three studies examining urbanization and climate warming effects on epiphytic lichen and moss biodiversity and ecology.
In the first study I revisited a historic urban lichen community study to assess how urban lichen communities have responded to regional air quality changes occurring over the last nearly two decades. I further investigated, for the first time, the biodiversity of urban tree canopy-dwelling lichen communities in a native coniferous tree species, Pseudotsuga menziesii. I found that urban parks and forested areas harbor a species rich community of lichens epiphytes. Further, I found evidence for the distinct homogenization of urban epiphytic lichen communities, suggesting that expanding beyond simplistic measures of biodiversity to consider community composition and functional biodiversity may be necessary when assessing the ecology and potential ecosystem services of epiphyte communites within urbanizing landscapes.
Next, I present the first tall tree canopy study across a regional gradient of urbanization near Portland, Oregon, USA. I found that tall tree canopy epiphyte communities change dramatically along gradients of increasing urbanization, most notably by the transitioning of species functional groups from sensitive, oligotrophic species to a dominance of urban-tolerant, eutrophic species. The implications these dramatic shifts in species composition have on essential PNW ecosystem processes, like N-fixation and canopy microclimate regulation, is still not well understood and is difficult to formally evaluate. However, I find strong evidence that native conifer trees in urban areas may provide a diversity of essential ecosystem services, including providing stratified habitat for epiphyte communities and their associated micro arthropod communities and the scavenging of atmospherically deposited nutrients. Future work is needed to understand how losses in canopy N fixation and species with large biomass (both lichens and bryophytes) will affect nutrient and hydrologic cycling in the PNW region, which continue to undergo rapid growth and urbanization.
The final chapter investigates the impacts of passive warming by Open Top Chambers (OTCs) in moss-dominated ecosystems located on the Western Antarctic Peninsula, an area of increasing climate warming. I compared species-specific temperature effects, moss canopy morphology, sexual reproductive effort and invertebrate communities between OTC and control moss communities for two moss species, Polytrichastrum alpinum and Sanionia uncinata, that make up over 65% of the terrestrial vegetative cover in the area. I found distinct reproductive shifts in P. alpinum under passive warming compared to controls. Moss communities under warming also had substantially larger total invertebrate communities than those in control moss communities, and invertebrate communities were significantly affected by moss species and moss reproductive effort. Further, substantial species-specific thermal differences among contiguous patches of these dominant moss species were revealed. These results suggest that continued warming will differentially impact the reproductive output of Antarctic moss species and is likely to dramatically alter terrestrial ecosystems dynamics from the bottom up.
This combined work provides a diverse contribution to the field of epiphyte ecology and biology by providing new insights on how human impacts will affect epiphyte lichen and moss communities across diverse ecosystems, in light of a rapidly changing planet.
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Dahlman, Lena. "Resource aquisition and allocation in lichens." Doctoral thesis, Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-115.
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Lines, Catherine Elizabeth Mary. "Studies in the biology of lichens." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238171.
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Sweidan, Alaa. "Antibiofilm activity of lichen secondary metabolites." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B017/document.
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Les bactéries buccales n'infectent pas seulement la bouche mais y resident. Elles peuvent également passer dans la voie sanguine et atteindre des organes secondaires. S’il n'est pas traité, le biofilm dentaire peut provoquer une inflammation destructrice dans la cavité buccale, entrainant de graves complications médicales. Dans ce biofilm, Streptococcus gordonii, colonisateur oral primaire, constitue la plate-forme sur laquelle des colonisateurs pathogènes tardifs comme Porphyromonas gingivalis, l'agent causal des maladies parodontales, se lieront. L'objectif de la première partie de la thèse était de déterminer l'activité antibactérienne de onze composés de lichens appartenant à différentes familles chimiques, pour découvrir de nouveaux antibiotiques pouvant combattre ces bactéries buccales. Nous avons montré que trois composés avaient des activités antibactériennes prometteuses. L'acide psoromique enregistrait les CMIs le plus faibles. De nouveaux analogues de butyrolactone ont ensuite été conçus et synthétisés sur la base des composés antibactériens licheniques connus, les acides lichesteriniques, en substituant différents groupes fonctionnels sur le cycle butyrolactone pour améliorer son activité sur S. gordonii et P. gingivalis. Parmi les dérivés, B-12 et B-13 avaient la plus faible CMI où ils se sont révélés être des bactéricides plus forts, 2 à 3 fois plus, que l'antibiotique, doxycycline. B-12 et B-13 étaient également les plus efficaces vis-à-vis de P. gingivalis. La cytotoxicité de ces 2 composés a ensuite été vérifiée contre les cellulaires épithéliales gingivales humaines et les macrophages. Ils ne présentaient pas de toxicité contre les cellules testées. Une étude préliminaire de relation structure-activité a révélé le double rôle important apporté par deux substituants, chaîne alkyle en C5 et groupe carboxyle en C4 positions, dans leur mécanisme d'action. Ceci a été suivi par l'étude de l’activité antibiofilmique de B-12 et B-13 contre les deux souches orales en utilisant un test de cristal violet et microscopie confocale. Les deux dérivés ont montré, à une concentration plus faible, une inhibition maximale de la formation du biofilm, LCMI, de 9.38 μg/mL contre S. gordonii et 1.17 μg/mL contre P. gingivalis. Cependant, lorsque des concentrations sous-inhibitrices de B-12 et B-13 ont été utilisées, nous avons démontré que les deux souches étudiées pouvaient former des biofilms in vitro, accompagné d’une diminution de l'expression des gènes impliqués dans l'adhésion et la formation de biofilm. Pour mieux comprendre les mécanismes d'action des butyrolactones, nous avons étudié la localisation bactérienne du composé B-13 en synthétisant un B-13 marqué au NBD (4-nitro-benzo [1,2,5] oxadiazole) fluorescent conservant son activité antibactérienne. Par microscopie confocale et HPLC, nous avons montré que ce composé se lie à la surface cellulaire de S. gordonii. Ensuite, B-13 induit une rupture de la paroi cellulaire conduisant à la libération des constituants bactériens et par conséquent, à la mort de S. gordonii, une bactérie Gram-positive. L'expression de deux gènes, murA et alr, impliqués dans la synthèse de la paroi cellulaire, a été modifiée en présence de cette butyrolactone. Les bactéries Gram négatives telles que P. gingivalis ont également montré des cellules abimées présentant une rupture de la paroi en présence de B-13, ce qui suggère que cette butyrolactone agit sur des Gram-positives et Gram-négatives avec une plus grande efficacité contre les Gram-négatives. En outre, nous avons également démontré que l'analogue de B-13, B-12, induit une perturbation de la morphologie de P. gingivalis et S. gordonii. Toutes ces études ont démontré que les butyrolactones dérivées de lichen peuvent être proposés comme des composés antibactériens puissants contre les agents pathogènes oraux qui causent des complications médicales gravesThe oral bacteria do not only infect the mouth and reside there, but also travel via the blood and reach distant body organs. If left untreated, the dental biofilm that can cause destructive inflammation in the oral cavity may result in serious systemic medical complications. In dental biofilm, Streptococcus gordonii, a primary oral colonizer, constitutes the platform on which late pathogenic colonizers like Porphyromonas gingivalis, the causative agent of periodontal diseases, will bind. The aim of the first study was to determine the antibacterial activity of eleven natural lichen compounds belonging to different chemical families to uncover new antibiotics which can fight against the oral bacteria. Three compounds were shown to have promising antibacterial activities where psoromic acid had the lowest MICs of 11.72 and 5.86 µg/mL against S. gordonii and P. gingivalis, respectively. Novel butyrolactone analogues were then designed and synthesized based on the known lichen antibacterial compounds, lichesterinic acids (B-10 and B-11), by substituting different functional groups on the butyrolactone ring trying to enhance its activity on S. gordonii and P. gingivalis.. Among the derivatives, B-12 and B-13 had the lowest MIC of 9.38 µg/mL where they have shown to be stronger bactericidals, by 2-3 times, than the reference antibiotic, doxycycline. B-12 and B-13 were also the most efficient on P. gingivalis exhibiting MIC of 0.037 and 0.293 µg/mL and MBC of 1.17 and 0.586 µg/mL, respectively. These 2 compounds were then checked for their cytotoxicity against human gingival epithelial cells and macrophages by MTT and LDH assays which confirmed their safety against the tested cell lines. A preliminary study of the structure-activity relationships unveiled the important dual role contributed by two substituents, alkyl chain at C4 and carboxyl group at C5 positions, in their mechanism of action. This was followed by the investigation of B-12 and B-13 for their antibiofilm activity against both oral strains using crystal violet assay and confocal microscopy. Both derivatives displayed a lowest concentration with maximal biofilm inhibition, LCMI, of 9.38 µg/mL against S. gordonii and 1.17 µg/mL against P. gingivalis. However, when sub-inhibitory concentrations of B-12 and B-13 were used, we demonstrated that the two investigated strains were able to form biofilms in vitro. Indeed, this antibiofilm activity decreased as indicated by the expression of the genes implicated in adhesion and biofilm formation. To better understand the mechanism of action of butyrolactones, we have investigated B-13 bacterial localization by synthesizing a fluorescently labeled B-13 with NBD (4-nitro-benzo[1,2,5]oxadiazole) conserving its antibacterial activity. By confocal microscope, we showed that this compound binds to S. gordonii cell surface and this was also demonstrated by HPLC analysis. By adhering to cell surface, B-13 induced cell wall disruption leading to the release of bacterial constituents and consequently, the death of S. gordonii, a Gram-positive bacterium. The expression of two genes, murA and alr, implicated in cell wall synthesis, was modified in the presence of this butyrolactone. Gram-negative bacteria such as P. gingivalis showed also cracked and ruptured cells in the presence of B-13, suggesting that this butyrolactone acts on Gram-positive and Gram-negative strains, but with greater efficacy against the Gram-negatives. Besides, we also demonstrated that the analogue of B-13, B-12, has also induced disruption of P. gingivalis and S. gordonii. All these studies demonstrated that butyrolactones derived from a lichen metabolite can be proposed as potent antibacterial agents against oral pathogens causing serious medical complications
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Lessard, Martine. "Caractérisation des produits naturels odorants retrouvés dans les lichens de genre usnea et bryoria de la région du mont Apica, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1990. http://theses.uqac.ca.
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Coste, Clother. "Écologie et fonctionnement des communautés lichéniques saxicoles-hydrophiles." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00745808.
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Algues et champignons ont formés par association symbiotique les lichens qui, de par leur amplitude écologique, ont pu coloniser tous les milieux. Nous proposons d'appeler " hydrophiles ", les lichens soumis à des périodes d'immersion par les eaux d'un cours d'eau Les compositions floristiques des communautés lichéniques hydrophiles ont été définies par leur durée annuelle d'immersion. Les groupements subhydrophiles sont immergés pendant moins de trois mois, les groupements mésohydrophiles pendant plus de trois mois et moins dix mois et enfin les groupements hyperhydrophiles sont immergés plus de dix mois de l'année. Sur la base de trois cent relevés effectués par la méthode de prélèvement intégral, un schéma phytosociologique a été construit. Les lichens présents aux différents niveaux de noyage et d'altitude des cours d'eau forment une classe au sein de laquelle sont identifiés les trois ordres phytosociologiques caractérisés par la durée annuelle d'immersion. Dans chacun de ces ordres, deux alliances sont définies par l'étage bioclimatique. Pour chacune de ces six alliances, des associations de plusieurs lichens existent et sont définies par leurs caractéristiques biotiques. Du fait de leur fréquence dans un niveau d'immersion et de l'importance de leur recouvrement, quatre lichens " modèles " ont été retenus (une espèce aérienne et trois hydrophyles). Pour la première fois concernant des lichens hydrophiles, les flux de CO2 et d'O2 ont été quantifiés sous différents éclairements, en milieux aquatique et aérien. Les pigments photosynthétiques ainsi que l'ergostérol ont été estimés ; la réponse du potentiel photochimique ( PSII) au taux d'hydratation a été caractérisée. L'activité photosynthétique et respiratoire des lichens hydrophiles est comparable à celle de la littérature pour les lichens aériens. Les lichens hydrophiles démontrent des cinétiques rapides d'hydratation-déshydratation lors des transitions immersion-exondation. PSII s'avère très sensible à ces transitions. Pour toutes les fonctions étudiées, des différences significatives apparaissent entre les lichens hyper et subhydrophile alors que les lichens mesohydrophiles se comportent de façon intermédiaire. Nos résultats constituent la première caractérisation écologique et fonctionnelle des lichens hydrophiles. Ils pourront certainement être exploités et développés pour permettre une meilleure compréhension du rôle des lichens dans la colonisation des terres émergées par les phanérogames.
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Welch, Anthony Richard. "The effect of anthropogenic nutrient addition on the growth and competitive abilities of Parmelia caperata, P. reddenda, P. saxatilis and Xanthoria parietina in Cornwall." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289005.
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Hernández, Padrón Consuelo E. "Flora y vegetación liquénica epífita de los sabinares herreños /." Berlin : J. Cramer, 1987. http://catalogue.bnf.fr/ark:/12148/cb39980218f.
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Johansson, Otilia. "Epiphytic lichen responses to nitrogen deposition." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-43751.
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Nitrogen (N) deposition has increased globally over the last 150 years and further increase is predicted for the future. Nitrogen is an important nutrient for lichens, involved in many processes in both photobiont and mycobiont. However, N can be a stressor, causing many lichens and lichen communities to disappear with increased deposition. The objective of this thesis was to investigate the response of epiphytic lichens to increased N load. This was done by simulating an increased N deposition to lichens in a boreal forest with low background N, including both short term studies with transplanted lichens and long term studies of naturally established lichens. Alectoria sarmentosa was used as a model species for a N-sensitive lichens and Platismatia glauca as a relatively more N-tolerant lichen. Nitrogen deposition was simulated by daily spraying during the growing season with water and isotopically labeled ammonium nitrate (NH4NO3). In Paper I, I found that when N is supplied in realistic doses (equivalent to deposition of 0.6, 6, 12.5, 25 and 50 kg N ha-1), there were no significant differences in uptake of NO3- or NH4+ in either of the lichen species. The results in Paper II indicate that A. samentosa may be limited by phosphorous (P) and not N limited as expected. That study highlights the importance of P, when studying the effects of N deposition, since P can both mitigate and intensify the negative effects of N on epiphytic lichens. Paper III shows that four years of simulated N deposition caused an alteration of the epiphytic lichen community, since A. sarmentosa decreased in the highest N loads (25 and 50 kg ha-1 year-1), Bryoria spp. decreased to 12.5 kg N and higher loads and Hypogymnia physodes decreased over time for all treatments except in 12.5 kg ha-1, where it only decreased during the first treatment year and then increased after 2007. The abundance of Platismatia glauca increased over time, independent of treatment. As hypothesized, responses to the treatments differed among species, reflecting their different N optima. In paper IV, the effects of N on carbon-based secondary compounds were studied. None of the studied species (P. glauca, A. sarmentosa, Lobaria scrobiculata and Xanthoria aureola) reduced their concentration of secondary compounds during the experimental period, but in P. glauca the concentration of all compounds were significantly lower in N treated thalli compared with control thalli. The results are consistent with a high degree of constitutive defence in three of the four studied lichens, and we conclude that all four studied lichens seem to have a robust chemical defence system despite considerable manipulation of the environmental conditions. However, we don't know if these lichens are able to keep up the high protection level over longer periods comprising a number of years when more new tissue is formed. In conclusion, long term experiments are necessary to understand lichen response to environmental changes.
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Siponen, M. (Maria). "Oral lichen planus – etiopathogenesis and management." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526214702.
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Abstract Oral lichen planus (OLP) is a chronic immune-mediated mucosal disease with unknown etiology. According to the current view, the pathogenesis of OLP involves activation of T-cell mediated immunity against the epithelial keratinocytes. A proportion of OLP patients are affected by painful symptoms, and the risk of oral cancer is increased in OLP. There is no curative treatment for OLP. Topical corticosteroids are used most commonly in the management of OLP. However, the evidence base for the effectiveness of any therapy is weak. The objective of this thesis was to study novel aspects of OLP etiopathogenesis and management. An epidemiologic, retrospective case-control study was conducted to determine whether systemic diseases, in particular thyroid diseases, are associated with OLP. In addition, a randomized controlled trial comparing the effectiveness of topical tacrolimus, triamcinolone acetonide and placebo in symptomatic OLP was carried out. Furthermore, immunohistochemical expression of toll-like receptors 4 and 9, hyaluronan and its principal receptor CD44 antigen, hyaluronan synthases 1-3, hyaluronidases 1-2 and cathepsin K was studied in OLP tissue samples and in healthy oral mucosa. The effect of topical tacrolimus on the expression of these molecules in OLP was also studied. The results of the present study showed that a history of hypothyroidism was associated with an approximately twofold risk of having OLP. Furthermore, both tacrolimus and triamcinolone acetonide were more efficient than placebo in reducing the signs and symptoms of OLP. No statistically significant differences were noted in the efficacy between tacrolimus and triamcinolone acetonide. In addition, the expression of the studied molecules was altered in the epithelium or stroma in OLP compared to healthy oral mucosa. Tacrolimus treatment decreased the expression of CD44 antigen in the stroma and the expression of cathepsin K in the epithelium in OLP. In conclusion, the present study extends our knowledge about systemic associated factors and management of OLP. In addition, the results improve our understanding of molecular level changes that occur in OLPTiivistelmä Suun punajäkälä on krooninen immuunivälitteinen limakalvotauti, jonka etiologia on tuntematon. Taudin syntymekanismiin liittyy tämän hetkisen näkemyksen mukaan T-soluvälitteisen immuniteetin aktivoituminen epiteelin keratinosyyttejä vastaan. Suun punajäkälä aiheuttaa osalle potilaista kivuliaita oireita ja lisää suusyövän riskiä. Parantavaa hoitoa tautiin ei ole. Yleisimmin suun punajäkälän oireiden hoidossa käytetään paikallisia kortikosteroidivalmisteita. Kuitenkin eri hoitomuotojen tehosta on vain heikkoa näyttöä. Tämän väitöskirjatyön tarkoituksena oli tutkia uusia näkökohtia liittyen suun punajäkälän etiopatogeneesiin ja hoitoon. Epidemiologisessa tapaus-verrokkitutkimuksessa selvitettiin, liittyvätkö yleissairaudet, erityisesti kilpirauhassairaudet, suun punajäkälään. Lisäksi satunnaistetussa kontrolloidussa tutkimuksessa verrattiin paikallisen takrolimuusin, triamsinoloniasetonidin ja lumelääkkeen tehoa oireisesta suun punajäkälästä kärsivillä potilailla. Tutkimuksessa selvitettiin myös tollin kaltaisten reseptorien 4 ja 9, hyaluronaanin ja sen pääasiallisen reseptorin CD44-antigeenin, hyaluronaanisyntaasien 1–3, hyaluronidaasien 1–2 sekä katepsiini K:n immunohistokemiallista ilmentymistä suun punajäkälänäytteissä ja terveessä suun limakalvossa. Lisäksi tutkittiin takrolimuusihoidon vaikutusta näiden molekyylien ilmentymiseen suun punajäkälässä. Tämän tutkimuksen tulokset osoittivat, että kilpirauhasen vajaatoimintaan liittyi noin kaksinkertainen riski sairastaa suun punajäkälää. Lisäksi havaittiin, että suun punajäkälässä sekä takrolimuusi että triamsinoloniasetonidi ovat tehokkaampia kuin lumelääke oireiden ja kliinisen taudinkuvan lievittämisessä. Takrolimuusin ja triamsinoloniasetonidin tehossa ei todettu tilastollisesti merkitseviä eroja. Lisäksi suun punajäkälänäytteissä tutkittujen molekyylien ilmentyminen oli muuttunut joko epiteelissä tai stroomassa verrattuna terveeseen limakalvoon. Takrolimuusihoito vähensi CD44-antigeenin ilmentymistä stroomassa ja katepsiini K:n ilmentymistä epiteelissä suun punajäkälässä. Yhteenvetona voidaan todeta, että tämä tutkimus lisää tietoa suun punajäkälään liittyvistä systeemisistä tekijöistä ja suun punajäkälän hoidosta. Lisäksi löydökset lisäävät ymmärtämystä suun punajäkälässä tapahtuvista molekyylitason muutoksista
31
Ellin, Simon J. "Epiphytic lichens and air pollution : effects of sulphur dioxide, ozone and wet acidic deposition, singly or in combination under field and solardome conditions, on foliose and fruticose lichen species with green photobionts." Thesis, University of Bradford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362085.
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Ménard, Thierry. "Etude phytosociologique et écologique des peuplements lichéniques saxicoles calcifuges du sud-est de la France." Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30088.
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L'etude ecologique et phytosociologique des groupements de lichens saxicoles calcifuges de la partie meridionale du sud-est mediterraneen francais s'est revelee riche d'enseignements. L'analyse de transects par prelevement integral, technique nouvelle en lichenologie, permet l'etude fine des ecotones et la mise en evidence de gradients, en particulier d'humidite et de luminosite. Au point de vue phytosociologique, 145 releves, dont 139 effectues selon la methode du prelevement integral, permettent de distinguer 22 associations, sous-associations ou groupements, dont 8 sont nouveaux, qui se repartissent aux etages supralittoral, adlittoral, thermomediterraneen superieur et mesomediterraneen. Ils sont classes par affinites ecologiques et floristiques et compares avec ceux d'espagne du sud-est et ceux de la region eurosiberienne ; ils montrent de grandes affinites avec les premiers. L'analyse quantitative des principaux facteurs microclimatiques (energie lumineuse, temperature et humidite de l'atmosphere au voisinage des thalles, temperature de la surface des thalles et humidite superficielle du substrat) permet de preciser les exigences ecologiques de 7 peuplements, qui se distinguent surtout du point de vue hydrique et photique. Elle confirme l'importance de la microtopographie et des ecoulements d'eau dans l'etablissement de peuplements licheniques varies. La dynamique de l'installation des peuplements est basee sur la comparaison de placettes entierement denudees par prelevement integral et relevees a nouveau dix ans apres. L'installation des lichens, relativement lente, est precedee par celle de colonies de cyanobacteries. Les modalites de la colonisation des substrats vierges sont variees ; en particulier, les groupements subhydrophiles s'installent bien plus rapidement que les groupements non soumis a des ecoulements. L'examen de roches mises a nu par incendie apporte un complement d'information.
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Dahl, Wivecke. "Contribution à l'étude des métabolites secondaires chez les lichens fructiculeux Cladina stellaris et Cladina rangiferina /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.
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Lõhmus, Piret. "Forest lichens and their substrata in Estonia /." Online version, 2005. http://dspace.utlib.ee/dspace/bitstream/10062/918/5/lohmus.pdf.
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Smith, Elizabeth. "Carbon accumulating mechanisms in lichens and bryophytes." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282765.
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Ucrospoma, Jara Marisa. "Ramalina (Lichens) en los parques de Lima." Pontificia Universidad Católica del Perú. Centro de Investigación en Geografía Aplicada, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/119300.
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El presente trabajo consiste en realizar evaluaciones de la calidad de aire, mediante indicadores biológicos, como en el caso de Ramalina, líquen que habita las zonas urbano metropolitana de Lima (Ciudad capital), especialmente las áreas verdes en los distritos de Lince, Jesús María, San Isidro, parte de Pueblo Libre y Barranco. Ramalina vive en forma epifita, es decir, sobre los árboles tanto en cortezas de troncos y ramas. Para realizar la evaluación se colectó líquenes cortícolas en las áreas verdes de los distritos mencionados; luego se realizó cortes morfológicos para observar su estructura interna a nivel de talo y soralias, estas últimas le ayudan a dispersarse vegetativamente debido a la costante humedad existente en estas áreas verdes durante todo el año. Lo interesante del caso es que para Lima Metropolitana se registra sólo un género: de líquen conícola: Ramalina, sobre árboles cultivados, no así encontrándose en los parques de Lima y el Cercado, de aquí que se determine que el aire de esos lugares se encuentran contaminados, porque los líquenes no tienen sistemas de eliminación para sustancias tóxicas como el monóxido de carbono producido por el parque automotor en mal estado, que circula por la ciudad, aparte de las fábricas que emiten gases de sus chimeneas.
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Erfanian, Nima, and Kaiser Ghodbeni. "Clinical Description of Patients Diagnosed with Oral and Genital Lichen Planus, a Register Study." Thesis, Umeå universitet, Institutionen för odontologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-143876.
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ABSTRACT The aim of this study is to chart a cohort of patients in the county of Västerbotten in Sweden who have been diagnosed with lichen planus. In addition to charting, the cohort has also been compared to similar previously studied groups. The studied group consist of patients who have been referred to the Department of Medical Biosciences and Pathology between years 2009-2015 with suspicious diagnosis of LP. After exclusion, 214 patients remained of which 130 were diagnosed with Oral LP and 84 with Genital LP. Different data such as age, medications and diseases was extracted from the dental journals. In this cohort women were more likely to be affected by LP. The mean age for females was 63 years and 53 years for men. In the studied group 17 % were being treated for hypertension, 14 % were treated with 5 or more different medications. Tobacco use was found in 17 % and 12 % were diagnosed with an autoimmune disease. The results from the studied cohort were in accordance with similar populations in previous studies. There is an undergoing discussion whether OLP and LP are the same disease that affects different sites.
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Caruso, Alexandro. "Lichen diversity on stems, slash, and stumps in managed boreal forests : impact of whole-tree harvest /." Uppsala : Swedish University of Agricultural Sciences, 2008. http://diss-epsilon.slu.se/archive/00001675/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2008.Includes reprints of four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks reprints of four papers and manuscripts.
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Semadi, Ammar. "Effets de la pollution atmosphérique (pollution globale, fluorée et plombique) sur la végétation dans la région de Annaba (Algérie)." Paris 6, 1989. http://www.theses.fr/1989PA066455.
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La région de Annaba (Est de l'Algérie) est soumise à une pollution atmosphérique intense et variée. L'utilisation des végétaux et notamment des lichens comme indicateurs biologiques a permis de préciser l'impact de la pollution globale, de la pollution fluorée et de la pollution plombique autour de Annaba. Ces trois aspects sont développés après la présentation des facteurs écologiques de cette région. L'observation des nécroses sur les feuilles de plusieurs espèces phanérogamiques et l'étude de la répartition des lichens ont permis d'établir une zonation de la pollution atmosphérique globale. L'accumulation du fluor chez les végétaux supérieurs et chez les lichens a été utilisée pour réaliser la cartographie de la pollution fluorée avec quatre zones d'isopollution autour de l'agglomération de Annaba. Enfin l'impact de la pollution plombique d'origine automobile a pu être précisé à partir de transects et de transplantation de lichens effectues de part et d'autre de trois principaux axes routiers desservant la ville de Annaba
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Reding, Jordan Michael. "Rock Climbing or Lichen Climbing? How Rock Climbing Impacts Bryophyte and Lichen Communities Within the Red River Gorge." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562584961670604.
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Downward, Kenneth. "Relationships between surface crusts and erosion in the Tabernas Badlands, Almeria, S.E. Spain." Thesis, University of Wolverhampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325975.
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Forbes, PBC, M. Thanjekwayo, JO Okokwo, M. Sekhula, and C. Zvinowanda. "Lichens as biomonitors for manganese and lead in Pretoria, South Africa." Fresenius Environmental Bulletin, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001756.
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Abstract
Parmotrema austrosinense (Zahlbr.) Hale lichens were
collected from the Pretoria central business district (CBD),
as well as three sites to the east of Pretoria; the National
Botanical Gardens, the CSIR campus and the suburb of
Lynnwood, with the aim of utilising these lichens as biomonitors
of air quality to determine the effects of the phasing
out of leaded petrol and the simultaneous introduction
of manganese anti-knock additives to fuel in South Africa.
In addition to lichens, roadside dust and soil samples were
collected from the CBD and CSIR campus, and all samples
were analysed by flame atomic absorption spectrometry after
acid digestion. There was no significant difference (95 %
confidence) between the Mn content of lichens from all
sampling sites (overall average of 97.1 ± 39.1 μg.g-1, n=
28), which was most likely due to an even suspension of
Mn-containing particles arising from soil dust. Additional
contributions to Mn loading as a result of vehicle emissions
were currently not evident. For all non-CBD sites, higher
Pb levels were found in lichens which were nearer to busy
roads, suggesting an historical impact by vehicular emissions
of Pb arising from leaded petrol usage. The Pb concentrations
in lichens found in the CBD (average of 181.1
± 98.0 μg.g-1, n=10) were significantly higher (95 % confidence
limits) than those of lichens growing outside of the
CBD area (average of 41.5 ± 36.4 μg.g-1, n=18), and the Pb
levels were higher than those of Mn, which was contrary
to that found in sites outside the CBD.
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Hesse, Volker. "Epiphytic lichen diversity and its dependence on chemical site factors in differently elevated dieback-affected spruce stands of the Harz Mountains /." Berlin : J. Cramer, 2002. http://catalogue.bnf.fr/ark:/12148/cb41308907z.
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Dailey, Rebecca N. "Toxicity of Xanthoparmelia chlorochroa and the lichen substance (+)-usnic acid in ruminants." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1798967551&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Signoret, Jonathan Müller Serge. "Etude de la qualité de l'air en Lorraine-Nord par les lichens contribution en tant que bioindicateurs écologiques, bioaccumulateurs d'éléments chimiques et biomarqueurs du stress oxydant /." Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2002/Signoret.Jonathan.SMZ0213.pdf.
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Jackson, Heather Bird. "Distribution of chemistry and sexual fecundity in the lichenized-fungi, Xanthoparmelia cumberlandia and Xanthoparmelia coloradon︠sis on Boulder Mountain, Aquarius Plateau, UT /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd623.pdf.
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Dandridge, Debra Elaine. "Lichen: the challenge for rock art conservation." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4695.
Full textAbstract:
This study investigates the effects that lichens have on rock surfaces in which
ancient rock art (petroglyphs and pictographs) may be found. The study area includes
four sites in the United States: one quartzite site in southwest Minnesota, two sandstone
sites in Wyoming, and one volcanic site in Central New Mexico. One additional granitic
site studied is located northeast Queensland, Australia. The questions driving the pursuit
of this dissertation research are:
1. How does the chemistry of the rock change with weathering and how deep is
the profile?
2. Do lichens cause differential chemical changes?
3. How does the chemistry of the unaltered rock influence these changes?
4. Do lichens strip the patina or âÂÂdesert varnishâ from the rock surfaces?
The results of this research confirm from elemental chemical analyses that
geochemical changes do take place in the presence of lichens. The combined
mechanical and chemical processes contribute to the degradation and greater erodability
of all the rock surfaces studied. Chemically, we have demonstrated that cements that
hold grains of rocks together can be dissoluble by lichen byproducts in the presence of an aqueous environment whether the rocks are sandstone or granite. This information
regarding the mechanical and geochemical processes at work in natural environments
has significant practical benefit for the management, conservation, and preservation of
rock art sites everywhere.
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Farrell, Anne M. "Lichen sclerosis : a study of its pathogenesis." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270288.
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BeGora, Michael D. "UV-induced lability of lichen secondary compounds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/MQ58014.pdf.
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Murtagh, Gareth James. "Sex and variation in lichen-forming fungi." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285566.
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