Dissertations / Theses on the topic 'Mosses'
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Cooke, Catherine Jane. "Sensing nitrogen status in mosses." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1445464/.
Full textDeakova, Timea. "Isoprene Emission in Polytrichaceae Mosses." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4984.
Full textCâmara, Paulo Eduardo Aguiar Saraiva. "A developmental, phylogenetic and taxonomic study on the moss genus Taxithelium Mitt. (Pylaisiadelphaceae)." Diss., St. Louis, Mo. : University of Missouri--St. Louis, 2008. http://etd.umsl.edu/r3061.
Full textChang, Ying. "Molecular phylogenetics of mosses and relatives." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37148.
Full textSnäll, Tord. "Distribution patterns and metapopulation dynamics of epiphytic mosses and lichens /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3904.
Full textBharali, Bhagawan. "Ecophysiological effects of atmospheric pollutants on terricolous mosses." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322300.
Full textGornall, Jemma. "The functional role of mosses in Arctic ecosystems." Thesis, University of Aberdeen, 2005. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=153316.
Full textCox, Cymon John. "Phylogenetic relationships of the Eubryalean mosses (Bryineae, Musci)." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270904.
Full textMwafongo, Elizabeth. "Phylogeographic patterns in three South African forest mosses." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/6144.
Full textLepfodon smithii (Leptodontaceae) and Pterogonium gracile (Leucodontaceae) are widespread and disjunctly distributed moss species, that in South Africa are confined to forest patches believed to be relics of vast forests that existed before the Pleistocene glaciation period. These two species exhibit similar distribution and ecologies and frequently co-occur. Wardia hygrometrica is a southwestern Cape endemic that is restricted to streams within the kloofs that the forests generally occupy. In an attempt to trace the species histories and their subsequent colonization of forest patches, two molecular markers, internal transcribed spacer (ITS) nuclear rDNA and trnL-F cpDNA were employed.
Eisenman, Matthew S. "Hawthorne's Transcendental Ambivalence in Mosses from an Old Manse." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/english_theses/114.
Full textEllwood, Neil. "Factors influencing phosphatase activities of mosses in upland streams." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268455.
Full textNoakes, Timothy David. "Water relations of mosses from maritime Antarctic cryptogamic fellfields." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315302.
Full textMaraist, Caitlin Ann. "Effect of Microbes on the Growth and Physiology of the Dioecious Moss, Ceratodon purpureus." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4353.
Full textSnäll, Tord. "Distribution Patterns and Metapopulation Dynamics of Epiphytic Mosses and Lichens." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3904.
Full textThis thesis examines the relative importance of local conditions, dispersal and dynamics of the trees on epiphyte distribution patterns and colonization-extinction dynamics. Study species are the mosses Orthotrichum speciosum and O. obtusifolium, and the red-listed Neckera pennata. The thesis also includes an attempt to parameterize a model for a lichen metapopulation (Lobaria pulmonaria) in a dynamic landscape, based on only presence/absence data of the epiphyte and its host trees.
The results show that epiphyte colonization of trees is affected by both local conditions, and by connectivity to occupied trees. The positive effect of connectivity, implying a restricted dispersal range, was established by both demographic and genetic studies. The important local conditions were tree diameter and vitality, and shade. Local extinctions from trees occurred among small trees with low local epiphyte abundance, but more often, were the results of tree fall.
The observed importance of connectivity on epiphyte colonization agrees with the assumptions of the classic metapopulation model. However, the classic metapopulation model assumes that the landscape is static, and that local extinctions occur for stochastic reasons. The dynamics of epiphytes are different. A new conceptual model is therefore suggested, the patch-tracking metapopulation model. It differs from the classic metapopulation model in that it includes dynamics of the patches, and in that local extinctions only occur as patches are destroyed.
Simulations of the dynamics of N. pennata showed that its future metapopulation size will be overestimated unless the dynamics of the trees are accounted for. The simulation results further suggest that the dynamics of N. pennata can be characterised by the patch-tracking metapopulation model.
The attempt to parameterize the L. pulmonaria metapopulation model showed that more information are required for rigorous parameterization, preferably of the past historic fire regime.
Sundberg, Sebastian. "The ecological significance of sexual reproduction in peat mosses (Sphagnum)." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526.
Full textPeat mosses (Sphagnum) are widely distributed and are a major component of mire vegetation and peat throughout the boreal and temperate regions. Most boreal Sphagnum species regularly produce sporophytes, but the ecological role of the spore has been questioned. This study shows that the spores can form a spore bank and have the ability to germinate and contribute to moss establishment whenever suitable conditions occur. The results suggest that spore production is important for explaining the wide distribution and omnipresence of Sphagnum in nutrient-poor wetlands. The results further imply that initial recruitment from spores predominates in Sphagnum after disturbance or formation of suitable habitats.
A series of experiments showed that addition of phosphorus-containing substrates, such as fresh plant litter or moose dung, resulted in spore establishment on bare, moist peat. A field experiment indicated establishment rates of about 1% of sown, germinable spores on peat with added substrates. Plant litter on moist soil, without a closed cover of bryophytes, is an important safe site for the establishment of Sphagnum spores. The results fit the observed pattern of colonisation by Sphagnum beneath Eriophorum vaginatum tussocks in mires severely disturbed by peat extraction. Successful long-distance dispersal was indicated by the occurrence of several regionally new or rare Sphagnum species in disturbed mires.
Spore number per sporophyte ranged among Sphagnum species from 18 500 to 240 000, with a trade-off between spore number and spore size. Annual spore production was estimated at 15 million spores per square metre on two investigated mires. Sporophyte production showed a large interannual variation. Sporophyte production was positively related to the amount of precipitation the preceding summer. This was probably because a high water level promoted gametangium formation. Spore dispersal occurred in July and August. The earlier timing of spore dispersal in the more drought-sensitive, hollow-inhabiting sphagna should reduce the risk of sporophytes drying out prematurely during summer droughts.
Spores kept refrigerated up to 13 years retained high germinability. A field experiment showed that Sphagnum can form a persistent spore bank, with a potential longevity of several decades.
Van, Gaalen Kenneth Eric, and University of Lethbridge Faculty of Arts and Science. "Photosynthetic CO2 exchange and spectral vegetation indices of boreal mosses." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/293.
Full textxi, 110 leaves : ill. (some col.) ; 29 cm.
Roads, Esme. "Reproduction strategies and population dynamics of two annual shuttle mosses." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414564.
Full textChilufya, Jedaidah, Kousha Mohensi, and Aruna Kilaru. "The Role of Anandamide in Biotic Stress Tolerance in Mosses." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/4843.
Full textStella, Giulio Rocco. "Light stress and photoprotection in green algae, mosses and diatoms." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066430/document.
Full textThe molecular bases of responses to light excess in photosynthetic organisms having different evolutionary histories and belonging to different lineages are still not completely characterized. Therefore I explored the functions of photoprotective antennae in green algae, mosses and diatoms, together with the role of the two xanthophyll cycles present in diatoms.I studied the Light Harvesting Complex Stress-Related (LHCSR) proteins in different organisms. In the green alga Chlamydomonas reinhardtii, LHCSR3 is a protein important for photoprotection. I used site-specific mutagenesis in vivo and in vitro and identified three residues of LHCSR3 that are responsible for its activation.With the moss Physcomitrella patens I studied the in vitro spectroscopic and quenching characteristics of different pigment-binding mutants of the protein LHCSR1, focusing in particular on chlorophylls A2 and A5.LHCSRs in diatoms are named LHCXs, and in Phaeodactylum tricornutum I found that multiple abiotic stress signals converge to regulate the LHCX content of cells, providing a way to fine-tune light harvesting and photoprotection.The other main driver of photoprotection in diatoms is the xanthophyll cycle. Here I found that the accumulation of viola- and zeaxanthin in P. tricornutum have a negative effect in the development of NPQ, showing that zeaxanthin does not participate in the enhancing of NPQ in diatoms.Thanks to these studies done on different organisms, we gained a deeper knowledge on the shared characteristics and on the peculiar features about photoprotection in green algae, mosses and diatoms
Stella, Giulio Rocco. "Light Stress and Photoprotection in Green algae, Mosses and Diatoms." Doctoral thesis, Paris 6, 2016. http://hdl.handle.net/11562/949538.
Full textStella, Giulio Rocco. "Light stress and photoprotection in green algae, mosses and diatoms." Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066430.pdf.
Full textThe molecular bases of responses to light excess in photosynthetic organisms having different evolutionary histories and belonging to different lineages are still not completely characterized. Therefore I explored the functions of photoprotective antennae in green algae, mosses and diatoms, together with the role of the two xanthophyll cycles present in diatoms.I studied the Light Harvesting Complex Stress-Related (LHCSR) proteins in different organisms. In the green alga Chlamydomonas reinhardtii, LHCSR3 is a protein important for photoprotection. I used site-specific mutagenesis in vivo and in vitro and identified three residues of LHCSR3 that are responsible for its activation.With the moss Physcomitrella patens I studied the in vitro spectroscopic and quenching characteristics of different pigment-binding mutants of the protein LHCSR1, focusing in particular on chlorophylls A2 and A5.LHCSRs in diatoms are named LHCXs, and in Phaeodactylum tricornutum I found that multiple abiotic stress signals converge to regulate the LHCX content of cells, providing a way to fine-tune light harvesting and photoprotection.The other main driver of photoprotection in diatoms is the xanthophyll cycle. Here I found that the accumulation of viola- and zeaxanthin in P. tricornutum have a negative effect in the development of NPQ, showing that zeaxanthin does not participate in the enhancing of NPQ in diatoms.Thanks to these studies done on different organisms, we gained a deeper knowledge on the shared characteristics and on the peculiar features about photoprotection in green algae, mosses and diatoms
Christy, John A. "Identity and limits of Limbella tricostata (Musci: Amblystegiaceae)." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24596.
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Botany, Department of
Graduate
Gabriel, Rosalina Maria de Almeida. "Ecophysiology of Azorean forest bryophytes." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326158.
Full textBurch, Jane Alison. "The response of bryophytes to elevated atmospheric deposition of nitrogen." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369943.
Full textWells, J. M. "The role of the cell wall in metal uptake, redistribution and tolerance in the moss Rhytidiadelphus squarrosus." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384440.
Full textBaker, Richard George Egerton. "The influence of nutrient supply on the morphology of Sphagnum cuspidatum." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328812.
Full textTaylor, Meghan. "Continental-scale validation of the temperature signal in oxygen isotopes of Sphagnum cellulose and its application as a paleoclimate proxy." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1597629811&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textBell, Neil Elliot. "Phylogeny and character evolution in the Rhizogoniaceae and related pleurocarpous mosses." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412806.
Full textShortlidge, Erin Elizabeth. "Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses." PDXScholar, 2014. http://pdxscholar.library.pdx.edu/open_access_etds/1951.
Full textShinde, Suhas, Shivakumar Devaiah, and Aruna Kilaru. "Profiling Abscisic Acid-Induced Changes in Fatty Acid Composition in Mosses." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/4745.
Full textWiklund, Karin. "Establishment, Growth and Population Dynamics in two Mosses of Old-growth Forests." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4446.
Full textHedderson, Terry Albert John. "Studies on life history evolution in mosses : constraints, tradeoffs and local adaptation." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240692.
Full textMerced-Alejandro, Amelia. "Evolution of stomata in mosses (Bryophyta): From molecules to form and function." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/1038.
Full textMeagher, Patricia. "The influence of peat and peat-substitute potting mix components on disease suppression, with particular reference to changes with time." Electronic version, 2008. http://epress.lib.uts.edu.au/dspace/handle/2100/553.
Full textLappalainen, N. (Niina). "The responses of ectohydric and endohydric mosses under ambient and enhanced ultraviolet radiation." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514262142.
Full textBrowne, Deborah. "Moss: a Closer Look at This Humble Plant and Its Place Within the Historical Context of Landscape Painting, Considering Its Ecological Significance With Reflections on Nature and Balance." Honors in the Major Thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/753.
Full textBachelors
Arts and Sciences
Liberal Studies
Baxter, Robert. "Physiological responses of Sphagnum cuspidatum Ehrh. (ex Hoffm.) to acidic deposition." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237507.
Full textLett, Signe. "Mosses as mediators of climate change : implications for tree seedling establishment in the tundra." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-130942.
Full textMcGrath, Kate. "Phylogeography and population genetics of two forest endemic mosses in the Cape Floristic Region." Bachelor's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/26502.
Full textMoore, Lucy. "The moss layer and ectomycorrhizal fungi as drivers of carbon and nutrient cycling in a Scots pine forest." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225948.
Full textWilliams, Trevor David. "Surviving Catastrophe: Resource Allocation and Plant Interactions Among the Mosses of Mount St. Helens Volcano." PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/3373.
Full textTremper, Anja Hedwig. "Biomonitoring methods to assess the impact of metals associated with ambient particles on mosses at roadsides." Thesis, University of Hertfordshire, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409473.
Full textKnudsen, Carola. "Kanalisering och restaurering av vattendrag och dess påverkan på mossamhällen i strandzonen." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-71690.
Full textUnder 1850-talet då flottning av timmer påbörjades i Sverige startade kanaliseringen av många vattendrag, vilket innebar att vattendragen rätades ut, sidokanaler stängdes, och stenar, träd och stenblock flyttades ut till vattendragens kanter. Dessa åtgärder förändrade vattendragens morfologi, orsakade fördämningar mellan vatten och strandzon och minskade översvämningsfrekvensen. När timmerflottningens era var slut började människan restaurera de kanaliserade vattendragen, främst för att det visat sig att fisket försämrats. Kanalisering och restaurering innebär stora störningar för ekosystemet de utförs i och denna studie syftar till att titta hur mossamhällen i strandzonen skiljer sig åt i diversitet, artrikedom och täckning beroende på vilken form av störning de utsatts för och tiden sedan de utsattes för störningen. Studien är gjord längs biflöden till Vindelälven i norra Sverige. Biflödena är dels kanaliserade vattendrag, bästa-praxis restaurerade vattendrag och demonstrationsåtgärdade vattendrag. Vid samtliga sträckor som ingår i studien har mossprover samlats in på två höjder från vattenytan, 0 och 40 centimeter. Dessa prover har sedan identifierats till lägsta möjliga taxonomiska nivå (art eller familj), och deras täckningsgrad har uppskattats. Resultaten visade att de demonstrationsåtgärdade vattendragen hade lägst artrikedom och diversitet och mellan kanaliserade vattendrag och bästa-praxis vattendrag kunde ingen signifikant skillnad i diversitet eller artrikedom påvisas. Gällande täckningsgraden fanns ingen signifikant skillnad mellan vattendragstyperna. Resultatet visade också att tiden spelar en viktig roll för återhämtningen hos mossamhällena då artrikedom och diversitet ökar med tiden sedan inträffad störning.
Campos, Andréia da Silva Fernandes. "Avaliação do potencial fotoprotetor de extratos de musgos e investigação de seus riscos toxicológicos." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9223.
Full textA radiação ultravioleta (UV) induz diversos efeitos nocivos nos organismos e a quantidade desta radiação que atinge a biosfera é afetada pela concentração de ozônio, latitude, altitude, clima e reflexão especular. As respostas de briófitas em relação aos efeitos da radiação UV e a presença de compostos que absorvem esta radiação têm sido estudadas. Sanionia uncinata, Holomitriopsis laevifolia e Leucobryum laevifolium são espécies de musgos encontrados em locais expostos a alta incidência de radiação UV e com habitats distintos. Considerando que as respostas de musgos contra os efeitos da radiação UV e seus mecanismos de proteção ainda são pouco caracterizados, o objetivo deste estudo foi investigar o potencial fotoprotetor e possíveis riscos toxicológicos associados aos extratos dos musgos S. uncinata, proveniente da Antártica e H. laevifolia e L. laevifolium, proveniente do Amazonas. Seus extratos metanólico (EM), aquoso (EA), hidroalcoólico (EH) e etanólico (EE) foram estudados com a caracterização química por absorção ao UV e visível e pela cromatografia líquida de alta eficiência; quantificação do índice total de compostos fenólicos; determinação da capacidade captadora do radical 2,2-difenil-1-picril-hidrazila a fim de avaliar as atividades antioxidantes; avaliação do potencial de fotoproteção cutânea pela determinação do fator de proteção solar; avaliações do potencial mutagênico e citototóxico, através do ensaio de Salmonella/microssoma, utilizando as cepas TA97, TA98, TA100, TA102 e TA104; do potencial fotomutagênico através do ensaio de fotomutagenicidade, usando as cepas TA102 e TA104; e investigação dos efeitos genotóxicos e fotogenotóxicos, pelo ensaio de micronúcleo e fotomicronúcleo, respectivamente, usando diferentes linhagens celulares estabelecidas. Foram encontradas atividades fotoprotetoras e antioxidantes e observou-se que os extratos se apresentaram singulares devido a sua composição química. Os resultados fotoprotetores, além dos mutagênicos/fotomutagênicos, genotóxicos/fotogenotóxicos e suas respectivas avaliações citotóxicas também permitiram selecionar extratos e suas concentrações, como promissores candidatos em fotoproteção Assim, os EA e EH de H. laevifolia e L. laevifolium apresentam, no geral, os resultados mais significativos, tornando-se potenciais para avaliações refinadas em fotoproteção e na separação de componentes que possam levar a futuras aplicações como antioxidantes e protetores solares ou como adjuvantes.
The ultraviolet radiation (UV) induces many harmful effects in all living organisms and the amount of this radiation that reaching the ground is affected by many factors including ozone concentration, latitude, altitude, climate and specular reflection. The responses of bryophytes against the effects of UV radiation and the presence of compounds that absorb the UV region have been studied. Mosses Sanionia uncinata, Holomitriopsis laevifolia and Leucobryum laevifolium are found in locations exposed to UV at high levels of radiation and in different habitats. Whereas that the responses of mosses against the effects of UV radiation and their protection systems are poorly characterized yet, the aim of this study was to investigate photoprotective potential and possible toxicological risks associated with extracts of mosses S. uncinata (from Antarctica) and H. laevifolia and L. laevifolium (from Amazônia). Methanol (ME), aqueous (AE), hydroalcoholic (HE) and ethanolic (EE) were studied by: chemical characterization by UV/visible spectrophotometry and by High performance liquid chromatography; phenolic content estimation; 2,2-diphenyl-1-picrylhydrazyl scavenging activity; potential of skin photoprotection by in vitro determination of sun protection factor; the mutagenic potential, and cytotoxic by Salmonella/microsome assay, using the TA97, TA98, TA100, TA102 and TA104 strains; photomutagenic potential by photomutagenicity test, using TA102 and TA104 strains and; investigation of genotoxic and photogenotoxic effects by micronucleus test and photo-micronucleous assay, respectively, using different established cell lines. Photoprotective and antioxidant activities were found and it was observed that the extracts showed strong uniqueness due to its chemical composition. From the photoprotective, mutagenic/photomutagenic and genotoxic/photogenotoxic results and their cytotoxic evaluations it was possible to select extracts and their concentrations as promising candidates for photoprotection. Thus, the EA and EH of H. laevifolia and L. laevifolium demonstrated the most significant results, becoming potential for refined evaluations in photoprotection and separating components that can lead to future applications such as sunscreens and antioxidants or as adjuvants.
Gerotto, Caterina. "Photoprotection mechanisms in the moss Physcomitrella patens: Insights on the photosynthesis adaptation during land colonization." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3421580.
Full textLa fotosintesi riveste un’importanza fondamentale per la biosfera: grazie a questo processo l’energia solare è utilizzata per fissare l’anidride carbonica atmosferica in biomassa, liberando ossigeno. Piante e alghe, però, sono molto spesso esposte a condizioni d’illuminazione molto variabili. In condizioni di elevata illuminazione è fondamentale che l’energia in eccesso venga dissipata, pena la formazione di specie radicaliche dell’ossigeno (ROS) molto dannose per la cellula. Uno dei principali sistemi di protezione dall’eccesso di luce viene attivato pochi secondi dopo una variazione di illuminazione ed è definito Non Photochemical Quenching (NPQ). L’NPQ permette di dissipare l’eccesso di stati eccitati della clorofilla come calore ed è attivato a seguito dell’acidificazione del pH lumenale. L’NPQ comprende diverse componenti, la più rapida delle quali è definita qE (da “Energy quenching” o “Feedback de-excitation”). L’NPQ è presente in tutti gli organismi fotosintetici anche se meccanismi di attivazione e proteine coinvolte sono diversi. Nelle piante vascolari (quali la pianta modello Arabidopsis thaliana) è noto che l’NPQ dipende da una proteina presente nelle membrane dei tilacoidi chiamata PSBS. Nelle alghe, quali diatomee o la Clorofita Chlamydomonas reinhartii, che pure sono in grado di attivare NPQ, PSBS è assente e l’attivazione dipende da una proteina diversa, detta LHCSR. In questo lavoro è stato utilizzato il muschio Physcomitrella patens come organismo modello per lo studio della regolazione della fotosintesi. Questa scelta è dettata da molteplici ragioni. Le briofite presentano un’interessante posizione evolutiva, dal momento che si sono separate dalle piante vascolari poco dopo la colonizzazione delle terre emerse: il loro studio può quindi fornire informazioni su quelli che sono i primi adattamenti degli organismi fotosintetici alla vita terrestre. Per quanto riguarda i meccanismi di fotoprotezione, Physcomitrella patens ha nel proprio genoma sia PSBS che LHCSR, le proteine indispensabili per l’NPQ nelle piante vascolari e nelle alghe. Physcomitrella, inoltre, presenta la capacità unica tra le piante analizzate fino ad ora di fare ricombinazione omologa, facilitando così la possibilità di ottenere mutanti specifici per le proteine di interesse. Nel particolare, in questo lavoro abbiamo ottenuto dei mutanti specifici per PSBS e LHCSR, le proteine caratteristiche dell’NPQ di piante ed alghe rispettivamente. Sfruttando la capacità di ricombinazione omologa di Physcomitrella, sono stati generati mutanti knock-out (KO) per PSBS (psbs KO) e le due isoforme di LHCSR (LHCSR1 e LHCSR2; lhcsr1 KO e lhcsr2 KO) presenti nel genoma del muschio. Queste mutazioni sono poi stati combinate in doppi KO (psbs lhcsr1 KO, psbs lhcsr2 KO and lhcsr1 lhcsr2 KO) ed in un triplo KO (psbs lhcsr1 lhcsr2 KO), genotipo in cui è stato eliminato il gene di tutte tre le proteine in analisi. La risposta di NPQ nelle varie linee di singoli e doppi KO ha dimostrato come tutti questi mutanti diminuiscano la loro capacità di indurre NPQ rispetto a muschi WT. Ciò nonostante, tutte queste linee sono comunque in grado di attivare una risposta qE, dimostrando che queste proteine non solo sono presenti nel genoma ma sono entrambe attive nell’NPQ. Inoltre, l’isoforma LHCSR1 risulta essere la maggiore responsabile dell’NPQ in questa specie. Al contrario, mutanti privi dei tre polipeptidi (triplo KO) non sono in grado di indurre alcuna risposta qE, con un fenotipo simile ai mutanti di Arabidopsis privi di PSBS. In Arabidopsis PSBS è l’unica proteina coinvolta nel qE, dal momento che le piante vascolari non possiedono geni per LHCSR, confermando ulteriormente che in Physcomitrella sia PSBS che LHCSR sono attive nell’NPQ. Gli effetti di una diminuita capacità di indurre NPQ sulla fotoprotezione di P. patens sono stati ulteriormente approfonditi analizzando la capacità di acclimatazione ad alta luce o basse temperature nel muschio WT e nelle varie linee di mutanti KO ottenute. I mutanti che già in condizioni di controllo mostravano la maggiore diminuzione di NPQ in queste condizioni di crescita mostrano anche la maggiore fotoinibizione, dimostrando l’importanza dell’NPQ per la fotoprotezione. Nei muschi WT, l’acclimatazione ad alta luce o basse temperature, infatti, è accompagnata da un aumento della capacità di attivare la risposta di NPQ che correla con un aumento dell’espressione sia di PSBS che LHCSR. Questi dati dimostrano che Physcomitrella è in grado di modulare la sua capacità di indurre NPQ modificando l’espressione delle proteine chiave di questo processo, PSBS e LHCSR, per ottenere una fotoprotezione adeguata alle condizioni di crescita in cui si trova. In aggiunta a mutanti KO per PSBS e LHCSR, durante questo lavoro sono state generate anche delle linee che over-esprimono (OE) queste proteine. Questi mutanti hanno permesso di dimostrare che sia PSBS che LHCSR sono in grado di attivare una risposta NPQ in Physcomitrella in assenza dell’altra proteina. Questo risultato dimostra che PSBS e LHCSR sono attive in modo indipendente l’una dall’altra, ed hanno quindi verosimilmente dei meccanismi di attivazione differenti ed autonomi. Anche i carotenoidi, e la zeaxantina in particolare, hanno un ruolo fondamentale nella protezione delle cellule dagli stress ossidativi dal momento che sono coinvolti in diversi meccanismi di fotoprotezione. Tra gli altri, la zeaxantina è in grado di amplificare la risposta NPQ in piante quali Arabidopsis. In Physcomitrella abbiamo ottenuto lo stesso risultato, dimostrando che la presenza di questo carotenoide è fondamentale per una completa attivazione di NPQ sia PSBS che LHCSR dipendente. Se queste due proteine non sono presenti, invece, il solo accumulo di zeaxantina non è in grado di attivare alcuna risposta di fotoprotezione rapida qE. Durante questo progetto di Dottorato è stata sfruttata la capacità di ricombinazione omologa di Physcomitrella anche per l’espressione di isoforme mutate di PSBS. Nel particolare, sono state ottenute le sequenze codificanti per PSBS con una delezione all’N- o al C- terminale della proteina matura. Si tratta di regioni conservate in PSBS di diverse specie di piante, che presentano rispettivamente carica positiva e negativa, e potrebbero quindi essere coinvolte in interazioni proteina-proteina che sembrano essere necessarie per il meccanismo di induzione NPQ PSBS-dipendente. L’espressione di queste isoforme in muschi psbs KO, però, ha portato alla complementazione del fenotipo in entrambi i casi, dimostrando che le regioni delete non sono fondamentali per l’attività di PSBS. Nell’ultima parte del lavoro, inoltre, abbiamo focalizzato l’attenzione sull’evoluzione del meccanismo di NPQ da alghe a piante. Come accennato in precedenza, Physcomitrella presenta una posizione evolutiva chiave per ottenere informazioni sugli adattamenti necessari alla colonizzazione delle terre emerse ed abbiamo esteso l’analisi anche ad alghe della linea Streptofita (alghe Carofita) per ottenere maggiori informazioni sull’evoluzione dell’NPQ. I dati ottenuti hanno dimostrato che nelle specie evolutivamente più vicine alle piante terrestri (Coleochatales e Charales, identificati come i probabili “sister group” delle piante terrestri) PSBS è presente. Queste analisi, unitamente a quanto riportato in precedenza per P. patens e a dati di letteratura, permettono di formulare un’ipotesi sull’evoluzione dell’NPQ da alghe a piante: in corrispondenza della colonizzazione delle terre emerse è stato evoluto un nuovo meccanismo di fotoprotezione (PSBS dipendente), che dapprima si è affiancato, poi sostituito completamente a quello LHCSR-dipendente tipico delle alghe.
Lieske, Kathrin [Verfasser]. "Vegetative reproduction and clonal diversity in pleurocarpous mosses (Bryopsida) of xeric habitats : a combined molecular and morpho-anatomical study in the three mosses Abietinella abietina (Hedw.) Fleisch. (Thuidiaceae), Homalothecium lutescens (Hedw.) Robins. (Brachytheciaceae) and Homalothecium sericeum (Hedw.) Schimp. (Brachytheciaceae) / Kathrin Lieske." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/1024744086/34.
Full textPoikolainen, J. (Jarmo). "Mosses, epiphytic lichens and tree bark as biomonitors for air pollutants – specifically for heavy metals in regional surveys." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514274792.
Full textDecker, Stephanie J. "Vermicomposting of cod (Gadus morhua) offal mixed with Sphagnum peat." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0029/MQ62381.pdf.
Full textSchmitz, Daniela. "Comunidades vegetais de área de degelo da Ilha Half Moon, arquipélago das Shetlands do Sul, Antártica." reponame:Repositório Institucional da UNIPAMPA, 2015. http://dspace.unipampa.edu.br:8080/xmlui/handle/riu/522.
Full textMade available in DSpace on 2016-09-16T14:48:23Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Comunidade vegetais de áreas de degelo da Ilha Half Moon, Arquipélago das Shetlands do Sul, Antártica.pdf: 769779 bytes, checksum: 794a3b4b95c7a64c38ab5708c8c281b2 (MD5) Previous issue date: 2015-07-28
Este trabalho apresenta os resultados do estudo das comunidades vegetais de áreas de degelo realizado durante os verões austrais de 2013/2014 e 2014/2015, nos meses de fevereiro e março, na Ilha Half Moon, no Arquipélago Shetlands do Sul, Antártica Marítima, com o objetivo de avaliar a distribuição e abundância de musgos e líquens, bem como para descrever e mapear as comunidades de plantas que ocorrem na área. As plantas foram correlacionadas com a ocorrência de aves marinhas, relevo e umidade para entender sua influência sobre a distribuição de plantas. Para aferir as comunidades existentes na ilha através da fitossociologia e quantificar as espécies com maior significância ecológica (IES) foi utilizada a metodologia de quadrados (20 x 20cm) de Braun-Blanquet adaptado às condições Antárticas. Para o mapeamento da área foi utilizado o DGPS Astech Promark II®, com precisão sub-metrica e posteriormente processados no software Astech Solutions®. Foram identificadas 37 espécies de briófitas, 59 liquens, uma angiosperma, a Deschampsia antarctica Desv., e duas espécies de algas macroscópicas. Foram dispostos 358 quadrados e identificadas cinco comunidades vegetais na ilha, distribuídas de acordo com a ocorrência de animais e a influência marítima. As comunidades descritas foram as seguintes: Comunidade Liquens fruticulosos, Comunidade carpete de musgos, Comunidade de Liquens Muscicolas, Comunidade de Liquens crustosos e Comunidade Turfa de musgos. A espécie que apresentou o IES mais elevado da ilha foi Sanionia uncinata (Hedw.) Loeske aparecendo em 71.78% dos quadrados amostrados. A comunidade que apresentou maior número de espécies foi a Carpete de musgos e a mais diversa foi a comunidade liquens crustosos, que tem sua maior parte localizada na área onde estão as colônias de pingüins.
This paper presents the results of the study of plant communities of free ice areas conducted during the austral summer of 2013/2014 and 2014/2015, in February and March, on Half Moon Island in the South Shetlands Archipelago, Maritime Antarctica, aiming to evaluate the distribution and abundance of mosses and lichens, as well as to describe the plant communities occurring in the area, with mapping of the vegetation communities. To assess existing communities on the island through the phytosociology and quantify the species with the highest ecological significance (IES) was used the methodology square (20 x 20cm) of Braun-Blanquet adapted to Antarctic conditions. . The area was mapped using an Astech Promark II® DGPS, yielding sub-metric precision after post-processing with Astech Solutions® software. The number of species totalized 38 bryophyte species, 59 lichens, only one flowering plant (Deschampsia antarctica Desv.) and two macroscopic terrestrial algae. Five plant communities were identified in the island, distributed accordingly to animal occurrence and to sea influence. The plant communities were described as follows: Fruticose lichens community, Moss-carpet community, Muscicolous Lichens community, Crustose lichens community and Moss turf community. The species with the highest IES of the island was Sanionia uncinata (Hedw.) Loeske appearing in 71.78% of sampled squares. The community with the highest richness species was the Moss Carpet, and the most diverse community was the crustosos lichens, which has mostly located in the area where the penguin colonies.
Rasmussen, Terence Edward. "Biofiltration of indoor air, the role of mosses and their associated microbial communities in a complex eco-system biofilter." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62922.pdf.
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