Дисертації з теми "Desiccation toleranc"
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Potts, Malcolm. "Desiccation tolerance." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/9528/.
Повний текст джерелаChaibenjawong, Plykaeow. "Desiccation Tolerance in Staphylococcus aureus." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522502.
Повний текст джерелаDace, Halford. "Metabolomics of desiccation tolerance in Xerophyta humilis." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9111.
Повний текст джерелаResurrection plants are unique in the ability to survive near complete water loss in vegetative tissues without loss of viability. In order to do so, they employ multifaceted strategies which include structural adaptations, antioxidant and photoprotective mechanisms, and the accumulation of proteins and metabolites that stabilise macromolecules. A full understanding of the phenomenon of vegetative desiccation tolerance will require a systems view of these adaptations at the levels of the genome, the control of gene expression, and the control of metabolic pathways. This dissertation reports a high-throughput metabolomic analysis of the changes that occur in vegetative tissues of resurrection plant Xerophyta humilis during dehydration. A combination of chromatography, mass spectrometry and nuclear magnetic resonance revealed numerous primary and secondary metabolites in the plant. Multivariate statistics identified a subset of metabolites that were significantly up- or down-regulated in response to water deficit stress. These metabolites both confirmed existing observations about the metabolic response of X. humilis to drying and revealed compounds not previously known to be associated with this response. Desiccation-associated metabolites were mapped onto known biochemical pathways, to generate hypotheses concerning possible regulatory schemes in the stress response, inviting deeper investigation in future.
Casteriano, Andrea Veronica. "Physiological mechanisms of desiccation tolerance in Rhizobia." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/10423.
Повний текст джерелаFleming, Erich David. "Responses of desiccation-tolerant cyanobacteria to environmental extremes /." view abstract or download file of text, 2006. http://wwwlib.umi.com/cr/uoregon/fullcit?p3211215.
Повний текст джерелаTypescript. Includes vita and abstract. Includes bibliographical references (leaves 115-129). Also available for download via the World Wide Web; free to University of Oregon users.
Sheen, Tamsin, and n/a. "Osmotic and desiccation stress-tolerance of Serratia entomophila." University of Otago. Department of Microbiology & Immunology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081208.114925.
Повний текст джерелаMontazeri, Mansoor. "Desiccation tolerance as a factor in mycoherbicides pathogenicity." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289535.
Повний текст джерелаRatnakumar, Sooraj. "Molecular mechanisms of desiccation tolerance in Saccharomyces cerevisiae." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612298.
Повний текст джерелаJones, Stephen Keith. "Sitka spruce (Picea sitchensis [Bong.] Carr.) seed germination in relation to seed development, dormancy and storage." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283746.
Повний текст джерелаLyall, Rafe. "Regulation of desiccation tolerance in Xerophyta seedlings and leaves." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22853.
Повний текст джерелаMadden, Christine Frances. "Eragrostis nindensis: unravelling senescence in an African desiccation tolerant grass." Doctoral thesis, Faculty of Science, 2019. https://hdl.handle.net/11427/31652.
Повний текст джерелаWright, Deborah J. "Molecular Biology of Desiccation Tolerance in the Cyanobacterium Nostoc commune." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9714.
Повний текст джерелаMaster of Science
Mulat, Teshome G. "Chemical desiccation tolerance and nonstructural carbohydrate dynamics in winter wheat." Access citation, abstract and download form; downloadable file 3.70 Mb, 2004. http://wwwlib.umi.com/dissertations/fullcit/3131690.
Повний текст джерелаDzobo, Kevin. "Characterization of polyphenols in leaves of four desiccation tolerant plant families." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/4256.
Повний текст джерелаPolyphenols in plants are known to act as antioxidants, antimicrobials, antifungal, photoreceptors, visual attractors and as light screens. In this study polyphenols in angiosperms found in southern Africa and called resurrection (desiccation tolerant) plants were studied. These plants are Myrothamnus flabellifolius, Xerophyta viscosa, Xerophyta humilis, Xerophyta schlecterii, Xerophyta villosa. Craterostigma wilmsii, Craterostigma plantagineum, Craterostigma pumilum and Eragrostis nindensis. These plants are able to tolerate water stress without undergoing permanent damage. During drying these plants are subjected to different stresses and one such stress is oxidative stress. It has been suggested that polyphenols function as stress protectants in plant cells by scavenging reactive oxygen species (ROS) produced during a period of oxidative stress. In this study the total phenolic content and the related antioxidant capacity of the plants leaf extracts were analysed.
López, Martínez Gema Isabel. "Functional characterization in vivo of essential Saccharomyces cerevisiae's hydrophilin for desiccation tolerance." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/311618.
Повний текст джерелаLa sobre expresión de las hidrofilinas STF2 y SIP18 en cepas de laboratorio, tienen un efecto positivo en la tolerancia a la deshidratación y rehidratación. Además, la sobre expresión de SIP18 en cuatro cepas comerciales de levadura industrial muestra el mismo fenotipo que las cepas de laboratorio sin alterar el proceso fermentativo. Estos resultados nos permiten proponer la sobre expresión de SIP18 como una posible forma de mejorar la viabilidad en la levadura seca activa (LSA) y obtener así un inóculo de alta calidad para las industrías alimentarias. Además se disminuirían los costes de almacenamiento y transporte. La sobre expresión de la hidrofilina SIP18 "preadapta" las células incrementando la capacidad de tolerancia a la deshidratación y posterior rehidratación debido no sólo a la acumulación intracelular de SIP18, sino también a los cambios de expresión proteica que la sobre expresión de SIP18 conlleva. Nosotros hemos mostrado la expresión diferencial de 45 proteínas que incrementan su abundancia y 27 que disminuyen durante el estrés como consecuencia de la sobre expresión de SIP18. Algunas de éstas proteínas han sido identificadas en el proceso de secado y rehidratación por primera vez. Hemos identificado otras moléculas involucradas en este proceso de estrés mediante un análisis de QTL de dos cepas de levadura comerciales. Entre los once genes caracterizados que mostraron diferencias en la secuencia aminopeptídica, sólo la sobre expresión de cinco de ellos muestra un cambio en la viabilidad después de la imposición al estrés en los dos contextos genéticos analizados. Estos resultados muestran que la tolerancia a la deshidratación no sólo depende de la activación o inhibición de determinados genes implicados en el proceso de estrés estudiado, sino también de la secuencia de los alelos. Los resultados presentados en ésta tesis doctoral profundizan en el conocimiento de los mecanismos moleculares y los metabolitos involucrados en la tolerancia a la deshidratación para la producción adecuada de LSA. Sin embargo, también sirve como modelo para futuras investigaciones en el almacenamiento de tejidos en condiciones de deshidratación.
Over expression of STF2 and SIP18 hydrophilin in laboratory has a positive effect on desiccation tolerance. Moreover, over expression of SIP18 in four commercial wine yeast strains produced the same desiccation phenotype as in the laboratory strain without altering fermentative performance. These common results lead us to propose the over expression of SIP18 as a possible way of improving the viability in Active Dried Wine Yeast (ADWY) formulations resulting in savings in transport and storage costs and some extend develope a high-quality inoculum for the food industry. Over-expression of the SIP18 hydrophilin ‘preadapts’ cells by increasing their capacity to overcome and enhance dehydration and rehydration stress. This cell preadaptation is due both to SIP18 accumulation and to changes in the expression of the membrane’s proteomic profile as a consequence of SIP18 accumulation. We shown that 45 proteins increased in numbers after stress imposition and 27 were found to be down regulated, some of which were identified for the first time in this study. Other molecules playin a leading role in enhancing dehydration tolerance were identified using QTL analysis in two commercial wine yeast strains. Characterization of genes with sequence changes between alleles showed that only over expression of five out of eleven genes had different viability for both genetic backgrounds. These results led us to suggest that dehydration tolerance is not gene induced but rather depends on the specific amino acid sequence of each allele in conjunction with other genes activating or inhibiting their function. The results present in this doctoral thesis not only deepen our understanding of the molecular mechanisms and metabolites involved in desiccation tolerance for the production of ADWY, but also serve as a model for future research in tissue storage without the need for a hydric solution.
Jamell, Sanna. "Differences in desiccation and freezing tolerance in limnic and limno-terrestrial tardigrades." Thesis, Högskolan Kristianstad, Sektionen för lärande och miljö, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-15027.
Повний текст джерелаVicre, Maїté. "Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii." Doctoral thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/8774.
Повний текст джерелаResurrection plants have the unique capacity to revive from an air-dried state. In order to cope with desiccation, resurrection plants have to overcome a number of stresses, mechanical stress being one. This occurs when the cytoplasm shrinks creating tension between the plasma membrane and the cell wall. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable wall folding. It is thought that this folding is a well controlled process rather than a simple collapse and that the ability of the wall to fold is important for the viability of the tissues upon drying. The aim of this study was to characterize the cell wall architecture and composition in hydrated and dry leaves of C. wilmsii using microscopical and biochemical techniques. Calcium and hormone contents were also determined during drying. The development of anhydrous fixation for microscopy confirmed the important folding of the wall previously observed with chemical fixation. Using immunocytochemical techniques and a variety of well characterized antibodies, the nature and composition of wall polymers was investigated. There was nothing unusual in the wall composition of C. wilmsii leaves as compared with other dicotyledonous plants. The results show a significant increase of the hemicellulosic polysaccharide xyloglucan and of the unesterified pectins during drying with levels declining again during rehydration. In contrast no increase was observed in others polysaccharides such as ß (1-4) galactans and methylesterified pectins. Biochemical analysis allowed further characterization of cell wall composition of C. wilmsii. The data demonstrate marked changes in the pectic and hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulose fraction of the dry plant. Together these findings show that dehydration causes important alteration of polysaccharides content in the cell wall of C. wilmsii. Such modifications might be involved in the modulation of the mechanical properties of the wall during dehydration. Furthermore calcium ions content was shown to increase in the cell wall of dry plants, this could also have a role in stabilizing the wall architecture. All these alterations might be under the control of auxin, an hormone whose content was shown to increase during dehydration.
Williams, Jason. "Links Between Desiccation Resistance and Cold-Tolerance in an Overwintering Insect: Seasonal and Geographic Trends." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1124223034.
Повний текст джерелаLayfield, Johnathon Blake. "Characterization of Hybrid Strains of Saccharomyces pastorianus for Desiccation Tolerance and Fermentation Performance." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-08182009-130032/.
Повний текст джерелаLima, Manuel de Jesus Vieira. "Desiccation tolerance, development, maturation and storage of seeds of several tropical tree species." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297637.
Повний текст джерелаKoonjul, Priyum K. "Investigating the mechanisms of desiccation tolerance in the resurrection plant, myrothamnus flabellifolius (WELW)." Doctoral thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9940.
Повний текст джерелаResurrection plants, including Myrothamnus flabellifolius, grow in shallow soil upon rocky outcrops where they experience regular periods of water stress. Associated with this is light stress. The presence of light under water limiting conditions can result in photo-oxidation which causes damage to plant tissues. M flabellifolius is a homoichlorophyllous plant and thus retains chlorophyll during desiccation. The mechanisms whereby this plant prevents photo-oxidation damage are not known and thus one of the objectives of this study was to characterise the chloroplasts and the changes they undergo during dehydration. It was shown that chloroplasts from M flabellifolius could only be isolated using trehalose gradients (instead of sucrose gradients) and were found to have a higher buoyant density than chloroplasts isolated from another resurrection plant, Craterostigma wilmsii. The latter had the same buoyant density as those isolated from the desiccation sensitive plant Pisum sativum. The increased buoyant density in M flabellifolius was ascribed to the unusual ultrastructure of the thylakoid membranes. The latter have a staggered conformation (staircase arrangement) rather than the discrete granal and intergranal conformation found in most plants.
Kruger, Lynette Anne. "Towards an understanding of the mechanisms of desiccation tolerance in Myrothamnus flabellifolius (WELW.)." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/17369.
Повний текст джерелаTo date, most of the studies on the homoiochlorophyllous desiccation-tolerant (HDT) plant Myrothamnus flabellifolius have been conducted on excised twigs or leaves. In this study drying (including prolonged exposure to the dry state), and recovery of whole plants was compared with that of detached twigs dried off the plant, and also with twigs excised after having dried on the plant. Study of the leaf response during drying and recovery in the presence and/or absence of roots, and following prolonged desiccation, can contribute towards understanding the mechanisms of desiccation tolerance in M. flabellifolius.
Koshawatana, Chutima. "Physiological, biochemical and chemical studies on desiccation tolerance primarily in developing wheat seeds." Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phk859.pdf.
Повний текст джерелаFerebee, James Harrison IV. "New Herbicide Strategies for Weed Management in Pumpkin and Soybean and Potato Vine Desiccation." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/86611.
Повний текст джерелаMaster of Science in Life Sciences
Herbicides effectively control weeds by either applying them to the soil prior to emergence or applying them to foliage. Herbicides are used for desiccation of potato vines to facilitate harvest, improve skin set, and regulate tuber size. Potatoes with tougher skin have a longer shelf life and are more resistant to disease. Potato grade classifications include size chef, A, and B potatoes. Size B potatoes hold the greatest value for redskinned potatoes. Experiments were conducted in Virginia to evaluate saflufenacil, glufosinate, saflufenacil plus glufosinate, and carfentrazone plus glufosinate as desiccants compared to diquat applied at 43, 31, and 17% B potatoes. All desiccants resulted in similar vine desiccation 14 days after treatment, skin set, and yield. This research demonstrates that glufosinate and saflufenacil are effective alternatives to diquat for potato vine desiccation; however, further research is needed to evaluate the safety of saflufenacil applied to potatoes prior to harvest. Soil applied herbicides are commonly used in pumpkin production. Fluridone and two acetochlor formulations, herbicides that effectively control troublesome weeds in other crops, were evaluated for pumpkin production in addition to fomesafen, ethalfluralin, clomazone, halosulfuron, and S-metolachlor. Fluridone and acetochlor formulations resulted in significant pumpkin injury early in the growing season and total crop loss was observed by fluridone in 2018. Fomesafen significantly reduced pumpkin iv stand and yield. S-metolachlor, a member of the same chemical family as acetochlor, provided similar weed control without significant pumpkin injury. This research demonstrates that fluridone and acetochlor formulations are poor candidates for pumpkin production. Palmer amaranth is a troublesome weed in soybean that grows rapidly and is resistant to many herbicides. Palmer amaranth is best controlled at a height of 10 cm or less, but timely applications are not always feasible. Fomesafen plus dicamba were applied to small Palmer amaranth (<5 cm, 0 day) and at simulated delays of 7, 14, 21, and 28 days. All treatments received lactofen plus dicamba 14 days after the initial postemergence. Palmer amaranth control 14 days after first postemergence was 100% when application was delayed 0 or 7 day whereas Palmer amaranth control was 62% when first postemergence was delayed 28 days. Lactofen plus dicamba applied second postemergence increased control to 88% when the first postemergence was delayed 28 days. Compared to nontreated plots, Palmer amaranth biomass was reduced 99% by all treatments. This research demonstrates that fomesafen plus dicamba followed by lacofen plus dicamba can be effective for rescue control of Palmer amaranth.
Silva, João Paulo Naldi [UNESP]. "Mecanismos de controle de tolerância à dissecação em sementes de Caesalpinia echinata LAM. (Pau-Brasil) e Caesalpinia peltophoroides BENTH. (Sibipiruna)." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/92096.
Повний текст джерелаFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A aquisição da tolerância à dessecação ocorre durante a maturação da semente, após acúmulo de reservas e antes do início do processo natural de secagem, porém, com o avanço da germinação a sensibilidade a dessecação aumenta. Estresses hídricos podem induzir ou restabelecer a tolerância à dessecação em sementes, porém, não se sabe em quais processos ele atua, como na ativação de genes. O objetivo deste trabalho foi avaliar a aquisição e perda de tolerância à dessecação em sementes de Caesalpinia echinata Lam. (pau-brasil), e a possibilidade de indução deste processo avaliando as modificações nos carboidratos solúveis e de ciclitóis, nos níveis endógenos de ABA e na expressão de aquaporinas. Foram observadas diferenças na aquisição de tolerância em sementes imaturas de mesma idade, produzidas nas mesmas matrizes em 2007 e 2008, com diferentes composições de carboidratos solúveis. Sementes maduras perdem a tolerância à dessecação logo após protrusão da raiz primária, em comprimentos dependentes do grau de deterioração da semente. Sementes imaturas e maduras tolerantes de C. echinata suportaram a desidratação de formas diferentes, utilizando reservas de amido e ciclitóis, com papel da sacarose quando secas. Esses resultados foram comparados com sementes de Caesalpinia peltophoroides Benth (sibipiruna), demonstrando comportamentos fisiológicos distintos, provavelmente relacionados com o tipo de reserva que acumulam
The acquisition of desiccation tolerance occurs during seed maturation, after reserves accumulation and before the natural process of drying, however, with seed germination the desiccation sensitivity increases. Water stress can induce or restore the desiccation tolerance in seeds, but it is unclear what processes it acts, like activation of genes. The objective of this work was to evaluate the acquisition and loss of desiccation tolerance in Caesalpinia echinata Lam (brazil-wood) seeds, and the possibility to induction this process, evaluating the soluble carbohydrates and cyclitols changes, the ABA endogenous levels and expression of aquaporins. Differences were observed in the tolerance acquisition in immature seeds of the same age, produced by the same trees in 2007 and 2008, showing different compositions of soluble carbohydrates. Mature seeds lose desiccation tolerance soon after radicle protrusion in length depending on the degree of seed deterioration lot. Immature and mature tolerant seeds of C. echinata support the dehydration by different ways, using starch reserves and cyclitols, seen sucrose when the seed dry. These results were compared with seeds of Caesalpinia peltophoroides (sibipiruna), showing different physiological parameters, probably related to the type of reserves that they accumulate
Otieno, Mary Atieno. "Proteomic Changes in Rhizobia after Growth in Peat Extract and Their Potential Role in Desiccation Tolerance." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17791.
Повний текст джерелаHill, Donna René. "Morphological, biochemical and molecular characterization of desiccation-tolerance in cyanobacterium Nostoc commune var. Vauch." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40154.
Повний текст джерелаPh. D.
Philip, Benjamin N. "Characterization and physiological role of aquaporins during desiccation and freezing in Eurosta solidaginis." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280843234.
Повний текст джерелаWiswedel, Stefan. "Mohria caffrorum (L.) Desv. : a new, unique model organism for the study of desiccation tolerance." Bachelor's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/23926.
Повний текст джерелаMilborrow, Evan. "Non-coding RNA networks regulating leaf vegetative desiccation tolerance in the resurrection plant Xerophyta humilis." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29437.
Повний текст джерелаPeng, Congyue. "Characterization of a membrane protein encoding cDNA (TrDr3) from the desiccation-tolerant moss Tortula ruralis /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1597629781&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Повний текст джерелаSilva, Joao Paulo Naldi. "Mecanismos de controle de tolerância à dissecação em sementes de Caesalpinia echinata LAM. (Pau-Brasil) e Caesalpinia peltophoroides BENTH. (Sibipiruna) /." Botucatu : [s.n.], 2010. http://hdl.handle.net/11449/92096.
Повний текст джерелаBanca: Jose Maria Rocha Faria
Banca: João Rodrigues Domingos
Resumo: A aquisição da tolerância à dessecação ocorre durante a maturação da semente, após acúmulo de reservas e antes do início do processo natural de secagem, porém, com o avanço da germinação a sensibilidade a dessecação aumenta. Estresses hídricos podem induzir ou restabelecer a tolerância à dessecação em sementes, porém, não se sabe em quais processos ele atua, como na ativação de genes. O objetivo deste trabalho foi avaliar a aquisição e perda de tolerância à dessecação em sementes de Caesalpinia echinata Lam. (pau-brasil), e a possibilidade de indução deste processo avaliando as modificações nos carboidratos solúveis e de ciclitóis, nos níveis endógenos de ABA e na expressão de aquaporinas. Foram observadas diferenças na aquisição de tolerância em sementes imaturas de mesma idade, produzidas nas mesmas matrizes em 2007 e 2008, com diferentes composições de carboidratos solúveis. Sementes maduras perdem a tolerância à dessecação logo após protrusão da raiz primária, em comprimentos dependentes do grau de deterioração da semente. Sementes imaturas e maduras tolerantes de C. echinata suportaram a desidratação de formas diferentes, utilizando reservas de amido e ciclitóis, com papel da sacarose quando secas. Esses resultados foram comparados com sementes de Caesalpinia peltophoroides Benth (sibipiruna), demonstrando comportamentos fisiológicos distintos, provavelmente relacionados com o tipo de reserva que acumulam
Abstract: The acquisition of desiccation tolerance occurs during seed maturation, after reserves accumulation and before the natural process of drying, however, with seed germination the desiccation sensitivity increases. Water stress can induce or restore the desiccation tolerance in seeds, but it is unclear what processes it acts, like activation of genes. The objective of this work was to evaluate the acquisition and loss of desiccation tolerance in Caesalpinia echinata Lam (brazil-wood) seeds, and the possibility to induction this process, evaluating the soluble carbohydrates and cyclitols changes, the ABA endogenous levels and expression of aquaporins. Differences were observed in the tolerance acquisition in immature seeds of the same age, produced by the same trees in 2007 and 2008, showing different compositions of soluble carbohydrates. Mature seeds lose desiccation tolerance soon after radicle protrusion in length depending on the degree of seed deterioration lot. Immature and mature tolerant seeds of C. echinata support the dehydration by different ways, using starch reserves and cyclitols, seen sucrose when the seed dry. These results were compared with seeds of Caesalpinia peltophoroides (sibipiruna), showing different physiological parameters, probably related to the type of reserves that they accumulate
Mestre
Shoko, Ryman. "A proteomic investigation of the rhizomes of the resurrection fern Mohria caffrorum L. (Desv.) in response to desiccation." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16779.
Повний текст джерелаAs there is limited information on the mechanisms of vegetative desiccation-tolerance in resurrection plant rhizomes, this work was undertaken to study the mechanisms of desiccation-tolerance in Mohria caffrorum rhizomes. Fronds of this plant have been previously characterized as being desiccation-tolerant in summer and desiccation-sensitive in winter. Since fern rhizomes are perennial organs, it was of interest to establish whether these organs are also perennially desiccation-tolerant and, whether or not the rhizomes regulate desiccation-tolerance in the fronds. Ultra-structural evidence using transmission electron microscopy and viability studies using electrolyte leakage analysis showed that the rhizomes were desiccation-tolerant throughout the seasons. Quantitative proteomics analysis using isobaric tags for relative and absolute quantification was employed to investigate molecular mechanisms of desiccation-tolerance in the rhizomes of this plant. Using a custom fern rhizome specific peptide sequence database, 236 proteins were identified. Of these, 16 proteins increased in abundance while 14 declined, in the summer collected rhizomes. On the other hand, 16 proteins increased in abundance and 20 declined in the winter form. Western blot analysis confirmed the expression trends of heat shock protein 70-2 and superoxide dismutase-[Cu-Zn], which were among the differentially expressed proteins. Bioinformatics analysis of the differentially expressed proteins was carried out using network enrichment tools, to identify key molecular processes and pathways involved in the rhizome response to desiccation stress. Results indicate that the rhizomes use different molecular mechanisms to achieve desiccation-tolerance in winter and summer. Potential cross-talks and cross-tolerances were identified in which mechanisms protecting the rhizomes against desiccation-tolerance appeared to also protect them against heat stress, and in winter an apparent cross-talk against desiccation and pathogen stresses was also identified. This study is the first report of evidence that M.caffrorum rhizomes are the 'master-regulator organs' responsible for regulating desiccation-tolerance in the fronds. This role was inferred from the rhizome's predicted up-/down-regulation of biological processes and pathways that relate to leaf senescence, shoot system morphogenesis and gametophyte development, among others.
Sines, Brian James. "Isolation and partial characterization of a water stress protein of the desiccation-tolerant cyanobacterium Nostoc commune UTEX 584 expressed in Escherichia coli." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/46434.
Повний текст джерелаMaster of Science
Svensson, Jan. "Functional studies of the role of plant dehydrins in tolerance to salinity, desiccation and low temperature /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5779-3.pdf.
Повний текст джерелаWalford, Sally-Ann. "Activation of seed-specific genes in leaves and roots of the desiccation tolerant plant, Xerophyta humilis." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4349.
Повний текст джерелаIncludes bibliographical references (leaves 131-169).
The ability of tissues to survive almost complete loss of cellular water is a trait found throughout the plant kingdom. While this desiccation tolerance is common in seeds of most angiosperms it is rare in their vegetative tissues. Xerophyta humilis (Bak.) Dur and Schintz belongs to a small group of resurrection angiosperms and it possesses the ability to withstand extreme desiccation of greater than 90% in both its seeds and vegetative tissues and return to active metabolism upon rehydration. We have tested the hypothesis that vegetative desiccation tolerance in angiosperms has evolved as an adaptation of seed desiccation tolerance.
Ludanyi, Monika. "Extreme radiation tolerance of Deinococcus deserti : Characterization of the central regulator IrrE." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4066.
Повний текст джерелаDeinococcus bacteria are famous for their extreme tolerance to high doses of radiation. Earlier studies have shown that IrrE protein is required for radiation tolerance and for induction of DNA repair genes after exposure of cells to radiation. However, for years it has remained unknown how IrrE activates gene expression. The aim of my thesis was to characterize the IrrE-dependent regulation pathway in Deinococcus deserti. For this, biochemical and genetic approaches were used. The first results strongly suggested that IrrE activates gene expression in an indirect manner. Then, using other in vivo and in vitro experiments, IrrE from Deinococcus deserti was found to interact with DdrO, a predicted regulator encoded by a radiation-induced gene that is, like irrE, highly conserved in Deinococcus. Moreover, IrrE was found to cleave DdrO in vitro and also in vivo when the proteins were co-expressed in Escherichia coli. This cleavage was not observed in the presence of the metal chelator EDTA. In D. deserti, IrrE-dependent cleavage of DdrO was observed only after exposure to radiation. Furthermore, DdrO-dependent repression of the promoter of a radiation-induced gene was shown. Our results demonstrate that IrrE is a metalloprotease and we propose that IrrE-mediated cleavage inactivates repressor protein DdrO, leading to transcriptional induction of various genes required for DNA repair and cell survival after exposure of Deinococcus to radiation
Smith-Espinoza, Claudia J. "Analysis of ABA and drought stress mediated gene expression in the desiccation tolerant resurrection plant Craterostigma plantagineum." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963130862.
Повний текст джерелаSmith, Michaela Madeleine 1972. "Maintenance of ultrastructural integrity during dehydration in a desiccation tolerant angiosperm as revealed by improved preservation techniques." Monash University, Dept. of Biological Sciences, 2002. http://arrow.monash.edu.au/hdl/1959.1/8323.
Повний текст джерелаDimson, Emily V. "Development and desiccation tolerance of the seeds of Acer rubrum L., Acer saccharinum L. and their hybrid." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ40408.pdf.
Повний текст джерелаGasulla, Vidal Francisco. "Insights on desiccation tolerance of the lichen photobiont trebouxia sp. pl. in both thalline and isolated ones." Doctoral thesis, Universitat de València, 2009. http://hdl.handle.net/10803/39081.
Повний текст джерелаEl estudio de la tolerancia a la desecación de los líquenes, y de sus fotobiontes en particular, ha sido principalmente enfocado hacia los sistemas antioxidantes que protegen a la célula frente al estrés fotoxidativo. Sin embargo, la tolerancia a la desecación no puede ser alcanzada solamente con sistemas antioxidantes. Por esta razón, el objetivo principal de esta tesis fue profundizar en el conocimiento de los mecanismos de tolerancia a la desecación en fotobiontes liquénicos. El fotobionte liquénico Trebouxia erici Ahmadjian mostró ser tolerante a la desecación incluso cuando es cultivado separado de su compañero micobionte. Sin embargo, la resistencia a la desecación dependió de la velocidad de deshidratación, del tiempo de desecación y del envejecimiento del cultivo. Tasas de deshidratación altas, largos periodos de desecación y cultivos viejos redujeron la capacidad de recuperación. Esto es debido a que la tolerancia a la desecación del fotobionte se consigue por un lado mediante mecanismos de protección celular que son constitutivamente expresados como, enzimas antioxidantes, xantofilas o proteínas LEA, junto con la activación Mientras que por otro, existen mecanismos que se activan durante la deshidratación, como son de la síntesis de proteínas implicadas en el transporte, la protección de membranas y proteínas, el citoesqueleto, el ciclo celular y el marcaje y la degradación de proteínas. Aunque los fotobiontes liquénicas tienen sus propios mecanismos para resistir la desecación, en la relación simbióntica la tolerancia a la desecación podría ser aumentada por otros mecanismos. Nuestros estudios con el liquen Ramalina farinacea Ach. y fotobiontes aislados mostraron que el gas bioactivo oxido de nitrógeno (NO) es liberado principalmente por el hongo durante la rehidratación del talo, el cual podría tener un papel importante en la maquinaria antioxidante del fotobionte durante las primeras fases de la rehidratación.
Joardar, Vinita. "Molecular analysis of genes involved in carbohydrate metabolism in the desiccation-tolerant cyanobacterium Nostoc commune UTEX 584." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/40311.
Повний текст джерелаPh. D.
Brown, Carly. "A comparison of some potential indicators of desiccation-tolerance in 2 Poikilochlorophyllous Xerophyta species and Homiochlorophyllous Craterostigma wilmsii." Bachelor's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/24762.
Повний текст джерелаBergh, Nicola G. "Aspects of the prevention of light damage during drying and rehydration of the desiccation-tolerant grass Eragrostis nindensis." Bachelor's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/25780.
Повний текст джерелаPereira, Luciano 1981. "Resistência à seca em plântulas de espécies arbóreas da floresta estacional semidecídua." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314924.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-18T12:00:54Z (GMT). No. of bitstreams: 1 Pereira_Luciano_M.pdf: 1574760 bytes, checksum: 86654daaeda73234eef3076e41dd937f (MD5) Previous issue date: 2011
Resumo: Apesar da alta pluviosidade nas florestas tropicais, há grande variação na disponibilidade hídrica para as plantas. Em escala local, essa disponibilidade pode variar dependendo da localização dos indivíduos em clareiras, sua posição no relevo e a composição do solo. Em escala regional, variações relacionadas ao volume e distribuição das chuvas, aliadas às alterações climáticas sazonais, podem também gerar diferentes condições de déficit hídrico, aumentando as taxas de mortalidade das espécies arbóreas mais sensíveis, em especial no estádio de plântula. Considerando o cenário mundial de mudanças climáticas, torna-se urgente a compreensão dos mecanismos que determinam a ecologia das comunidades das florestas tropicais, principalmente em relação aos padrões de chuvas e secas. Neste trabalho analisamos as diferentes estratégias de resistência à seca de plântulas de espécies arbóreas, com o objetivo de entender como diferentes espécies arbóreas respondem à variação da disponibilidade hídrica, de modo a conhecer como essa variação filtra as espécies e conseqüentemente contribui para organizar a comunidade florestal. No primeiro capítulo apresentamos as principais estratégias de resistência à seca e as possíveis abordagens teóricas, descritas na literatura, para plântulas de espécies arbóreas, demonstrando a importância dessas estratégias na distribuição, abundância e coexistência de espécies nas florestas tropicais. As diferenças entre as florestas tropicais úmidas e secas, pelo baixo compartilhamento de espécies e os diferentes graus de resistência à seca apresentados por espécies arbóreas, indicam uma clara diferenciação de nichos. Espécies mais resistentes à seca ocupam, com maior abundância, locais mais secos, quando comparadas às espécies mais sensíveis, tanto em escala local quanto regional. Estratégias de resistência à seca podem ser de dois tipos: de tolerância à dessecação e de evitação à dessecação. No estádio de plântula, estratégias de tolerância parecem ser mais determinantes para a resistência à seca, principalmente a presença de caracteres que conferem tolerância a baixos potenciais hídricos, como resistência à cavitação. No segundo capítulo investigamos a hipótese de que há uma relação entre a abundância de algumas espécies em locais com diferentes intensidades de sombreamento e/ou sua posição na vertente (com provável gradiente hídrico) da Floresta Estacional Semidecídua e a presença de estratégias fisiológicas de trocas de gases relacionadas à resistência à seca. Avaliamos a troca de gases, dessecação e rebrota de plantas de duas espécies tardias (Esenbeckia leiocarpa e Astronium graveolens) e duas espécies pioneiras (Croton floribundus e Aegiphila selowiana) em um experimento de seca súbita em casa de vegetação. Encontramos maior resistência à seca nas espécies com maior abundância e de estádio sucessional tardio (E. leiocarpa e A. graveolens). A resistência à seca esteve associada às menores taxas de troca de gases, e as espécies com maior aproveitamento fotossintético exibiram menor resistência à seca. Essas espécies ocorrem mais abundantemente nos sítios de ocupação menos sombreados, reforçando a teoria de uma demanda conflitante para espécies que ou investem em resistência à seca ou na capacidade de aproveitamento de luz. A disponibilidade sazonal de água, assim como a diferença de luz entre as diferentes ecounidades, pode explicar a coexistência das espécies na floresta estacional
Abstract: The rainfall is high in tropical forests, but there is great variation in water availability to plants. On a local scale, this availability may vary depending on the location of individuals in gaps, their position in the landscape and soil composition. On a regional scale, variations related to the volume and distribution of rainfall, coupled with seasonal climatic changes, can also generate different water stress conditions, increasing the mortality rates of tree species most sensitive, especially at the seedling stage. Considering the global scenario of climatic changes, it is imperative to understand the mechanisms that determine the ecology of communities of tropical forests, especially in relation to patterns of rainfall and drought. We examined different strategies of drought resistance of seedlings of tree species, to determine the organization of the community and the contribution of water availability to the selection of species in these forests. The first chapter presents a review of the principal studies available on strategies for drought resistance in seedlings of tree species and the possible theoretical approaches, demonstrating the increasing importance of these studies for understanding the processes that determine the distribution, abundance and species coexistence in tropical forests. The differences between wet and dry tropical forests, in view of the low number of species in common and the different degrees of drought resistance presented by the tree species present, show a clear differentiation of niches. Species more resistant to drought present higher abundance in drier sites, compared to more sensitive species, at local and regional levels. Strategies for drought resistance may be of two kinds: desiccation tolerance and avoidance of desiccation. In the seedling stage tolerance strategies seem to be more crucial for resistance to drought, especially the presence of characteristics that confer tolerance to low water potentials, as resistance to cavitation. In the second chapter we investigated the hypothesis that there is a relationship between the existence of abundant species only at certain sites of the semi-deciduous forest and the presence of physiological strategies of gas exchange related to drought resistance. We evaluated the gas exchange process and desiccation and regrowth of plants of four species (Esenbeckia leiocarpa, Astronium graveolens, Croton floribundus and Aegiphila selowiana), during a sudden drought experiment in a greenhouse. E. leiocarpa, A. graveolens are late-successional species and C. floribundus and A. selowiana are pioneers species. We found greater resistance to drought in the most abundant and latesuccessional species. The drought resistance was associated with lower rates of gas exchange. Species with higher photosynthetic efficiency showed lower resistance to drought. These species occur most abundantly on sites less shaded, reinforcing the theory of a trade off between investment in drought resistance and ability to use light. The seasonal availability of water, similarly to differences between light of different eco-units, can explain species coexistence in the tropical seasonal forest
Mestrado
Biologia Vegetal
Mestre em Biologia Vegetal
Gardner, Michael Jack. "Resources for the investigation of the desiccation tolerance mechanisms of the roots of Xerophyta humilis (Bak) Dur and Schinz." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/4263.
Повний текст джерелаAlthough roots play an integral role in the sensing and amelioration of environmenatl stresses, there are no reports that specifically detail their involvement in the desiccation tolerance mechanisms of resurrection plants. Very lttle is known about even the genral anatomy and physiology of the roots of plants such as X. humilis, and almost nothing about the molecular responses that confer their ability to survive desiccation. This report details foundational studies of the functional anatomy and large-scale molecular responses of the roots during dehydrtion and rehydration.
Peng, Xiaobing Carleton University Dissertation Biology. "The role of abscisic acid and abscisic acid-analogs in inducing desiccation tolerance in microspore-derived embryos of Brassica Napus." Ottawa, 1994.
Знайти повний текст джерелаBurdine, Justin D. "Factors influencing bee communities and pollination services across an urban environment." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1554460864439054.
Повний текст джерелаMoore, John Paul. "The role of polyphenols and the cell wall in relation to the desiccation tolerance of the resurrection plant, Myrothamnus flabellifolia (Welw.)." Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4299.
Повний текст джерелаResurrection plants are unique in that their vegetative tissue has the ability of survive reversible dehydration to an air-dry state. The widespread African resurrection plant Myrothamnus flabellifolia (Welw), woody shrub, is one of the largest of these plants. In addition to its resurrection ability it is also an important medicinal plant and is used by local tribes in the various regions where it grows to treat a wide variety of ailments. This thesis has investigated a number of morphological, ultrastructural and biochemical adaptations of the leaves of M. flabellifolia to dessication and associated stresses. The main aim of this thesis was to ascertain the role of polyphenols and the cell wall of M. flabellifolia in relation to its desiccation tolerance.
Abu, Sharkh Sawsan E. "Spectroscopic & thermodynamic investigations of the physical basis of anhydrobiosis in caenorhabditis elegans dauer larvae." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-164661.
Повний текст джерела