Littérature scientifique sur le sujet « Desiccation toleranc »
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Articles de revues sur le sujet "Desiccation toleranc"
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Englert, John M., Keith Warren, Leslie H. Fuchigami et Tony H. H. Chen. « Antidesiccant Compounds Improve the Survival of Bare-root Deciduous Nursery Trees ». Journal of the American Society for Horticultural Science 118, no 2 (mars 1993) : 228–35. http://dx.doi.org/10.21273/jashs.118.2.228.
Texte intégralRésumé :
Desiccation stress during the postharvest handling of bare-root deciduous trees can account for dieback and poor regrowth after transplanting. Desiccation tolerance of three bare-root deciduous hardwood species was determined at monthly harvest intervals from Sept. 1990 through Apr. 1991. Among the three species tested red oak (Quercus rubra L.) was most tolerant to desiccation, followed by Norway maple (Acer platanoides L.) and Washington hawthorn (Crataegus phaenopyrum Medic.). Maximum desiccation tolerance of all three species occurred during the January and February harvests. Of 20 film-forming compounds tested, the antidesiccant Moisturin was the most effective in reducing water loss from bare-root trees during desiccation stress and in improving survival and plant performance during re-establishment in the laboratory, greenhouse, and field. Moisturin-treated plants lost up to 80% less water than untreated plants. Washington hawthorn seedlings treated with Moisturin before severe desiccating conditions had the highest survival, lowest dieback/plant, and highest root growth ratings. The results indicate that Moisturin is an effective means of overcoming postharvest desiccation stress in desiccation sensitive plants, such as Washington hawthorn.
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Wolkers, Willem F., et Folkert A. Hoekstra. « In situFTIR Assessment of Desiccation-Tolerant Tissues ». Spectroscopy 17, no 2-3 (2003) : 297–313. http://dx.doi.org/10.1155/2003/831681.
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This essay shows how Fourier transform infrared (FTIR) microspectroscopy can be applied to study thermodynamic parameters and conformation of endogenous biomolecules in desiccation-tolerant biological tissues. Desiccation tolerance is the remarkable ability of some organisms to survive complete dehydration. Seed and pollen of higher plants are well known examples of desiccation-tolerant tissues. FTIR studies on the overall protein secondary structure indicate that during the acquisition of desiccation tolerance, plant embryos exhibit proportional increases inα-helical structures and thatµ-sheet structures dominate upon drying of desiccation sensitive-embryos. During ageing of pollen and seeds, the overall protein secondary structure remains stable, whereas drastic changes in the thermotropic response of membranes occur, which coincide with a complete loss of viability. Properties of the cytoplasmic glassy matrix in desiccation-tolerant plant organs can be studied by monitoring the position of the OH-stretching vibration band of endogenous carbohydrates and proteins as a function of temperature. By applying these FTIR techniques to maturation-defective mutant seeds ofArabidopsis thalianawe were able to establish a correlation between macromolecular stability and desiccation tolerance. Taken together,in situFTIR studies can give unique information on conformation and stability of endogenous biomolecules in desiccation-tolerant tissues.
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Pardo, Jeremy, Ching Man Wai, Hannah Chay, Christine F. Madden, Henk W. M. Hilhorst, Jill M. Farrant et Robert VanBuren. « Intertwined signatures of desiccation and drought tolerance in grasses ». Proceedings of the National Academy of Sciences 117, no 18 (23 avril 2020) : 10079–88. http://dx.doi.org/10.1073/pnas.2001928117.
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Grasses are among the most resilient plants, and some can survive prolonged desiccation in semiarid regions with seasonal rainfall. However, the genetic elements that distinguish grasses that are sensitive versus tolerant to extreme drying are largely unknown. Here, we leveraged comparative genomic approaches with the desiccation-tolerant grass Eragrostis nindensis and the related desiccation-sensitive cereal Eragrostis tef to identify changes underlying desiccation tolerance. These analyses were extended across C4 grasses and cereals to identify broader evolutionary conservation and divergence. Across diverse genomic datasets, we identified changes in chromatin architecture, methylation, gene duplications, and expression dynamics related to desiccation in E. nindensis. It was previously hypothesized that transcriptional rewiring of seed desiccation pathways confers vegetative desiccation tolerance. Here, we demonstrate that the majority of seed-dehydration–related genes showed similar expression patterns in leaves of both desiccation-tolerant and -sensitive species. However, we identified a small set of seed-related orthologs with expression specific to desiccation-tolerant species. This supports a broad role for seed-related genes, where many are involved in typical drought responses, with only a small subset of crucial genes specifically induced in desiccation-tolerant plants.
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Tapia, Hugo, Lindsey Young, Douglas Fox, Carolyn R. Bertozzi et Douglas Koshland. « Increasing intracellular trehalose is sufficient to confer desiccation tolerance toSaccharomyces cerevisiae ». Proceedings of the National Academy of Sciences 112, no 19 (27 avril 2015) : 6122–27. http://dx.doi.org/10.1073/pnas.1506415112.
Texte intégralRésumé :
Diverse organisms capable of surviving desiccation, termed anhydrobiotes, include species from bacteria, yeast, plants, and invertebrates. However, most organisms are sensitive to desiccation, likely due to an assortment of different stresses such as protein misfolding and aggregation, hyperosmotic stress, membrane fracturing, and changes in cell volume and shape leading to an overcrowded cytoplasm and metabolic arrest. The exact stress(es) that cause lethality in desiccation-sensitive organisms and how the lethal stresses are mitigated in desiccation-tolerant organisms remain poorly understood. The presence of trehalose in anhydrobiotes has been strongly correlated with desiccation tolerance. In the yeastSaccharomyces cerevisiae, trehalose is essential for survival after long-term desiccation. Here, we establish that the elevation of intracellular trehalose in dividing yeast by its import from the media converts yeast from extreme desiccation sensitivity to a high level of desiccation tolerance. This trehalose-induced tolerance is independent of utilization of trehalose as an energy source, de novo synthesis of other stress effectors, or the metabolic effects of trehalose biosynthetic intermediates, indicating that a chemical property of trehalose is directly responsible for desiccation tolerance. Finally, we demonstrate that elevated intracellular maltose can also make dividing yeast tolerant to short-term desiccation, indicating that other disaccharides have stress effector activity. However, trehalose is much more effective than maltose at conferring tolerance to long-term desiccation. The effectiveness and sufficiency of trehalose as an antagonizer of desiccation-induced damage in yeast emphasizes its potential to confer desiccation tolerance to otherwise sensitive organisms.
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Oliver, Melvin J., Jill M. Farrant, Henk W. M. Hilhorst, Sagadevan Mundree, Brett Williams et J. Derek Bewley. « Desiccation Tolerance : Avoiding Cellular Damage During Drying and Rehydration ». Annual Review of Plant Biology 71, no 1 (29 avril 2020) : 435–60. http://dx.doi.org/10.1146/annurev-arplant-071219-105542.
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Desiccation of plants is often lethal but is tolerated by the majority of seeds and by vegetative tissues of only a small number of land plants. Desiccation tolerance is an ancient trait, lost from vegetative tissues following the appearance of tracheids but reappearing in several lineages when selection pressures favored its evolution. Cells of all desiccation-tolerant plants and seeds must possess a core set of mechanisms to protect them from desiccation- and rehydration-induced damage. This review explores how desiccation generates cell damage and how tolerant cells assuage the complex array of mechanical, structural, metabolic, and chemical stresses and survive.Likewise, the stress of rehydration requires appropriate mitigating cellular responses. We also explore what comparative genomics, both structural and responsive, have added to our understanding of cellular protection mechanisms induced by desiccation, and how vegetative desiccation tolerance circumvents destructive, stress-induced cell senescence.
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Fu, J. R., J. P. Jin, Y. F. Peng et Q. H. Xia. « Desiccation tolerance in two species with recalcitrant seeds : Clausena lansium (Lour.) and Litchi chinensis (Sonn.) ». Seed Science Research 4, no 2 (juin 1994) : 257–61. http://dx.doi.org/10.1017/s0960258500002245.
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AbstractSeeds were collected at weekly intervals from mid-maturation to the fully ripened stage. As seed development progressed, desiccation tolerance increased. Desiccation tolerance of C. lansium seeds was greatest at 67 days after anthesis (DAA), when they tolerated air drying for 9 days; 74 DAA was considered as physiological maturity, and their full viability was only maintained for up to 3 days of drying; overripened seeds (88 DAA) had the lowest desiccation tolerance. In L. chinensis, the desiccation sensitivity of seeds at 98 DAA (fully mature) was higher than that at 84 and 91 DAA (less mature); among the excised embryonic axes at different developmental stages, the less mature ones were less sensitive to desiccation than the fully mature ones; excised embryonic axes of the same stage were more tolerant of desiccation than whole seeds.
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Greggains, Valerie, William E. Finch-Savage, W. Paul Quick et Neil M. Atherton. « Putative desiccation tolerance mechanisms in orthodox and recalcitrant seeds of the genusAcer ». Seed Science Research 10, no 3 (septembre 2000) : 317–27. http://dx.doi.org/10.1017/s0960258500000362.
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AbstractRecalcitrant seeds are shed moist from the plant and do not survive desiccation to the low moisture contents required for prolonged storage. It has been widely hypothesised that during desiccation of these seeds a stress induced metabolic imbalance develops that leads to free radical mediated damage and viability loss. We investigated this hypothesis in a comparison of two sympatric species ofAcerduring late seed development and post-harvest desiccation:A. platanoides(Norway maple) has orthodox seeds andA. pseudoplatanus(sycamore) has recalcitrant seeds. In both species, respiration rates declined to similar levels at shedding, and the extent of defences against free radicals appears no less in sycamore than that in Norway maple. During drying there was no evidence for the accumulation of a stable free radical, increased lipid peroxidation or decline in free radical scavenging enzymes in either species. In addition, there was a very similar, large increase in total tocopherol in both species. This increase in sycamore was largely of alpha-tocopherol, whereas in Norway maple the increase was largely from its precursor, gamma-tocopherol. Arguably this suggests a similar mechanism in both species, but increased oxidative stress in sycamore. In general, the results suggest that, although damage resulting in viability loss was clearly taking place, the limitation to desiccation tolerance did not result from inadequate free radical scavenging. Soluble carbohydrates and dehydrin-like proteins were also measured during late seed development and drying in sycamore and Norway maple. The greater concentrations of sucrose, raffinose and stachyose and amounts of dehydrins in the radicles and cotyledons of Norway maple compared with those in sycamore was consistent with greater desiccation tolerance in the former. Sycamore seeds are dormant and at the tolerant end of the continuum of desiccation sensitivity among recalcitrant species, and this may account for their different response to that of the seeds of other more sensitive recalcitrant species studied.
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Sinzar-Sekulic, Jasmina, Marko Sabovljevic et Branka Stevanovic. « Comparison of desiccation tolerance among mosses from different habitats ». Archives of Biological Sciences 57, no 3 (2005) : 189–92. http://dx.doi.org/10.2298/abs0503189s.
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Three moss species from the karst region were compared to establish their respective patterns of desiccation tolerance. Different life forms of bryophytes were chosen to obtain evidence of their life strategies during drought conditions. Comparative analyses of electrolyte leakage were performed to screen for tolerance of the membrane to water stress and for signs of damage to the fine structure of the protoplasm. The experiments were carried out by exposing the plants to water stress caused by PEG 600. The results show that the most desiccation tolerant species is Thamnobryum alopecurum, less but fairly tolerant is Anomodon viticulosus, while the aquatic Rhynchostegium riparioides is intolerant of desiccation.
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Marks, Rose A., Mpho Mbobe, Marilize Greyling, Jennie Pretorius, David Nicholas McLetchie, Robert VanBuren et Jill M. Farrant. « Variability in Functional Traits along an Environmental Gradient in the South African Resurrection Plant Myrothamnus flabellifolia ». Plants 11, no 10 (18 mai 2022) : 1332. http://dx.doi.org/10.3390/plants11101332.
Texte intégralRésumé :
Many desiccation-tolerant plants are widely distributed and exposed to substantial environmental variation across their native range. These environmental differences generate site-specific selective pressures that could drive natural variation in desiccation tolerance across populations. If identified, such natural variation can be used to target tolerance-enhancing characteristics and identify trait associations within a common genetic background. Here, we tested for natural variation in desiccation tolerance across wild populations of the South African resurrection plant Myrothamnus flabellifolia. We surveyed a suite of functional traits related to desiccation tolerance, leaf economics, and reproductive allocation in M. flabellifolia to test for trait associations and tradeoffs. Despite considerable environmental variation across the study area, M. flabellifolia plants were extremely desiccation tolerant at all sites, suggesting that tolerance is either maintained by selection or fixed in these populations. However, we detected notable associations between environmental variation, population characteristics, and fitness traits. Relative to mesic sites, plants in xeric sites were more abundant and larger, but were slower growing and less reproductive. The negative association between growth and reproduction with plant size and abundance pointed towards a potential growth–abundance tradeoff. The finding that M. flabellifolia is more common in xeric sites despite reductions in growth rate and reproduction suggests that these plants thrive in extreme aridity.
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WRIGHT, JONATHAN C. « Desiccation Tolerance and Water-Retentive Mechanisms in Tardigrades ». Journal of Experimental Biology 142, no 1 (1 mars 1989) : 267–92. http://dx.doi.org/10.1242/jeb.142.1.267.
Texte intégralRésumé :
Tardigrades entering a state of anhydrobiosis (cryptobiosis) show considerable interspecific variation in desiccation tolerance, lower lethal humidities for initial desiccation ranging from 78 to 53 %. Species most tolerant of rapid initial drying also show the most rapid acquisition of tolerance to low humidities (25–31 %) following drying in high humidity. Surface area reduction during tun formation shows a significant positive regression against desiccation tolerance in the Eutardigrada. The most desiccation-tolerant species thus infold the largest areas of cuticle. By comparison, the heterotardigrade Echiniscus testudo shows a very poor capacity for surface area reduction. The thick dorsal plates may restrict cuticle intucking in this species. When hydrated tardigrades are desiccated in 80 % relative humidity they show a characteristic profile of mass loss, dehydrating rapidly in the first few minutes and then showing an abrupt reduction in transpiration (the ‘permeability slump'). This applies to living animals, which form tuns when desiccated, and to dead animals remaining extended. The permeability slump is not, therefore, a metabolic phenomenon and is not related to tun formation. Subsequent transpiration rates are very low and decline exponentially. The permeability slump allows animals to retain considerable amounts of internal water when desiccated, although less water is retained if the desiccation rate is increased. This may determine upper tolerable desiccation rates if a certain minimum quantity of water is required for the metabolic synthesis of membrane protectants. A significant positive regression between water retention and desiccation tolerance supports this hypothesis.
Thèses sur le sujet "Desiccation toleranc"
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Potts, Malcolm. « Desiccation tolerance ». Thesis, Durham University, 1995. http://etheses.dur.ac.uk/9528/.
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Despite the fundamental significance of desiccation in determining the distributions and activities of living organisms, there is virtually no insight as to the state of the cytoplasm of an air-dried, or even a wet, cell. In bacterial cells that have been subjected to air-drying the evaporation of free cytoplasmic water (Vf) can be instantaneous, and an equilibrium between cell-bound water (VQ and the environmental water (vapor) potential (Ψwv)) may be achieved very rapidly. In the air-dried state some bacteria survive only for seconds, others can tolerate desiccation for thousands, perhaps for millions, of years. The means by which certain cells, the anhydrobiotes, overcome and then tolerate acute water deficit remains one of the most intractable problems in cell biology. One such anhydrobiote, the cyanobacterium Nostoc commune, is cosmopolitan, its colonies form visually-conspicuous and abundant growths in situ, and it constitutes an ecologically-significant component of terrestial nitrogen-fixing communities. The cyanobacteria are phylogenetically-significant organisms that provide model systems for the study of a broad range of problems in cell biology. The studies described in this thesis established the molecular ecology and cell biology of Nostoc commune, and they provide a chronicle of the development of this microorganism as the prokaryotic model for the anhydrobiotic cell. In the design of experiments to investigate this problem the bias was, and remains, this: to understand desiccation tolerance, understand an organism that tolerates desiccation. The thesis documents an investigation into the consequences of acute cell-water deficit and the cellular basis for desiccation tolerance. An eclectic approach has been adopted to study desiccation tolerance and it includes the application of techniques of cell biology, biochemistry, microbiology, molecular biology, structural biology and biophysics.
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Chaibenjawong, Plykaeow. « Desiccation Tolerance in Staphylococcus aureus ». Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522502.
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Dace, Halford. « Metabolomics of desiccation tolerance in Xerophyta humilis ». Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9111.
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Includes bibliographical referencesResurrection 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.
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Casteriano, Andrea Veronica. « Physiological mechanisms of desiccation tolerance in Rhizobia ». Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/10423.
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One of the main factors affecting the survival of rhizobia on seed is desiccation stress. The poor survival of rhizobia affects nodulation, nitrogen fixation and legume yield. A better understanding of desiccation tolerance and how it may be enhanced may contribute to the development of strategies to improve survival of rhizobia on seed. This study aimed to improve the survival of rhizobia by enhancing inherent mechanisms of desiccation tolerance through the manipulation of the growth medium. Accumulation of intracellular trehalose by rhizobia increases in response to osmotic and desiccation stress, and has also been related to an improved capacity for desiccation tolerance. In this study, a linear relationship was observed between intracellular trehalose accumulation in Rhizobium leguminosarum bv. trifolii (TA1) and Bradyrhizobium japonicum (CB1809) and increasing osmotic pressure of a defined growth medium (JMM) from 1.0 atm to 2.8 atm. Although increased concentrations of intracellular trehalose did not improve survival of rhizobia immediately after vacuum drying, survival was significantly improved after 10 days of storage at low relative humidity (9%). Resuspending rhizobia in trehalose solution, to provide external protection to cells during drying, significantly increased survival immediately after drying and storage. The increased protection during drying allowed the positive effect of intracellular trehalose on rhizobial survival to be observed. Cells of TA1 and CB1809 extracted from peat after solid-state fermentation survived significantly better immediately after vacuum drying (22-fold and 5-fold respectively) and during storage than cells grown in JMM (1.0 atm). However, it was difficult to extract adequate V cell mass to measure intracellular trehalose and consequently cells were grown in water extracts of peat to simulate the conditions that rhizobia would be exposed to in traditional peat cultures. Growing TA1 and CB1809 in aqueous peat extract increased trehalose accumulation compared to cells grown in JMM and also significantly improved survival (18-fold) of TA1. Although survival of CB1809 was generally improved after growth in peat extract, it was not significantly different to cells grown in JMM. Cells grown in peat extract exhibited changes in cell morphology and protein expression similar to those observed after solid-state fermentation in peat. Electron microscopy revealed the accumulation of an electron-dense material around the plasma membrane that occupied the periplasmic space in both TA1 and CB1809. Similar changes to cell morphology have been previously linked to improved survival. Peptide analysis by liquid chromatography-mass spectrometry indicated increased expression of stress response proteins in TA1 and CB1809 after growth in peat extract. Some of those proteins included membrane repair proteins (PspA) and proteins generated to combat periplasmic stress (OstA) and oxidative damage (thioredoxin). A cell viability assay using alamarBlue® reagent showed that growing rhizobia in peat extract reduces metabolic activity compared to that of cells grown in JMM, and membrane integrity analysis of the same cells using a LIVE/DEAD® viability kit showed that peat extract increased membrane permeability to propidium iodide (PI). Environmental stresses have been reported to cause reversible changes to membrane function and permeability, demonstrated by changes in PI-uptake. This finding, together with the changes in cell morphology and increased expression of stress response proteins, suggests that improved survival after growth of rhizobia in peat extract is related to adaptive changes of cells in response to water-extractable constituents of peat. VI Findings from this work suggest that desiccation tolerance in rhizobia is a multifactorial process that involves the accumulation of trehalose together with the expression of proteins involved in maintaining cell envelope integrity and stability, as well as the repair and prevention of DNA and protein damage caused by oxidative stress. Determining chemical elicitors of adaptive changes in cells may assist in further development of inoculant technology to improve survival of rhizobia on seed.
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Fleming, 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.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. 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.
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Sheen, Tamsin, et 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.
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Serratia entomophila, the causative agent of amber disease, is an endemic bacterium used for the biocontrol of New Zealand grass grub larvae. Although the available biopesticide is effective, its use is limited to areas where sub-surface application is feasible, and is also impacted by soil conditions such as moisture levels and osmolarity. The aim of this study was to elucidate the responses of S. entomophila to osmotic and desiccation stresses in relation to challenges encountered during production, storage and soil application, with the goal of developing a more robust and versatile biocontrol agent.
RpoS is a key factor in the stress response of many enteric bacteria. In order to dissociate the effect of RpoS from subsequent cellular stress studies, an rpoS mutant was constructed by site-directed mutagenesis. Assessment of the rpoS mutant showed that RpoS was not implicated in NaC1 or desiccation tolerance of S. entomophila. The rpoS mutant was instead found to have enhanced salt tolerance and could be distinguished from the wild-type by the ability to ferment arabinose, a phenotype that was confirmed through complementation. Complete abolition of the amber disease process was observed using an rpoS strain also missing the Sep virulence genes, suggesting that RpoS is a regulator of the S. entomophila anti-feeding prophage (Afp). These findings indicate a subtle interplay between NaC1 tolerance, virulence and RpoS-mediated regulation of amber disease in S. entomophila.
A transposon mutagenesis screen was carried out to identify genes associated with NaC1 tolerance in S. entomophila. Fourteen mutants displaying NaC1 sensitivity were identified, two of which had mutations in genes with potential implications for the formulation of the bacterium as a biocontrol agent. The gene leuO that encodes a LysR-family transcriptional regulator was found to be essential for S. entomophila NaC1 tolerance. The toxicity of increased cellular LeuO from an over-expression vector led to the investigation of the effects of leuO mutation on the proteome. Multiple protein changes observed by two-dimensional gel analysis suggested that LeuO may be a global regulator in S. entomophila, as has been hypothesised for Salmonella species. A second NaC1-sensitive mutant contained an insertion in afp15, the product of which is thought to be involved in assembly of the Afp. As well as being sensitive to NaC1, the afp15 mutant was unable to induce the anti-feeding component of amber disease, again highlighting the link between stress tolerance and virulence in S. entomophila.
This study also determined that pre-exposure to NaC1 in conjunction with the provision of exogenous glycine betaine significantly enhanced the survival of S. entomophila either in a desiccated state or after application to soil, regardless of the soil moisture content. The implication of this finding on the future formulation of S. entomophila led to investigation of the underlying genetic mechanisms involved in glycine betaine synthesis and NaC1 tolerance. The genes involved in glycine betaine biosynthesis from choline were identified through genomic comparison, degenerate PCR and primer walking. A 6.5 kb region was sequenced and found to contain four genes with homology and similar chromosomal arrangement to the E. coli bet genes (betTIBA). The S. entomophila betIBA genes comprised an operon, flanked by the divergently-transcribed betT gene whose product is responsible for choline transport. To ascertain the relative transcription levels of components of the bet operon, quantitative RT-PCR was performed. Results of qRT-PCR showed that choline in conjunction with NaC1 induced the greatest levels of bet gene transcription, and that levels of the betA transcript were significantly lower than those of the other bet genes. Examination of the betA 5� non-coding region identified a previously undetected hairpin region, possibly accounting for the observed decrease in betA transcript levels.
The findings of this study have significantly advanced our understanding of how S. entomophiia responds to stress, and will contribute to the development of formulation strategies for the production of a robust product capable of application to pasture by a range of teclmiques. In addition, there is significant potential to utilise these findings in the development of other bacterial inocula for a range of biotechnological applications.
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Montazeri, 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.
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Ratnakumar, 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.
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Jones, 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.
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Lyall, Rafe. « Regulation of desiccation tolerance in Xerophyta seedlings and leaves ». Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22853.
Texte intégralRésumé :
A small, diverse group of angiosperms known as resurrection plants display vegetative desiccation tolerance and can survive loss of up to 95% of cellular water, a feat only seen in the seeds and pollen of other angiosperms. Xerophyta humilis is a resurrection plant native to Southern Africa that has been the target of previous transcriptomic and proteomic studies into the mechanisms of plant desiccation tolerance. The aim of this study was to investigate the hypothesis that vegetative desiccation tolerance is derived from the networks that control desiccation tolerance in seeds and germinating seedlings in angiosperms, particularly the epigenetically silenced seed maturation genes. Germinating seedlings of X. humilis and the related resurrection plant X. viscosa were found to be VDT from the earliest stages of germination, and exhibited the characteristic vegetative trait of poikilochlorophylly as seen in mature leaves. The X. humilis desiccation transcriptome comprising 76,768 distinct gene clusters was successfully assembled from sequencing samples at five relative water contents (100%, 80%, 60%, 40% and 5%) to identify the networks activated in response to water loss. Desiccation was associated with successive waves of transcription factor induction, as well as widespread down-regulation of histone modification enzymes. Many seed-specific genes, such as late embryogenesis abundant (LEA) proteins, seed storage proteins and oleosins, were induced in vegetative tissue. LEA transcripts in particular were highly up-regulated during desiccation, and the large number of distinct LEA transcripts (over 150) suggests possible LEA gene expansion in Xerophyta compared to desiccation-sensitive plants. Components of the PYL/SnRK2/ABF ABA-signalling pathway were also induced, although the ABF transcription factors activated in response to desiccation were most similar to those induced by drought in A. thaliana rather than seed maturation. Of the canonical seed master regulators (such as the LEC1/ABI3/FUS3/LEC2 network and ABI5) only three ABI3 transcripts were expressed, all of which encoded proteins lacking the seed motif-binding B3-domain. The results of this study suggest that vegetative desiccation tolerance in X. humilis is not associated with re-activation of seed master regulators in vegetative tissue, but may instead involve activation of seed genes by vegetative drought response regulators.
Livres sur le sujet "Desiccation toleranc"
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Jenks, Matthew A., et Andrew J. Wood, dir. Plant Desiccation Tolerance. Oxford, UK : Blackwell Publishing Ltd, 2007. http://dx.doi.org/10.1002/9780470376881.
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Lüttge, Ulrich, Erwin Beck et Dorothea Bartels, dir. Plant Desiccation Tolerance. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0.
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Erwin, Beck, Bartels Dorothea et SpringerLink (Online service), dir. Plant Desiccation Tolerance. Berlin, Heidelberg : Springer-Verlag Berlin Heidelberg, 2011.
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A, Jenks Matthew, et Wood Andrew J, dir. Plant desiccation tolerance. Ames, Iowa : Blackwell Pub., 2007.
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Michael, Black, et Pritchard H. W, dir. Desiccation and survival in plants : Drying without dying. Oxon, UK : CABI Pub., 2002.
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Beck, Erwin, Ulrich Lüttge et Dorothea Bartels. Plant Desiccation Tolerance. Springer, 2011.
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Jenks, Matthew A., et Andrew J. Wood. Plant Desiccation Tolerance. Wiley & Sons, Incorporated, John, 2008.
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(Editor), Matthew A. Jenks, et Andrew Wood (Editor), dir. Plant Desiccation Tolerance. Wiley-Blackwell, 2007.
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Beck, Erwin, Ulrich Lüttge et Dorothea Bartels. Plant Desiccation Tolerance. Springer Berlin / Heidelberg, 2013.
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Cerono, Julio Cesar. Possible associations of soluble carbohydrates with chemical desiccation and drought resistance in winter wheat. 1997.
Trouver le texte intégralChapitres de livres sur le sujet "Desiccation toleranc"
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Bartels, Dorothea, Ulrich Lüttge et Erwin Beck. « Introduction ». Dans Plant Desiccation Tolerance, 3–8. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_1.
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Steudle, Ernst. « Hydraulic Architecture of Vascular Plants ». Dans Plant Desiccation Tolerance, 185–207. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_10.
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Scheibe, Renate, et Erwin Beck. « Drought, Desiccation, and Oxidative Stress ». Dans Plant Desiccation Tolerance, 209–31. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_11.
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Heilmeier, Hermann, et Wolfram Hartung. « Chamaegigas intrepidus DINTER : An Aquatic Poikilohydric Angiosperm that Is Perfectly Adapted to Its Complex and Extreme Environmental Conditions ». Dans Plant Desiccation Tolerance, 233–51. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_12.
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Grene, Ruth, Cecilia Vasquez-Robinet et Hans J. Bohnert. « Molecular Biology and Physiological Genomics of Dehydration Stress ». Dans Plant Desiccation Tolerance, 255–87. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_13.
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Eriksson, Sylvia K., et Pia Harryson. « Dehydrins : Molecular Biology, Structure and Function ». Dans Plant Desiccation Tolerance, 289–305. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_14.
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Cushman, John C., et Melvin J. Oliver. « Understanding Vegetative Desiccation Tolerance Using Integrated Functional Genomics Approaches Within a Comparative Evolutionary Framework ». Dans Plant Desiccation Tolerance, 307–38. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_15.
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Bartels, Dorothea, et Syed Sarfraz Hussain. « Resurrection Plants : Physiology and Molecular Biology ». Dans Plant Desiccation Tolerance, 339–64. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_16.
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Bartels, Dorothea, Ulrich Lüttge et Erwin Beck. « Synopsis : Drying Without Dying ». Dans Plant Desiccation Tolerance, 367–73. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_17.
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Büdel, Burkhard. « Cyanobacteria : Habitats and Species ». Dans Plant Desiccation Tolerance, 11–21. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19106-0_2.
Texte intégralActes de conférences sur le sujet "Desiccation toleranc"
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Chakraborty, Nilay, Michael A. Menze, Heidi Elmoazzen, Steve C. Hand et Mehmet Toner. « Choline Chloride Improves the Desiccation Tolerance of Chinese Hamster Ovary Cells ». Dans ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19606.
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Recently there has been much interest in using sugars such as trehalose to preserve mammalian cells in a dry state as an alternative to cryopreservation (1–5). However, some studies indicate that sugars alone may not be sufficient to prevent cell injury during drying. Other factors like sodium toxicity, ionic imbalance and pH excursions during dehydration are a few of the mechanisms that have been hypothesized to decrease the viability of mammalian cells. In the present study, we investigated whether or not substituting sodium chloride with choline chloride (2-hydroxy-N, N,N-trimethylethanaminium chloride) in the preservation medium improves desiccation tolerance of Chinese Hamster Ovary (CHO) cells.
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Li, Dai-xi, et Xiaoming He. « Desiccation Dependent Structure and Stability of an Anhydrobiotic Nematode Late Embryogenesis Abundant (LEA) Protein ». Dans ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206862.
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A number of organisms have been found to be capable of surviving severe water deficit as a result of extreme drought and cold in nature by entering a state of suspended animation (i.e., anhydrobiosis or life without water) [1]. Although the precise molecular repertoire of desiccation tolerance in anhydrobiotic organisms is still not fully understood, results from recent studies indicate the crucial role of stress proteins such as the late embryogenesis abundant (LEA) proteins [2]. LEA proteins have been proposed to play a variety of roles in protecting biologicals from damaging by dehydration stress such as molecular chaperone and shield, ion chelator, antioxidant, and space filler. The multifunctional capacity of LEA proteins has been attributed in part to their structural plasticity: they are unfolded and when fully hydrated and become folded during water deficit [1]. However, the structural stability of LEA protein in response to desiccation is still not fully understood. In this study, the structure alteration of a group 3 LEA protein from an anhydrobiotic nematode (AavLEA1) [2] were investigated using the molecular dynamics (MD) simulation approach to understand the structural stability at different water contents.
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Lee, Richard E. E. « Surviving climate change on the Antarctic peninsula : Cold and desiccation tolerance in the southernmost insect ». Dans 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.94930.
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Manzanera, M., J. J. Narváez-Reinaldo, L. SantaCruz-Calvo, J. I. Vílchez, J. González-López et C. Calvo. « New isolation method of desiccation-tolerant microorganisms for the bioremediation of arid and semiarid soils ». Dans ENVIRONMENTAL TOXICOLOGY 2010. Southampton, UK : WIT Press, 2010. http://dx.doi.org/10.2495/etox100121.
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Baxter, Bonnie K., Breanne Eddington, Misty R. Riddle, Tabitha N. Webster et Brian J. Avery. « Great Salt Lake halophilic microorganisms as models for astrobiology : evidence for desiccation tolerance and ultraviolet irradiation resistance ». Dans Optical Engineering + Applications, sous la direction de Richard B. Hoover, Gilbert V. Levin, Alexei Y. Rozanov et Paul C. W. Davies. SPIE, 2007. http://dx.doi.org/10.1117/12.732621.
Texte intégralRapports d'organisations sur le sujet "Desiccation toleranc"
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Glazer, Itamar, Randy Gaugler, Daniel Segal, Parwinder Grewal, Yitzhak Spiegel et Senthamizh Selvan. Genetic Enhancement of Environmental Stability and Efficacy of Entomopathogenic Nematodes for Biological Control. United States Department of Agriculture, août 1995. http://dx.doi.org/10.32747/1995.7695833.bard.
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The overall obejctive of the research project was to enhance the intrinsic biological control potential of entomopathogenic nematodes through genetic manipulation. We have chosen heat and desiccation tolerance as prime traits to be enhanced in order to increase the overall efficacy of these nematodes against insect pests under harsh conditions. Initially, we used mutagenesis and selection approaches to enhance these traits. In the mutagenesis experiments several morphological mutants of Heterorhabditis bacteriophora HP88 were isolated and characterized phenotypically and genetically. Infective juveniles of H. bacteriophora HP88 were subjected to heat and desiccation selection regimes for several generations. Small increase was recorded, after 4 and 6 rearing cycles for both traits. However, in both selection regimes a significant deterioration in the reproductive capability of the nematodes was observed. In a screen of new nematode populations, from arid regions in Israel, a heat tolerant (IS5 strain) and desiccation tolerant (IS6 strain) were isolated. Both strains were taxonomically identified and their beneficial characteristics (environmental tolerance, insecticidal virulence and reproduction) were determined. We further investigated the stability of the enhanced heat tolerance trait in, and the storage capacity of, the newly discovered IS5 strain. Genetic studies demonstrated that the heat tolerance of the IS5 strain is genetically based and is dominant. The trait for heat tolerance was transferred from the IS5 strain to the HP88 strain of H. bacteriophora. The transfer was accomplished by allowing the heat tolerant strain (IS5) to mate with the commercial strain (HP88). The hybrid nature of the progeny was confirmed using a recessive marker mutant of the HP88 strain (H-dpy-2). We have used (RAPD-PCR) to compare genetic variation in the IS5 and the HP88 strains of H. baceriophora. The results indicated that genetic variation in the HP88 was significantly less than in the IS5 strain which was recently isolated from the field. The new IS5 strain may be used as an effective biological control agent in warm environments. In addition, IS5 can be used as a genetic source for cross-hybridization with other H. bacteriophora strains.
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Sela, Shlomo, et Michael McClelland. Desiccation Tolerance in Salmonella and its Implications. United States Department of Agriculture, mai 2013. http://dx.doi.org/10.32747/2013.7594389.bard.
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Salmonella enterica is a worldwide food-borne pathogen, which regularly causes large outbreaks of food poisoning. Recent outbreaks linked to consumption of contaminated foods with low water-activity, have raised interest in understanding the factors that control fitness of this pathogen to dry environment. Consequently, the general objective of this study was to extend our knowledge on desiccation tolerance and long-term persistence of Salmonella. We discovered that dehydrated STm entered into a viable-but-nonculturable state, and that addition of chloramphenicol reduced bacterial survival. This finding implied that adaptation to desiccation stress requires de-novo protein synthesis. We also discovered that dried STm cells develop cross-tolerance to multiple stresses that the pathogen might encounter in the agriculture/food environment, such as high or low temperatures, salt, and various disinfectants. These findings have important implications for food safety because they demonstrate the limitations of chemical and physical treatments currently utilized by the food industry to completely inactivate Salmonella. In order to identify genes involved in desiccation stress tolerance, we employed transcriptomic analysis of dehydrated and wet cells and direct screening of knock-out mutant and transposon libraries. Transcriptomic analysis revealed that dehydration induced expression of ninety genes and down-regulated seven. Ribosomal structural genes represented the most abundant functional group with a relatively higher transcription during dehydration. Other large classes of induced functional groups included genes involved in amino acid metabolism, energy production, ion transport, transcription, and stress response. Initial genetic analysis of a number of up-regulated genes was carried out). It was found that mutations in rpoS, yahO, aceA, nifU, rpoE, ddg,fnr and kdpE significantly compromised desiccation tolerance, supporting their role in desiccation stress response.
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Sela, Shlomo, et Michael McClelland. Investigation of a new mechanism of desiccation-stress tolerance in Salmonella. United States Department of Agriculture, janvier 2013. http://dx.doi.org/10.32747/2013.7598155.bard.
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Low-moisture foods (LMF) are increasingly involved in foodborne illness. While bacteria cannot grow in LMF due to the low water content, pathogens such as Salmonella can still survive in dry foods and pose health risks to consumer. We recently found that Salmonella secretes a proteinaceous compound during desiccation, which we identified as OsmY, an osmotic stress response protein of 177 amino acids. To elucidate the role of OsmY in conferring tolerance against desiccation and other stresses in Salmonella entericaserovarTyphimurium (STm), our specific objectives were: (1) Characterize the involvement of OsmY in desiccation tolerance; (2) Perform structure-function analysis of OsmY; (3) Study OsmY expression under various growth- and environmental conditions of relevance to agriculture; (4) Examine the involvement of OsmY in response to other stresses of relevance to agriculture; and (5) Elucidate regulatory pathways involved in controlling osmY expression. We demonstrated that an osmY-mutant strain is impaired in both desiccation tolerance (DT) and in long-term persistence during cold storage (LTP). Genetic complementation and addition of a recombinantOsmY (rOsmY) restored the mutant survival back to that of the wild type (wt). To analyze the function of specific domains we have generated a recombinantOsmY (rOsmY) protein. A dose-response DT study showed that rOsmY has the highest protection at a concentration of 0.5 nM. This effect was protein- specific as a comparable amount of bovine serum albumin, an unrelated protein, had a three-time lower protection level. Further characterization of OsmY revealed that the protein has a surfactant activity and is involved in swarming motility. OsmY was shown to facilitate biofilm formation during dehydration but not during bacterial growth under optimal growth conditions. This finding suggests that expression and secretion of OsmY under stress conditions was potentially associated with facilitating biofilm production. OsmY contains two conserved BON domains. To better understand the role of the BON sites in OsmY-mediated dehydration tolerance, we have generated two additional rOsmY constructs, lacking either BON1 or BON2 sites. BON1-minus (but not BON2) protein has decreased dehydration tolerance compared to intact rOsmY, suggesting that BON1 is required for maximal OsmY-mediated activity. Addition of BON1-peptide at concentration below 0.4 µM did not affect STm survival. Interestingly, a toxic effect of BON1 peptide was observed in concentration as low as 0.4 µM. Higher concentrations resulted in complete abrogation of the rOsmY effect, supporting the notion that BON-mediated interaction is essential for rOsmY activity. We performed extensive analysis of RNA expression of STm undergoing desiccation after exponential and stationary growth, identifying all categories of genes that are differentially expressed during this process. We also performed massively in-parallel screening of all genes in which mutation caused changes in fitness during drying, identifying over 400 such genes, which are now undergoing confirmation. As expected OsmY is one of these genes. In conclusion, this is the first study to identify that OsmY protein secreted during dehydration contributes to desiccation tolerance in Salmonella by facilitating dehydration- mediated biofilm formation. Expression of OsmY also enhances swarming motility, apparently through its surfactant activity. The BON1 domain is required for full OsmY activity, demonstrating a potential intervention to reduce pathogen survival in food processing. Expression and fitness screens have begun to elucidate the processes of desiccation, with the potential to uncover additional specific targets for efforts to mitigate pathogen survival in desiccation.
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Gaugler, Randy, Itamar Glazer, Daniel Segal et Sarwar Hashmi. Molecular Approach for Improving the Stability of Insecticidal Nematodes. United States Department of Agriculture, novembre 2002. http://dx.doi.org/10.32747/2002.7580680.bard.
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Our overall goal is to improve insecticidal nematodes by genetically engineering strains capable of entering an enhanced state of dormancy that provides improved stability. Objectives: 1. Clone and sequence tps-l homologue from Steinernema carpocapsae. (Revised: A failure to isolate the tps gene group from Steinernema precipitated a redirection to identifying other genes involved in insecticidal nematode desiccation process.) 2. Incorporate cloned tps-l gene into S. carpocapsae to obtain overexpression, thereby, enhancing desiccation tolerance. (Revised: Other stress genes in addition to tps-l genes were cloned and efforts at expression in S. carpocapsae were conducted) 3. Characterize the transgenic strains. No other biological control agent offers more impressive attributes than insecticidal nematodes. However, their potential is limited by the bane of nearly all biological control agents: poor stability. This leads to inadequate shelf-life and ultimately reduced field efficacy. Nematode storage is based on desiccation, yet insecticidal species are only capable of partial desiccation termed quiescent anhydrobiosis. Overwhelming evidence has shown that when the disaccharide compound trehalose is elevated in anhydrobiotic organisms such as yeast, plants, and nematodes it enables these organisms the ability to survive environmental stresses i.e., desiccation. Armed with this information our goal was to improve insecticidal nematodes stability by engineering trehalose overexpression.
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Kirchhoff, Helmut, et Ziv Reich. Protection of the photosynthetic apparatus during desiccation in resurrection plants. United States Department of Agriculture, février 2014. http://dx.doi.org/10.32747/2014.7699861.bard.
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In this project, we studied the photosynthetic apparatus during dehydration and rehydration of the homoiochlorophyllous resurrection plant Craterostigmapumilum (retains most of the photosynthetic components during desiccation). Resurrection plants have the remarkable capability to withstand desiccation, being able to revive after prolonged severe water deficit in a few days upon rehydration. Homoiochlorophyllous resurrection plants are very efficient in protecting the photosynthetic machinery against damage by reactive oxygen production under drought. The main purpose of this BARD project was to unravel these largely unknown protection strategies for C. pumilum. In detail, the specific objectives were: (1) To determine the distribution and local organization of photosynthetic protein complexes and formation of inverted hexagonal phases within the thylakoid membranes at different dehydration/rehydration states. (2) To determine the 3D structure and characterize the geometry, topology, and mechanics of the thylakoid network at the different states. (3) Generation of molecular models for thylakoids at the different states and study the implications for diffusion within the thylakoid lumen. (4) Characterization of inter-system electron transport, quantum efficiencies, photosystem antenna sizes and distribution, NPQ, and photoinhibition at different hydration states. (5) Measuring the partition of photosynthetic reducing equivalents between the Calvin cycle, photorespiration, and the water-water cycle. At the beginning of the project, we decided to use C. pumilum instead of C. wilmsii because the former species was available from our collaborator Dr. Farrant. In addition to the original two dehydration states (40 relative water content=RWC and 5% RWC), we characterized a third state (15-20%) because some interesting changes occurs at this RWC. Furthermore, it was not possible to detect D1 protein levels by Western blot analysis because antibodies against other higher plants failed to detect D1 in C. pumilum. We developed growth conditions that allow reproducible generation of different dehydration and rehydration states for C. pumilum. Furthermore, advanced spectroscopy and microscopy for C. pumilum were established to obtain a detailed picture of structural and functional changes of the photosynthetic apparatus in different hydrated states. Main findings of our study are: 1. Anthocyan accumulation during desiccation alleviates the light pressure within the leaves (Fig. 1). 2. During desiccation, stomatal closure leads to drastic reductions in CO2 fixation and photorespiration. We could not identify alternative electron sinks as a solution to reduce ROS production. 3. On the supramolecular level, semicrystalline protein arrays were identified in thylakoid membranes in the desiccated state (see Fig. 3). On the electron transport level, a specific series of shut downs occur (summarized in Fig. 2). The main events include: Early shutdown of the ATPase activity, cessation of electron transport between cyt. bf complex and PSI (can reduce ROS formation at PSI); at higher dehydration levels uncoupling of LHCII from PSII and cessation of electron flow from PSII accompanied by crystal formation. The later could severe as a swift PSII reservoir during rehydration. The specific order of events in the course of dehydration and rehydration discovered in this project is indicative for regulated structural transitions specifically realized in resurrection plants. This detailed knowledge can serve as an interesting starting point for rationale genetic engineering of drought-tolerant crops.
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Newton, Ronald, Joseph Riov et John Cairney. Isolation and Functional Analysis of Drought-Induced Genes in Pinus. United States Department of Agriculture, septembre 1993. http://dx.doi.org/10.32747/1993.7568752.bard.
Texte intégralRésumé :
Drought is a common factor limiting timber production in the U.S. and Israel. Loblolly (Pinus taeda) and alleppo pine (Pinus halepensis) seedling survival is reduced when out planted, and growth and reproduction are often hindered by periodic droughts during later stages of tree development. Molecular and gene responses to drought stress have not been characterized. The objectives were to characterize drought-induced gene clones from these pines, to determine the effects of a growth regulator on drought tolerance, ABA levels, and drought-induced gene expression in alleppo pine, and to develop procedures for loblolly pine transformation. Nearly 20 cDNA clones influenced by gradual, prolonged drought stress have been isolated. Many of these have been shown to be induced by drought stress, whereas several others are down-regulated. These are the first drought-induced genes isolated from a pine species. Two genomic clones (lp5-1 and lp3-1) have been sequenced and characterized, and each has been found to be associated with a gene family. Clone lp5 appears to code for a cell wall protein, and clone lp3 codes for a nuclear protein. The former may be associated with changing the elastic properties of the cell wall, while the latter may be involved in signal transduction and/or protection from desiccation in the nucleus. Clone lp3 is similar to a drought-induced gene from tomato and is regulated by ABA. Several DNA sequences that are specific to induction during growth-retardation in alleppo pine by uniconazole have been identified. The active DNA species is now being identified. Promoters from genomic clones, lp3 and lp5, have been sequenced. Both are functional when fused with the gus reporter gene and transferred to other plant tissues as well as responding to a simulated drought stress. Through exodeletion analysis, it has been established that the promoter ABRE element of lp3 responds to ABA and that drought-induction of lp3 expression may also involve ABA. Stable tobacco transformants carrying either the lp5 or the lp3 promoter fused to a reporter gus gene have been obtained. The lp5lgus fusion was expressed at several stages of tobacco development and differentiation including the reproductive stage. There was no difference in phenotype between the transformants and the wild type. Embryogenesis procedures were developed for slash pine, but attempts to couple this process with gene transfer and plantlet transformation were not successful. Transformation of pine using Agrobacterium appears tractable, but molecular data supporting stable integration of the Agrobacterium-transferred gene are still inconclusive.