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In situ FTIR assessment of desiccation?tolerant tissues  [PDF]
Willem F. Wolkers,Folkert A. Hoekstra
Spectroscopy: An International Journal , 2003, DOI: 10.1155/2003/831681
Abstract: 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 in α-helical structures and that µ-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 of Arabidopsis thaliana we were able to establish a correlation between macromolecular stability and desiccation tolerance. Taken together, in situ FTIR studies can give unique information on conformation and stability of endogenous biomolecules in desiccation?tolerant tissues.
Effects of desiccation on Euterpe edulis Martius seeds
Panza,Víctor; Láinez,Verónica; Maldonado,Sara; Maroder,Horacio L;
Biocell , 2007,
Abstract: information on desiccation sensitivity of euterpe edulis seeds under two drying rates is presented. the sensitivity was studied during the course of germination and normal germination. the water content was evaluated for both seeds and embryos. results showed the following: (a) for both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) for both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. from the beginning of both drying treatments, changes in nuclei and vacuoles were observed, but, when seed water content was reduced to below critical values, the cells became severely plasmolyzed, the vacuoles highly distorted, and the nuclei formed an almost homogeneous mass with the chromatin and the nucleoplasm, which suggests irreversible dna damages.
Effects of desiccation on Euterpe edulis Martius seeds
Víctor Panza,Verónica Láinez,Sara Maldonado,Horacio L Maroder
Biocell , 2007,
Abstract: Information on desiccation sensitivity of Euterpe edulis seeds under two drying rates is presented. The sensitivity was studied during the course of germination and normal germination. The water content was evaluated for both seeds and embryos. Results showed the following: (a) For both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) For both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) Under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) Critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. Critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. From the beginning of both drying treatments, changes in nuclei and vacuoles were observed, but, when seed water content was reduced to below critical values, the cells became severely plasmolyzed, the vacuoles highly distorted, and the nuclei formed an almost homogeneous mass with the chromatin and the nucleoplasm, which suggests irreversible DNA damages.
What makes desiccation tolerable?
Hans J Bohnert
Genome Biology , 2000, DOI: 10.1186/gb-2000-1-2-reviews1010
Abstract: It is no small feat for an organism, after losing more than 90% of its cellular water, to live and continue growing after rehydration. Many plants, one might argue, perform this trick when seeds develop; the topic here, however, is not seed maturation, dormancy and successful germination, but tolerance to extreme desiccation in the vegetative state. This involves, for example, the often rapid, non-destructive drying of existing leaves and their survival after water is returned. The ability to withstand such water loss is common to many algae and lichens, and is also found in liverworts, mosses, fern-like species and some ferns. The ability is missing entirely from gymnosperms but appears again in a few angiosperms. Oliver, Tuba and Mishler cover extremist strategies for survival under water deficit in a recent article [1] entitled 'The evolution of desiccation tolerance in land plants'. Their discussion offers an evolutionary view, outlines different strategies of tolerance acquisition, introduces emerging molecular genetic components, and finally outlines future work with a focus on genomic analyses. Knowing, it is argued, the genetic and biochemical makeup that brings about tolerance to vegetative desiccation might provide strategies to engineer protection of plants under less severe conditions.When the precursors of higher plants first appeared on land - species without any water-conducting organs - desiccation stress became a possibility and a threat. Descendants of the early colonizers, the liverworts, hornworts and mosses (bryophytes), display implicitly primitive tolerance mechanisms by being 'always prepared'. They constitutively express proteins, which, while not totally protecting existing tissues from damage during drying, minimize damage by a focus on the repair of cell structures during the rehydration phase. Repair capacity is stored in ribonucleoprotein particles (RNPs). Three foundations for survival are brought out by Oliver et al.: the first is to
NThe Study of Desiccation-Tolerance in Drying Leaves of the Desiccation-Tolerant Grass Sporobolus elongatus and the Desiccation-Sensitive Grass Sporobolus pyramidalis  [PDF]
Hamid Reza Ghasempour,Jahanbakheshe Kianian
Pakistan Journal of Biological Sciences , 2007,
Abstract: Hydrated leaves of the resurrection grass Sporobolus elongatus are not desiccation tolerant (DT), but moderate to severe drought stress can induce their DT with the leaves remain attach to drying intact plants. In vivo protein synthesis was studied with SDS-page of extracts of leaves of intact drying plants of S. elongatus (a desiccation-Tolerant grass (DT)) and S. pyramidalis (a desiccation-sensitive species (DS)). Free proline increased in drying leaves. Soluble sugar contents also increased with drying but were less than fully hydrated leaves at 8% RWC. Total protein also showed an increase with an exception at 8% RWC which showed a decrease. SDS-page of extracts of drying leaves of both DT and DS plants were studied as relative water contents (RWC) decreased. In first phase, DT species at 58% RWC (80-51% RWC range), two proteins increased in contents. In the second phase, at 8% (35-4% RWC range) two new bands increased and two bands decreased. In leaves of DS species some bands decreased as drying progressed. Also, as drying advanced free proline increased in DT species. Total protein increased as drying increased but at 8% RWC decreased. All data of results are consistent with current views about studied factors and their roles during drying and induction of desiccation tolerance in DT plants.
Desiccation resistance in Arcobacter butzleri
Otth, Laura;Wilson, Myra;Fernández, Heriberto;
Brazilian Journal of Microbiology , 2001, DOI: 10.1590/S1517-83822001000400011
Abstract: the desiccation resistance of a. butzleri was studied. two, 3 and 4 of the strains did not resist desiccation for more than 2, 12 and 36 h, respectively. two strains resisted desiccation for > 48 h. a. butzleri seems to be more resistant to desiccation than the classical enteropathogenic campylobacter species.
Desiccation resistance in Arcobacter butzleri  [cached]
Otth Laura,Wilson Myra,Fernández Heriberto
Brazilian Journal of Microbiology , 2001,
Abstract: The desiccation resistance of A. butzleri was studied. Two, 3 and 4 of the strains did not resist desiccation for more than 2, 12 and 36 h, respectively. Two strains resisted desiccation for > 48 h. A. butzleri seems to be more resistant to desiccation than the classical enteropathogenic Campylobacter species.
Desiccation of a clay film: Cracking versus peeling  [PDF]
Supti Sadhukhan,Janett Prehl,Peter Blaudeck,K. H. Hoffmann,Tapati Dutta,Sujata Tarafdar
Physics , 2008, DOI: 10.1140/epje/i2008-10401-9
Abstract: Cracking and peeling of a layer of clay on desiccation has been simulated using a spring model. A vertical section through the layer with finite thickness is represented by a rectangular array of nodes connected by linear springs on a square lattice. The effect of reduction of the natural length of the springs, which mimics the drying is studied. Varying the strength of adhesion between sample and substrate and the rate of penetration of the drying front produces an interesting phase diagram, showing cross-over from peeling to cracking behavior. Changes in the number and width of cracks on varying the layer thickness is observed to reproduce experimental reports.
ASSOCIA O DA MOET E OPU-PIV NA PRODU O DE EMBRI ES BOVINOS ASSOCIATION OF THE MOET AND OPU-PIV IN THE PRODUCTION OF BOVINE EMBRYOS  [cached]
Caliê Castilho,Andréa Renesto,Fábio Camara Mustafa,José Otávio Folino Silva
Ciência Animal Brasileira , 2009,
Abstract: Objetivou-se avaliar, em vacas da ra a Nelore, a associa o das biotécnicas MOET e OPU-PIV. Para tanto, foram testadas a superovula o ovariana (SOV), iniciada 48 a 60 horas após a aspira o folicular, em fase aleatória do ciclo estral (OPU1), e a produ o in vitro (PIV) de embri es de oócitos aspirados (OPU2) em diferentes momentos após a aplica o de prostaglandina F2? (PGF2?). As fêmeas (n=23), após a OPU1, receberam implante de progestágeno, e 48 a 60 horas após a OPU iniciou-se a SOV convencional, acrescida da aplica o de 25 mg de LH exógeno para realizar a IA (insemina o artificial) com tempo fixo. No dia da colheita dos embri es, os animais foram separados para testar seis tratamentos, sendo os grupos T(0-144) (n=4), T(48-120) (n=5), T(48-96) (n=4), T(72-96) (n=3), T(96-72) (n=4), T(96-48) (n=3), que variaram de acordo com os momentos da administra o de prostaglandina e da OPU2 após a SOV. Aplicou-se prostaglandina no dia da colheita (dia 0) 0, 48, 72 e 96 horas após, realizando-se a OPU2 144, 96, 72 ou 48 horas após a prostaglandina. Houve diferen a (p<0,05) no número de oócitos recuperados, sendo que a recupera o no T(96-48) foi (p<0,05) menor, comparada ao T(48-96) e T(72-96); a OPU próxima da prostaglandina (48 h após) prejudicou a recupera o de oócitos. Concluiu-se que é possível realizar a associa o das biotécnicas sem prejudicar os índices de produ o, desde que a OPU ocorra após a lise dos CLs presentes nos ovários após a superestimula o, ou seja, a partir de 96 horas após a aplica o de PGF2?, depois, portanto, da colheita de embri es in vivo. PALAVRAS-CHAVES: Aspira o folicular, oócito, embri o, MOET, oócito, Nelore. It has been the aim to value, in Nelore cows, the association of the assisted reproduction MOET e OPU-PIV. For this, it has tested the ovarian superovulation (SOV) 48 to 60 h after the OPU (ovum pick-up) at a random phase of the estral cycle (OPU1) and the in vitro production (PIV) of recovered oocytes embryos (OPU2) in different moments after the prostaglandin F2? (PGF2?) application. The females (n=23) after the OPU1 received progestogen implant and 48 to 60 h after the OPU, then it has began the SOV, with FSH 180 mg / cows in 8 doses, for 4 days. In 6th and 7th applications of FSH, there were administered 500 μg of PGF2? being the implants withdrawn in the 7th dose. After 12 h of the SOV, it was applied 25mg of LH to realize AI (artificial insemination) with fixed time. In the day of the embryos recovery 6 treatments were tested: T (0-144) (n=4), T (48-120) (n=5), T (48-96) (n=4), T (72-96) (n=3), T (96-72) (n=4
Effects of Abscisic Acid on Somatic Embryogenesis and Induction of Desiccation Tolerance in Brassica napus  [PDF]
R. Angoshtari,R. Tavakkol Afshari,S. Kalantari,M. Omidi
Asian Journal of Plant Sciences , 2009,
Abstract: The present study describes, firstly, the effect of cultivar, photoenvironment and different abscisic acid (ABA) treatments on somatic embryogenesis in Brassica napus and secondly, describes the effects of ABA and drying rates on acquisition desiccation tolerance in cultivar Opera. In embryogenesis experiment, 20 days old cotyledon-derived calli were cultured in somatic embryo induction media with different concentrations of ABA (0, 0.5, 10 and 50 μM). These were incubated either in the dark or light. The calli were transferred to the same medium with either the same ABA or different ABA concentrations every 10 days. After 30 days the numbers of mature somatic embryos were counted. The results showed that light stimulated somatic embryo formation and maturation. Furthermore, differences in ABA response related to somatic embryogenesis were observed between cultivars. Also, embryos were likely more sensitive to ABA in days 1-10 and 21-30. For desiccation experiment, three ABA treatments were chosen from cultivar Opera. Then these embryos were cultured in germination medium without dehydration or dehydrated either with a fast dehydration rate or a slow dehydration rate before culturing in germination medium. The results showed that ABA treated embryos were more desiccation tolerant than non ABA treated embryos. It also showed that as the concentration of ABA increased, embryos tolerance to desiccation also increased. Moreover, slow drying rate was more beneficial for desiccation tolerance induction than fast drying in ABA treated embryos. In addition, ABA treated embryos had higher germination rates even when they were not dehydrated.
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