WorldWideScience

Sample records for reduced-cost heat-actuated desiccant

  1. An assessment of desiccant cooling and dehumidification technology

    Energy Technology Data Exchange (ETDEWEB)

    Mei, V.C.; Chen, F.C. (Oak Ridge National Lab., TN (United States)); Lavan, Z. (Illinois Inst. of Tech., Chicago, IL (United States)); Collier, R.K. Jr. (Collier Engineering Services, Merritt Island, FL (United States)); Meckler, G. (Gershon Meckler Associates, P.C., Herndon, VA (United States))

    1992-07-01

    Desiccant systems are heat-actuated cooling and dehumidification technology. With the recent advances in this technology, desiccant systems can now achieve a primary energy coefficient of performance (COP) between 1.3 and 1.5, with potential to go to 1.7 and higher. It is becoming one of the most promising alternatives to conventional cooling systems. Two important and well-known advantages of desiccant cooling systems are that they are CFC free and they can reduce the electricity peak load. Another important but lesser-known advantage of desiccant technology is its potential for energy conservation. The energy impact study in this report indicated that a possible 13% energy saving in residential cooling and 8% in commercial cooling is possible. Great energy saving potential also exists in the industrial sector if industrial waste heat can be used for desiccant regeneration. The latest study on desiccant-integrated building heating, ventilating, and air conditioning (HVAC) systems indicated that the initial cost for the conventional cooling equipment was greatly reduced by using desiccant technology because of downsized compressors, fans, and ductworks. This cost reduction was more than enough to offset the cost of desiccant equipment. Besides, the system operation cost was also reduced. All these indicate that desiccant systems are also cost effective. This study provides an updated state-of-the-art assessment forsiccant technology in the field of desiccant materials, systems, computer models, and theoretical analyses. From this information the technology options were derived and the future research and development needs were identified. Because desiccant technology has already been applied in the commercial building sector with very encouraging results, it is expected that future market breakthroughs will probably start in this sector. A market analysis for the commercial building application is therefore included.

  2. Desiccation tolerance of prokaryotes

    National Research Council Canada - National Science Library

    Potts, M

    1994-01-01

    ...) may be achieved rapidly. In the air-dried state some bacteria survive only for seconds whereas others can tolerate desiccation for thousands, perhaps millions, of years. The desiccated (anhydrobiotic...

  3. Desiccation resistance in Arcobacter butzleri

    Directory of Open Access Journals (Sweden)

    Otth Laura

    2001-01-01

    Full Text Available 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.

  4. Desiccant aging and its effect on desiccant cooling system performance

    Energy Technology Data Exchange (ETDEWEB)

    Belding, W.A. [Innovative Research Enterprises, Danville, CA (United States); Delmas, M.P.F.; Holeman, W.D. [LaRoche Industries Inc., Baton Rouge, LA (United States)

    1996-05-01

    Desiccants used for the purpose of space conditioning or enthalpy transfer can be subjected to hundreds of thousands of adsorption/regeneration cycles over their useful life. Studying the loss of a desiccant`s equilibrium water adsorption capacity after exposure to thermal cycling is a common method for quantifying desiccant aging. Since isotherm shape and desiccant capacity can be related to overall cooling-system performance, system cooling capacity and coefficients of performance over time can be predicted. Adsorption isotherms for several different desiccants have been determined after subjecting the materials to varying numbers of thermal cycles in a specially designed test unit capable of adsorption/desorption cycling every 10 min. Aging curves for a new Type 1M desiccant developed specifically for desiccant cooling applications by LaRoche Industries Inc. are compared to other commonly used desiccants. (author)

  5. Cracking in desiccating soils

    OpenAIRE

    Ledesma Alberto

    2016-01-01

    Soil shrinkage is produced typically under desiccating conditions. Eventually shrinkage may generate cracks in the soil mass, a phenomenon that is being studied by several researchers, because its prediction is far from being a routine in Soil Mechanics. Within this context, Unsaturated Soil Mechanics provides a promising framework to understand the mechanisms involved. In addition to that, physical modelling of desiccating soils constitutes a good tool to explore the nature of this problem. ...

  6. Simulation of Desiccant Cooling

    Directory of Open Access Journals (Sweden)

    Kamaruddin A.

    2017-06-01

    Full Text Available Desiccant cooling system has been an attractive topic for study lately, due to its environmentally friendly nature. It also consume less electricity and capable to be operated without refrigerant. A simulation study was conducted using 1.5 m long ducting equipped with one desiccant wheel, one sensible heat exchanger wheel, one evaporative cooling chamber and two blowers and one electric heater. The simulation study used 8.16 m/s primary air, the drying coefficient from desiccant wheel, k1=2.1 (1/s, mass transfer coefficient in evaporative cooling, k2=1.2 kg vapor/s, heat transfer coefficient in desiccant wheel, h1=4.5 W/m2 oC, and heat transfer coefficient in sensible heat exchanger wheel h2= 4.5 W/m2 oC. The simulation results show that the final temperature before entering into the air conditioning room was 25 oC and RH of 65 %, were in accordance with the Indonesian comfort index.

  7. Desiccation tolerance of prokaryotes.

    Science.gov (United States)

    Potts, M

    1994-12-01

    The removal of cell-bound water through air drying and the addition of water to air-dried cells are forces that have played a pivotal role in the evolution of the prokaryotes. 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 (Vb) and the environmental water (vapor) potential (psi wv) may be achieved rapidly. In the air-dried state some bacteria survive only for seconds whereas others can tolerate desiccation for thousands, perhaps millions, of years. The desiccated (anhydrobiotic) cell is characterized by its singular lack of water--with contents as low as 0.02 g of H2O g (dry weight)-1. At these levels the monolayer coverage by water of macromolecules, including DNA and proteins, is disturbed. As a consequence the mechanisms that confer desiccation tolerance upon air-dried bacteria are markedly different from those, such as the mechanism of preferential exclusion of compatible solutes, that preserve the integrity of salt-, osmotically, and freeze-thaw-stressed cells. Desiccation tolerance reflects a complex array of interactions at the structural, physiological, and molecular levels. Many of the mechanisms remain cryptic, but it is clear that they involve interactions, such as those between proteins and co-solvents, that derive from the unique properties of the water molecule. A water replacement hypothesis accounts for how the nonreducing disaccharides trehalose and sucrose preserve the integrity of membranes and proteins. Nevertheless, we have virtually no insight into the state of the cytoplasm of an air-dried cell. There is no evidence for any obvious adaptations of proteins that can counter the effects of air drying or for the occurrence of any proteins that provide a direct and a tangible contribution to cell stability. Among the prokaryotes that can exist as anhydrobiotic cells, the cyanobacteria have a marked capacity to do so. One

  8. Low-Cost "Vacuum Desiccator"

    Science.gov (United States)

    Sweet, Frederick

    2004-10-01

    Described are individualized, low-cost, and safe desiccators that can be efficiently and rapidly made with an inexpensive kitchen aid sold for shrink-wrapping food. The device can be used for enclosing small vials or bottles and also jars that are too large to be placed in conventional glass or plastic desiccators. This shrink-wrapping device is proposed for producing "vacuum desiccators" in large undergraduate chemistry laboratories or in graduate and research laboratories.

  9. DETERMINING ENERGY SAVINGS IN BUILDINGS USING THE REDUCING COSTS METHOD

    Directory of Open Access Journals (Sweden)

    STAN IVAN F.E.

    2015-03-01

    Full Text Available The paper is structured in four parts. The first part presents the importance of thermal insulation for buildings energy economy and some insulation properties. In the second part of the paper it is described the reducing cost method to determine the energy savings. The third part of the paper includes an analysis and a comparison for an exterior wall provided with different thicknesses of insulation layer in order to determine the average savings cost. The last part presents conclusions and discussion.

  10. Desiccation tolerance of somatic embryoids.

    OpenAIRE

    Tetteroo, F.A.A.

    1996-01-01

    This thesis describes the research performed on the subject "Desiccation tolerance in somatic embryoids". Somatic embryoids are bipolar structures formed in tissue culture, with both a shoot and a root apex, which resemble very much zygotic embryos found in seeds. Through simultaneous development of root and shoot, these embryoids can grow out into complete plantlets.In Chapter 2 we describe an optimized method to produce completely desiccation tolerant carrot ( Daucus carota ) embryoids. Usi...

  11. Desiccation tolerance in Staphylococcus aureus.

    Science.gov (United States)

    Chaibenjawong, Plykaeow; Foster, Simon J

    2011-02-01

    Staphylococcus aureus is a multidrug-resistant pathogen that not only causes a diverse array of human diseases, but also is able to survive in potentially dry and stressful environments, such as the human nose, on skin and on inanimate surfaces such as clothing and surfaces. This study investigated parameters governing desiccation tolerance of S. aureus and identified several components involved in the process. Initially, the role of environmental parameters such as temperature, growth phase, cell density, desiccation time and protectants in desiccation tolerance were determined. This established a robust model of desiccation tolerance in which S. aureus has the ability to survive on dry plastic surfaces for more than 1,097 days. Using a combination of a random screen and defined mutants, clpX, sigB and yjbH were identified as being required for desiccation tolerance. ClpX is a part of the ATP-dependent ClpXP protease, important for protein turnover, and YjbH has a proposed linked function. SigB is an accessory sigma factor with a role in generalized stress resistance. Understanding the molecular mechanisms that govern desiccation tolerance may determine the break points to be exploited to prevent the spread of this dangerous pathogen in hospitals and communities.

  12. DEMAND ILLUSION AS A WAY TO REDUCE COSTS

    Directory of Open Access Journals (Sweden)

    Kirill N. Sosnovskij

    2014-01-01

    Full Text Available Article devoted to a technique that reduces costs to retailers, as well as increase the speed of discounted products. This article deals with the laws of visual merchandising that have a significant impact on the implementation of the company’s products. The analysis of the first law, with the subsequent introduction into it of a new additional method. Consider the effect of «Illusion of deficit» arising from the application of the proposed method. The article also defines the basic hypothesis of the existence of methods and effect, and the conditions for their effective implementation. To confirm the effectiveness of the developed method, quantitative surveys are conducted for different age groups creating situational model, which allows respondents to feel as a consumer.

  13. Desiccant contamination research: Report on the desiccant contamination test facility

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A.A.; Bingham, C.E.

    1991-07-01

    The activity in the cooling systems research involves research on high performance dehumidifiers and chillers that can operate efficiently with the variable thermal outputs and delivery temperatures associated with solar collectors. It also includes work on advanced passive cooling techniques. This report describes the work conducted to improve the durability of solid desiccant dehumidifiers by investigating the causes of degradation of desiccant materials from airborne contaminants and thermal cycling. The performance of a dehumidifier strongly depends on the physical properties and durability of the desiccant material. To make durable and reliable dehumidifiers, an understanding is needed of how and to what degree the performance of a dehumidifier is affected by desiccant degradation. This report, an account of work under Cooling Systems Research, documents the efforts to design and fabricate a test facility to investigate desiccant contamination based on industry and academia recommendations. It also discusses the experimental techniques needed for obtaining high-quality data and presents plans for next year. Researchers of the Mechanical and Industrial Technology Division performed this work at the Solar Energy Research Institute in FY 1988 for DOE's Office of Solar Heat Technologies. 7 refs., 19 figs., 1 tab.

  14. Seminar 14 - Desiccant Enhanced Air Conditioning: Desiccant Enhanced Evaporative Air Conditioning (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.

    2013-02-01

    This presentation explains how liquid desiccant based coupled with an indirect evaporative cooler can efficiently produce cool, dry air, and how a liquid desiccant membrane air conditioner can efficiently provide cooling and dehumidification without the carryover problems of previous generations of liquid desiccant systems. It provides an overview to a liquid desiccant DX air conditioner that can efficiently provide cooling and dehumidification to high latent loads without the need for reheat, explains how liquid desiccant cooling and dehumidification systems can outperform vapor compression based air conditioning systems in hot and humid climates, explains how liquid desiccant cooling and dehumidification systems work, and describes a refrigerant free liquid desiccant based cooling system.

  15. Energy-efficient induction motors designing with application of a modified criterion of reduced costs

    Directory of Open Access Journals (Sweden)

    V.S. Petrushin

    2014-03-01

    Full Text Available The paper introduces a modified criterion of reduced costs that employs coefficients of operation significance and priority of ohmic loss accounting to allow matching maximum efficiency with minimum reduced costs. Impact of the inflation factor on the criterion of reduced costs is analyzed.

  16. Stiffness of desiccating insect wings

    Energy Technology Data Exchange (ETDEWEB)

    Mengesha, T E; Vallance, R R [Department of Mechanical Engineering, The George Washington University, 738 Phillips Hall, 801 22nd St NW, Washington, DC 20052 (United States); Mittal, R, E-mail: vallance@gwu.edu [Department of Mechanical Engineering, Johns Hopkins University, 126 Latrobe Hall, 3400 N Charles Street, Baltimore, MD 21218 (United States)

    2011-03-15

    The stiffness of insect wings is typically determined through experimental measurements. Such experiments are performed on wings removed from insects. However, the wings are subject to desiccation which typically leads to an increase in their stiffness. Although this effect of desiccation is well known, a comprehensive study of the rate of change in stiffness of desiccating insect wings would be a significant aid in planning experiments as well as interpreting data from such experiments. This communication presents a comprehensive experimental analysis of the change in mass and stiffness of gradually desiccating forewings of Painted Lady butterflies (Vanessa cardui). Mass and stiffness of the forewings of five butterflies were simultaneously measured every 10 min over a 24 h period. The averaged results show that wing mass declined exponentially by 21.1% over this time period with a time constant of 9.8 h, while wing stiffness increased linearly by 46.2% at a rate of 23.4 {mu}N mm{sup -1} h{sup -1}. For the forewings of a single butterfly, the experiment was performed over a period of 1 week, and the results show that wing mass declined exponentially by 52.2% with a time constant of 30.2 h until it reached a steady-state level of 2.00 mg, while wing stiffness increased exponentially by 90.7% until it reached a steady-state level of 1.70 mN mm{sup -1}. (communication)

  17. Desiccation tolerance of somatic embryoids.

    NARCIS (Netherlands)

    Tetteroo, F.A.A.

    1996-01-01

    This thesis describes the research performed on the subject "Desiccation tolerance in somatic embryoids". Somatic embryoids are bipolar structures formed in tissue culture, with both a shoot and a root apex, which resemble very much zygotic embryos found in seeds. Through simultaneous development of

  18. Steady state modeling of desiccant wheels

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin Ryhl

    2014-01-01

    Desiccant wheels are rotary desiccant dehumidifiers used in air conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete sys...... be taken into account in a future version of the model. More experimental data have to be gathered to implement eventual missing phenomena and validate the model for all input parameters....... systems. A steady state two-dimensional model is formulated and implemented aiming to obtain good accuracy and short computational times. Comparison with experimental data from the literature shows that the model reproduces the physical behavior of desiccant wheels. Mass diffusion in the desiccant should......Desiccant wheels are rotary desiccant dehumidifiers used in air conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete...

  19. Unravelling desiccation tolerance in germinated Arabidopsis seeds

    NARCIS (Netherlands)

    Maia de Oliveira, J.

    2014-01-01

    How different organisms survive in the absence or under very limited amounts of water is still an open question. The aim of the research presented in this thesis is to explore the molecular basis of desiccation tolerance in seeds. We investigated the possibilities of using germinated desiccation sen

  20. Water isotopes in desiccating lichens

    Science.gov (United States)

    Cuntz, Matthias; Máguas, Cristina; Lakatos, Michael

    2009-01-01

    The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition. PMID:19888598

  1. Seed desiccation mechanisms co-opted for vegetative desiccation in the resurrection grass Oropetium thomaeum.

    Science.gov (United States)

    VanBuren, Robert; Wai, Ching Man; Zhang, Qingwei; Song, Xiaomin; Edger, Patrick P; Bryant, Doug; Michael, Todd P; Mockler, Todd C; Bartels, Dorothea

    2017-10-01

    Resurrection plants desiccate during periods of prolonged drought stress, then resume normal cellular metabolism upon water availability. Desiccation tolerance has multiple origins in flowering plants, and it likely evolved through rewiring seed desiccation pathways. Oropetium thomaeum is an emerging model for extreme drought tolerance, and its genome, which is the smallest among surveyed grasses, was recently sequenced. Combining RNA-seq, targeted metabolite analysis and comparative genomics, we show evidence for co-option of seed-specific pathways during vegetative desiccation. Desiccation-related gene co-expression clusters are enriched in functions related to seed development including several seed-specific transcription factors. Across the metabolic network, pathways involved in programmed cell death inhibition, ABA signalling and others are activated during dehydration. Oleosins and oil bodies that typically function in seed storage are highly abundant in desiccated leaves and may function for membrane stability and storage. Orthologs to seed-specific LEA proteins from rice and maize have neofunctionalized in Oropetium with high expression during desiccation. Accumulation of sucrose, raffinose and stachyose in drying leaves mirrors sugar accumulation patterns in maturing seeds. Together, these results connect vegetative desiccation with existing seed desiccation and drought responsive pathways and provide some key candidate genes for engineering improved drought tolerance in crop plants. © 2017 John Wiley & Sons Ltd.

  2. Optimisation of a desiccant cooling system design with indirect evaporative cooler

    Energy Technology Data Exchange (ETDEWEB)

    Goldsworthy, M.; White, S. [CSIRO Energy Technology, 10 Murray Dwyer Cr., Mayfield, 2300 Newcastle (Australia)

    2011-01-15

    Solar desiccant-based air-conditioning has the potential to significantly reduce cost and/or greenhouse gas emissions associated with cooling of buildings. Parasitic energy consumption for the operation of supply fans has been identified as a major hindrance to achieving these savings. The cooling performance is governed by the trade-off between supplying larger flow-rates of cool air or lower flow-rates of cold air. The performance of a combined solid desiccant-indirect evaporative cooler system is analysed by solving the heat and mass transfer equations for both components simultaneously. Focus is placed on varying the desiccant wheel supply/regeneration and indirect cooler secondary/primary air-flow ratios. Results show that for an ambient reference condition, and 70 C regeneration temperature, a supply/regeneration flow ratio of 0.67 and an indirect cooler secondary/primary flow ratio of 0.3 gives the best performance with COP{sub e} > 20. The proposed cooling system thus has potential to achieve substantial energy and greenhouse gas emission savings. (author)

  3. Tardigrades Use Intrinsically Disordered Proteins to Survive Desiccation.

    Science.gov (United States)

    Boothby, Thomas C; Tapia, Hugo; Brozena, Alexandra H; Piszkiewicz, Samantha; Smith, Austin E; Giovannini, Ilaria; Rebecchi, Lorena; Pielak, Gary J; Koshland, Doug; Goldstein, Bob

    2017-03-16

    Tardigrades are microscopic animals that survive a remarkable array of stresses, including desiccation. How tardigrades survive desiccation has remained a mystery for more than 250 years. Trehalose, a disaccharide essential for several organisms to survive drying, is detected at low levels or not at all in some tardigrade species, indicating that tardigrades possess potentially novel mechanisms for surviving desiccation. Here we show that tardigrade-specific intrinsically disordered proteins (TDPs) are essential for desiccation tolerance. TDP genes are constitutively expressed at high levels or induced during desiccation in multiple tardigrade species. TDPs are required for tardigrade desiccation tolerance, and these genes are sufficient to increase desiccation tolerance when expressed in heterologous systems. TDPs form non-crystalline amorphous solids (vitrify) upon desiccation, and this vitrified state mirrors their protective capabilities. Our study identifies TDPs as functional mediators of tardigrade desiccation tolerance, expanding our knowledge of the roles and diversity of disordered proteins involved in stress tolerance.

  4. Desiccation tolerance in Bryophytes: relevance to the evolution of desiccation tolerance in Land Plants

    Science.gov (United States)

    The majority of desiccation-tolerant plants are found in the less complex clades that constitute the algae, lichens and bryophytes. However, within the larger and more complex groups of vascular land plants there are some 120-130 species that exhibit some degree of vegetative desiccation tolerance. ...

  5. Improved climatic chamber for desiccation simulation

    Directory of Open Access Journals (Sweden)

    Lozada Catalina

    2016-01-01

    Full Text Available The climatic chamber at the Universidad de Los Andes was improved for modeling desiccation in soil layers. This chamber allows the measurement of different environmental variables. In this research, evaporation tests were conducted in water imposing boundary conditions for drying, and then these tests were performed in a soil layer. The soil was prepared from a slurry state and was drying controlling the temperature, the infrared radiation, the wind velocity, and the relative humidity. In the first part of this paper, a description of the climatic chamber, operation ranges and theoretical work principles of the climatic chamber are presented. Then, the second part shows the results for desiccation in water and soil. The desiccation tests performed with the climatic chamber allow simulating all environmental conditions accurately during drying coupling the effect of all environmental variables. As a result, the evaporation rate increases with infrared radiation in soil and water. The rate at the beginning of the desiccation tests in clays is the same as in water. However, this evaporation rate decreases as the soil becomes desiccated.

  6. Transcriptomic analysis of Salmonella desiccation resistance.

    Science.gov (United States)

    Li, Haiping; Bhaskara, Anuhya; Megalis, Christina; Tortorello, Mary Lou

    2012-12-01

    The survival of Salmonella in low moisture foods and processing environments remains a great challenge for the food industry and public health. To explore the mechanisms of Salmonella desiccation resistance, we studied the transcriptomic responses in Salmonella Tennessee (Tennessee), using Salmonella Typhimurium LT2 (LT2), a strain weakly resistant to desiccation, as a reference strain. In response to 2 h of air-drying at 11% equilibrated relative humidity, approximately one-fourth of the open reading frames (ORFs) in the Tennessee genome and one-fifth in LT2 were differentially expressed (>2-fold). Among all differentially expressed functional groups (>5-fold) in both strains, the expression fold change associated with fatty acid metabolism was the highest, and constituted 51% and 35% of the total expression fold change in Tennessee and LT2, respectively. Tennessee showed greater changes in expression of genes associated with stress response and envelope modification than LT2, while showing lesser changes in protein biosynthesis expression. Expression of flagella genes was significantly more inhibited in stationary phase cells of Tennessee than LT2 both before and after desiccation. The accumulation of the osmolyte trehalose was significantly induced by desiccation in Tennessee, but no increase was detectable in LT2, which is consistent with the expression patterns of the entire trehalose biosynthesis and degradation pathways in both strains. Results from this study present a global view of the dynamic desiccation responses in Salmonella, which will guide future research efforts to control Salmonella in low moisture environments.

  7. Does probability guided hysteroscopy reduce costs in women investigated for postmenopausal bleeding?

    NARCIS (Netherlands)

    Breijer, M C; van Hanegem, N; Visser, N C M; Verheijen, R H M; Mol, B W J; Pijnenborg, J M A; Opmeer, B C; Timmermans, A

    2015-01-01

    OBJECTIVE: To evaluate whether a model to predict a failed endometrial biopsy in women with postmenopausal bleeding (PMB) and a thickened endometrium can reduce costs without compromising diagnostic accuracy. DESIGN, SETTING, AND POPULATION: Model based cost-minimization analysis. METHODS: A decisio

  8. Context-aware computing-based reducing cost of service method in resource discovery and interaction

    Institute of Scientific and Technical Information of China (English)

    TANG Shan-cheng; HOU Yi-bin

    2004-01-01

    Reducing cost of service is an important goal for resource discovery and interaction technologies. The shortcomings of transhipment-method and hibernation-method are to increase holistic cost of service and to slower resource discovery respectively. To overcome these shortcomings, a context-aware computing-based method is developed. This method, firstly,analyzes the courses of devices using resource discovery and interaction technologies to identify some types of context related to reducing cost of service, then, chooses effective methods such as stopping broadcast and hibernation to reduce cost of service according to information supplied by the context but not the transhipment-method's simple hibernations. The results of experiments indicate that under the worst condition this method overcomes the shortcomings of transhipment-method, makes the "poor" devices hibernate longer than hibernation-method to reduce cost of service more effectively, and discovers resources faster than hibernation-method; under the best condition it is far better than hibernation-method in all aspects.

  9. In situ FTIR assessment of desiccation-tolerant tissues

    NARCIS (Netherlands)

    Wolkers, W.F.; Hoekstra, F.A.

    2003-01-01

    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 dehy

  10. In situ FTIR assessment of desiccation-tolerant tissues

    NARCIS (Netherlands)

    Wolkers, W.F.; Hoekstra, F.A.

    2003-01-01

    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 dehy

  11. Desiccant-assisted cooling fundamentals and applications

    CERN Document Server

    Brum, Nisio

    2014-01-01

    The increasing concern with indoor air quality has led to air-quality standards with increased ventilation rates. Although increasing the volume flow rate of outside air is advisable from the perspective of air-quality, it is detrimental to energy consumption, since the outside air has to be brought to the comfort condition before it is insufflated to the  conditioned ambient. Moreover, the humidity load carried within outside air has challenging HVAC engineers to design cooling units which are able to satisfactorily handle both sensible and latent contributions to the thermal load. This constitutes a favorable scenario for the use of solid desiccants to assist the cooling units. In fact, desiccant wheels have been increasingly applied by HVAC designers, allowing distinct processes for the air cooling and dehumidification. In fact, the ability of solid desiccants in moisture removal is effective enough to allow the use of evaporative coolers, in opposition to the traditional vapor-compression cycle, resultin...

  12. A Review of Solar Desiccant Air Conditioner

    Directory of Open Access Journals (Sweden)

    Dr. U. V. Kongre, D. P. Mahure, P. A. Zamre

    2014-04-01

    Full Text Available This paper represents a detailed study and description of a new solar-based air-conditioning technique. It uses solar energy to produce cold or hot air. This technology can be used to reduce the energy consumption and environmental impact of mechanical cooling system. The use of Desiccant cooling is used to perform air dehumidification operation by utilizing low grade heat source. The solar desiccant air conditioner uses solar power as the main energy source to help in the thermodynamic heat transfer process as well as heat transfer principles to convert ambient air into cooling air. With our constructed design we have seen temperature as well as humidity level drops throughout the desiccant cooling system. A significant advantage of this system is, it have no moving parts consequently they are noiseless, non-corrosive, cheap to maintain, long lasting in addition to being environmentally friendly with zero ozone depletion as well as zero global warming potentials.

  13. Comparative metabolic profiling between desiccation-sensitive and desiccation-tolerant species of Selaginella reveals insights into the resurrection trait

    Science.gov (United States)

    Spike-mosses (Selaginellaceae) represent an ancient lineage of vascular plants in which some species have evolved or revolved desiccation tolerance (DT). A sister group comparison was conducted between a desiccation-tolerant species, Selaginella lepidophylla, and a desiccation-sensitive species, S. ...

  14. Trehalose Accumulation Triggers Autophagy during Plant Desiccation.

    Directory of Open Access Journals (Sweden)

    Brett Williams

    2015-12-01

    Full Text Available Global climate change, increasingly erratic weather and a burgeoning global population are significant threats to the sustainability of future crop production. There is an urgent need for the development of robust measures that enable crops to withstand the uncertainty of climate change whilst still producing maximum yields. Resurrection plants possess the unique ability to withstand desiccation for prolonged periods, can be restored upon watering and represent great potential for the development of stress tolerant crops. Here, we describe the remarkable stress characteristics of Tripogon loliiformis, an uncharacterised resurrection grass and close relative of the economically important cereals, rice, sorghum, and maize. We show that T. loliiformis survives extreme environmental stress by implementing autophagy to prevent Programmed Cell Death. Notably, we identified a novel role for trehalose in the regulation of autophagy in T.loliiformis. Transcriptome, Gas Chromatography Mass Spectrometry, immunoblotting and confocal microscopy analyses directly linked the accumulation of trehalose with the onset of autophagy in dehydrating and desiccated T. loliiformis shoots. These results were supported in vitro with the observation of autophagosomes in trehalose treated T. loliiformis leaves; autophagosomes were not detected in untreated samples. Presumably, once induced, autophagy promotes desiccation tolerance in T.loliiformis, by removal of cellular toxins to suppress programmed cell death and the recycling of nutrients to delay the onset of senescence. These findings illustrate how resurrection plants manipulate sugar metabolism to promote desiccation tolerance and may provide candidate genes that are potentially useful for the development of stress tolerant crops.

  15. Polymers as advanced materials for desiccant applications

    Energy Technology Data Exchange (ETDEWEB)

    Czanderna, A.W.

    1990-12-01

    This research is concerned with solid materials used as desiccants for desiccant cooling systems (DCSs) that process water vapor in an atmosphere to produce cooling. Background information includes an introduction to DCSs and the role of the desiccant as a system component. The water vapor sorption performance criteria used for screening the modified polymers prepared include the water sorption capacity from 5% to 80% relative humidity (R.H.), isotherm shape, and rate of adsorption and desorption. Measurements are presented for the sorption performance of modified polymeric advanced desiccant materials with the quartz crystal microbalance. Isotherms of polystyrene sulfonic acid (PSSA) taken over a 5-month period show that the material has a dramatic loss in capacity and that the isotherm shape is time dependent. The adsorption and desorption kinetics for PSSA and all the ionic salts of it studied are easily fast enough for commercial DCS applications with a wheel rotation speed of 6 min per revolution. Future activities for the project are addressed, and a 5-year summary of the project is included as Appendix A. 34 refs., 20 figs., 3 tabs.

  16. Tolerance to environmental desiccation in moss sperm.

    Science.gov (United States)

    Shortlidge, Erin E; Rosenstiel, Todd N; Eppley, Sarah M

    2012-05-01

    • Sexual reproduction in mosses requires that sperm be released freely into the environment before finding and fertilizing a receptive female. After release from the male plant, moss sperm may experience a range of abiotic stresses; however, few data are available examining stress tolerance of moss sperm and whether there is genetic variation for stress tolerance in this important life stage. • Here, we investigated the effects of environmental desiccation and recovery on the sperm cells of three moss species (Bryum argenteum, Campylopus introflexus, and Ceratodon purpureus). • We found that a fraction of sperm cells were tolerant to environmental desiccation for extended periods (d) and that tolerance did not vary among species. We found that this tolerance occurs irrespective of ambient dehydration conditions, and that the addition of sucrose during dry-down improved cell recovery. Although we observed no interspecific variation, significant variation among individuals within species in sperm cell tolerance to environmental desiccation was observed, suggesting selection could potentially act on this basic reproductive trait. • The observation of desiccation-tolerant sperm in multiple moss species has important implications for understanding bryophyte reproduction, suggesting the presence of a significant, uncharacterized complexity in the ecology of moss mating systems. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  17. Desiccant cooling using unglazed transpired solar collectors

    Science.gov (United States)

    Pesaran, A. A.; Wipke, K.

    1992-05-01

    The use of unglazed solar collectors for desiccant regeneration in a solid desiccant cooling cycle was investigated because these collectors are lower in cost than conventional glazed flat-plate collectors. Using computer models, the performance of a desiccant cooling ventilation cycle integrated with either unglazed transpired collectors or conventional glazed flat-plate collectors was obtained. We found that the thermal performance of the unglazed system was lower than the thermal performance of the glazed system because the unglazed system could not take advantage of the heat of adsorption released during the dehumidification process. For a 3-ton cooling system, although the area required for the unglazed collector was 69 percent more than that required for the glazed collector, the cost of the unglazed collector array was 44 percent less than the cost of the glazed collector array. The simple payback period of the unglazed system was half of the payback period of the glazed collector when compared to an equivalent gas-fired system. Although the use of unglazed transpired collectors makes economic sense, some practical considerations may limit their use in desiccant regeneration.

  18. Desiccant cooling: State-of-the-art assessment

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A.A.; Penney, T.R.; Czanderna, A.W.

    1992-10-01

    The objectives of this document are to present an overview of the work accomplished to date on desiccant cooling to provide assessment of the state of the art of desiccant cooling technology in the field of desiccant material dehumidifier components, desiccant systems, and models. The report also discusses the factors that affect the widespread acceptance of desiccant cooling technology. This report is organized as follows. First, a basic description and historical overview of desiccant cooling technology is provided. Then, the recent research and development (R&D) program history (focusing on DOE`s funded efforts) is discussed. The status of the technology elements (materials, components, systems) is discussed in detail and a preliminary study on the energy impact of desiccant technology is presented. R&D needs for advancing the technology in the market are identified. The National Renewable Energy Laboratory`s unique desiccant test facilities and their typical outputs are described briefly. Finally, the results of a comprehensive literature search on desiccant cooling are presented in a bibliography. The bibliography contains approximately 900 citations on desiccant cooling.

  19. Desiccant cooling: State-of-the-art assessment

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A.A.; Penney, T.R.; Czanderna, A.W.

    1992-10-01

    The objectives of this document are to present an overview of the work accomplished to date on desiccant cooling to provide assessment of the state of the art of desiccant cooling technology in the field of desiccant material dehumidifier components, desiccant systems, and models. The report also discusses the factors that affect the widespread acceptance of desiccant cooling technology. This report is organized as follows. First, a basic description and historical overview of desiccant cooling technology is provided. Then, the recent research and development (R D) program history (focusing on DOE's funded efforts) is discussed. The status of the technology elements (materials, components, systems) is discussed in detail and a preliminary study on the energy impact of desiccant technology is presented. R D needs for advancing the technology in the market are identified. The National Renewable Energy Laboratory's unique desiccant test facilities and their typical outputs are described briefly. Finally, the results of a comprehensive literature search on desiccant cooling are presented in a bibliography. The bibliography contains approximately 900 citations on desiccant cooling.

  20. TOR and RAS pathways regulate desiccation tolerance in Saccharomyces cerevisiae

    Science.gov (United States)

    Welch, Aaron Z.; Gibney, Patrick A.; Botstein, David; Koshland, Douglas E.

    2013-01-01

    Tolerance to desiccation in cultures of Saccharomyces cerevisiae is inducible; only one in a million cells from an exponential culture survive desiccation compared with one in five cells in stationary phase. Here we exploit the desiccation sensitivity of exponentially dividing cells to understand the stresses imposed by desiccation and their stress response pathways. We found that induction of desiccation tolerance is cell autonomous and that there is an inverse correlation between desiccation tolerance and growth rate in glucose-, ammonia-, or phosphate-limited continuous cultures. A transient heat shock induces a 5000–fold increase in desiccation tolerance, whereas hyper-ionic, -reductive, -oxidative, or -osmotic stress induced much less. Furthermore, we provide evidence that the Sch9p-regulated branch of the TOR and Ras-cAMP pathway inhibits desiccation tolerance by inhibiting the stress response transcription factors Gis1p, Msn2p, and Msn4p and by activating Sfp1p, a ribosome biogenesis transcription factor. Among 41 mutants defective in ribosome biogenesis, a subset defective in 60S showed a dramatic increase in desiccation tolerance independent of growth rate. We suggest that reduction of a specific intermediate in 60S biogenesis, resulting from conditions such as heat shock and nutrient deprivation, increases desiccation tolerance. PMID:23171550

  1. Development of Membrane-Based Desiccant Fiber for Vacuum Desiccant Cooling.

    Science.gov (United States)

    Yang, Yifan; Rana, Dipak; Lan, Christopher Q; Matsuura, Takeshi

    2016-06-22

    A novel hydrophobic membrane-based desiccant fiber (MDF) was developed by loading lithium chloride into hydrophobic hollow fiber membranes. The MDF thus made was then tested for vapor absorption under controlled conditions. Furthermore, an MDF pad, which was made by weaving MDF into a piece of garment, was built into a laboratory vacuum desiccant cooling (VDC) setup, which included the MDF pad as the desiccant layer and a cooling towel saturated with water as the water reservoir, to test the cooling effects at atmospheric pressure and vacuum of 25 in. of Hg. Results indicate that MDF is suitable for applications such as in VDC. Mass and heat transfer of vapor absorption by MDF were also analyzed.

  2. Study of an aqueous lithium chloride desiccant system Part II: Desiccant regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Fumo, Nelson [Universidad Nacional Experimental del Tachira, San Cristobal (Venezuela); Goswami, Yogi [University of Florida, Gainesville (United States)

    2000-07-01

    Desiccant systems have been proposed as alternative to handle the latent load in vapor compression air conditioning for energy saving. The air dehumidification occurs because of the difference in vapor pressure which let the moisture diffuse from the air to the liquid desiccant. The diffused moisture cause a dilution of the desiccant which must be regenerated to return it to the original conditions. This paper presents the results from a study of the performance of a packed tower regenerator for an aqueous lithium chloride desiccant dehumidification system. The rate of water evaporation, as well as the effectiveness of the regeneration process were assessed under the effects of variables such as air and desiccant flow rates, air temperature and humidity, and desiccant temperature and concentration. A variation of the oeberg and Goswami mathematical model was used to predict the experimental findings given satisfactory results. [Spanish] Se han propuesto sistemas desecantes para hacerse cargo de la carga latente en acondicionamiento de aire por compresion de vapor para el ahorro de energia. La deshumidificacion del aire ocurre en razon de la diferencia de presion de vapor que deja la humedad difusa del aire en el desecante liquido. La humedad difusa del aire origina una dilucion del desecante el cual debe de ser regenerado para regresarlo a sus condiciones originales. Este documento presenta los resultados de un estudio sobre el comportamiento de un regenerador de torre empacada para un sistema de deshumidificacion de solucion desecante de cloruro de litio. El regimen de evaporacion de agua, asi como tambien la efectividad del proceso de regeneracion que se evaluo bajo los efectos de variables tales como los regimenes de flujo de aire y de desecante, temperatura del aire y humedad, y temperatura y concentracion del desecante. Una variacion del modelo matematico de Oberg y Goswami se uso para predecir los resultados experimentales que dieron resultados satisfactorios.

  3. Desiccant dehumidification and cooling systems assessment and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Collier, R.K. Jr. [Collier Engineering, Reno, NV (United States)

    1997-09-01

    The objective of this report is to provide a preliminary analysis of the principles, sensitivities, and potential for national energy savings of desiccant cooling and dehumidification systems. The report is divided into four sections. Section I deals with the maximum theoretical performance of ideal desiccant cooling systems. Section II looks at the performance effects of non-ideal behavior of system components. Section III examines the effects of outdoor air properties on desiccant cooling system performance. Section IV analyzes the applicability of desiccant cooling systems to reduce primary energy requirements for providing space conditioning in buildings. A basic desiccation process performs no useful work (cooling). That is, a desiccant material drying air is close to an isenthalpic process. Latent energy is merely converted to sensible energy. Only when heat exchange is applied to the desiccated air is any cooling accomplished. This characteristic is generic to all desiccant cycles and critical to understanding their operation. The analyses of Section I show that desiccant cooling cycles can theoretically achieve extremely high thermal CoP`s (>2). The general conclusion from Section II is that ventilation air processing is the most viable application for the solid desiccant equipment analyzed. The results from the seasonal simulations performed in Section III indicate that, generally, the seasonal performance of the desiccant system does not change significantly from that predicted for outdoor conditions. Results from Section IV show that all of the candidate desiccant systems can save energy relative to standard vapor-compression systems. The largest energy savings are achieved by the enthalpy exchange devise.

  4. Experimental Analysis on Solar Desiccant Air Conditioner

    Directory of Open Access Journals (Sweden)

    Dr. U. V. Kongre, C. M. Singh, A. B. Biswas

    2014-05-01

    Full Text Available The experiment investigated and evaluated the feasibility of an solar desiccant air conditioner. Its effectiveness as a possible air conditioner option used in household air conditioner or as an energy efficient and environmentally friendly alternative to conventional air conditioning units used in houses are evaluated. A solar water heater was used as heat gain. The model utilizes the technology of solar air conditioner system. The purpose in the long term would be reduced the consumption of electricity used for air conditioning, reduce harmful emission and hence saving money.

  5. Transcriptomes of the desiccation- tolerant resurrection plant Craterostigma plantagineum

    DEFF Research Database (Denmark)

    Rodriguez, M. C.; Edsgard, Stefan Daniel; Hussain, S. S.

    2010-01-01

    Studies of the resurrection plant Craterostigma plantagineum have revealed some of the mechanisms which these desiccation-tolerant plants use to survive environments with extreme dehydration and restricted seasonal water. Most resurrection plants are polyploid with large genomes, which has hindered...... of the array of cellular responses controlled by gene expression that allow resurrection plants to survive desiccation....

  6. Performance and evaluation of desiccant based air conditioning system.

    Directory of Open Access Journals (Sweden)

    Gaurav S. Wani

    2014-12-01

    Full Text Available This Project work presents study and experimental analysis of Desiccant based air conditioning system.The main purpose of this project is to increase the efficency of air conditioning system.In the convenstional air conditioning system cooling coli has two load latent load and sensible load. Cooling has to cool the air and simultaneously to dehumidify it.It increases load on cooling coil and affects performance to the system. To increase the efficiency the air conditioning system desiccant materials are used at the inlet of the air conditioning test rig. Desiccant materials attract moisture based on differences in vapor pressure. Due to their enormous affinity to absorb water and considerable ability to hold water. Due to use of desiccant material load on the cooling coil reduces since moisture is absorbed by desiccant; cooling coil has to take only sensible load. Analysis is done using different desiccant materials and based on the observation, power consumption before and after desiccant is calculated. From this conclusion is made that desiccant material improves the efficiency of air conditioning test rig

  7. Molecular mechanisms of desiccation tolerance in resurrection plants.

    Science.gov (United States)

    Gechev, Tsanko S; Dinakar, Challabathula; Benina, Maria; Toneva, Valentina; Bartels, Dorothea

    2012-10-01

    Resurrection plants are a small but diverse group of land plants characterized by their tolerance to extreme drought or desiccation. They have the unique ability to survive months to years without water, lose most of the free water in their vegetative tissues, fall into anabiosis, and, upon rewatering, quickly regain normal activity. Thus, they are fundamentally different from other drought-surviving plants such as succulents or ephemerals, which cope with drought by maintaining higher steady state water potential or via a short life cycle, respectively. This review describes the unique physiological and molecular adaptations of resurrection plants enabling them to withstand long periods of desiccation. The recent transcriptome analysis of Craterostigma plantagineum and Haberlea rhodopensis under drought, desiccation, and subsequent rehydration revealed common genetic pathways with other desiccation-tolerant species as well as unique genes that might contribute to the outstanding desiccation tolerance of the two resurrection species. While some of the molecular responses appear to be common for both drought stress and desiccation, resurrection plants also possess genes that are highly induced or repressed during desiccation with no apparent sequence homologies to genes of other species. Thus, resurrection plants are potential sources for gene discovery. Further proteome and metabolome analyses of the resurrection plants contributed to a better understanding of molecular mechanisms that are involved in surviving severe water loss. Understanding the cellular mechanisms of desiccation tolerance in this unique group of plants may enable future molecular improvement of drought tolerance in crop plants.

  8. Streptococcus pneumoniae Is Desiccation Tolerant and Infectious upon Rehydration

    Science.gov (United States)

    Walsh, Rebecca L.; Camilli, Andrew

    2011-01-01

    ABSTRACT Streptococcus pneumoniae (pneumococcus) is a frequent colonizer of the nasopharynx and one of the leading causative agents of otitis media, pneumonia, and meningitis. The current literature asserts that S. pneumoniae is transmitted person to person via respiratory droplets; however, environmental surfaces (fomites) have been linked to the spread of other respiratory pathogens. Desiccation tolerance has been to shown to be essential for long-term survival on dry surfaces. This study investigated the survival and infectivity of S. pneumoniae following desiccation under ambient conditions. We recovered viable bacteria after all desiccation periods tested, ranging from 1 h to 4 weeks. Experiments conducted under nutrient limitation indicate that desiccation is a condition separate from starvation. Desiccation of an acapsular mutant and 15 different clinical isolates shows that S. pneumoniae desiccation tolerance is independent of the polysaccharide capsule and is a species-wide phenomenon, respectively. Experiments demonstrating that nondesiccated and desiccated S. pneumoniae strains colonize the nasopharynx at comparable levels, combined with their ability to survive long-term desiccation, suggest that fomites may serve as alternate sources of pneumococcal infection. PMID:21610120

  9. Introduction to desiccation biology: from old borders to new frontiers.

    Science.gov (United States)

    Leprince, Olivier; Buitink, Julia

    2015-08-01

    A special issue reviews the recent progress made in our understanding of desiccation tolerance across various plant and animal kingdoms. It has been known for a long time that seeds can survive near absolute protoplasmic dehydration through air drying and complete germination upon rehydration because of their desiccation tolerance. This property is present both in prokaryotes and eukaryotes across all life kingdoms. These dry organisms suspend their metabolism when dry, are extremely tolerant to acute environmental stresses and are relatively stable during long periods of desiccation. Studies aiming at understanding the mechanisms of survival in the dry state have emerged during the past 40 years, moving from in vitro to genomic models and comparative genomics, and from a view that tolerance is an all-or-nothing phenomenon to a quantitative trait. With the prospect of global climate change, understanding the mechanisms of desiccation tolerance appears to be a promising avenue as a prelude to engineering crops for improved drought tolerance. Understanding desiccation is also useful for seed banks that rely on dehydration tolerance to preserve plant genetic resources in the form of these propagules. Articles in this special issue explore the recent progress in our understanding of desiccation tolerance, including the evolutionary mechanisms that have been adopted across various plant (algae, lichens, seeds, resurrection plants) and animal model systems (Caenorhabditis elegans, brine shrimp). We propose that the term desiccation biology defines the discipline dedicated to understand the desiccation tolerance in living organisms as well as the limits and time constraints thereof.

  10. Desiccant Dewpoint Cooling System Independent of External Water Sources

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Markussen, Wiebke B.

    2015-01-01

    This paper presents a patent pending technical solution aiming to make desiccant cooling systems independent of external water sources, hence solving problems of water availability, cost and treatment that can decrease the system attractiveness. The solution consists in condensing water from the ...... to the desiccant dew-point system without water recovery, the required regeneration temperature increases and the system thermal efficiency decreases.......This paper presents a patent pending technical solution aiming to make desiccant cooling systems independent of external water sources, hence solving problems of water availability, cost and treatment that can decrease the system attractiveness. The solution consists in condensing water from...... the air that regenerates the desiccant dehumidifier, and using it for running the evaporative coolers in the system. A closed regeneration circuit is used for maximizing the amount of condensed water. This solution is applied to a system with a desiccant wheel dehumidifier and a dew point cooler, termed...

  11. Experimental study on performance of celdek packed liquid desiccant dehumidifier

    Science.gov (United States)

    Kumar, Rakesh; Asati, A. K.

    2016-09-01

    Dehumidifier is the main component of liquid desiccant dehumidification system. Effect of the inlet parameters on various outlet parameters of the dehumidifier is studied in the present paper with structured pads as packing material and calcium chloride as liquid desiccant to process the air. The outlet parameters are change in specific humidity, mass transfer coefficient, moisture removal rate, air temperature, solution temperature, effectiveness and the corresponding inlet process parameters; mass flow rate of air, temperature of air, temperature and flow rate of desiccant solution. It is observed that mass transfer coefficient and moisture removal rate increase with increasing mass flow rate of the air and desiccant while these parameters decrease with increasing temperature of air and desiccant solution. Dehumidifier effectiveness gets increased with increasing solution flow rate. The present investigations are compared with the results of the researchers in the past.

  12. Efficient energy storage in liquid desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Hublitz, Astrid

    2008-07-18

    Liquid Desiccant Cooling Systems (LDCS) are open loop sorption systems for air conditioning that use a liquid desiccant such as a concentrated salt solution to dehumidify the outside air and cool it by evaporative cooling. Thermochemical energy storage in the concentrated liquid desiccant can bridge power mismatches between demand and supply. Low-flow LDCS provide high energy storage capacities but are not a state-of-the-art technology yet. The key challenge remains the uniform distribution of the liquid desiccant on the heat and mass transfer surfaces. The present research analyzes the factors of influence on the energy storage capacity by simulation of the heat and mass transfer processes and specifies performance goals for the distribution of the process media. Consequently, a distribution device for the liquid desiccant is developed that reliably meets the performance goals. (orig.)

  13. The role of photoperiods on photobioreactors - A potential strategy to reduce costs.

    Science.gov (United States)

    Maroneze, Mariana Manzoni; Siqueira, Stefania Fortes; Vendruscolo, Raquel Guidetti; Wagner, Roger; de Menezes, Cristiano Ragagnin; Zepka, Leila Queiroz; Jacob-Lopes, Eduardo

    2016-11-01

    The aim of this work was evaluate the role of photoperiods (long-term, frequencies and short) on the growth and lipid content of microalgae Scenedesmus obliquus CPCC05. The results showed that Scenedesmus obliquus can store sufficient energy to sustain cell growth for continuous periods of up to 2h in the dark, without affecting the photosynthetic rate. The values for maximum biomass (9.58mg/Lh) and lipid productivities (2.56mg/Lh) were obtained at photoperiod of 0.91:0.09s (light:dark) and 48 t/d, respectively. Moreover, the best trade-offs between biomass productivity and light energy economy occurred in photoperiods of 0.5:0.5s and 0.91:0.09s (light:dark), and those between lipid productivity and light energy economy occurred in the frequency photoperiod of 24 and 48 t/d. Thus, the use of the photoperiods are an effective strategy for reducing costs of microalgal biomass production.

  14. Evaluation of a Reduced Cost Active NDVI Sensor for Crop Nutrient Management

    Directory of Open Access Journals (Sweden)

    Jared Crain

    2012-01-01

    Full Text Available There are methods to increase fertilizer nitrogen use efficiency through optical sensor-based nitrogen application; however, the sensors are expensive and cost prohibitive to farmers in the developing world. This study evaluated a novel, reduced cost, prototype, and optical sensor to determine if it could be used with the same level of accuracy as a commercial sensor. The stability of the prototype sensor (pocket sensor to maintain an accurate calibration over time, the effect of operator on sensor readings, and sensor performance in maize and wheat were assessed. Evaluation of the sensor performance was conducted in existing wheat and maize trials, as well as turf grass canopies at the International Maize and Wheat Improvement Center, Ciudad Obregon, Mexico.The prototype sensors were highly correlated to the commercial GreenSeeker NDVI sensor in turf grass, wheat, and maize canopies (r2>0.97, r2>0.95, and r2>0.91, resp.. The Pocket Sensors lacked some precision in comparison to the commercial sensor; however, even with the reduced precision, the cost of the sensor and robustness of N fertilizer algorithms compensate for this apparent weakness. The pocket sensor is a new and viable tool to assess wheat and maize nitrogen status and make nitrogen recommendations based upon the data collected with this sensor.

  15. The AskIT Service Desk: A Model for Improving Productivity and Reducing Costs

    Energy Technology Data Exchange (ETDEWEB)

    Ashcraft, Phillip Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fogle, Blythe G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cummings, Susan M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lopez, Leon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-29

    This was prepared for the business process improvement presentation to the Department of Energy. Los Alamos National Laboratory provides a single point of contact, the AskIT Service Desk, to address issues that impact customer productivity. At the most basic level, what customers want is for their calls to be received, to get a response from a knowledgeable analyst, and to have their issues resolved and their requests fulfilled. Providing a centralized, single point of contact service desk makes initiating technical or business support simple for the customer and improves the odds of immediately resolving the issue or correctly escalating the request to the next support level when necessary. Fulfilling customer requests through automated workflow also improves customer productivity and reduces costs. Finally, customers should be provided the option to solve their own problems through easy access to self-help resources such as frequently asked questions (FAQs) and how-to guides. To accomplish this, everyone who provides and supports services must understand how these processes and functions work together. Service providers and those who support services must “speak the same language” and share common objectives. The Associate Directorate for Business Innovation (ADBI) began the journey to improve services by selecting a known service delivery framework (Information Technology Infrastructure Library, or ITIL). From this framework, components that contribute significant business value were selected.

  16. Reduced cost design of liquid lithium target for international fusion material irradiation facility (IFMIF)

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hiroo; Ida, Mizuho; Sugimoto, Masayoshi; Takeuchi, Hiroshi [Department of Fussion Engineering Research, Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Yutani, Toshiaki [Toshiba Corp., Tokyo (Japan)

    2001-01-01

    The International Fusion Materials Irradiation Facility (IFMIF) is being jointly planned to provide an accelerator-based D-Li neutron source to produce intense high energy neutrons (2 MW/m{sup 2}) up to 200 dpa and a sufficient irradiation volume (500 cm{sup 3}) for testing the candidate materials and components up to about a full lifetime of their anticipated use in ITER and DEMO. To realize such a condition, 40 MeV deuteron beam with a current of 250 mA is injected into high speed liquid lithium flow with a speed of 20 m/s. Following Conceptual Design Activity (1995-1998), a design study with focus on cost reduction without changing its original mission has been done in 1999. The following major changes to the CAD target design have been considered in the study and included in the new design: i) number of the Li target has been changed from 2 to 1, ii) spare of impurity traps of the Li loop was removed although the spare will be stored in a laboratory for quick exchange, iii) building volume was reduced via design changes in lithium loop length. This paper describes the reduced cost design of the lithium target system and recent status of Key Element Technology activities. (author)

  17. Effective information channels for reducing costs of environmentally- friendly technologies: evidence from residential PV markets

    Science.gov (United States)

    Rai, Varun; Robinson, Scott A.

    2013-03-01

    Realizing the environmental benefits of solar photovoltaics (PV) will require reducing costs associated with perception, informational gaps and technological uncertainties. To identify opportunities to decrease costs associated with residential PV adoption, in this letter we use multivariate regression models to analyze a unique, household-level dataset of PV adopters in Texas (USA) to systematically quantify the effect of different information channels on aspiring PV adopters’ decision-making. We find that the length of the decision period depends on the business model, such as whether the system was bought or leased, and on special opportunities to learn, such as the influence of other PV owners in the neighborhood. This influence accrues passively through merely witnessing PV systems in the neighborhood, increasing confidence and motivation, as well as actively through peer-to-peer communications. Using these insights we propose a new framework to provide public information on PV that could drastically reduce barriers to PV adoption, thereby accelerating its market penetration and environmental benefits. This framework could also serve as a model for other distributed generation technologies.

  18. Desiccant-Based Preconditioning Market Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J.

    2001-01-11

    A number of important conclusions can be drawn as a result of this broad, first-phase market evaluation. The more important conclusions include the following: (1) A very significant market opportunity will exist for specialized outdoor air-handling units (SOAHUs) as more construction and renovation projects are designed to incorporate the recommendations made by the ASHRAE 62-1989 standard. Based on this investigation, the total potential market is currently $725,000,000 annually (see Table 6, Sect. 3). Based on the market evaluations completed, it is estimated that approximately $398,000,000 (55%) of this total market could be served by DBC systems if they were made cost-effective through mass production. Approximately $306,000,000 (42%) of the total can be served by a non-regenerated, desiccant-based total recovery approach, based on the information provided by this investigation. Approximately $92,000,000 (13%) can be served by a regenerated desiccant-based cooling approach (see Table 7, Sect. 3). (2) A projection of the market selling price of various desiccant-based SOAHU systems was prepared using prices provided by Trane for central-station, air-handling modules currently manufactured. The wheel-component pricing was added to these components by SEMCO. This resulted in projected pricing for these systems that is significantly less than that currently offered by custom suppliers (see Table 4, Sect. 2). Estimated payback periods for all SOAHU approaches were quite short when compared with conventional over-cooling and reheat systems. Actual paybacks may vary significantly depending on site-specific considerations. (3) In comparing cost vs benefit of each SOAHU approach, it is critical that the total system design be evaluated. For example, the cost premium of a DBC system is very significant when compared to a conventional air handling system, yet the reduced chiller, boiler, cooling tower, and other expense often equals or exceeds this premium, resulting in a

  19. Photosynthetic recovery of desiccated intertidal seaweeds after rehydration

    Institute of Scientific and Technical Information of China (English)

    JI Yan; GAO Kunshan; TANAKA Jiro

    2005-01-01

    Intertidal seaweeds experience periodical desiccation and rehydration to different extents due to the tidal cycles and their vertical distributions. Their photosynthetic recovery process during the rehydration may show different patterns among the seaweeds from different zonations or depths at intertidal zone. In this study 12 species of seaweeds collected from the upper, middle, lower and sublittoral zones were examined. The relationship of the photosynthetic recovery to vertical distribution was assessed by comparing their patterns of photosynthetic and respiratory performances after rehydration following desiccation. Both the photosynthesis and dark respiration declined during emersion, showing certain degrees of recovery after re-immersion into seawater for most species, but the extents were markedly different from one species to the other. The species from upper intertidal zone after being rehydrated for 1 hour, following 2 hours of desiccation, achieved 100 % recovery of their initial physiological activity, while most of the lower or sublittoral species did not achieve full recovery. It is the ability to withstand desiccation stress (fast recovery during rehydration), but not that to avoid desiccation (water retain ing ability) that determines the distribution of intertidal seaweeds. Such physiological behavior during rehydration after desiccation reflects the adaptive strategy of intertidal seaweeds against desiccation and their capabilityof primary production in the process of rehydration.

  20. Desiccation stress induces developmental heterochrony in Drosophila melanogaster

    Indian Academy of Sciences (India)

    LEENA THORAT; DASHARATH P OULKAR; KAUSHIK BANERJEE; BIMALENDU B NATH

    2016-09-01

    Stressful environments are known to perturb developmental patterns in insects. In the purview of desiccation as astressor, relatively little is known about the developmental consequences linked with desiccation tolerance. In thisstudy, we have particularly focused on the exploration of the temporal profile of postembryonic development inresponse to desiccation exposure in Drosophila melanogaster and the associated trade-offs. We document a correlationbetween variations in 20-hydroxyecdysone levels and the altered timing of metamorphic events during the lifecycle. Following desiccation, we observed an extension in the larval longevity whereas the duration of the pupal andadult stages was significantly shortened. Alternately, feeding of 20-hydroxyecdysone apparently led to the restorationof the normal temporal pattern of development in the desiccated group. In spite of the desiccation-responsiveheterochronic shifts in development, the overall lifespan post recovery remained almost unaltered among thedesiccated and undesiccated groups suggesting plasticity in developmental control. This observation reminisces ‘canalization-like’ phenomenon that buffers alterations in the overall lifespan. We thus identified a desiccation responsiveperiod in the lifespan of D. melanogaster during which variations in ecdysone levels are capable to alter thetemporal course of development.

  1. Analysis of advanced solar hybrid desiccant cooling systems for buildings

    Energy Technology Data Exchange (ETDEWEB)

    Schlepp, D.; Schultz, K.

    1984-10-01

    This report describes an assessment of the energy savings possible from developing hybrid desiccant/vapor-compression air conditioning systems. Recent advances in dehumidifier design for solar desiccant cooling systems have resulted in a dehumidifier with a low pressure drop and high efficiency in heat and mass transfer. A recent study on hybrid desiccant/vapor compression systems showed a 30%-80% savings in resource energy when compared with the best conventional systems with vapor compression. A system consisting of a dehumidifier with vapor compression subsystems in series was found to be the simplest and best overall performer.

  2. Comparison of desiccation tolerance among mosses from different habitats

    Directory of Open Access Journals (Sweden)

    Šinžar-Sekulić Jasmina B.

    2005-01-01

    Full Text Available 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.

  3. Development of a solar desiccant dehumidifier. Third technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Gunderson, M.E.

    1979-06-12

    This program is aimed at the development of a solar desiccant dehumidifier featuring a rotary bed of granular silica gel and a rotary regenerator. Design, fabrication, performance, commercialization studies, and test stand development are described in detail. (WHK)

  4. Desiccation Stress and the Effect of Humidity in Mosses

    Directory of Open Access Journals (Sweden)

    Aina Arinola FAJUKE

    2010-03-01

    Full Text Available Mosses show fair degree of structural adaptations to different environmental conditions. The effects caused by desiccation were determined in the shoots of six moss species, collected from various locations of the Obafemi Awolowo University Ile-Ife campus, Osun State, Nigeria. Using 0.1 g of fresh weights, desiccation of moss species over time at 0%, 52%, and 100% relative humidity, were determined by putting the shoots into desiccators and reweighing at intervals of 15 min, 30 min, 1 hr and on the 8th day. It was concluded that the locations of the moss species, and the fact that the cell walls of all the mosses were thick, were regarded as the adaptations which helped these mosses survived desiccation stress.

  5. Effect of Desiccation of Marine Environment on Beam Structure

    Institute of Scientific and Technical Information of China (English)

    CHEN Da; WANG Na; HOU Li-jun; LIAO Ying-di

    2013-01-01

    This paper presents the study on the effect of desiccation for different part of offshore structure corresponding to the water level.A coupled elastoplastic damage model is proposed to describe the mechanical behavior of cement-based materials under external loading and desiccation,in which both the plastic and damage behaviors under multi-axial stress are considered in composition with the desiccation effect.The comparison between numerical simulation and experimental data indicates that the proposed model can well predict the mechanical characteristics of cement-based materials with different saturations.In addition,a series of small beams subjected to desiccation are further analyzed to reveal the response of structure in the drying process.

  6. Effect of desiccation of marine environment on beam structure

    Science.gov (United States)

    Chen, Da; Wang, Na; Hou, Li-jun; Liao, Ying-di

    2013-03-01

    This paper presents the study on the effect of desiccation for different part of offshore structure corresponding to the water level. A coupled elastoplastic damage model is proposed to describe the mechanical behavior of cement-based materials under external loading and desiccation, in which both the plastic and damage behaviors under multi-axial stress are considered in composition with the desiccation effect. The comparison between numerical simulation and experimental data indicates that the proposed model can well predict the mechanical characteristics of cement-based materials with different saturations. In addition, a series of small beams subjected to desiccation are further analyzed to reveal the response of structure in the drying process.

  7. Chemical desiccation for early harvest in soybean cultivars

    National Research Council Canada - National Science Library

    Tamara Pereira; Cileide Maria Medeiros Coelho; Clovis Arruda Souza; Analu Mantovani; Vanderléia Mathias

    2015-01-01

    .... The objective of this work was to assess the production performance and germination seeds in response to differents stages and desiccation chemicals products to early harvest of soybean cultivars...

  8. Desiccant Enhanced Evaporative Air Conditioning: Parametric Analysis and Design; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Woods, J.; Kozubal, E.

    2012-10-01

    This paper presents a parametric analysis using a numerical model of a new concept in desiccant and evaporative air conditioning. The concept consists of two stages: a liquid desiccant dehumidifier and a dew-point evaporative cooler. Each stage consists of stacked air channel pairs separated by a plastic sheet. In the first stage, a liquid desiccant film removes moisture from the process (supply-side) air through a membrane. An evaporatively-cooled exhaust airstream on the other side of the plastic sheet cools the desiccant. The second-stage indirect evaporative cooler sensibly cools the dried process air. We analyze the tradeoff between device size and energy efficiency. This tradeoff depends strongly on process air channel thicknesses, the ratio of first-stage to second-stage area, and the second-stage exhaust air flow rate. A sensitivity analysis reiterates the importance of the process air boundary layers and suggests a need for increasing airside heat and mass transfer enhancements.

  9. The relationship between water binding and desiccation tolerance in tissues

    Science.gov (United States)

    Vertucci, C. W.; Leopold, A. C.

    1987-01-01

    In an effort to define the nature of desiccation tolerance, a comparison of the water sorption characteristics was made between tissues that were resistant and tissues that were sensitive to desiccation. Water sorption isotherms were constructed for germinated and ungerminated soybean axes and also for fronds of several species of Polypodium with varying tolerance to dehydration. The strength of water binding was determined by van't Hoff as well as D'Arcy/Watt analyses of the isotherms at 5, 15, and/or 25 degrees C. Tissues which were sensitive to desiccation had a poor capacity to bind water tightly. Tightly bound water can be removed from soybean and pea seeds by equilibration at 35 degrees C over very low relative humidities; this results in a reduction in the viability of the seed. We suggest that region 1 water (i.e. water bound with very negative enthalpy values) is an important component of desiccation tolerance.

  10. New cylinder head concept for reducing costs, weight and friction losses; Neues Zylinderkopfkonzept - Reduzierung von Kosten, Masse und Reibungsverlusten

    Energy Technology Data Exchange (ETDEWEB)

    Heywood, Jonathan [ThyssenKrupp Presta Chemnitz GmbH, Chemnitz (Germany). Simulation/Testing R and D Valve Train Systems

    2009-11-15

    The camshaft bearing in an internal combustion engine plays a major role in the design of the cylinder head. The name Presta Integrated Cam Assembly (PICA) describes a large number of different development approaches for the cylinder head area. ThyssenKrupp presents a solution for reducing costs, weight and friction losses while at the same time providing lower engine-out emissions. (orig.)

  11. Genetic analysis of desiccation tolerance in Sachharomyces cerevisiae.

    Science.gov (United States)

    Calahan, Dean; Dunham, Maitreya; DeSevo, Chris; Koshland, Douglas E

    2011-10-01

    Desiccation tolerance, the ability to survive nearly total dehydration, is a rare strategy for survival and reproduction observed in all taxa. However, the mechanism and regulation of this phenomenon are poorly understood. Correlations between desiccation tolerance and potential effectors have been reported in many species, but their physiological significance has not been established in vivo. Although the budding yeast Saccharomyces cerevisiae exhibits extreme desiccation tolerance, its usefulness has been hampered by an inability to reduce tolerance more than a few fold by physiological or genetic perturbations. Here we report that fewer than one in a million yeast cells from low-density logarithmic cultures survive desiccation, while 20-40% of cells from saturated cultures survive. Using this greatly expanded metric, we show that mutants defective in trehalose biosynthesis, hydrophilins, responses to hyperosmolarity, and hypersalinity, reactive oxygen species (ROS) scavenging and DNA damage repair nevertheless retain wild-type levels of desiccation tolerance, suggesting that this trait involves a unique constellation of stress factors. A genome-wide screen for mutants that render stationary cells as sensitive as log phase cells identifies only mutations that block respiration. Respiration as a prerequisite for acquiring desiccation tolerance is corroborated by respiration inhibition and by growth on nonfermentable carbon sources. Suppressors bypassing the respiration requirement for desiccation tolerance reveal at least two pathways, one of which, involving the Mediator transcription complex, is associated with the shift from fermentative to respiratory metabolism. Further study of these regulators and their targets should provide important clues to the sensors and effectors of desiccation tolerance.

  12. Variation of desiccation tolerance and longevity in fern spores.

    Science.gov (United States)

    Ballesteros, Daniel; Hill, Lisa M; Walters, Christina

    2017-04-01

    This work contributes to the understanding of plant cell responses to extreme water stress when it is applied at different intensity and duration. Fern spores are used to explore survival at relative humidity (RH)desiccation damage occurs in desiccation tolerant cells, and that it is expressed as a time-dependent response, otherwise known as aging. Copyright © 2017 Elsevier GmbH. All rights reserved.

  13. Genetic Analysis of Desiccation Tolerance in Saccharomyces cerevisiae

    Science.gov (United States)

    Calahan, Dean; Dunham, Maitreya; DeSevo, Chris; Koshland, Douglas E.

    2011-01-01

    Desiccation tolerance, the ability to survive nearly total dehydration, is a rare strategy for survival and reproduction observed in all taxa. However, the mechanism and regulation of this phenomenon are poorly understood. Correlations between desiccation tolerance and potential effectors have been reported in many species, but their physiological significance has not been established in vivo. Although the budding yeast Saccharomyces cerevisiae exhibits extreme desiccation tolerance, its usefulness has been hampered by an inability to reduce tolerance more than a few fold by physiological or genetic perturbations. Here we report that fewer than one in a million yeast cells from low-density logarithmic cultures survive desiccation, while 20–40% of cells from saturated cultures survive. Using this greatly expanded metric, we show that mutants defective in trehalose biosynthesis, hydrophilins, responses to hyperosmolarity, and hypersalinity, reactive oxygen species (ROS) scavenging and DNA damage repair nevertheless retain wild-type levels of desiccation tolerance, suggesting that this trait involves a unique constellation of stress factors. A genome-wide screen for mutants that render stationary cells as sensitive as log phase cells identifies only mutations that block respiration. Respiration as a prerequisite for acquiring desiccation tolerance is corroborated by respiration inhibition and by growth on nonfermentable carbon sources. Suppressors bypassing the respiration requirement for desiccation tolerance reveal at least two pathways, one of which, involving the Mediator transcription complex, is associated with the shift from fermentative to respiratory metabolism. Further study of these regulators and their targets should provide important clues to the sensors and effectors of desiccation tolerance. PMID:21840858

  14. Desiccant Cooling System for Thermal Comfort: A Review

    Directory of Open Access Journals (Sweden)

    HEMANT PARMAR,

    2011-05-01

    Full Text Available Desiccant cooling system (DCS is alternate suitable option against conventional cooling system in humid climates. A typical system combines a dehumidifier that uses dry desiccant wheel, with direct or indirect evaporative systems and a sensible cooling system. DCS is the environmental protection technique for cooling purpose of the building. This system reduces the CFC level in the environment because it restricts the use of conventional refrigerant. In this paper, all the working principles and expected research areashave been discussed. Through detailed literature survey it has been observed that a desiccant cooling system may be a suitable option for thermal comfort in the climate where the humidity is higher. Thedesiccant cooling system (DCS has proven their feasibility and cost saving in the field of air conditioning. This review provides a brief overview on the development of desiccant cooling system in different fields. Finally, concluding remarks regarding further development of desiccant cooling for thermal comfort are also provided. This technology is economically feasible and optimizes with low cost. This review is useful for making opportunities to further research in different areas of desiccant cooling system.

  15. Rate of Dehydration and Cumulative Desiccation Stress Interacted to Modulate Desiccation Tolerance of Recalcitrant Cocoa and Ginkgo Embryonic Tissues1

    Science.gov (United States)

    Liang, Yongheng; Sun, Wendell Q.

    2002-01-01

    Rate of dehydration greatly affects desiccation tolerance of recalcitrant seeds. This effect is presumably related to two different stress vectors: direct mechanical or physical stress because of the loss of water and physicochemical damage of tissues as a result of metabolic alterations during drying. The present study proposed a new theoretic approach to represent these two types of stresses and investigated how seed tissues responded differently to two stress vectors, using the models of isolated cocoa (Theobroma cacao) and ginkgo (Ginkgo biloba) embryonic tissues dehydrated under various drying conditions. This approach used the differential change in axis water potential (ΔΨ/Δt) to quantify rate of dehydration and the intensity of direct physical stress experienced by embryonic tissues during desiccation. Physicochemical effect of drying was expressed by cumulative desiccation stress [∫\\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\pagestyle{empty} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{_{o}^{t}}}\\end{equation*}\\end{document}f(ψ,t)], a function of both the rate and time of dehydration. Rapid dehydration increased the sensitivity of embryonic tissues to desiccation as indicated by high critical water contents, below which desiccation damage occurred. Cumulative desiccation stress increased sharply under slow drying conditions, which was also detrimental to embryonic tissues. This quantitative analysis of the stress-time-response relationship helps to understand the physiological basis for the existence of an optimal dehydration rate, with which maximum desiccation tolerance could be achieved. The established numerical analysis model will prove valuable for the design of experiments that aim to elucidate biochemical and physiological mechanisms of desiccation tolerance. PMID:11950981

  16. Developing sporophytes transition from an inducible to a constitutive ecological strategy of desiccation tolerance in the moss Aloina ambigua: effects of desiccation on fitness.

    Science.gov (United States)

    Stark, Lloyd R; Brinda, John C

    2015-03-01

    Two ecological strategies of desiccation tolerance exist in plants, constitutive and inducible. Because of difficulties in culturing sporophytes, very little is known about desiccation tolerance in this generation and how desiccation affects sexual fitness. Cultured sporophytes and vegetative shoots from a single genotype of the moss Aloina ambigua raised in the laboratory were tested for their strategy of desiccation tolerance by desiccating the shoot-sporophyte complex and vegetative shoots at different intensities, and comparing outcomes with those of undried shoot-sporophyte complexes and vegetative shoots. By using a dehardened clonal line, the effects of field, age and genetic variance among plants were removed. The gametophyte and embryonic sporophyte were found to employ a predominantly inducible strategy of desiccation tolerance, while the post-embryonic sporophyte was found to employ a moderately constitutive strategy of desiccation tolerance. Further, desiccation reduced sporophyte fitness, as measured by sporophyte mass, seta length and capsule size. However, the effects of desiccation on sporophyte fitness were reduced if the stress occurred during embryonic development as opposed to postembryonic desiccation. The effects of desiccation on dehardened sporophytes of a bryophyte are shown for the first time. The transition from one desiccation tolerance strategy to the other in a single structure or generation is shown for only the second time in plants and for the first time in bryophytes. Finding degrees of inducible strategies of desiccation tolerance in different life phases prompts the formulation of a continuum hypothesis of ecological desiccation tolerance in mosses, where desiccation tolerance is not an either/or phenomenon, but varies in degree along a gradient of ecological inducibility. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email

  17. Desiccation resistance in tropical insects: causes and mechanisms underlying variability in a Panama ant community.

    Science.gov (United States)

    Bujan, Jelena; Yanoviak, Stephen P; Kaspari, Michael

    2016-09-01

    Desiccation resistance, the ability of an organism to reduce water loss, is an essential trait in arid habitats. Drought frequency in tropical regions is predicted to increase with climate change, and small ectotherms are often under a strong desiccation risk. We tested hypotheses regarding the underexplored desiccation potential of tropical insects. We measured desiccation resistance in 82 ant species from a Panama rainforest by recording the time ants can survive desiccation stress. Species' desiccation resistance ranged from 0.7 h to 97.9 h. We tested the desiccation adaptation hypothesis, which predicts higher desiccation resistance in habitats with higher vapor pressure deficit (VPD) - the drying power of the air. In a Panama rainforest, canopy microclimates averaged a VPD of 0.43 kPa, compared to a VPD of 0.05 kPa in the understory. Canopy ants averaged desiccation resistances 2.8 times higher than the understory ants. We tested a number of mechanisms to account for desiccation resistance. Smaller insects should desiccate faster given their higher surface area to volume ratio. Desiccation resistance increased with ant mass, and canopy ants averaged 16% heavier than the understory ants. A second way to increase desiccation resistance is to carry more water. Water content was on average 2.5% higher in canopy ants, but total water content was not a good predictor of ant desiccation resistance or critical thermal maximum (CT max), a measure of an ant's thermal tolerance. In canopy ants, desiccation resistance and CT max were inversely related, suggesting a tradeoff, while the two were positively correlated in understory ants. This is the first community level test of desiccation adaptation hypothesis in tropical insects. Tropical forests do contain desiccation-resistant species, and while we cannot predict those simply based on their body size, high levels of desiccation resistance are always associated with the tropical canopy.

  18. Desiccation tolerance of Sphagnum revisited: a puzzle resolved.

    Science.gov (United States)

    Hájek, T; Vicherová, E

    2014-07-01

    As ecosystem engineers, Sphagnum mosses control their surroundings through water retention, acidification and peat accumulation. Because water retention avoids desiccation, sphagna are generally intolerant to drought; however, the literature on Sphagnum desiccation tolerance (DT) provides puzzling results, indicating the inducible nature of their DT. To test this, various Sphagnum species and other mesic bryophytes were hardened to drought by (i) slow drying; (ii) ABA application and (iii) chilling or frost. DT tolerance was assessed as recovery of chlorophyll fluorescence parameters after severe desiccation. We monitored the seasonal course of DT in bog bryophytes. Under laboratory conditions, following initial de-hardening, untreated Sphagnum shoots lacked DT; however, DT was induced by all hardening treatments except chilling, notably by slow drying, and in Sphagnum species of the section Cuspidata. In the field, sphagna in hollows and lawns developed DT several times during the growing season, responding to reduced precipitation and a lowered water table. Hummock and aquatic species developed DT only in late autumn, probably as a response to frost. Sphagnum protonemata failed to develop DT; hence, desiccation may limit Sphagnum establishment in drier habitats with suitable substrate chemistry. Desiccation avoiders among sphagna form compact hummocks or live submerged; thus, they do not develop DT in the field, lacking the initial desiccation experience, which is frequent in hollow and lawn habitats. We confirmed the morpho-physiological trade-off: in contrast to typical hollow sphagna, hummock species invest more resources in water retention (desiccation avoidance), while they have a lower ability to develop physiological DT. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  19. Active Desiccant-Based Preconditioning Market Analysis and Product Development

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J.

    2001-01-11

    The Phase 1 report (ORNL/Sub/94-SVO44/1), completed earlier in this program, involved a comprehensive field survey and market analysis comparing various specialized outdoor air handling units. This initial investigation included conventional cooling and reheat, conventional cooling with sensible recovery, total energy recovery systems (passive desiccant technology) and various active desiccant systems. The report concluded that several markets do promise a significant sales opportunity for a Climate Changer-based active desiccant system offering. (Climate Changer is a registered trademark of Trane Company.) This initial market analysis defined the wants and needs of the end customers (design engineers and building owners), which, along with subsequent information included in this report, have been used to guide the determination of the most promising active desiccant system configurations. This Phase 2 report begins with a summary of a more thorough investigation of those specific markets identified as most promising for active desiccant systems. Table 1 estimates the annual sales potential for a cost-effective product line of active desiccant systems, such as that built from Climate Changer modules. The Product Development Strategy section describes the active desiccant system configurations chosen to best fit the needs of the marketplace while minimizing system options. Key design objectives based on market research are listed in this report for these active desiccant systems. Corresponding performance goals for the dehumidification wheel required to meet the overall system design objectives are also defined. The Performance Modeling section describes the strategy used by SEMCO to design the dehumidification wheels integrated into the prototype systems currently being tested as part of the U.S. Department of Energy's Advanced Desiccant Technology Program. Actual performance data from wheel testing was used to revise the system performance and energy analysis

  20. Increasing intracellular trehalose is sufficient to confer desiccation tolerance to Saccharomyces cerevisiae.

    Science.gov (United States)

    Tapia, Hugo; Young, Lindsey; Fox, Douglas; Bertozzi, Carolyn R; Koshland, Douglas

    2015-05-12

    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 yeast Saccharomyces 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.

  1. Insect capa neuropeptides impact desiccation and cold tolerance.

    Science.gov (United States)

    Terhzaz, Selim; Teets, Nicholas M; Cabrero, Pablo; Henderson, Louise; Ritchie, Michael G; Nachman, Ronald J; Dow, Julian A T; Denlinger, David L; Davies, Shireen-A

    2015-03-03

    The success of insects is linked to their impressive tolerance to environmental stress, but little is known about how such responses are mediated by the neuroendocrine system. Here we show that the capability (capa) neuropeptide gene is a desiccation- and cold stress-responsive gene in diverse dipteran species. Using targeted in vivo gene silencing, physiological manipulations, stress-tolerance assays, and rationally designed neuropeptide analogs, we demonstrate that the Drosophila melanogaster capa neuropeptide gene and its encoded peptides alter desiccation and cold tolerance. Knockdown of the capa gene increases desiccation tolerance but lengthens chill coma recovery time, and injection of capa peptide analogs can reverse both phenotypes. Immunohistochemical staining suggests that capa accumulates in the capa-expressing Va neurons during desiccation and nonlethal cold stress but is not released until recovery from each stress. Our results also suggest that regulation of cellular ion and water homeostasis mediated by capa peptide signaling in the insect Malpighian (renal) tubules is a key physiological mechanism during recovery from desiccation and cold stress. This work augments our understanding of how stress tolerance is mediated by neuroendocrine signaling and illustrates the use of rationally designed peptide analogs as agents for disrupting protective stress tolerance.

  2. Alternative splicing enhances transcriptome complexity in desiccating seeds.

    Science.gov (United States)

    Srinivasan, Arunkumar; Jiménez-Gómez, José M; Fornara, Fabio; Soppe, Wim J J; Brambilla, Vittoria

    2016-12-01

    Before being dispersed in the environment, mature seeds need to be dehydrated. The survival of seeds after dispersal depends on their low hydration in combination with high desiccation tolerance. These characteristics are established during seed maturation. Some key seed maturation genes have been reported to be regulated by alternative splicing (AS). However, so far AS was described only for single genes and a comprehensive analysis of AS during seed maturation has been lacking. We investigated gene expression and AS during Arabidopsis thaliana seed development at a global level, before and after desiccation. Bioinformatics tools were developed to identify differentially spliced regions within genes. Our data suggest the importance and shows the peculiar features of AS during seed desiccation. We identified AS in 34% of genes that are expressed at both timepoints before and after desiccation. Most of these AS transcript variants had not been found before in other tissues. Among the AS genes some seed master regulators could be found. Interestingly, 6% of all expressed transcripts were not transcriptionally regulated during desiccation, but only modified by AS. We propose that AS should be more routinely taken into account in the analysis of transcriptomic data to prevent overlooking potentially important regulators. © 2016 Institute of Botany, Chinese Academy of Sciences.

  3. Insect capa neuropeptides impact desiccation and cold tolerance

    Science.gov (United States)

    Terhzaz, Selim; Teets, Nicholas M.; Cabrero, Pablo; Henderson, Louise; Ritchie, Michael G.; Nachman, Ronald J.; Dow, Julian A. T.; Denlinger, David L.; Davies, Shireen-A.

    2015-01-01

    The success of insects is linked to their impressive tolerance to environmental stress, but little is known about how such responses are mediated by the neuroendocrine system. Here we show that the capability (capa) neuropeptide gene is a desiccation- and cold stress-responsive gene in diverse dipteran species. Using targeted in vivo gene silencing, physiological manipulations, stress-tolerance assays, and rationally designed neuropeptide analogs, we demonstrate that the Drosophila melanogaster capa neuropeptide gene and its encoded peptides alter desiccation and cold tolerance. Knockdown of the capa gene increases desiccation tolerance but lengthens chill coma recovery time, and injection of capa peptide analogs can reverse both phenotypes. Immunohistochemical staining suggests that capa accumulates in the capa-expressing Va neurons during desiccation and nonlethal cold stress but is not released until recovery from each stress. Our results also suggest that regulation of cellular ion and water homeostasis mediated by capa peptide signaling in the insect Malpighian (renal) tubules is a key physiological mechanism during recovery from desiccation and cold stress. This work augments our understanding of how stress tolerance is mediated by neuroendocrine signaling and illustrates the use of rationally designed peptide analogs as agents for disrupting protective stress tolerance. PMID:25730885

  4. The Effects of Desiccation on Methanogens Under Aerobic and Anaerobic Conditions

    Science.gov (United States)

    Murphy, C.; Kral, T. A.

    2010-04-01

    Survival of methanogens following desiccation depends on whether they are maintained under aerobic or anaerobic conditions. Cells maintained in a desiccated state in the presence of oxygen did not survive as well as those maintained anaerobically.

  5. Zero Carryover Liquid-Desiccant Air Conditioner for Solar Applications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Lowenstein, A.; Slayzak, S.; Kozubal, E.

    2006-07-01

    A novel liquid-desiccant air conditioner that dries and cools building supply air will transform the use of direct-contact liquid-desiccant systems in HVAC applications, improving comfort, air quality, and providing energy-efficient humidity control.

  6. Chemical dehumidification by liquid desiccants: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.M.; Gasparella, A.; Longo, G.A. [Universita di Padova, Dip. di Tecnica e Gestione dei Sistemi Industriale, Vicenza (Italy)

    1999-06-01

    Chemical dehumidification of air by a liquid desiccant in a packed tower has been investigated both theoretically and experimentally for air conditioning and industrial applications. A computer model of a packed tower, able to determine heat and mass transfer between air and desiccant, has been developed and a parametrical study was carried out considering the solutions H{sub 2}O/LiBr and H{sub 2}O/CaCl{sub 2} to determine the optimum operative conditions. An experimental apparatus including a packed tower and a desiccant regenerator has been described together with experimental results: a set of 70 experimental runs with H{sub 2}O/LiBr. Data have been reported and compared against the results of the computer code simulations. (Author)

  7. Chemical dehumidification by liquid desiccants. Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.M.; Gasparella, A. [Instituto di Ingegneria Gestionale dell`Universita di Padova, Padova (Italy); Longo, G.A. [Instituto di Fisica Tecnica dell`Universita di Padova, Padova (Italy)

    1997-06-01

    Chemical dehumidification of air by a liquid desiccant in packed tower has been investigated both theoretically and experimentally for air conditioning and industrial applications. A computer model of a packed tower, able to determine the heat and mass transfer between air and desiccant, has been developed and a parametrical study was carried out considering the solutions H2O/LiBr and H2O/CaCl2 to determine the optimum operative conditions. An experimental apparatus including a packed tower and a desiccant regenerator has been describe together with experimental results: a set of 70 experimental runs with H2O/LiBr. Dat have been reported and compared against the results of the computer code simulations. 16 refs.

  8. Self-desiccation Effect of High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    JIANG Zheng-wu; SUN Zhen-ping; WANG Pei-ming

    2004-01-01

    Effects of water to binder ratio (mW/mB), types and addition content of mineral admixtures on the autogenous relative humidity (ARH) change of concrete resulting from self-desiccation were studied. The parameters of coefficient of mineral self-desiccation-effect k and efficient water to binder ratio re were proposed, and experimental results were fitted non-linearly and analyzed using these proposed parameters. The experimental results indicate that ARH reduction of concrete at different ages increases with the decrease of mW/mB. The ARH change laws of concrete with mW/mB lower than 0.4 can be expressed with a non-linear equation. The extent of the effect of types and addition content of mineral admixtures on ARH reduction of concrete resulting from self-desiccation can be reflected by the non-linear equation with the parameter of efficient water to binder ratio re effectively.

  9. Acquisition and loss of desiccation tolerance in seeds : from experimental model to biological relevance

    NARCIS (Netherlands)

    Dekkers, Bas J W|info:eu-repo/dai/nl/326091572; Costa, Maria Cecilia D; Maia, Julio; Bentsink, Leónie|info:eu-repo/dai/nl/241338735; Ligterink, Wilco; Hilhorst, Henk W M

    2015-01-01

    MAIN CONCLUSION: Besides being an important model to study desiccation tolerance, the induction of desiccation tolerance in germinated seeds may also play an ecological role in seedling establishment. Desiccation tolerance (DT) is the ability of certain organisms to survive extreme water losses with

  10. The role of macromolecular stability in desiccation tolerance

    NARCIS (Netherlands)

    Wolkers, W.F.

    1998-01-01

    The work presented in this thesis concerns a study on the molecular interactions that play a role in the macromolecular stability of desiccation-tolerant higher plant organs. Fourier transform infrared microspectroscopy was used as the main experimental technique to assess macromolecular st

  11. Development of a solar desiccant dehumidifier. Second technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Gunderson, M.E.; Hwang, K.C.; Railing, S.M.; Rousseau, J.

    1978-11-10

    Research and development of a solar desiccant dehumidifier featuring a rotary bed of granular silica gel and a rotary regenerator for air conditioning is described. The results of the system optimization studies are presented. The studies involved an extensive investigation of the energy saving potential and economic viability of the solar desiccant dehumidifier in different locations in the United States. Conventional electric vapor compression, and solar absorption and Rankine systems also were investigated for comparison. In general, it was found that the solar desiccant equipment, either by itself or in a hybrid system with an electric vapor compression air conditioner, is economically viable for all three locations considered. Substantial energy savings can be effected as well. Seal tests done at AiResearch to develop practical dynamic air seals are described. Leakage and friction tests were performed on a variety of material combinations and configurations. Dacron felt and silicone rubber were found to give an acceptable combination of leakage, friction, and cost characteristics. As part of the commercialization studies for the desiccant equipment, a questionnaire was sent to residential air conditioning equipment distributors. The results of the questionnaire are presented. The specifications and drawings for the 1.5-ton prototype are included. (WHK)

  12. Simple Model of Shape Evolution of Desiccated Colloidal Sessile Drop

    OpenAIRE

    Tarasevich, Yu. Yu.; Vodolazskaya, I. V.; Isakova, O. P.

    2011-01-01

    We propose simple model of colloidal sessile drop desiccation. The model describes correctly both evolution of the phase boundary between sol and gel inside such a drop and the final shape of the dried film (deposit). The model is based on mass conservation and natural assumption that deposit (gel phase) prevents flows and evaporation.

  13. Antioxidant defense during desiccation of the resurrection plant Haberlea rhodopensis.

    Science.gov (United States)

    Georgieva, Katya; Dagnon, Soleya; Gesheva, Emiliya; Bojilov, Dimitar; Mihailova, Gergana; Doncheva, Snezhana

    2017-05-01

    Maintaining a strong antioxidant system is essential for preventing drought-induced oxidative stress. Thus, in the present study we investigated the role of some non-enzymic and enzymic antioxidants in desiccation tolerance of Haberlea rhodopensis. The effects of high light upon desiccation on antioxidant capacity was estimated by comparing the response of shade and sun plants. The significant enhancement of the antioxidant capacity at 8% RWC corresponded to an enormous increase in flavonoid content. The important role of ascorbate-glutathione cycle in overcoming oxidative stress during drying of H. rhodopensis was established. The antioxidant capacity increased upon dehydration of both shade and sun plants but some differences in non-enzymatic and enzymatic antioxidants were observed. Investigations on the role of polyphenols in desiccation tolerance are scarce. In the present study the polyphenol profiles (fingerprints) of the resurrection plant Haberlea rhodopensis, including all components of the complex are obtained for the first time. It was clarified that the polyphenol complex of H. rhodopensis includes only two types of glycosides - phenylethanoid glucosides and hispidulin 8-C-glucosides. Upon desiccation the polyphenol content increase and the main role of phenylethanoid glucosides in the protection of H. rhodopensis was revealed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. The role of macromolecular stability in desiccation tolerance.

    NARCIS (Netherlands)

    Wolkers, W.

    1998-01-01

    The work presented in this thesis concerns a study on the molecular interactions that play a role in the macromolecular stability of desiccation-tolerant higher plant organs. Fourier transform infrared microspectroscopy was used as the main experimental technique to assess macromolecular structures

  15. Soil desiccation cracks as a suction–contraction process

    KAUST Repository

    Cordero, J. A.

    2017-10-05

    Recent macro- and particle-scale advances in unsaturated soil behaviour have led to an enhanced understanding of the effects of moisture changes on soil response. This research examines desiccation cracks as a suction–contraction-coupled process using sand–clay mixtures. Suction–moisture measurements highlight the role of fines on suction potential even at low fines content; on the other hand, oedometer tests exhibit a marked transition from sand-controlled to clay-controlled compressibility. Time-lapse photography of desiccation tests in flat trays show the onset of crack initiation and the subsequent evolution in horizontal strains; concurrent gravimetric water content measurements relate crack nucleation to suction at air entry. Suction and compressibility increase with the soil-specific surface and have a compounded effect on desiccation-driven lateral contraction. Both layer thickness and its lateral extent affect the development of desiccation cracks. The recently proposed revised soil classification system properly anticipates the transitions in compressibility and capillary phenomena observed in this study (between 15 and 35% fines content).

  16. IAQ control in nursing homes using integrated desiccant technology

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B.M. [Engelhard ICC, Philadelphia, PA (United States); Miyauchi, Hikoo [Nichimen Engine Sales, Tokyo (Japan)

    1996-07-01

    The demographics of the Japanese population indicate a need to provide a greater degree of elderly care, largely due to the long life expectancy of the Japanese people. It is explained that in response to this need Japan has embarked upon a dramatic programme to construct 5000 facilities by the year 2001. Air conditioning requirements of the elderly are somewhat different than those for other facilities and present an opportunity for the use of specialized equipment that will satisfy those requirements. A new facility care unit for the elderly has been built in Nagano, Japan and will start operation at the end of 1996. A new desiccant air conditioning unit designed for this facility is described. It combines humidity control of a desiccant sub-system and the thermal control of a conventional chiller in a single air-handling system. Regeneration of the desiccant is realized by a propane boiler at 88C, which also supplies heat in winter. It is emphasized that this new and exciting approach to air conditioning will change the expectations of society about indoor air quality and comfort control, which have been governed by the use of conventional equipment only, together with its inherent limitations. Other potential applications of desiccant technology are in supermarkets, industrial spaces, Pachinko halls, etc.

  17. Cryopreservation of Citrus aurantifolia seeds and embryonic axes using a desiccation protocol.

    Science.gov (United States)

    Cho, Eun Gi; Noor, Normah M; Kim, Haeng Hoon; Rao, V Ramanatha; Engelmann, Florent

    2002-01-01

    The desiccation and freezing tolerance of seeds, with and without testas, and embryonic axes of Citrus aurantifolia were investigated. Seeds were desiccated with silica gel, under the laminar air flow cabinet or by placing them on a laboratory bench. Whatever the desiccation method employed, survival before and after cryopreservation was higher for seeds without testas. When freezing intact seeds, the highest survival percentage (41.3 %) was achieved after desiccation to 7.3 % moisture content (fresh weight basis) on the laboratory bench. Survival of seeds cryopreserved without testas could reach up to 85 % after desiccation under the laminar air flow cabinet or on the laboratory bench, corresponding to moisture contents of 7.1 and 4.5 %, respectively. After desiccation with silica gel, survival reached a maximum of 60.0 %, for a seed moisture content of 3.3 %. Survival of control embryonic axes was high (80-100 %) whatever the sucrose concentration in the preculture medium and the duration of the desiccation period. After cryopreservation, no survival was noted with embryonic axes, which had not been precultured nor desiccated. Survival of non-desiccated embryonic axes after cryopreservation increased progressively in line with increasing sucrose concentrations in the preculture medium, from 7.5 % with 0.1 M sucrose to 77.5 % with 0.7 M sucrose. Survival of desiccated and cryopreserved embryos was always high, whatever the preculture treatment and desiccation period, ranging from 55.8 % to 92.5 %.

  18. Implications of the lack of desiccation tolerance in recalcitrant seeds

    Directory of Open Access Journals (Sweden)

    Patricia eBerjak

    2013-11-01

    Full Text Available A suite of interacting processes and mechanisms enables tolerance of desiccation and storage (conservation of orthodox seeds in the dry state. While this is a long-term option under optimised conditions, dry orthodox seeds are not immortal, with life spans having been characterised as short, intermediate and long. Factors facilitating desiccation tolerance are metabolic ‘switch-off’ and intracellular dedifferentiation. Recalcitrant seeds lack these mechanisms, contributing significantly to their desiccation sensitivity.Consequently, recalcitrant seeds, which are shed at high water contents, can be stored only in the short-term, under conditions not allowing dehydration. The periods of such hydrated storage are constrained by germination that occurs without the need for extraneous water, and the proliferation of seed-associated fungi. Cryopreservation is viewed as the only option for long-term conservation of the germplasm of recalcitrant-seeded species. This is not easily achieved, as each of the necessary procedures imposes oxidative damage. Intact recalcitrant seeds cannot be cryopreserved, the common practice being to use excised embryos or embryonic axes as explants. Dehydration is a necessary procedure prior to exposure to cryogenic temperatures, but this is associated with metabolism-linked injury mediated by uncontrolled ROS generation and failing anti-oxidant systems. While the extent to which this occurs can be curtailed by maximising drying rate (flash drying it cannot be completely obviated. Explant cooling for, and rewarming after, cryostorage must necessarily be rapid, to avoid ice crystallisation. The ramifications of desiccation sensitivity are discussed, as are problems involved in cryostorage, particularly those accompanying dehydration and damage consequent upon ice crystallisation. While desiccation sensitivity is a ‘fact’ of seed recalcitrance, resolutions of the difficulties involved germplasm conservation are

  19. Proteomics of desiccation tolerance during development and germination of maize embryos

    DEFF Research Database (Denmark)

    Huang, Hui; Møller, Ian Max; Song, Song-Quan

    2012-01-01

    Maize seeds were used to identify the key embryo proteins involved in desiccation tolerance during development and germination. Immature maize embryos (28N) during development and mature embryos imbibed for 72 h (72HN) are desiccation sensitive. Mature maize embryos (52N) during development...... are desiccation tolerant. Thiobarbituric acid reactive substance and hydrogen peroxide contents decreased and increased with acquisition and loss of desiccation tolerance, respectively. A total of 111 protein spots changed significantly (1.5 fold increase/decrease) in desiccation-tolerant and -sensitive embryos...... protein, major allergen Bet v 1.01C and proteasome subunit alpha type 1, accumulated during embryo maturation, decreased during germination and increased in desiccation-tolerant embryos during desiccation. Two proteins, Rhd6-like 2 and low-molecular-weight heat shock protein precursor, showed the inverse...

  20. Cooperative Purchasing Reduces Costs.

    Science.gov (United States)

    Kula, Edwin J.

    1981-01-01

    Several suburban Chicago (Illinois) school districts are members of the South Suburban School Purchasing Cooperative, which serves as a conduit for volume purchases of educational supplies. (Author/MLF)

  1. Deep Vadose Zone Treatability Test for the Hanford Central Plateau. Interim Post-Desiccation Monitoring Results, Fiscal Year 2015

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Strickland, Christopher E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oostrom, Martinus [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Christian D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tartakovsky, Guzel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clayton, Ray E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chronister, Glen B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-01

    A field test of desiccation is being conducted as an element of the Deep Vadose Zone Treatability Test Program. The active desiccation portion of the test has been completed. Monitoring data have been collected at the field test site during the post-desiccation period and are reported herein. This is an interim data summary report that includes about 4 years of post-desiccation monitoring data. The DOE field test plan proscribes a total of 5 years of post-desiccation monitoring.

  2. Experimental heat and mass transfer of the separated and coupled rotating desiccant wheel and heat wheel

    Energy Technology Data Exchange (ETDEWEB)

    Enteria, Napoleon; Yoshino, Hiroshi; Mochida, Akashi; Takaki, Rie [Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Satake, Akira [Technical Research Institute, Maeda Corporation, Tokyo 179-8914 (Japan); Yoshie, Ryuichiro [Faculty of Engineering, Tokyo Polytechnic University, Atsugi 243-0297 (Japan); Mitamura, Tiruaki [Faculty of Engineering, Ashikaga Institute of Technology, Ashikaga 326-8558 (Japan); Baba, Seizo [Earth Clean Tohoku Co., Ltd., Sendai 984-0038 (Japan)

    2010-07-15

    The experimental evaluation of the separated and coupled rotating desiccant wheel and heat wheel is reported. The study aims to investigate the performance of the desiccant wheel and of the heat wheel both when operated separately and jointly. The performance evaluation of the desiccant wheel is based on its moisture removal capacity (MRC), moisture removal regeneration (MRR), and moisture mass balance (MMB). In addition, the study used the total energy balance (TEB), sensible coefficient of performance (COP{sub Sensible}), latent coefficient of performance (COP{sub Latent}) and, total coefficient of performance (COP{sub Total}). The performance of the heat wheel is based on its effectiveness. The COP{sub Sensible}, COP{sub Latent} and, COP{sub Total} are used in the performance evaluation of the coupled desiccant wheel and heat wheel. The general results of the study show that the MRC, MRR and MMB coupled with the TEB, COP{sub Latent}, COP{sub Sensible} and COP{sub Total} predict adequately the performance of the desiccant wheel. In addition, the coupled operation of the desiccant wheel and heat wheel, contributed to the reduction of the external thermal energy requirement for the regeneration of the desiccant wheel. This study can be applied in other researches seeking evaluation of the desiccant wheel, heat wheel, and their combined operation. Moreover, the data presented here are significant for the desiccant wheel benchmarking and for evaluation of the desiccant wheel models. (author)

  3. Proteomics of desiccation tolerance during development and germination of maize embryos.

    Science.gov (United States)

    Huang, Hui; Møller, Ian Max; Song, Song-Quan

    2012-02-02

    Maize seeds were used to identify the key embryo proteins involved in desiccation tolerance during development and germination. Immature maize embryos (28N) during development and mature embryos imbibed for 72 h (72HN) are desiccation sensitive. Mature maize embryos (52N) during development are desiccation tolerant. Thiobarbituric acid reactive substance and hydrogen peroxide contents decreased and increased with acquisition and loss of desiccation tolerance, respectively. A total of 111 protein spots changed significantly (1.5 fold increase/decrease) in desiccation-tolerant and -sensitive embryos before (28N, 52N and 72HN) and after (28D, 52D and 72HD) dehydration. Nine pre-dominantly proteins, 17.4 kDa Class I heat shock protein 3, late embryogenesis abundant protein EMB564, outer membrane protein, globulin 2, TPA:putative cystatin, NBS-LRR resistance-like protein RGC456, stress responsive protein, major allergen Bet v 1.01C and proteasome subunit alpha type 1, accumulated during embryo maturation, decreased during germination and increased in desiccation-tolerant embryos during desiccation. Two proteins, Rhd6-like 2 and low-molecular-weight heat shock protein precursor, showed the inverse pattern. We infer that these eleven proteins are involved in seed desiccation tolerance. We conclude that desiccation-tolerant embryos make more economical use of their resources to accumulate protective molecules and antioxidant systems to deal with maturation drying and desiccation treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Experimental analysis and regression prediction of desiccant wheel behavior in high temperature heat pump and desiccant wheel air-conditioning system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Sun, Yuexia

    2014-01-01

    The objectives of this study are to evaluate the performance of desiccant wheel (DW) in the running system and obtain the useful data for practical application. The combined influences of multiple variables on the performance of desiccant wheel are investigated based on evaluating the indexes of ...

  5. Transcriptomes of the desiccation-tolerant resurrection plant Craterostigma plantagineum.

    Science.gov (United States)

    Rodriguez, Maria C Suarez; Edsgärd, Daniel; Hussain, Syed S; Alquezar, David; Rasmussen, Morten; Gilbert, Thomas; Nielsen, Bjørn H; Bartels, Dorothea; Mundy, John

    2010-07-01

    Studies of the resurrection plant Craterostigma plantagineum have revealed some of the mechanisms which these desiccation-tolerant plants use to survive environments with extreme dehydration and restricted seasonal water. Most resurrection plants are polyploid with large genomes, which has hindered efforts to obtain whole genome sequences and perform mutational analysis. However, the application of deep sequencing technologies to transcriptomics now permits large-scale analyses of gene expression patterns despite the lack of a reference genome. Here we use pyro-sequencing to characterize the transcriptomes of C. plantagineum leaves at four stages of dehydration and rehydration. This reveals that genes involved in several pathways, such as those required for vitamin K and thiamin biosynthesis, are tightly regulated at the level of gene expression. Our analysis also provides a comprehensive picture of the array of cellular responses controlled by gene expression that allow resurrection plants to survive desiccation.

  6. Self-desiccation mechanism of high-performance concrete

    Institute of Scientific and Technical Information of China (English)

    杨全兵; 张树青

    2004-01-01

    Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relativehumidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely.The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (Tr/Tte ratio).

  7. Experimental Research on Liquid Desiccant Air-conditioning Unit

    Directory of Open Access Journals (Sweden)

    Feng Yueyan

    2016-01-01

    Full Text Available An experimental device of liquid desiccant air conditioning system is established. Experimental tests about the temperature difference between diluted solution of inlet and concentrated solution of exit in the solution heat exchanger are carried on, and CaCl2 solution is used as desiccant. Results show that: the fluctuation range in the day at different times of the basic difference of the measured temperature does not exceed 1°C, and the temperature difference between diluted solution of inlet and concentrated solution of exit in solution heat exchanger appears the minimum value of 2.7°C and the maximum value of 10.2°C. Also, the percent of the additional load and the ratio of additional load to the evaporator load are analyzed.

  8. Chemical desiccation for early harvest in soybean cultivars

    Directory of Open Access Journals (Sweden)

    Tamara Pereira

    2015-08-01

    Full Text Available The use of desiccants is an alternative to anticipate the soybean harvest and keep the physiological quality of seed. The objective of this work was to assess the production performance and germination seeds in response to differents stages and desiccation chemicals products to early harvest of soybean cultivars. The experiment was conducted in Campos Novos, in two harvests, it was used a randomized complete block design disposed in split-split-plots. Two phenological stages of application (stage R7.1 and R7.3 were tested in the main plot. Five soybean cultivars (NA 5909 RG, CD 2585 RR, BMX Turbo RR, SYN 1059 RR and BENSO 1RR were evaluated in the subplots, and three desiccants ammonium glufosinate, paraquat, carfentrazone-ethyl in the 2011/12 season and one control (without the desiccant application were evaluated in the sub-subplots. In the 2012/13 season the carfentrazone-ethyl was substituted by diquat. It were evaluated the number of the days in the early harvest, yield, number of pods per plant, number of seeds per pod, mass of 100 seeds and germination percentage. The chemical dessecation with the use of glufosinate ammonium and paraquat applied in R7.1 stage allowed to anticipate the harvest in six days (2011/12 and provided maintenance germination percentage (90% and 92% compared to control (76%. The dessecation didn’t influence negatively on seeds productivity, but reduced the mass of seeds in the two growing seasons, and early harvest was dependent of pre-harvest rain absence, with this preamble. The use of dessicants is a possibility of early harvest in production field of soybean seeds.

  9. Desiccation effects on germination and vigor of King palm seeds

    OpenAIRE

    Martins Cibele C.; Bovi Marilene L. A.; Nakagawa João

    2003-01-01

    The desiccation tolerance of Archontophoenix alexandrae (Wendl. & Drude) seeds was determined and the most sensitive vigor test for assessing seed deterioration of this species was identified. Mature fruits were harvested in the palm collection of the Instituto Agronomico in Campinas, Brazil. Depulped fruits were transported in impermeable packages to the Faculdade de Agronomia in Botucatu, where the seeds were dried. As the seed moisture decreased, germination, seedling length, electrica...

  10. Reversible Inactivation and Desiccation Tolerance of Silicified Viruses

    Energy Technology Data Exchange (ETDEWEB)

    Laidler, James J.; Shugart, Jessica A.; Cady, Sherry L.; Bahjat, Keith S.; Stedman, Kenneth M.

    2013-11-19

    Long-distance host-independent virus dispersal is poorly understood, especially for viruses found in isolated ecosystems. To demonstrate a possible dispersal mechanism, we show that bacteriophage T4, archaeal virus SSV-K and Vaccinia are reversibly inactivated by mineralization in silica under conditions similar to volcanic hot springs. By contrast, bacteriophage PRD1 is not silicified. Moreover silicification provides viruses with remarkable desiccation resistance, which could allow extensive aerial dispersal.

  11. Reversible inactivation and desiccation tolerance of silicified viruses.

    Science.gov (United States)

    Laidler, James R; Shugart, Jessica A; Cady, Sherry L; Bahjat, Keith S; Stedman, Kenneth M

    2013-12-01

    Long-distance host-independent virus dispersal is poorly understood, especially for viruses found in isolated ecosystems. To demonstrate a possible dispersal mechanism, we show that bacteriophage T4, archaeal virus Sulfolobus spindle-shaped virus Kamchatka, and vaccinia virus are reversibly inactivated by mineralization in silica under conditions similar to volcanic hot springs. In contrast, bacteriophage PRD1 is not silicified. Moreover, silicification provides viruses with remarkable desiccation resistance, which could allow extensive aerial dispersal.

  12. Development and Analysis of Desiccant Enhanced Evaporative Air Conditioner Prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.; Woods, J.; Judkoff, R.

    2012-04-01

    This report documents the design of a desiccant enhanced evaporative air conditioner (DEVAP AC) prototype and the testing to prove its performance. Previous numerical modeling and building energy simulations indicate a DEVAP AC can save significant energy compared to a conventional vapor compression AC (Kozubal et al. 2011). The purposes of this research were to build DEVAP prototypes, test them to validate the numerical model, and identify potential commercialization barriers.

  13. Gas Engine-Driven Heat Pump with Desiccant Dehumidification

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Bo [ORNL; Abu-Heiba, Ahmad [ORNL

    2017-01-01

    About 40% of total U.S. energy consumption was consumed in residential and commercial buildings. Improved air-conditioning technology has by far the greatest potential impact on the electric industry compared to any other technology that uses electricity. This paper describes the development of an innovative natural gas, propane, LNG or bio-gas IC engine-driven heat pump (GHP) with desiccant dehumidification (GHP/DD). This integrated system has higher overall efficiencies than conventional equipment for space cooling, addresses both new and existing commercial buildings, and more effectively controls humidity in humid areas. Waste heat is recovered from the GHP to provide energy for regenerating the desiccant wheel and to augment heating capacity and efficiency. By combining the two technologies, an overall source COP of greater that 1.5 (hot, humid case) can be achieved by utilizing waste heat from the engine to reduce the overall energy required to regenerate the desiccant. Moreover, system modeling results show that the sensible heat ratio (SHR- sensible heat ratio) can be lowered to less 60% in a dedicated outdoor air system application with hot, humid cases.

  14. Evaluation of desiccated and deformed diaspores from natural building materials

    Directory of Open Access Journals (Sweden)

    Tamás Henn

    2015-03-01

    Full Text Available With the increasing sophistication of paleoethnobotanical methods, it is now possible to reconstruct new aspects of the day-to-day life of past peoples, and, ultimately, gain information about their cultivated plants, land-use practices, architecture, diet, and trade. Reliable identification of plant remains, however, remains essential to the study of paleoethnobotany, and there is still much to learn about precise identification. This paper describes and evaluates the most frequent types of deformed desiccated diaspores revealed from adobe bricks used in buildings in Southwestern Hungary that were built primarily between 1850 and 1950. A total of 24,634 diaspores were recovered from 333.05 kg adobe samples. These seeds and fruits belong to 303 taxa, and the majority were arable and ruderal weed species. A total of 98.97% of the diaspores were identified to species. In other cases, identification was possible only to genus or family (0.93% and 0.10% of diaspores, respectively. Difficulties in identification were caused mainly by morphological changes in the size, shape, color, and surface features of diaspores. Most diaspores were darker in color and significantly smaller than fresh or recently desiccated seeds and fruits. Surface features were often absent or fragmented. The most problematic seeds to identify were those of Centaurea cyanus, Consolida regalis, Scleranthus annuus and Daucus carota ssp. carota, which are discussed in detail. Our research aids archaeobotanists in the identification of desiccated and deformed diaspores.

  15. Comparative metabolic profiling between desiccation-sensitive and desiccation-tolerant species of Selaginella reveals insights into the resurrection trait.

    Science.gov (United States)

    Yobi, Abou; Wone, Bernard W M; Xu, Wenxin; Alexander, Danny C; Guo, Lining; Ryals, John A; Oliver, Melvin J; Cushman, John C

    2012-12-01

    Spike mosses (Selaginellaceae) represent an ancient lineage of vascular plants in which some species have evolved desiccation tolerance (DT). A sister-group contrast to reveal the metabolic basis of DT was conducted between a desiccation-tolerant species, Selaginella lepidophylla, and a desiccation-sensitive species, Selaginella moellendorffii, at 100% relative water content (RWC) and 50% RWC using non-biased, global metabolomics profiling technology, based on GC/MS and UHLC/MS/MS(2) platforms. A total of 301 metabolites, including 170 named (56.5%) and 131 (43.5%) unnamed compounds, were characterized across both species. S.  lepidophylla retained significantly higher abundances of sucrose, mono- and polysaccharides, and sugar alcohols than did S. moellendorffii. Aromatic amino acids, the well-known osmoprotectant betaine and flavonoids were also more abundant in S. lepidophylla. Notably, levels of γ-glutamyl amino acid, linked with glutathione metabolism in the detoxification of reactive oxygen species, and with possible nitrogen remobilization following rehydration, were markedly higher in S. lepidophylla. Markers for lipoxygenase activity were also greater in S. lepidophylla, especially at 50% RWC. S. moellendorffii contained more than twice the number of unnamed compounds, with only a slightly greater abundance than in S. lepidophylla. In contrast, S. lepidophylla contained 14 unnamed compounds of fivefold or greater abundance than in S. moellendorffii, suggesting that these compounds might play critical roles in DT. Overall, S. lepidophylla appears poised to tolerate desiccation in a constitutive manner using a wide range of metabolites with some inducible components, whereas S. moellendorffii mounts only limited metabolic responses to dehydration stress.

  16. Salinity effects on the dynamics and patterns of desiccation cracks

    Science.gov (United States)

    Shokri, N.; Zhou, P.

    2012-12-01

    Cracking arising from desiccation is a ubiquitous phenomenon encountered in various industrial and geo-environmental applications including drying of clayey soil, cement, ceramics, gels, and many more colloidal suspensions. Presence of cracks in muddy sediments modifies the characteristics of the medium such as pore structure, porosity, and permeability which in turn influence various flow and transport processes. Thus it remains a topic of great interest in many disciplines to describe the dynamics of desiccation cracking under various boundary conditions. To this end, we conducted a comprehensive study to investigate effects of NaCl concentrations on cracking dynamics and patterns during desiccation of Bentonite. Mixtures of Bentonite and NaCl solutions were prepared with NaCl concentration varying from 2 to 10 percent in 0.5 percent increment (totally 17 configurations). The slurry was placed in a Petri dish mounted on a digital balance to record the evaporation dynamics. The atmospheric conditions were kept constant using an environmental chamber. An automatic camera was used to record the dynamics of macro-cracks (mm scale) at the surface of desiccating clay each minute. The obtained results illustrate the significant effects of salt concentration on the initiation, propagation, morphology and general dynamics of macro-cracks. We found that higher salt concentrations results in larger macro cracks' lengths attributed to the effects of NaCl on compressing the electric double layer of particles at increasing electrolyte concentrations which reduce considerably the repulsive forces among the particles and causing instability of the slurry and flocculation of the colloidal particles. Rheological measurements by means of a stress controlled rheometer revealed that the yield stress of the slurry decreases as NaCl concentration increases which may indicate aggregation of larger units in the slurry as a result of flocculation causing larger cracks' lengths due to

  17. Preparation of perlite-based magnesium perchlorate desiccant with colour indicator.

    Science.gov (United States)

    Wu, L; He, H

    1994-05-01

    A new desiccant consisting of magnesium perchlorate, expanded perlite and metal chelate was prepared. The performance tests show that the desiccant is superior to magnesium perchlorate desiccant in dehydration efficiency, absorption capacity for water, flow resistance, color indicator and regeneration. It can reduce the amount of water in gases to approximately 0.7 ppm(v/v). Its applications in gas analysis and purification were investigated.

  18. Effect of Nitrogen Starvation on Desiccation Tolerance of Arctic Microcoleus Strains (Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Daria eTashyreva

    2015-04-01

    Full Text Available Although desiccation tolerance of Microcoleus species is a well-known phenomenon, there is very little information about their limits of desiccation tolerance in terms of cellular water content, the survival rate of their cells, and the environmental factors inducing their resistance to drying. We have discovered that three Microcoleus strains, isolated from terrestrial habitats of the High Arctic, survived extensive dehydration (to 0.23 g water g-1 dry mass, but did not tolerate complete desiccation (to 0.03 g water g-1 dry mass regardless of pre-desiccation treatments. However, these treatments were critical for the survival of incomplete desiccation: cultures grown under optimal conditions failed to survive even incomplete desiccation; a low temperature enabled only 0 to 15% of cells to survive, while 39.8 to 65.9% of cells remained alive and intact after nitrogen starvation. Unlike Nostoc, which co-exists with Microcoleus in Arctic terrestrial habitats, Microcoleus strains are not truly anhydrobiotic and do not possess constitutive desiccation tolerance. Instead, it seems that the survival strategy of Microcoleus in periodically dry habitats involves avoidance of complete desiccation, but tolerance to milder desiccation stress, which is induced by suboptimal conditions (e.g. nitrogen starvation.

  19. Triple-bore hollow fiber membrane contactor for liquid desiccant based air dehumidification

    KAUST Repository

    Bettahalli, N.M. Srivatsa

    2016-04-26

    Dehumidification is responsible for a large part of the energy consumption in cooling systems in high humidity environments worldwide. Improving efficiency is therefore essential. Liquid desiccants offer a promising solution for dehumidification, as desired levels of humidity removal could be easily regulated. The use of membrane contactors in combination with liquid desiccant is attractive for dehumidification because they prevent direct contact between the humid air and the desiccant, removing both the potential for desiccant carryover to the air and the potential for contamination of the liquid desiccant by dust and other airborne materials, as well as minimizing corrosion. However, the expected additional mass transport barrier of the membrane surface can lower the expected desiccation rate per unit of desiccant surface area. In this context, hollow fiber membranes present an attractive option for membrane liquid desiccant contactors because of their high surface area per unit volume. We demonstrate in this work the performance of polyvinylidene fluoride (PVDF) based triple-bore hollow fiber membranes as liquid desiccant contactors, which are permeable to water vapor but impermeable to liquid water, for dehumidification of hot and humid air.

  20. Somatic embryogenesis and peroxidase activity of desiccation toler-ant mature somatic embryos of loblolly pine

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    White, translucent, glossy mucilaginous callus was initiated from the mature zygotic embryos explants on callus induction medium with 2,4-D, BA, and kinetin in the 3-9th week of culture. This type of callus induction occurred at a lower frequency with either a-naphthaleneacetic acid (NAA) or IBA (both 8 mg/L). White, translucent, glossy mucilaginous callus was embryogenic and mainly developed from the cotyledons of the mature zygotic embryo. Somatic embryos were formed on differentiation medium. Desiccation tolerance can be induced by culturing somatic embryos of loblolly pine (Pinus taeda L.) on medium supplemented with 50 mm abscisic acid (ABA) and/or 8.5% polyethylene glycol (PEG6000). Scanning electron microscopy of desiccated somatic embryos showed that the size and external morphology of the desiccation tolerant somatic embryos recov-ered to the pre-desiccation state within 24-36 h, whereas the sensitive somatic embryos did not recover and remained shriveled, after the desiccated somatic embryos had been rehydrated. Peroxidase activity of desiccated somatic embryos increased shar-ply after 3 days of desiccation treatment, and desiccation tolerant somatic embryos had higher peroxidase activity compared to sensitive somatic embryos. Higher peroxidase activity of desiccation tolerant somatic embryos was possibly advantage of cata-lyzing the reduction of H2O2 which was produced by drought stress, and protecting somatic embryos from oxidative damage.

  1. Effect of nitrogen starvation on desiccation tolerance of Arctic Microcoleus strains (cyanobacteria).

    Science.gov (United States)

    Tashyreva, Daria; Elster, Josef

    2015-01-01

    Although desiccation tolerance of Microcoleus species is a well-known phenomenon, there is very little information about their limits of desiccation tolerance in terms of cellular water content, the survival rate of their cells, and the environmental factors inducing their resistance to drying. We have discovered that three Microcoleus strains, isolated from terrestrial habitats of the High Arctic, survived extensive dehydration (to 0.23 g water g(-1) dry mass), but did not tolerate complete desiccation (to 0.03 g water g(-1) dry mass) regardless of pre-desiccation treatments. However, these treatments were critical for the survival of incomplete desiccation: cultures grown under optimal conditions failed to survive even incomplete desiccation; a low temperature enabled only 0-15% of cells to survive, while 39.8-65.9% of cells remained alive and intact after nitrogen starvation. Unlike Nostoc, which co-exists with Microcoleus in Arctic terrestrial habitats, Microcoleus strains are not truly anhydrobiotic and do not possess constitutive desiccation tolerance. Instead, it seems that the survival strategy of Microcoleus in periodically dry habitats involves avoidance of complete desiccation, but tolerance to milder desiccation stress, which is induced by suboptimal conditions (e.g., nitrogen starvation).

  2. Trehalose transporter from African chironomid larvae improves desiccation tolerance of Chinese hamster ovary cells.

    Science.gov (United States)

    Chakraborty, Nilay; Menze, Michael A; Elmoazzen, Heidi; Vu, Halong; Yarmush, Martin L; Hand, Steven C; Toner, Mehmet

    2012-04-01

    Dry preservation has been explored as an energy-efficient alternative to cryopreservation, but the high sensitivity of mammalian cells to desiccation stress has been one of the major hurdles in storing cells in the desiccated state. An important strategy to reduce desiccation sensitivity involves use of the disaccharide trehalose. Trehalose is known to improve desiccation tolerance in mammalian cells when present on both sides of the cell membrane. Because trehalose is membrane impermeant the development of desiccation strategies involving this promising sugar is hindered. We explored the potential of using a high-capacity trehalose transporter (TRET1) from the African chironomid Polypedilum vanderplanki[21] to introduce trehalose into the cytoplasm of mammalian cells and thereby increase desiccation tolerance. When Chinese hamster ovary cells (CHO) were stably transfected with TRET1 (CHO-TRET1 cells) and incubated with 0.4M trehalose for 4h at 37°C, a sevenfold increase in trehalose uptake was observed compared to the wild-type CHO cells. Following trehalose loading, desiccation tolerance was investigated by evaporative drying of cells at 14% relative humidity. After desiccation to 2.60g of water per gram dry weight, a 170% increase in viability and a 400% increase in growth (after 7days) was observed for CHO-TRET1 relative to control CHO cells. Our results demonstrate the beneficial effect of intracellular trehalose for imparting tolerance to partial desiccation. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. A footprint of desiccation tolerance in the genome of Xerophyta viscosa.

    Science.gov (United States)

    Costa, Maria-Cecília D; Artur, Mariana A S; Maia, Julio; Jonkheer, Eef; Derks, Martijn F L; Nijveen, Harm; Williams, Brett; Mundree, Sagadevan G; Jiménez-Gómez, José M; Hesselink, Thamara; Schijlen, Elio G W M; Ligterink, Wilco; Oliver, Melvin J; Farrant, Jill M; Hilhorst, Henk W M

    2017-03-27

    Desiccation tolerance is common in seeds and various other organisms, but only a few angiosperm species possess vegetative desiccation tolerance. These 'resurrection species' may serve as ideal models for the ultimate design of crops with enhanced drought tolerance. To understand the molecular and genetic mechanisms enabling vegetative desiccation tolerance, we produced a high-quality whole-genome sequence for the resurrection plant Xerophyta viscosa and assessed transcriptome changes during its dehydration. Data revealed induction of transcripts typically associated with desiccation tolerance in seeds and involvement of orthologues of ABI3 and ABI5, both key regulators of seed maturation. Dehydration resulted in both increased, but predominantly reduced, transcript abundance of genomic 'clusters of desiccation-associated genes' (CoDAGs), reflecting the cessation of growth that allows for the expression of desiccation tolerance. Vegetative desiccation tolerance in X. viscosa was found to be uncoupled from drought-induced senescence. We provide strong support for the hypothesis that vegetative desiccation tolerance arose by redirection of genetic information from desiccation-tolerant seeds.

  4. Investigation on regeneration and energy storage characteristics of a solar liquid desiccant air-conditioning system

    Institute of Scientific and Technical Information of China (English)

    SHI Mingheng; DU Bin; ZHAO Yun

    2007-01-01

    Solar liquid desiccant air-conditioner is a new air-conditioning system in which liquid desiccant can be regenerated by solar energy and energy can be stored in the form of chemical energy in the liquid desiccant.In this paper regeneration and energy storage characteristics were studied theoretically and experimentally.Two criterion equations for heat and mass transfer in the regeneration process were obtained.The main factors that influence the regeneration process were analyzed.A principal solar liquid desiccant air-conditioning system under energy storage operating mode is proposed.

  5. An intervention to improve care and reduce costs for high-risk patients with frequent hospital admissions: a pilot study

    Directory of Open Access Journals (Sweden)

    Kostrowski Shannon

    2011-10-01

    Full Text Available Abstract Background A small percentage of high-risk patients accounts for a large proportion of Medicaid spending in the United States, which has become an urgent policy issue. Our objective was to pilot a novel patient-centered intervention for high-risk patients with frequent hospital admissions to determine its potential to improve care and reduce costs. Methods Community and hospital-based care management and coordination intervention with pre-post analysis of health care utilization. We enrolled Medicaid fee-for-service patients aged 18-64 who were admitted to an urban public hospital and identified as being at high risk for hospital readmission by a validated predictive algorithm. Enrolled patients were evaluated using qualitative and quantitative interview techniques to identify needs such as transportation to/advocacy during medical appointments, mental health/substance use treatment, and home visits. A community housing partner initiated housing applications in-hospital for homeless patients. Care managers facilitated appropriate discharge plans then worked closely with patients in the community using a harm reduction approach. Results Nineteen patients were enrolled; all were male, 18/19 were substance users, and 17/19 were homeless. Patients had a total of 64 inpatient admissions in the 12 months before the intervention, versus 40 in the following 12 months, a 37.5% reduction. Most patients (73.3% had fewer inpatient admissions in the year after the intervention compared to the prior year. Overall ED visits also decreased after study enrollment, while outpatient clinic visits increased. Yearly study hospital Medicaid reimbursements fell an average of $16,383 per patient. Conclusions A pilot intervention for high-cost patients shows promising results for health services usage. We are currently expanding our model to serve more patients at additional hospitals to see if the pilot's success can be replicated. Trial registration

  6. Desiccation tolerance of iron bacteria biofilms on Mars regolith simulants

    Science.gov (United States)

    Feyh, Nina; Szewzyk, Ulrich

    2010-05-01

    Iron oxidizing bacteria play an important role in the geological redox cycling of iron on earth. The redox change between Fe(II) and Fe(III) can be used for biological energy production [1]. Therefore iron oxidation in the iron rich martian soils may be or may have been microbially mediated. The microbial conversion of iron is considered to be an ancient form of metabolism [2], so it might have evolved on Mars as well. However, to exist in recent martian soils, bacteria must be able to endure dry and cold conditions. Neutrophilic iron oxidizers can be found in various iron rich aquatic environments, where they lead to the precipitation of insoluble ferric hydroxides. Some of these environments fall temporarily dry, what could have led to an adaptation to desiccation by bacteria, existing there. One strategy of iron bacteria to endure drought stress might be the formation of biofilms by excreting Extracellular Polymeric Substances (EPS). The deposition of iron hydroxides could enable them to endure dry conditions as well. For our experiments, neutrophilic iron oxidizing bacteria have been isolated from a creek in Bad Salzhausen/Hesse and temporarily drying out pools in Tierra del Fuego. Strains from aquatic environments in the national park "Unteres Odertal" and from water wells in Berlin/Brandenburg are included in the tests as well. In desiccation experiments, the capability of iron bacteria to tolerate dry conditions are investigated. The aim of our first experiment is the adaptation to dry conditions. Biofilms of 15 strains are grown on ceramic beads in liquid medium containing complexed Fe(II), established biofilms contain Fe(III) precipitates. The cultures are desiccated in a sterile airflow until the weight of the cultures remained constant. After a desiccation period of 9 h up to 7 d, the beads are transferred to fresh liquid medium. Adapted strains are used in further desiccation experiments, where biofilms are grown on two martian regolith simulants. These

  7. Enzymes and Metabolites in Carbohydrate Metabolism of Desiccation Tolerant Plants

    Directory of Open Access Journals (Sweden)

    Qingwei Zhang

    2016-12-01

    Full Text Available Resurrection plants can tolerate extreme water loss. Substantial sugar accumulation is a phenomenon in resurrection plants during dehydration. Sugars have been identified as one important factor contributing to desiccation tolerance. Phylogenetic diversity of resurrection plants reflects the diversity of sugar metabolism in response to dehydration. Sugars, which accumulate during dehydration, have been shown to protect macromolecules and membranes and to scavenge reactive oxygen species. This review focuses on the performance of enzymes participating in sugar metabolism during dehydration stress. The relation between sugar metabolism and other biochemical activities is discussed and open questions as well as potential experimental approaches are proposed.

  8. Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

    NARCIS (Netherlands)

    Gechev, Tsanko S.; Benina, Maria; Obata, Toshihiro; Tohge, Takayuki; Sujeeth, Neerakkal; Minkov, Ivan; Hille, Jacques; Temanni, Mohamed-Ramzi; Marriott, Andrew S.; Bergstrom, Ed; Thomas-Oates, Jane; Antonio, Carla; Mueller-Roeber, Bernd; Schippers, Jos H. M.; Fernie, Alisdair R.; Toneva, Valentina

    2013-01-01

    Haberlea rhodopensis is a resurrection plant with remarkable tolerance to desiccation. Haberlea exposed to drought stress, desiccation, and subsequent rehydration showed no signs of damage or severe oxidative stress compared to untreated control plants. Transcriptome analysis by next-generation sequ

  9. Antioxidant defences in hydrated and desiccated states of the tardigrade Paramacrobiotus richtersi.

    Science.gov (United States)

    Rizzo, Angela M; Negroni, Manuela; Altiero, Tiziana; Montorfano, Gigliola; Corsetto, Paola; Berselli, Patrizia; Berra, Bruno; Guidetti, Roberto; Rebecchi, Lorena

    2010-06-01

    Reactive oxygen species (ROS) are formed in all aerobic organisms, potentially leading to oxidative damage of all biological molecules. A number of defence mechanisms have developed to protect the organism from attack by ROS. Desiccation tolerance is correlated with an increase in the antioxidant potential in several organisms, but the regulation of the antioxidant defence system is complex and its role in desiccation-tolerant organisms is not yet firmly established. To determine if anhydrobiotic tardigrades have an antioxidant defence system, capable of counteracting ROS, we compared the activity of several antioxidant enzymes, the fatty acid composition and Heat shock protein expression in two physiological states (desiccated vs. hydrated) of the tardigrade Paramacrobiotus richtersi. In hydrated tardigrades, superoxide dismutase and catalase show comparable activities, while in desiccated specimens the activity of superoxide dismutase increases. Both glutathione peroxidase and glutathione were induced by desiccation. The percentage of fatty acid composition of polyunsaturated fatty acids and the amount of thiobarbituric acid reactive substances are higher in desiccated animals than in hydrated ones. Lastly, desiccated tardigrades did not differ significantly from the hydrated ones in the relative levels of Hsp70 and Hsp90. These results indicate that the possession of antioxidant metabolism could represent a crucial strategy to avoid damages during desiccation in anhydrobiotic tardigrades.

  10. Applicability of a desiccant dew-point cooling system independent of external water sources

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin Ryhl

    2015-01-01

    The applicability of a technical solution for making desiccant cooling systems independent of external water sources is investigated. Water is produced by condensing the desorbed water vapour in a closed regeneration circuit. Desorbed water recovery is applied to a desiccant dew-point cooling...

  11. 9 CFR 113.29 - Determination of moisture content in desiccated biological products.

    Science.gov (United States)

    2010-01-01

    ... desiccated biological products. 113.29 Section 113.29 Animals and Animal Products ANIMAL AND PLANT HEALTH... biological products. Methods provided in this section must be used when a determination of moisture content in desiccated biological products is prescribed in an applicable Standard Requirement or in the...

  12. The competence to acquire cellular desiccation tolerance is independent of seed morphological development.

    Science.gov (United States)

    Golovina, E A; Hoekstra, F A; Van Aelst, A C

    2001-05-01

    Acquisition of desiccation tolerance and the related changes at the cellular level in wheat (Triticum aestivum cv. Priokskaya) kernels during normal development and premature drying on the ear were studied using a spin probe technique and low temperature scanning electron microscopy. During normal development, the ability of embryos to germinate after rapid drying and rehydration was acquired after completion of morphological development, which is a few days before mass maturity. The acquisition of desiccation tolerance, as assessed by germination, was associated with an upsurge in cytoplasmic viscosity, the onset of accumulation of protein and oil bodies, and the retention of membrane integrity upon dehydration/rehydration. These features were also used to assess cellular desiccation tolerance in the cases when germination could not occur. Slow premature drying was used to decouple the acquisition of cellular desiccation tolerance from morphogenesis. Upon premature drying of kernels on the ears of plants cut at 5 d after anthesis, desiccation-tolerant dwarf embryos were formed that were able to germinate. When plants were cut at earlier stages poorly developed embryos were formed that were unable to germinate, but cellular desiccation tolerance was nevertheless acquired. In such prematurely dried kernels, peripheral meristematic endosperm cells had already passed through similar physiological and ultrastructural changes associated with the acquisition of cellular desiccation tolerance. It is concluded that despite the apparent strong integration in seed development, desiccation tolerance can be acquired by the meristematic cells in the developing embryo and cambial layer of endosperm, independently of morphological development.

  13. Is the loss of desiccation tolerance in orthodox seeds affected by provenance?

    NARCIS (Netherlands)

    Pereira, W.V.S.; Faria, J.M.R.; José, Anderson Cleiton; Tonetti, O.A.O.; Ligterink, W.; Hilhorst, H.W.M.

    2017-01-01

    There is little information about the influence of the environment on seed morphological and physiological characteristics, especially on desiccation tolerance. Therefore, the objective of this study was to investigate the loss of desiccation tolerance in germinating orthodox seeds of the tree sp

  14. Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

    NARCIS (Netherlands)

    Gechev, Tsanko S.; Benina, Maria; Obata, Toshihiro; Tohge, Takayuki; Sujeeth, Neerakkal; Minkov, Ivan; Hille, Jacques; Temanni, Mohamed-Ramzi; Marriott, Andrew S.; Bergstrom, Ed; Thomas-Oates, Jane; Antonio, Carla; Mueller-Roeber, Bernd; Schippers, Jos H. M.; Fernie, Alisdair R.; Toneva, Valentina

    2013-01-01

    Haberlea rhodopensis is a resurrection plant with remarkable tolerance to desiccation. Haberlea exposed to drought stress, desiccation, and subsequent rehydration showed no signs of damage or severe oxidative stress compared to untreated control plants. Transcriptome analysis by next-generation sequ

  15. A footprint of desiccation tolerance in the genome of Xerophyta viscosa

    NARCIS (Netherlands)

    Dias Costa, M.C.; Silva Artur, M.A.; Maia de Oliveira, Julio; Jonkheer, Eef; Derks, M.F.L.; Nijveen, H.; Williams, B.; Mundree, Sagadevan; Jiménez-Gómez, José M.; Hesselink, T.; Schijlen, E.G.W.M.; Ligterink, W.; Oliver, Melvin J.; Farrant, Jill M.; Hilhorst, H.W.M.

    2017-01-01

    Desiccation tolerance is common in seeds and various other organisms, but only a few angiosperm species possess vegetative desiccation tolerance. These ‘resurrection species’ may serve as ideal models for the ultimate design of crops with enhanced drought tolerance. To understand the molecular and g

  16. Rapid desiccation hardening changes the cuticular hydrocarbon profile of Drosophila melanogaster.

    Science.gov (United States)

    Stinziano, Joseph R; Sové, Richard J; Rundle, Howard D; Sinclair, Brent J

    2015-02-01

    The success of insects in terrestrial environments is due in large part to their ability to resist desiccation stress. Since the majority of water is lost across the cuticle, a relatively water-impermeable cuticle is a major component of insect desiccation resistance. Cuticular permeability is affected by the properties and mixing effects of component hydrocarbons, and changes in cuticular hydrocarbons can affect desiccation tolerance. A pre-exposure to a mild desiccation stress increases duration of desiccation survival in adult female Drosophila melanogaster, via a decrease in cuticular permeability. To test whether this acute response to desiccation stress is due to a change in cuticular hydrocarbons, we treated male and female D. melanogaster to a rapid desiccation hardening (RDH) treatment and used gas chromatography to examine the effects on cuticular hydrocarbon composition. RDH led to reduced proportions of unsaturated and methylated hydrocarbons compared to controls in females, but although RDH modified the cuticular hydrocarbon profile in males, there was no coordinated pattern. These data suggest that the phenomenon of RDH leading to reduced cuticular water loss occurs via an acute change in cuticular hydrocarbons that enhances desiccation tolerance in female, but not male, D. melanogaster. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. A sister group metabolomic contrast delineates the biochemical regulation underlying desiccation tolerance in Sporobolus stapfianus

    Science.gov (United States)

    Understanding how plant cells tolerate dehydration is a vital prerequisite for developing strategies for improving drought tolerance. The desiccation tolerant grass Sporobolus stapfianus and the desiccation sensitive S. pyramidalis were used to form a sister-group contrast to reveal adaptive metabo...

  18. Formulation and validation of a two-dimensional steady-state model of desiccant wheels

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin R.;

    2015-01-01

    Desiccant wheels are rotary desiccant dehumidifiers used in air-conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete...

  19. Slow desiccation improves dehydration tolerance and accumulation of compatible osmolytes in earthworm cocoons (Dendrobaena octaedra Savigny)

    DEFF Research Database (Denmark)

    Petersen, Christina R; Holmstrup, Martin; Malmendal, Anders

    2008-01-01

    The earthworm, Dendrobaena octaedra, is a common species in temperate and subarctic regions of the northern hemisphere. The egg capsules ('cocoons') of D. octaedra are deposited in the upper soil layers where they may be exposed to desiccation. Many previous studies on desiccation tolerance in soil...... accumulation, the gradually desiccated cocoons also tolerated a higher degree of water loss, demonstrating that gradually dehydrated D. octaedra cocoons are able to survive loss of approximately 95% of the original water content. Although D. octaedra embryos can probably not be categorized as a truly...... invertebrates have examined acute exposure to harsh desiccating conditions, however, these animals are often more likely to be exposed to a gradually increasing drought stress. In the present study we slowly desiccated D. octaedra cocoons to simulate ecologically realistic drought conditions and the results...

  20. Meta-analysis of geographical clines in desiccation tolerance of Indian drosophilids.

    Science.gov (United States)

    Rajpurohit, Subhash; Nedved, Oldrich; Gibbs, Allen G

    2013-02-01

    Tropical fruit flies (Drosophilidae) differ from temperate drosophilids in several ecophysiological traits, such as desiccation tolerance. Moreover, many species show significant differences in desiccation tolerance across geographical populations. Fruit flies from the tropical and subtropical Indian subcontinent show a clinal pattern for desiccation tolerance which is similar for more than a dozen species studied so far, suggesting adaptation to climatic differences. We performed a meta-analysis to investigate which particular climatic patterns modulate desiccation tolerance in natural populations of drosophilids. Latitude of the sampling site explained most of the variability. Seasonal thermal amplitude (fluctuations in temperature expressed as coefficient of variation) was the strongest climatic factor shaping desiccation tolerance of flies, while factors measuring humidity directly were not important. Implications for survival of flies after future climate change are suggested. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Constitutive components and induced gene expression are involved in the desiccation tolerance of Selaginella tamariscina.

    Science.gov (United States)

    Liu, Mao-Sen; Chien, Ching-Te; Lin, Tsan-Piao

    2008-04-01

    Selaginella tamariscina, one of the most primitive vascular plants, can remain alive in a desiccated state and resurrect when water becomes available. To evaluate the nature of desiccation tolerance in this plant, we compared the composition of soluble sugars and saturation ratios of phospholipids (PLs) between hydrated and desiccated tissues of S. tamariscina using gas chromatography. In this study, differences in gene expression and ABA contents were also analyzed during dehydration. The results revealed that trehalose (at >130 mg g(-1) DW) was the major soluble sugar, and low saturated fatty acid content in PLs (0.31) was maintained in both hydrated and desiccated tissues. In addition, the ABA content of S. tamariscina increased 3-fold, and genes involved in ABA signaling and cellular protection were up-regulated while photosystem-related genes were down-regulated during dehydration. The biochemical and molecular findings suggest that both constitutive and inducible protective molecules contribute to desiccation tolerance of S. tamariscina.

  2. Extended periods of hydration do not elicit dehardening to desiccation tolerance in regeneration trials of the moss Syntrichia caninervis

    Science.gov (United States)

    Dehardening (deacclimation) to water stress is seldom studied in plants, and yet is an integral phase of desiccation tolerance. Most bryophytes are desiccation tolerant (DT), and yet even fully DT species lose a significant portion of their ability to withstand desiccation if dehardened. Shoots of t...

  3. Death by desiccation: Effects of hermetic storage on cowpea bruchids

    KAUST Repository

    Murdock, Larry L.

    2012-04-01

    When cowpea grain is stored in airtight containers, destructive populations of the cowpea bruchid (. Callosobruchus maculatus) don\\'t develop even though the grain put into the store is already infested with sufficient . C. maculatus to destroy the entire store within a few months. The surprising effectiveness of hermetic storage for preserving grain against insect pests has long been linked with the depletion of oxygen in the hermetic container and with the parallel rise in carbon dioxide. With . C. maculatus, low oxygen (hypoxia) leads to cessation of larval feeding activity, whereas elevated levels of carbon dioxide (hypercarbia) have little or no effect on feeding. Cessation of feeding arrests the growth of the insects, which don\\'t mature and don\\'t reproduce. As a result, population growth ceases and damaging infestations don\\'t develop. . C. maculatus eggs, larvae, and pupae subjected to hypoxia eventually die after exposures of various duration. The cause of death is desiccation resulting from an inadequate supply of water. We demonstrate that blocking the supply of oxygen interdicts the main supply of water for . C. maculatus. This leads to inactivity, cessation of population growth, desiccation and eventual death. © 2012 Elsevier Ltd.

  4. The structure of the desiccated Richtersius coronifer (Richters, 1903).

    Science.gov (United States)

    Czerneková, Michaela; Jönsson, K Ingemar; Chajec, Lukasz; Student, Sebastian; Poprawa, Izabela

    2017-05-01

    Tun formation is an essential morphological adaptation for entering the anhydrobiotic state in tardigrades, but its internal structure has rarely been investigated. We present the structure and ultrastructure of organs and cells in desiccated Richtersius coronifer by transmission and scanning electron microscopy, confocal microscopy, and histochemical methods. A 3D reconstruction of the body organization of the tun stage is also presented. The tun formation during anhydrobiosis of tardigrades is a process of anterior-posterior body contraction, which relocates some organs such as the pharyngeal bulb. The cuticle is composed of epicuticle, intracuticle and procuticle; flocculent coat; and trilaminate layer. Moulting does not seem to restrict the tun formation, as evidenced from tardigrade tuns that were in the process of moulting. The storage cells of desiccated specimens filled up the free inner space and surrounded internal organs, such as the ovary and digestive system, which were contracted. All cells (epidermal cells, storage cells, ovary cells, cells of the digestive system) underwent shrinkage, and their cytoplasm was electron dense. Lipids and polysaccharides dominated among reserve material of storage cells, while the amount of protein was small. The basic morphology of specific cell types and organelles did not differ between active and anhydrobiotic R. coronifer.

  5. Simulations and economic analyses of desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Shelpuk, B. C.; Hooker, D. W.; Jorgensen, G. J.; Bingham, C. E.

    1979-06-01

    The progress to date in the development and analysis of computer simulations of solar-powered desiccant cooling using an axial-flow disc-type dehumidifier wheel, solar-powered space heating, and electrically driven, standard vapor-compression air-conditioning systems for residential use is documented. Computer simulations for both solar and conventional heating and cooling systems were performed for 12-month heating and cooling seasons. Annual thermal performance and the resulting life cycle costs for both types of systems were analyzed and compared. The heating/cooling season simulations were run for five U.S. cities representing a wide range of climatic conditions and insolation. With the informaion resulting from these simulations, the optimum air-conditioning system was chosen to maximize the conservation of fossil fuels and minimize operating costs. Because of the increasing use of residential air conditioning employing electrically driven vapor-compression coolers, the five locations were studied to determine if it would be beneficial (in terms of both economics and fossil fuel displacement) to displace fossil-fuel-powered vapor-compression coolers and natural gas space heaters with solar-powered heating and desiccant cooling systems.

  6. Hydrogen sulfide exposure increases desiccation tolerance in Drosophila melanogaster.

    Science.gov (United States)

    Zhong, Jian-Feng; Wang, Shu-Ping; Shi, Xiao-Qin; Mu, Li-li; Li, Guo-Qing

    2010-12-01

    Hydrogen sulfide (H(2)S) has been shown to effect physiological alterations in several animals, frequently leading to an improvement in survival in otherwise lethal conditions. In the present paper, a volatility bioassay system was developed to evaluate the survivorship of Drosophila melanogaster adults exposed to H(2)S gas that emanated from a K(2)S donor. Using this bioassay system, we found that H(2)S exposure significantly increased the survival of flies under arid and food-free conditions, but not under humid and food-free conditions. This suggests that H(2)S plays a role in desiccation tolerance but not in nutritional stress alleviation. To further confirm the suggestion, the mRNA levels of two desiccation tolerance-related genes Frost and Desat2, and a starvation-related gene Smp-30, from the control and treated flies were measured by quantitative real-time PCR. These genes were up-regulated within 2h when the flies transferred to the arid and food-free bioassay system. Addition of H(2)S further increased Frost and Desat2 mRNA levels, in contrast to Smp-30. Thus, our molecular results were consistent with our bioassay findings. Because of the molecular and genetic tools available for Drosophila, the fly will be a useful system for determining how H(2)S regulates various physiological alterations. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Rapid changes in desiccation resistance in Drosophila melanogaster are facilitated by changes in cuticular permeability.

    Science.gov (United States)

    Bazinet, Aimee L; Marshall, Katie E; MacMillan, Heath A; Williams, Caroline M; Sinclair, Brent J

    2010-12-01

    Insects can improve their desiccation resistance by one or more of (1) increasing their water content; (2) decreasing water loss rate; or (3) increasing the amount of water able to be lost before death. Female Drosophila melanogaster have previously been reported to increase their resistance to desiccation after a desiccation pre-treatment and recovery, but the mechanism of this increased desiccation resistance has not been explored. We show that female, but not male adult D. melanogaster increased their resistance to desiccation after 1h of recovery from a 3 to 4.5h pre-treatment that depletes them of 10% of their water content. The pre-treatment did not result in an increase in water content after recovery, and there is a slight increase in water content at death in pre-treated females (but no change in males), suggesting that the amount of water loss tolerated is not improved. Metabolic rate, measured on individual flies with flow-through respirometry, did not change with pre-treatment. However, a desiccation pre-treatment did result in a reduction in water loss rate, and further investigation indicated that a change in cuticular water loss rate accounted for this decrease. Thus, the observed increase in desiccation resistance appears to be based on a change in cuticular permeability. However, physiological changes in response to the desiccation pre-treatment were similar in male and female, which therefore does not account for the difference in rapid desiccation hardening between the sexes. We speculate that sex differences in fuel use during desiccation may account for the discrepancy.

  8. Desiccation tolerance in Anopheles coluzzii: the effects of spiracle size and cuticular hydrocarbons.

    Science.gov (United States)

    Arcaz, Arthur C; Huestis, Diana L; Dao, Adama; Yaro, Alpha S; Diallo, Moussa; Andersen, John; Blomquist, Gary J; Lehmann, Tovi

    2016-06-01

    The African malaria mosquitoes Anopheles gambiae and Anopheles coluzzii range over forests and arid areas, where they withstand dry spells and months-long dry seasons, suggesting variation in their desiccation tolerance. We subjected a laboratory colony (G3) and wild Sahelian mosquitoes during the rainy and dry seasons to desiccation assays. The thoracic spiracles and amount and composition of cuticular hydrocarbons (CHCs) of individual mosquitoes were measured to determine the effects of these traits on desiccation tolerance. The relative humidity of the assay, body water available, rate of water loss and water content at death accounted for 88% of the variation in desiccation tolerance. Spiracle size did not affect the rate of water loss or desiccation tolerance of the colony mosquitoes, as was the case for the total CHCs. However, six CHCs accounted for 71% of the variation in desiccation tolerance and three accounted for 72% of the variation in the rate of water loss. Wild A. coluzzii exhibited elevated desiccation tolerance during the dry season. During that time, relative thorax and spiracle sizes were smaller than during the rainy season. A smaller spiracle size appeared to increase A. coluzzii's desiccation tolerance, but was not statistically significant. Seasonal changes in CHC composition were detected in Sahelian A. coluzzii Stepwise regression models suggested the effect of particular CHCs on desiccation tolerance. In conclusion, the combination of particular CHCs along with the total amount of CHCs is a primary mechanism conferring desiccation tolerance in A. coluzzii, while variation in spiracle size might be a secondary mechanism. © 2016. Published by The Company of Biologists Ltd.

  9. Understanding desiccation tolerance using the resurrection plant Boea hygrometrica as a model system

    Directory of Open Access Journals (Sweden)

    Jayeeta eMitra

    2013-11-01

    Full Text Available Vegetative tissues of Boea hygrometrica, a member of the Gesneriaceae family, can tolerate severe water loss to desiccated state and fully recover upon rehydration. Unlike many other so called resurrection plants, the detached leaves of B. hygrometrica also possess the same level of capacity for desiccation tolerance as that of whole plant. B. hygrometrica is distributed widely from the tropics to northern temperate regions in East Asia and grows vigorously in areas around limestone rocks, where dehydration occurs frequently, rapidly and profoundly. The properties of detached B. hygrometrica leaves and relative ease of culture have made it a useful system to study the adaptive mechanisms of desiccation tolerance. Extensive studies have been conducted to identify the physiological, cellular and molecular mechanisms underlying desiccation tolerance in the last decade, including specific responses to water stress, such as cell wall folding and pigment-protein complex stabilizing in desiccated leaves. In this review, the insight into the structural, physiological and biochemical, and molecular alterations that accompany the acquisition of desiccation tolerance in B. hygrometrica is described. Finally a future perspective is proposed, with an emphasis on the emerging regulatory roles of retroelements and histone modifications in the acquisition of DT, and the need of establishment of genome sequence database and high throughput techniques to identify novel regulators for fully understanding of the matrix of desiccation tolerance.

  10. Desiccation tolerance in resurrection plants: new insights from transcriptome, proteome and metabolome analysis

    Directory of Open Access Journals (Sweden)

    Dinakar eChallabathula

    2013-11-01

    Full Text Available Most higher plants are unable to survive desiccation to an air-dried state. An exception is a small group of vascular angiosperm plants, termed resurrection plants. They have evolved unique mechanisms of desiccation tolerance and thus can tolerate severe water loss, and mostly adjust their water content with the relative humidity in the environment. Desiccation tolerance is a complex phenomenon and depends on the regulated expression of numerous genes during dehydration and subsequent rehydration. Most of the resurrection plants have a large genome and are difficult to transform which makes them unsuitable for genetic approaches. However, technical advances have made it possible to analyse changes in gene expression on a large scale. These approaches together with comparative studies with non-desiccation tolerant plants provide novel insights into the molecular processes required for desiccation tolerance and will shed light on identification of orphan genes with unknown functions. Here, we review large scale recent transcriptomic, proteomic and metabolomic studies that have been performed in desiccation tolerant plants and discuss how these studies contribute to understanding the molecular basis of desiccation tolerance.

  11. Comparison of frozen versus desiccated reference human red blood cells for hemagglutination assays.

    Science.gov (United States)

    Ho, David; Schierts, Jennifer; Zimmerman, Zea; Gadsden, Isaac; Bruttig, Stephen

    2009-10-01

    Red blood cells (RBCs) are commonly used fresh or stored in frozen format for identification of patients' antibodies and serologic specificity of such antibodies at reference laboratories. However, maintaining a large pool of fresh RBCs is impossible in a blood-banking environment and blood in frozen format poses a logistic disadvantage in terms of accessibility, maintenance cost, safety, and sample recovery. This study explores an alternative, desiccation storage method for RBCs to provide a reagent that supports greater utilization and flexibility for reference laboratories. RBCs from five donors were used in the study. RBCs were processed and kept in either frozen or desiccated format. Study variables for either the frozen or the desiccated cells included cell recovery as quantified by cell counts, gross microscopic examination, and hemagglutination assays. The mean percentage of cell recovery for thawed and washed frozen RBCs was 20% versus 50% for rehydrated and washed desiccated RBCs. Microscopic examination of thawed cells from the frozen preparation showed cells with irregular shapes, a sharp contrast when compared with rehydrated cells from the desiccated preparation, where cells are mostly intact, smooth surface, and biconcave in structure. Cells in both preparations performed well in manual agglutination tests. Desiccation preservation of RBCs provides a somewhat better RBC recovery and cell structure stability, while maintaining the necessary antigen-antibody reactions for cell surface markers, which will allow desiccated RBCs to be archived in blood collecting and processing reference laboratories.

  12. Effects of periodic desiccation on the synthesis of the UV-screening compound, scytonemin, in cyanobacteria.

    Science.gov (United States)

    Fleming, Erich D; Castenholz, Richard W

    2007-06-01

    Scytonemin is an ultraviolet radiation (UVR)-screening compound synthesized by some sheathed cyanobacteria exposed to high solar and sky radiation. It is primarily produced in response to UVA radiation, but certain environmental stresses can enhance synthesis. This study focuses on the effects of periodic desiccation on scytonemin synthesis in three desiccation-tolerant cyanobacterial strains, Nostoc punctiforme PCC 73102, Chroococcidiopsis CCMEE 5056 and Chroococcidiopsis CCMEE 246. Nostoc punctiforme and Chroococcidiopsis CCMEE 5056 exposed to UVA radiation produced more concentrated scytonemin screens when experiencing periodic desiccation (i.e. 1 day desiccated for every 2 days hydrated) than when continuously hydrated. A more concentrated scytonemin screen would reduce the amount of UVR damage accrued when cells are desiccated and metabolically inactive. This might allow the cyanobacteria to allocate more energy to systems other than UVR damage repair during rehydration, which would facilitate recovery. The scytonemin screen is extremely stable, remaining largely intact in the sheaths of desiccated N. punctiforme even when continuously exposed to UVA radiation for about 2 months. In contrast to the above findings, scytonemin synthesis in Chroococcidiopsis CCMEE 246, a strain that produces scytonemin constitutively under low visible light (no UVA), was partially inhibited by periodic desiccation.

  13. Study of parameters affecting the performance of solar desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A A; Hoo, E A

    1993-01-01

    The performance of a solar desiccant cooling system depends on the performance of its components, particularly the desiccant dehumidifier and solar collectors. The desiccant dehumidifier performance is affected by the properties of the desiccant, particularly the shape of the isotherm and the regeneration temperature. The performance of a solar collector, as one would expect, depends on its operating temperature, which is very close to the desiccant regeneration temperature. The purpose of this study was to identify the desiccant isotherm shape (characterized by separation factor) that would result in the optimum performance - based on thermal coefficient of performance and cooling capacity - of a desiccant cooling cycle operating in ventilation mode. Different regeneration temperatures ranging from 65{degree}C to 160{degree}C were investigated to identify the corresponding optimum isotherm shape at each. Thermal COP dictates the required area of the solar collectors, and the cooling capacity is an indication of the size and cost of the cooling equipment. Staged and no-staged regeneration methods were studied.

  14. Study of parameters affecting the performance of solar desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A.A.; Hoo, E.A.

    1993-01-01

    The performance of a solar desiccant cooling system depends on the performance of its components, particularly the desiccant dehumidifier and solar collectors. The desiccant dehumidifier performance is affected by the properties of the desiccant, particularly the shape of the isotherm and the regeneration temperature. The performance of a solar collector, as one would expect, depends on its operating temperature, which is very close to the desiccant regeneration temperature. The purpose of this study was to identify the desiccant isotherm shape (characterized by separation factor) that would result in the optimum performance - based on thermal coefficient of performance and cooling capacity - of a desiccant cooling cycle operating in ventilation mode. Different regeneration temperatures ranging from 65[degree]C to 160[degree]C were investigated to identify the corresponding optimum isotherm shape at each. Thermal COP dictates the required area of the solar collectors, and the cooling capacity is an indication of the size and cost of the cooling equipment. Staged and no-staged regeneration methods were studied.

  15. Desiccation tolerance in resurrection plants: new insights from transcriptome, proteome and metabolome analysis.

    Science.gov (United States)

    Dinakar, Challabathula; Bartels, Dorothea

    2013-01-01

    Most higher plants are unable to survive desiccation to an air-dried state. An exception is a small group of vascular angiosperm plants, termed resurrection plants. They have evolved unique mechanisms of desiccation tolerance and thus can tolerate severe water loss, and mostly adjust their water content with the relative humidity in the environment. Desiccation tolerance is a complex phenomenon and depends on the regulated expression of numerous genes during dehydration and subsequent rehydration. Most of the resurrection plants have a large genome and are difficult to transform which makes them unsuitable for genetic approaches. However, technical advances have made it possible to analyze changes in gene expression on a large-scale. These approaches together with comparative studies with non-desiccation tolerant plants provide novel insights into the molecular processes required for desiccation tolerance and will shed light on identification of orphan genes with unknown functions. Here, we review large-scale recent transcriptomic, proteomic, and metabolomic studies that have been performed in desiccation tolerant plants and discuss how these studies contribute to understanding the molecular basis of desiccation tolerance.

  16. Influence of Ventilation Ratio on Desiccant Air Conditioning System's Efficiency Performance

    Science.gov (United States)

    Tran, Thien Nha; Akisawa, Atsushi; Kashiwagi, Takao; Hamamoto, Yoshinori

    Ventilation air is a concern for engineers since ventilated air controls indoor air contamination; additional ventilation, however, increases the energy consumption of buildings. The study investigates the energy efficiency performance of the desiccant dehumidification air conditioning system in the context of ventilation for a hot-humid climate such as summer in Japan. The investigation focuses on the variable ratio of ventilation air as required by the application of air conditioning system. The COP of the desiccant air conditioning system is determined. The evaluation is subsequently performed by comparing the desiccant based system with the conventional absorption cooling system and the vapor compression cooling system. Based on 12 desiccant rotor simulations, it is found that the desiccant regeneration temperature required varies between 47°C to 85°C as ventilation ratio increases from 0. 0 to 100%, and up to 52. 5°C as the ventilation ratio achieves 14%. The heat required for regenerating desiccant accounts for 55% and higher of the system's total heat consumption; the system is expected to be energy efficient by using wasted heat from the absorption chiller for desiccant regeneration; and its energy efficiency expands as the ratio of ventilation air rises above 15% compared with the conventional absorption cooling system. The energy efficiency also benefits as the ratio rises beyond 70% against the conventional vapor compression cooling system.

  17. Aquatic insects dealing with dehydration: do desiccation resistance traits differ in species with contrasting habitat preferences?

    Directory of Open Access Journals (Sweden)

    Susana Pallarés

    2016-08-01

    Full Text Available Background Desiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to drying stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions. Methods We examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae with contrasting habitat specificity (lentic vs. lotic systems and different salinity optima from fresh- to hypersaline waters. We measured survival, recovery capacity and key traits related to desiccation resistance (fresh mass, % water content, % cuticle content and water loss rate under controlled exposure to desiccation, and explored their variability within and between species. Results Meso- and hypersaline species were more resistant to desiccation than freshwater and hyposaline ones, showing significantly lower water loss rates and higher water content. No clear patterns in desiccation resistance traits were observed between lotic and lentic species. Intraspecifically, water loss rate was positively related to specimens’ initial % water content, but not to fresh mass or % cuticle content, suggesting that the dynamic mechanism controlling water loss is mainly regulated by the amount of body water available. Discussion Our results support previous hypotheses suggesting that the evolution of desiccation resistance is associated with the colonization of saline habitats by aquatic beetles. The interespecific patterns observed in Enochrus also suggest that freshwater species may be more vulnerable than saline ones to drought intensification expected under climate change in semi-arid regions such as the Mediterranean Basin.

  18. Crucial Role of Extracellular Polysaccharides in Desiccation and Freezing Tolerance in the Terrestrial Cyanobacterium Nostoc commune

    Science.gov (United States)

    Tamaru, Yoshiyuki; Takani, Yayoi; Yoshida, Takayuki; Sakamoto, Toshio

    2005-01-01

    The cyanobacterium Nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. In this study, the role of extracellular polysaccharides (EPS) in the desiccation tolerance of photosynthesis in N. commune was examined. Although photosynthetic O2 evolution was not detected in desiccated colonies, the ability of the cells to evolve O2 rapidly recovered after rehydration. The air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural colonies with EPS were highly water absorbent and were rapidly hydrated by atmospheric moisture. The cells embedded in EPS in Nostoc colonies were highly desiccation tolerant, and O2 evolution was not damaged by air drying. Although N. commune was determined to be a mesophilic cyanobacterium, the cells with EPS were heat tolerant in a desiccated state. EPS could be removed from cells by homogenizing colonies with a blender and filtering with coarse filter paper. This treatment to remove EPS did not damage Nostoc cells or their ability to evolve O2, but O2 evolution was significantly damaged by desiccation treatment of the EPS-depleted cells. Similar to the EPS-depleted cells, the laboratory culture strain KU002 had only small amount of EPS and was highly sensitive to desiccation. In the EPS-depleted cells, O2 evolution was also sensitive to freeze-thaw treatment. These results strongly suggest that EPS of N. commune is crucial for the stress tolerance of photosynthesis during desiccation and during freezing and thawing. PMID:16269775

  19. Desiccation tolerance in resurrection plants: new insights from transcriptome, proteome and metabolome analysis

    Science.gov (United States)

    Dinakar, Challabathula; Bartels, Dorothea

    2013-01-01

    Most higher plants are unable to survive desiccation to an air-dried state. An exception is a small group of vascular angiosperm plants, termed resurrection plants. They have evolved unique mechanisms of desiccation tolerance and thus can tolerate severe water loss, and mostly adjust their water content with the relative humidity in the environment. Desiccation tolerance is a complex phenomenon and depends on the regulated expression of numerous genes during dehydration and subsequent rehydration. Most of the resurrection plants have a large genome and are difficult to transform which makes them unsuitable for genetic approaches. However, technical advances have made it possible to analyze changes in gene expression on a large-scale. These approaches together with comparative studies with non-desiccation tolerant plants provide novel insights into the molecular processes required for desiccation tolerance and will shed light on identification of orphan genes with unknown functions. Here, we review large-scale recent transcriptomic, proteomic, and metabolomic studies that have been performed in desiccation tolerant plants and discuss how these studies contribute to understanding the molecular basis of desiccation tolerance. PMID:24348488

  20. Identification of proteins involved in desiccation tolerance in the red seaweed Pyropia orbicularis (Rhodophyta, Bangiales).

    Science.gov (United States)

    López-Cristoffanini, Camilo; Zapata, Javier; Gaillard, Fanny; Potin, Philippe; Correa, Juan A; Contreras-Porcia, Loretto

    2015-12-01

    Extreme reduction in cellular water content leads to desiccation, which, if persistent, affects the physiology of organisms, mainly through oxidative stress. Some organisms are highly tolerant to desiccation, including resurrection plants and certain intertidal seaweeds. One such species is Pyropia orbicularis, a rhodophycean that colonizes upper intertidal zones along the Chilean coast. Despite long, daily periods of air exposure due to tides, this alga is highly tolerant to desiccation. The present study examined the proteome of P. orbicularis by 2DE and LC-MS/MS analyses to determine the proteins associated with desiccation tolerance (DT). The results showed that, under natural conditions, there were significant changes in the protein profile during low tide as compared to naturally hydrated plants at high tide. These changes were mainly in newly appeared proteins spots such as chaperones, monodehydroascorbate reductase, and manganese superoxide dismutase, among others. Previously undescribed proteins under desiccation conditions included phycobiliproteins, glyoxalase I, and phosphomannomutase. These changes evidenced that several physiological responses involved in DT are activated during low tide, including decreased photosynthetic activity, increased antioxidant capacity, and the preservation of cell physiology by regulating water content, cell wall structure, and cell volume. Similar responses have been observed in resurrection plants and bryophytes exposed to desiccation. Therefore, the coordinated activation of different desiccation tolerance pathways in P. orbicularis could explain the successful biological performance of this seaweed in the upper intertidal rocky zones. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Molecular mechanisms involved in the response to desiccation stress and persistence in Acinetobacter baumannii.

    Science.gov (United States)

    Gayoso, Carmen M; Mateos, Jesús; Méndez, José A; Fernández-Puente, Patricia; Rumbo, Carlos; Tomás, María; Martínez de Ilarduya, Oskar; Bou, Germán

    2014-02-07

    Desiccation tolerance contributes to the maintenance of bacterial populations in hospital settings and may partly explain its propensity to cause outbreaks. Identification and relative quantitation of proteins involved in bacterial desiccation tolerance was made using label-free quantitation and iTRAQ labeling. Under desiccating conditions, the population of the Acinetobacter baumannii clinical strain AbH12O-A2 decreased in the first week, and thereafter, a stable population of 0.5% of the original population was maintained. Using label-free quantitation and iTRAQ labeling, 727 and 765 proteins, respectively, were detected; 584 of them by both methods. Proteins overexpressed under desiccation included membrane and periplasmic proteins. Proteins associated with antimicrobial resistance, efflux pumps, and quorum quenching were overexpressed in the samples subjected to desiccation stress. Electron microscopy revealed clear morphological differences between desiccated and control bacteria. We conclude that A. baumannii is able to survive long periods of desiccation through the presence of cells in a dormant state, via mechanisms affecting control of cell cycling, DNA coiling, transcriptional and translational regulation, protein stabilization, antimicrobial resistance, and toxin synthesis, and that a few surviving cells embedded in a biofilm matrix are able to resume growth and restore the original population in appropriate environmental conditions following a "bust-and-boom" strategy.

  2. Generational Differences in Response to Desiccation Stress in the Desert Moss Tortula inermis

    Science.gov (United States)

    Stark, Lloyd R.; Oliver, Melvin J.; Mishler, Brent D.; McLetchie, D. Nicholas

    2007-01-01

    Background and Aims Active growth in post-embryonic sporophytes of desert mosses is restricted to the cooler, wetter months. However, most desert mosses have perennial gametophytes. It is hypothesized that these life history patterns are due, in part, to a reduced desiccation tolerance for sporophytes relative to gametophytes. Methods Gametophytes with attached post-embryonic sporophytes of Tortula inermis (early seta elongation phenophase) were exposed to two levels of desiccation stress, one rapid-dry cycle and two rapid-dry cycles, then moistened and allowed to recover, resume development, and/or regenerate for 35 d in a growth chamber. Key Results Gametophytes tolerated the desiccation treatments well, with 93 % survival through regenerated shoot buds and/or protonemata. At the high stress treatment, a significantly higher frequency of burned leaves and browned shoots occurred. Sporophytes were far more sensitive to desiccation stress, with only 23 % surviving after the low desiccation stress treatment, and 3 % surviving after the high desiccation stress treatment. While the timing of protonemal production and sporophytic phenophases was relatively unaffected by desiccation stress, shoots exposed to one rapid-dry cycle produced shoots more rapidly than shoots exposed to two rapid-dry cycles. Conclusions It is concluded that sporophytes of Tortula inermis are more sensitive to rapid drying than are maternal gametophytes, and that sporophyte abortion in response to desiccation results from either reduced desiccation tolerance of sporophytes relative to gametophytes, or from a termination of the sporophyte on the part of the gametophyte in response to stress. PMID:17098752

  3. Expression profile of desiccation tolerance factors in intertidal seaweed species during the tidal cycle.

    Science.gov (United States)

    Fierro, Camila; López-Cristoffanini, Camilo; Meynard, Andrés; Lovazzano, Carlos; Castañeda, Francisco; Guajardo, Eduardo; Contreras-Porcia, Loretto

    2017-06-01

    The transcriptional modulation of desiccation tolerance factors in P. orbicularis explains its successful recuperation after water deficit. Differential responses to air exposure clarify seaweed distribution along intertidal rocky zones. Desiccation-tolerant seaweed species, such as Pyropia orbicularis, can tolerate near 96% water loss during air exposure. To understand the phenotypic plasticity of P. orbicularis to desiccation, several tolerance factors were assessed by RT-qPCR, Western-blot analysis, and enzymatic assays during the natural desiccation-rehydration cycle. Comparative enzymatic analyses were used to evidence differential responses between P. orbicularis and desiccation-sensitive species. The results showed that during desiccation, the relative mRNA levels of genes associated with basal metabolism [trehalose phosphate synthase (tps) and pyruvate dehydrogenase (pdh)] were overexpressed in P. orbicularis. Transcript levels related to antioxidant metabolism [peroxiredoxin (prx); thioredoxin (trx); catalase (cat); lipoxygenase (lox); ferredoxin (fnr); glutathione S-transferase (gst)], cellular detoxification [ABC transporter (abc) and ubiquitin (ubq)], and signal transduction [calmodulin (cam)] increased approximately 15- to 20-fold, with the majority returning to basal levels during the final hours of rehydration. In contrast, actin (act) and transcription factor 1 (tf1) transcripts were down-regulated. ABC transporter protein levels increased in P. orbicularis during desiccation, whereas PRX transcripts decreased. The antioxidant enzymes showed higher specific activity in P. orbicularis under desiccation, and sensitive species exhibited enzymatic inactivation and scarce ABC and PRX protein detection following prolonged desiccation. In conclusion, the reported findings contribute towards understanding the ecological distribution of intertidal seaweeds at the molecular and functional levels.

  4. Cover Your Cough! A Short and Simple Activity to Demonstrate the Antimicrobial Effect of Desiccation

    Directory of Open Access Journals (Sweden)

    Jennifer Cook Easterwood

    2013-08-01

    Full Text Available Many undergraduate microbiology laboratory manuals include exercises demonstrating the antimicrobial effects of physical agents, such as UV light and heat, and chemical agents, such as disinfectants and antibiotics (3, 4. There is, however, a lack of exercises examining the effects of desiccation on bacterial growth and survival. This particular form of antimicrobial control is especially relevant today with an increased emphasis on coughing and sneezing into one’s sleeve or a tissue, where microbes will not contaminate hands and will eventually desiccate and die (2. Desiccation can have bacteriostatic or bactericidal effects depending on the species, the material on which the organism has desiccated, and the length of time. The absence of water can damage many cellular components, including enzymes, nucleic acids, and cell membranes (1. However, many prokaryotes have some degree of resistance to desiccation, with Escherichia coli surviving around 24 hours and Bacillus species surviving upwards of 300 years, though these numbers can vary due to a number of confounding factors (5. Some of these factors include the method by which desiccation occurred, whether desiccation occurred in a natural or laboratory situation, and the species itself (5. To address the effects of desiccation on bacterial growth and survival, a short, simple exercise was developed. By inoculating various materials with bacterial cultures and allowing them to air-dry for 24 hours, students can visualize the effects of desiccation by analyzing the growth, or lack thereof, when organisms are transferred to nutrient agar plates. This exercise has been used in a health professions microbiology course as well as a microbiology course for biology and biochemistry majors. It is short enough to be conducted during a standard lecture period or during a longer laboratory period in conjunction with other experiments demonstrating the effectiveness of physical agents on microbial

  5. Numerical modelling of desiccation cracking of clayey soil

    Directory of Open Access Journals (Sweden)

    Vo Thi Dong

    2016-01-01

    Full Text Available The formation and propagation of desiccation cracks in soil is an extremely complex phenomenon because of the coupling between hydraulic and mechanical behaviour of soil, which are constituted here by the presence of capillary forces and discontinuities. The formation of a cracks network strongly influences the mechanical and hydraulic properties of soil. The main objective of this research is to study the evolution of suction and strain fields, the initiation and propagation of cracks under the effect of drying, using the finite element method. A simulation of a soil sample with four cohesive joints shows the results similar to experimental data. In addition, a simulation of multijoints shows that cracks does not open in all potentials positions and it gives similar spacing.

  6. A new heat pump desiccant dehumidifier for supermarket application

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R. M.; Castellotti, F. [Department of Management and Engineering, University of Padova, Vicenza (Italy)

    2007-07-01

    Recently a new equipment for dehumidification was put onto the market. It is a self-regenerating liquid desiccant cooling system able to dehumidify, heating or cooling the ambient air by an electric heat pump that is a part of the equipment. Its operation is here studied in a supermarket application where air temperature and relative humidity play a very important role and the air-conditioning becomes necessary not only to assure a suitable thermal comfort, but also to make the refrigerated display cabinets operate properly. In this paper possible energy savings, compared to a traditional mechanical dehumidification, are evaluated by means of a numerical model that simulates a typical Italian supermarket. (author)

  7. Optimizing the performance of desiccant beds for solar-regenerated cooling

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, R.; Collier, K.

    1981-03-01

    Detailed computer simulations as well as a simplified psychrometric analysis are used to determine the increase in cooling system performance that can be realized through the use of nonhomogeneous or staged desiccant beds. A staged bed of four hypothetical desiccants is shown to give a 10% higher cooling capacity than a silica gel bed of the same thickness. Alternatively, the same cooling capacity is produced by a staged bed 37% thinner than the silica gel bed. These effects could be employed to reduce the parasitic power requirements of desiccant cooling systems.

  8. Laboratory and Modeling Evaluations in Support of Field Testing for Desiccation at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Oostrom, Martinus; Freedman, Vicky L.; Strickland, Christopher E.; Wietsma, Thomas W.; Tartakovsky, Guzel D.; Ward, Anderson L.

    2011-02-23

    The Deep Vadose Zone Treatability Test Plan for the Hanford Central Plateau includes testing of the desiccation technology as a potential technology to be used in conjunction with surface infiltration control to limit the flux of technetium and other contaminants in the vadose zone to the groundwater. Laboratory and modeling efforts were conducted to investigate technical uncertainties related to the desiccation process and its impact on contaminant transport. This information is intended to support planning, operation, and interpretation of a field test for desiccation in the Hanford Central Plateau.

  9. Solar space heating and cooling by selective use of the components of a desiccant cooling system

    Science.gov (United States)

    Abbud, Ihsan Aladdin

    The economic advantages of by-passing various components of a desiccant cooling system under conditions not requiring their use are estimated by evaluating the annual costs of heating and cooling a commercial building in three representative U.S. cities. Life-cycle costs of systems employing solar heat for space heating and desiccant regeneration are compared with those using electric heat. The costs of purchasing and operating heating and desiccant cooling systems, with and without solar heat supply, are compared with those employing conventional heating and vapor compression cooling. The conditions under which commercial buildings can be cooled with desiccant systems at costs competitive with conventional systems are identified. A commercially available vapor compression air conditioner is used as a standard of comparison for energy consumption and room comfort. Heating and cooling requirements of the building are determined by use of the BLAST computer model in a simulation of long term system operation. Performance of the desiccant cooling system and life cycle savings obtained by its use are determined by simulation employing the TRNSYS computer model. TRNSYS compatible subroutines are developed to simulate operation of the desiccant equipment, the building, and the controllers that operate and monitor the system components. The results are presented in tabular and graphical form. This study shows that in the widely different climates represented in Los Angeles, New York, and Miami, by-passing various components in the desiccant cooling system when they are not needed is economically advantageous. Operation cost of the complete system decreased by 47.3% in Los Angeles, by 30.9% in New York City, and by 23.9% in Miami by not operating the desiccant wheel and other elements. The ventilation desiccant cooling system has major economic advantage over conventional systems under conditions of moderate humidity, as in Los Angeles and New York City. In Miami, however

  10. Tolerance to oxidative stress induced by desiccation in Porphyra columbina (Bangiales, Rhodophyta)

    Science.gov (United States)

    Contreras-Porcia, Loretto; Thomas, Daniela; Flores, Verónica; Correa, Juan A.

    2011-01-01

    Unravelling the mechanisms underlying desiccation tolerance is crucial in order to understand the position of algal species in the intertidal zone. The alga Porphyra columbina lives in the uppermost part of the rocky intertidal zones around the world and was selected as a model for this study. Naturally desiccated plants were collected during low tide and studied for morphological changes, oxidative burst induction, biomolecule oxidation, antioxidant responses, and photosynthetic status. Naturally hydrated plants collected during high tides were used for comparative purposes. In addition, changes induced by desiccation were assessed in vitro and the capacity to recover from desiccation was determined by rehydrating the fronds in seawater. The global results show that desiccation induces morphological and cellular alterations accompanied by a loss of ∼96% of the water content. Overproduction of reactive oxygen species (ROS) was induced by desiccation and two peaks of H2O2 were detected at 1 and 3 h of desiccation. However, during in vitro rehydration post-desiccation, the ROS quickly returned to the basal levels. At the biomolecular level, only a low production of oxidized proteins was recorded during desiccation, whereas the activity of diverse antioxidant enzymes increased. However, this activity diminished to near basal levels during rehydration. The photosynthetic efficiency (Fv/Fm) during desiccation declined by 94–96% of the values recorded in hydrated plants. This reduction was generated by the low levels of trapped energy flux per cross-section (TRo/CS), electron transport flux per CS (ETo/CS), and density of reaction centres (RC/SCo) as well as the chlorophyll content. The inverse pattern was observed for the levels of phycocyanin and phycoerythrin content. Fv/Fm and the photosynthetic indicators were restored to normal levels after only 5 min of rehydration. The results indicate that desiccation in P. columbina causes overproduction of ROS that is

  11. REINDUCTION OF DESICCATION TOLERANCE IN SEEDS OF Bauhinia forficata LINK (FABACEAE.

    Directory of Open Access Journals (Sweden)

    Amanda Cristiane Rodrigues

    2015-12-01

    Full Text Available Bauhinia forficata is a tree with medicinal and agronomic interest. Due to the importance of the species, the work aimed to evaluate some characteristics of germination of B. forficata and estimate its capacity to maintain the desiccation tolerance after the germination. The results indicate that B. forficata is a species with capacity to reinduction of the desiccation tolerance. The scanning electron micrographs show the benefits of slow drying in germinated seeds. In conclusion, B. forficata is a species with capacity to reinduction to desiccation tolerance until 4mm of radicle, when subjected to treatment using PEG -1,4MPa.

  12. The signature of seeds in resurrection plants: a molecular and physiological comparison of desiccation tolerance in seeds and vegetative tissues.

    Science.gov (United States)

    Illing, Nicola; Denby, Katherine J; Collett, Helen; Shen, Arthur; Farrant, Jill M

    2005-11-01

    Desiccation-tolerance in vegetative tissues of angiosperms has a polyphyletic origin and could be due to 1) appropriation of the seed-specific program of gene expression that protects orthodox seeds against desiccation, and/or 2) a sustainable version of the abiotic stress response. We tested these hypotheses by comparing molecular and physiological data from the development of orthodox seeds, the response of desiccation-sensitive plants to abiotic stress, and the response of desiccation-tolerant plants to extreme water loss. Analysis of publicly-available gene expression data of 35 LEA proteins and 68 anti-oxidant enzymes in the desiccation-sensitive Arabidopsis thaliana identified 13 LEAs and 4 anti-oxidants exclusively expressed in seeds. Two (a LEA6 and 1-cys-peroxiredoxin) are not expressed in vegetative tissues in A. thaliana, but have orthologues that are specifically activated in desiccating leaves of Xerophyta humilis. A comparison of antioxidant enzyme activity in two desiccation-sensitive species of Eragrostis with the desiccation-tolerant E. nindensis showed equivalent responses upon initial dehydration, but activity was retained at low water content in E. nindensis only. We propose that these antioxidants are housekeeping enzymes and that they are protected from damage in the desiccation-tolerant species. Sucrose is considered an important protectant against desiccation in orthodox seeds, and we show that sucrose accumulates in drying leaves of E. nindensis, but not in the desiccation-sensitive Eragrostis species. The activation of "seed-specific" desiccation protection mechanisms (sucrose accumulation and expression of LEA6 and 1-cys-peroxiredoxin genes) in the vegetative tissues of desiccation-tolerant plants points towards acquisition of desiccation tolerance from seeds.

  13. Desiccant-Based Combined Systems: Integrated Active Desiccant Rooftop Hybrid System Development and Testing Final Report- Phase 4

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J

    2005-05-06

    This report summarizes the results of a research and development (R&D) program to design and optimize an active desiccant-vapor compression hybrid rooftop system. The primary objective was to combine the strengths of both technologies to produce a compact, high-performing, energy-efficient system that could accommodate any percentage of outdoor air and deliver essentially any required combination of temperature and humidity, or sensible heat ratio (SHR). In doing so, such a product would address the significant challenges imposed on the performance capabilities of conventional packaged rooftop equipment by standards 62 and 90.1 of the American Society of Heating, Refrigerating and Air-Conditioning Engineers. The body of work completed as part of this program built upon previous R&D efforts supported by the U.S. Department of Energy and summarized by the Phase 3b report ''Active Desiccant Dehumidification Module Integration with Rooftop Packaged HVAC Units'' (Fischer and Sand 2002), in addition to Fischer, Hallstrom, and Sand 2000; Fischer 2000; and Fischer and Sand 2004. All initial design objectives established for this development program were successfully achieved. The performance flexibility desired was accomplished by a down-sized active desiccant wheel that processes only a portion of the supply airflow, which is pre-conditioned by a novel vapor compression cycle. Variable-speed compressors are used to deliver the capacity control required by a system handling a high percentage of outdoor air. An integrated direct digital control system allows for control capabilities not generally offered by conventional packaged rooftop systems. A 3000-cfm prototype system was constructed and tested in the SEMCO engineering test laboratory in Columbia, MO, and was found to operate in an energy-efficient fashion relative to more conventional systems. Most important, the system offered the capability to independently control the supply air temperature and

  14. Experimental and Numerical Investigations of Soil Desiccation for Vadose Zone Remediation: Report for Fiscal Year 2007

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Andy L.; Oostrom, Mart; Bacon, Diana H.

    2008-02-04

    Apart from source excavation, the options available for the remediation of vadose zone metal and radionuclide contaminants beyond the practical excavation depth (0 to 15 m) are quite limited. Of the available technologies, very few are applicable to the deep vadose zone with the top-ranked candidate being soil desiccation. An expert panel review of the work on infiltration control and supplemental technologies identified a number of knowledge gaps that would need to be overcome before soil desiccation could be deployed. The report documents some of the research conducted in the last year to fill these knowledge gaps. This work included 1) performing intermediate-scale laboratory flow cell experiments to demonstrate the desiccation process, 2) implementing a scalable version of Subsurface Transport Over Multiple Phases–Water-Air-Energy (STOMP-WAE), and 3) performing numerical experiments to identify the factors controlling the performance of a desiccation system.

  15. Low consumption air conditioning. Desiccation and evaporation; Climatisation basse consommation. Dessication et evaporation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    This technical note recalls the principle of air treatment by desiccation and evaporative cooling and gives some cost and performance indications about this technique. An example of realization is presented. (J.S.)

  16. Development of desiccant based air conditioning for hotels and motels. Final report, phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Banks, N.J.

    1994-10-01

    This report contains final reports from two phases of field tests: Phase I at the Marriott Courtyard in West Palm Beach, completed in October 1991, and Phase II at the Walt Disney World Swan Hotel in Orlando, completed in August 1993. The goal was to measure the performance and reliability of the desiccant units. The successfull program proved the value of the gas-fired desiccant technology to the hospitality industry. The desiccant units reduced moisture by 15 to 20% relative humidity. Measurements of temperature, humidity, and wallboard moisture content showed a dramatic reduction in the humidity levels experienced prior to installation of the units and in the control areas without desiccants. Moisture damage was kept in check and remodelling due to it was eliminated.

  17. Experimental analysis on performance of high temperature heat pump and desiccant wheel system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Deng, Na

    2013-01-01

    In order to solve the problem of high energy consumption for regeneration of desiccant wheel in the rotary desiccant system, high temperature heat pump and desiccant wheel (HTHP&DW) system and corresponding air conditioning unit is built and tested in the extensive thermal hygrometric environment....... When the mixture refrigerant BY-3 is involved in the air source heat pump, the supply air temperatures are in the range as expected except that when in the extreme hot environment (above 36°C), dehumidification capability are satisfied and the regeneration temperatures can satisfy the regeneration...... requirement of desiccant without additional heat. It is also found that outdoor air temperature, humidity ratio and regeneration air flow rate have great impact on the performance of heat pump based on the coefficient of performance (COP) evaluated. COP is not quite high, as the maximum value is 2.26 for heat...

  18. The effect of desiccation on viability and membrane lipid composition of Acer pseudoplatanus seeds

    Directory of Open Access Journals (Sweden)

    Stanisława Pukacka

    2014-02-01

    Full Text Available The viability of desiccation-intolerant sycamore (Acer pseudoplatanus L. seeds during desiccation was investigated by tetrazolium and by a germinability test, together with membrane permeability and membrane phospholipid composition. Loss of viability was associated with an increase of solute leakage, reduced content of all phospholipid groups, decrease of unsaturated fatty acids and the unsaturated/saturated fatty acids ratio. Growth of malondialdehyde content was also observed. Some results were compared with those for tolerant to desiccation Norway maple (Acer platanoides L. seeds. The results indicate active participation of membranes in the desiccation process in tolerant seeds and their decomposition in intolerant ones. The destruction of membranes was the result of lipid peroxidation, probably due to the free radical effect.

  19. Influence of osmotic stress on desiccation and irradiation tolerance of (hyper)-thermophilic microorganisms.

    Science.gov (United States)

    Beblo-Vranesevic, Kristina; Galinski, Erwin A; Rachel, Reinhard; Huber, Harald; Rettberg, Petra

    2017-01-01

    This study examined the influence of prior salt adaptation on the survival rate of (hyper)-thermophilic bacteria and archaea after desiccation and UV or ionizing irradiation treatment. Survival rates after desiccation of Hydrogenothermus marinus and Archaeoglobus fulgidus increased considerably when the cells were cultivated at higher salt concentrations before drying. By doubling the concentration of NaCl, a 30 times higher survival rate of H. marinus after desiccation was observed. Under salt stress, the compatible solute diglycerol phosphate in A. fulgidus and glucosylglycerate in H. marinus accumulated in the cytoplasm. Several different compatible solutes were added as protectants to A. fulgidus and H. marinus before desiccation treatment. Some of these had similar effects as intracellularly produced compatible solutes. The survival rates of H. marinus and A. fulgidus after exposure to UV-C (254 nm) or ionizing X-ray/gamma radiation were irrespective of the salt-induced synthesis or the addition of compatible solutes.

  20. Responses of the Lichen Photobiont Trebouxia erici to Desiccation and Rehydration (II) Proteomics

    Science.gov (United States)

    Lichen desiccation tolerance is associated with cellular protection mechanisms directed against the oxidative stress produced during dehydration and/or rehydration, however, these mechanisms are not well understood. In other poikilohydric organisms, changes in the synthesis of proteins have bee...

  1. Low-Flow Liquid Desiccant Air Conditioning: General Guidance and Site Considerations

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.; Herrmann, L.; Deru, M.; Clark, J.

    2014-09-01

    Dehumidification or latent cooling in buildings is an area of growing interest that has been identified as needing more research and improved technologies for higher performance. Heating, ventilating, and air-conditioning (HVAC) systems typically expend excessive energy by using overcool-and-reheat strategies to dehumidify buildings. These systems first overcool ventilation air to remove moisture and then reheat the air to meet comfort requirements. Another common strategy incorporates solid desiccant rotors that remove moisture from the air more efficiently; however, these systems increase fan energy consumption because of the high airside pressure drop of solid desiccant rotors and can add heat of absorption to the ventilation air. Alternatively, liquid desiccant air-conditioning (LDAC) technology provides an innovative dehumidification solution that: (1) eliminates the need for overcooling and reheating from traditional cooling systems; and (2) avoids the increased fan energy and air heating from solid desiccant rotor systems.

  2. Construction and initial operation of the combined solar thermal and electric desiccant cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Enteria, Napoleon; Yoshino, Hiroshi; Mochida, Akashi; Takaki, Rie [Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Satake, Akira [Technical Research Institute, Maeda Corporation, Tokyo 179-8914 (Japan); Yoshie, Ryuichiro [Faculty of Engineering, Tokyo Polytechnic University, Atsugi 243-0297 (Japan); Mitamura, Teruaki [Faculty of Engineering, Ashikaga Institute of Technology, Ashikaga 326-8558 (Japan); Baba, Seizo [Earth Clean Tohoku Co., Ltd., Sendai 984-0038 (Japan)

    2009-08-15

    This paper reports the constructed combined solar thermal and electric desiccant cooling system - its initial operation and operational procedures. The system, as designed, can be operated during nighttime and daytime. The nighttime operation is for thermal energy storage using the auxiliary electric heater, while the daytime operation is for solar energy collection and desiccant cooling. Ongoing experimental evaluation is being undertaken to observe and determine the long-term performance of the system. (author)

  3. The response of foodborne pathogens to osmotic and desiccation stresses in the food chain

    DEFF Research Database (Denmark)

    Burgess, Catherine M.; Gianotti, Andrea; Gruzdev, Nadia

    2016-01-01

    In combination with other strategies, hyperosmolarity and desiccation are frequently used by the food processing industry as a means to prevent bacterial proliferation, and particularly that of foodborne pathogens, in food products. However, it is increasingly observed that bacteria, including...... human pathogens, encode mechanisms to survive and withstand these stresses. This review provides an overview of the mechanisms employed by Salmonella spp., Shiga toxin producing E. coli, Cronobacter spp., Listeria monocytogenes and Campylobacter spp. to tolerate osmotic and desiccation stresses...

  4. Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.(C) 2007 Yan Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  5. Low-Flow Liquid Desiccant Air-Conditioning: Demonstrated Performance and Cost Implications

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.; Herrmann, L.; Deru, M.; Clark, J.; Lowenstein, A.

    2014-09-01

    Cooling loads must be dramatically reduced when designing net-zero energy buildings or other highly efficient facilities. Advances in this area have focused primarily on reducing a building's sensible cooling loads by improving the envelope, integrating properly sized daylighting systems, adding exterior solar shading devices, and reducing internal heat gains. As sensible loads decrease, however, latent loads remain relatively constant, and thus become a greater fraction of the overall cooling requirement in highly efficient building designs, particularly in humid climates. This shift toward latent cooling is a challenge for heating, ventilation, and air-conditioning (HVAC) systems. Traditional systems typically dehumidify by first overcooling air below the dew-point temperature and then reheating it to an appropriate supply temperature, which requires an excessive amount of energy. Another dehumidification strategy incorporates solid desiccant rotors that remove water from air more efficiently; however, these systems are large and increase fan energy consumption due to the increased airside pressure drop of solid desiccant rotors. A third dehumidification strategy involves high flow liquid desiccant systems. These systems require a high maintenance separator to protect the air distribution system from corrosive desiccant droplet carryover and so are more commonly used in industrial applications and rarely in commercial buildings. Both solid desiccant systems and most high-flow liquid desiccant systems (if not internally cooled) add sensible energy which must later be removed to the air stream during dehumidification, through the release of sensible heat during the sorption process.

  6. Campomanesia adamantium (Cambess.) O. Berg seed desiccation: influence on vigor and nucleic acids.

    Science.gov (United States)

    Dresch, Daiane M; Masetto, Tathiana E; Scalon, Silvana P Q

    2015-01-01

    The aim of this study was to evaluate the sensitivity of Campomanesia adamantium seeds to desiccation by drying in activated silica gel (fast) and under laboratory conditions (slow). To assess the sensitivity of the seeds to desiccation, we used drying with silica gel and drying under laboratory conditions (25 °C), in order to obtain seeds with moisture content of 45, 35, 30, 25, 20, 15, 10 and 5%. The physiological potential of the seeds after desiccation was evaluated by measuring primary root protrusion, percentage of normal seedlings, germination seed index, seedling length, total seedling dry mass, electrical conductivity and DNA and RNA integrities. The C. adamantium seeds were sensitive to desiccation and to a reduction in moisture content to 21.1% or less by desiccation using silica gel, and to 17.2% or less by desiccation under laboratory conditions; impairment of the physiological potential of the seeds was observed at these low moisture content levels. The integrity of the seed genomic DNA was not affected after drying seeds in the two methods. However, drying in silica gel to 4.5% moisture content and drying under laboratory conditions to 5.4% moisture content resulted in the loss of seed RNA integrity.

  7. Extracellular superoxide production, viability and redox poise in response to desiccation in recalcitrant Castanea sativa seeds.

    Science.gov (United States)

    Roach, Thomas; Beckett, Richard P; Minibayeva, Farida V; Colville, Louise; Whitaker, Claire; Chen, Hongying; Bailly, Christophe; Kranner, Ilse

    2010-01-01

    Reactive oxygen species (ROS) are implicated in seed death following dehydration in desiccation-intolerant 'recalcitrant' seeds. However, it is unknown if and how ROS are produced in the apoplast and if they play a role in stress signalling during desiccation. We studied intracellular damage and extracellular superoxide (O(2)(.-)) production upon desiccation in Castanea sativa seeds, mechanisms of O(2)(.-) production and the effect of exogenously supplied ROS. A transient increase in extracellular O(2)(.-) production by the embryonic axes preceded significant desiccation-induced viability loss. Thereafter, progressively more oxidizing intracellular conditions, as indicated by a significant shift in glutathione half-cell reduction potential, accompanied cell and axis death, coinciding with the disruption of nuclear membranes. Most hydrogen peroxide (H(2)O(2))-dependent O(2)(.-) production was found in a cell wall fraction that contained extracellular peroxidases (ECPOX) with molecular masses of approximately 50 kDa. Cinnamic acid was identified as a potential reductant required for ECPOX-mediated O(2)(.-) production. H(2)O(2), applied exogenously to mimic the transient ROS burst at the onset of desiccation, counteracted viability loss of sub-lethally desiccation-stressed seeds and of excised embryonic axes grown in tissue culture. Hence, extracellular ROS produced by embryonic axes appear to be important signalling components involved in wound response, regeneration and growth.

  8. What distinguishes cyanobacteria able to revive after desiccation from those that cannot: the genome aspect.

    Science.gov (United States)

    Murik, Omer; Oren, Nadav; Shotland, Yoram; Raanan, Hagai; Treves, Haim; Kedem, Isaac; Keren, Nir; Hagemann, Martin; Pade, Nadin; Kaplan, Aaron

    2017-02-01

    Filamentous cyanobacteria are the main founders and primary producers in biological desert soil crusts (BSCs) and are likely equipped to cope with one of the harshest environmental conditions on earth including daily hydration/dehydration cycles, high irradiance and extreme temperatures. Here, we resolved and report on the genome sequence of Leptolyngbya ohadii, an important constituent of the BSC. Comparative genomics identified a set of genes present in desiccation-tolerant but not in dehydration-sensitive cyanobacteria. RT qPCR analyses showed that the transcript abundance of many of them is upregulated during desiccation in L. ohadii. In addition, we identified genes where the orthologs detected in desiccation-tolerant cyanobacteria differs substantially from that found in desiccation-sensitive cells. We present two examples, treS and fbpA (encoding trehalose synthase and fructose 1,6-bisphosphate aldolase respectively) where, in addition to the orthologs present in the desiccation-sensitive strains, the resistant cyanobacteria also possess genes with different predicted structures. We show that in both cases the two orthologs are transcribed during controlled dehydration of L. ohadii and discuss the genetic basis for the acclimation of cyanobacteria to the desiccation conditions in desert BSC.

  9. Shoot desiccation and hydraulic failure in temperate woody angiosperms during an extreme summer drought.

    Science.gov (United States)

    Nardini, Andrea; Battistuzzo, Marta; Savi, Tadeja

    2013-10-01

    Plant water status and hydraulics were measured in six woody angiosperms growing in a karstic woodland, during an extreme summer drought. Our aim was to take advantage of an unusual climatic event to identify key traits related to species-specific drought damage. The damage suffered by different species was assessed in terms of percentage of individuals showing extensive crown desiccation. Stem water potential (Ψstem ) and percent loss of hydraulic conductivity (PLC) were measured in healthy and desiccated individuals. Vulnerability to cavitation was assessed in terms of stem water potential inducing 50% PLC (Ψ50 ). Stem density (ρstem ) was also measured. Species-specific percentage of desiccated individuals was correlated to Ψ50 and ρstem . Crown desiccation was more widespread in species with less negative Ψ50 and lower ρstem . Desiccated individuals had lower Ψstem and higher PLC than healthy ones, suggesting that hydraulic failure was an important mechanism driving shoot dieback. Drought-vulnerable species showed lower safety margins (Ψstem  - Ψ50 ) than resistant ones. The Ψ50 , safety margins and ρstem values emerge as convenient traits to be used for tentative predictions of differential species-specific impact of extreme drought events on a local scale. The possibility that carbohydrate depletion was also involved in induction of desiccation symptoms is discussed. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  10. Anhydrobiosis quotient: a novel approach to evaluate stability in desiccated bacterial cells.

    Science.gov (United States)

    Hernández, A; Zamora, J; González, N; Salazar, E; Sánchez, M D C

    2009-08-01

    The major objective of this study was the development of a methodology to quantify the anhydrobiotic ability of bacteria and its application to evaluate the stability of desiccated bacterial cells using the biocontrol agent Tsukamurella paurometabola C-924 as a model of anhydrobiote. Tsukamurella paurometabola C-924 was desiccated by spray-drying. Samples of desiccated cells were stored at several temperatures and viability and residual moisture were measured at different intervals of time. The term anhydrobiosis quotient (epsilon) was defined, and a scale of anhydrobiotic ability for classifying micro-organisms in terms of tolerance to desiccation was established (1 < or = epsilon < or = 15). The anhydrobiosis quotient was used to evaluate the stability of the anhydrobiotic cells. As a main result, changes in the anhydrobiosis quotient at several temperatures were fitted using a reparameterized Weibull model, which was found to be robust for the prediction of the stability at 4 degrees C. A novel methodology was developed to evaluate the desiccated state in bacteria. The anhydrobiosis quotient allows the quantitative estimation of the anhydrobiotic ability, and the mathematical model developed allows the prediction of the desiccated state of bacterial populations. The new methodology could be applied in studying the anhydrobiosis state of bacterial populations as a predictive tool for industrial and environmental microbiology.

  11. Molecular strategies of the Caenorhabditis elegans dauer larva to survive extreme desiccation.

    Science.gov (United States)

    Erkut, Cihan; Vasilj, Andrej; Boland, Sebastian; Habermann, Bianca; Shevchenko, Andrej; Kurzchalia, Teymuras V

    2013-01-01

    Massive water loss is a serious challenge for terrestrial animals, which usually has fatal consequences. However, some organisms have developed means to survive this stress by entering an ametabolic state called anhydrobiosis. The molecular and cellular mechanisms underlying this phenomenon are poorly understood. We recently showed that Caenorhabditis elegans dauer larva, an arrested stage specialized for survival in adverse conditions, is resistant to severe desiccation. However, this requires a preconditioning step at a mild desiccative environment to prepare the organism for harsher desiccation conditions. A systems approach was used to identify factors that are activated during this preconditioning. Using microarray analysis, proteomics, and bioinformatics, genes, proteins, and biochemical pathways that are upregulated during this process were identified. These pathways were validated via reverse genetics by testing the desiccation tolerances of mutants. These data show that the desiccation response is activated by hygrosensation (sensing the desiccative environment) via head neurons. This leads to elimination of reactive oxygen species and xenobiotics, expression of heat shock and intrinsically disordered proteins, polyamine utilization, and induction of fatty acid desaturation pathway. Remarkably, this response is specific and involves a small number of functional pathways, which represent the generic toolkit for anhydrobiosis in plants and animals.

  12. A comparative study between Solenopsis invicta and Solenopsis richteri on tolerance to heat and desiccation stresses.

    Science.gov (United States)

    Chen, Jian; Rashid, Tahir; Feng, Guolei

    2014-01-01

    Solenopsis invicta and Solenopsis richteri are two very closely related invasive ant species; however, S. invicta is a much more successful invader. Physiological tolerance to abiotic stress has been hypothesized to be important to the success of an invasive species. In this study, we tested the hypothesis that S. invicta is more tolerant to heat and desiccation stress than S. richteri. The data strongly support our hypothesis. S. invicta was found to be significantly less vulnerable than S. richteri to both heat and desiccation stress. Despite S. richteri having significantly higher body water content, S. invicta was less sensitive to desiccation stress due to its significantly lower water loss rate (higher desiccation resistance). After the cuticular lipid was removed, S. invicta still had a significantly lower water loss rate than S. richteri, indicating that cuticular lipids were not the only factors accounting for difference in the desiccation resistance between these two species. Since multiple biological and/or ecological traits can contribute to the invasion success of a particular species, whether the observed difference in tolerance to heat and desiccation stresses is indeed associated with the variation in invasion success between these two species can only be confirmed by further extensive comparative study.

  13. Desiccation tolerance of gastrointestinal nematode third-stage larvae: exploring the effects on survival and fitness.

    Science.gov (United States)

    Chylinski, C; Lherminé, E; Coquille, M; Cabaret, J

    2014-08-01

    The free-living third-stage larvae (L3) of gastrointestinal nematodes are able to tolerate extreme weather conditions such as desiccation, but little is known about the consequent effects this has on their fitness. This study explored how the desiccation of Haemonchus contortus L3 larvae affected their absolute fitness by examining their success at consequent life cycle stages for a complete generation, and comparing them against a control. The stages examined include establishment, fecundity, larval development and pathogenicity. The results show that while desiccation greatly reduced the survival of the L3 prior to infection in sheep, their absolute fitness was not negatively impacted. Instead, it appears desiccation slightly augmented H. contortus fitness by triggering increases in fecundity. The study further explored what influence different gastrointestinal nematode (GIN) species (H. contortus, Trichostrongylus colubriformis, Teladorsagia circumcincta), isolates and age of L3 had on their capacity to revive following various periods of desiccation. The results showed desiccation tolerance varied as a function of each of these variables. The greatest L3 survival was found in Te. circumcincta followed by Tr. colubriformis and finally H. contortus. Significant variation was observed between individual species isolates and as a function of age. The results of this study carry important practical implications for the epidemiological understanding of gastrointestinal nematode species of economic importance.

  14. A comparative study between Solenopsis invicta and Solenopsis richteri on tolerance to heat and desiccation stresses.

    Directory of Open Access Journals (Sweden)

    Jian Chen

    Full Text Available Solenopsis invicta and Solenopsis richteri are two very closely related invasive ant species; however, S. invicta is a much more successful invader. Physiological tolerance to abiotic stress has been hypothesized to be important to the success of an invasive species. In this study, we tested the hypothesis that S. invicta is more tolerant to heat and desiccation stress than S. richteri. The data strongly support our hypothesis. S. invicta was found to be significantly less vulnerable than S. richteri to both heat and desiccation stress. Despite S. richteri having significantly higher body water content, S. invicta was less sensitive to desiccation stress due to its significantly lower water loss rate (higher desiccation resistance. After the cuticular lipid was removed, S. invicta still had a significantly lower water loss rate than S. richteri, indicating that cuticular lipids were not the only factors accounting for difference in the desiccation resistance between these two species. Since multiple biological and/or ecological traits can contribute to the invasion success of a particular species, whether the observed difference in tolerance to heat and desiccation stresses is indeed associated with the variation in invasion success between these two species can only be confirmed by further extensive comparative study.

  15. Differential gene expression in Pyropia columbina (Bangiales, Rhodophyta under natural hydration and desiccation conditions

    Directory of Open Access Journals (Sweden)

    Loretto Contreras-Porcia

    2013-11-01

    Full Text Available In rocky shores, desiccation is triggered by daily tide changes, and experimental evidence suggests that local distribution of algal species across the intertidal rocky zone is related to their capacity to tolerate desiccation. In this context, the permanence of Pyropia columbina in the high intertidal rocky zone is explained by its exceptional physiological tolerance to desiccation. This study explored the metabolic pathways involved in tolerance to desiccation in the Chilean P. columbina, by characterizing its transcriptome under contrasting conditions of hydration. We obtained 1,410 ESTs from two subtracted cDNA libraries in naturally hydrated and desiccated fronds. Results indicate that transcriptome from both libraries contain transcripts from diverse metabolic pathways related to tolerance. Among the transcripts differentially expressed, 15% appears involved in protein synthesis, processing and degradation, 14.4% are related to photosynthesis and chloroplast, 13.1% to respiration and mitochondrial function (NADH dehydrogenase and cytochrome c oxidase proteins, 10.6% to cell wall metabolism, and 7.5% are involved in antioxidant activity, chaperone and defense factors (catalase, thioredoxin, heat shock proteins, cytochrome P450. Both libraries highlight the presence of genes/proteins never described before in algae. This information provides the first molecular work regarding desiccation tolerance in P. columbina, and helps, to some extent, explaining the classical patterns of ecological distribution described for algae across the intertidal zone.

  16. Distinct contractile and cytoskeletal protein patterns in the Antarctic midge are elicited by desiccation and rehydration.

    Science.gov (United States)

    Li, Aiqing; Benoit, Joshua B; Lopez-Martinez, Giancarlo; Elnitsky, Michael A; Lee, Richard E; Denlinger, David L

    2009-05-01

    Desiccation presents a major challenge for the Antarctic midge, Belgica antarctica. In this study, we use proteomic profiling to evaluate protein changes in the larvae elicited by dehydration and rehydration. Larvae were desiccated at 75% relative humidity (RH) for 12 h to achieve a body water loss of 35%, approximately half of the water that can be lost before the larvae succumb to dehydration. To evaluate the rehydration response, larvae were first desiccated, then rehydrated for 6 h at 100% RH and then in water for 6 h. Controls were held continuously at 100% RH. Protein analysis was performed using 2-DE and nanoscale capillary LC/MS/MS. Twenty-four identified proteins changed in abundance in response to desiccation: 16 were more abundant and 8 were less abundant; 84% of these proteins were contractile or cytoskeletal proteins. Thirteen rehydration-regulated proteins were identified: 8 were more abundant and 5 were less abundant, and 69% of these proteins were also contractile or cytoskeletal proteins. Additional proteins responsive to desiccation and rehydration were involved in functions including stress responses, energy metabolism, protein synthesis, glucogenesis and membrane transport. We conclude that the major protein responses elicited by both desiccation and rehydration are linked to body contraction and cytoskeleton rearrangements.

  17. Heat and desiccation tolerances of Heterorhabditis bacteriophora strains and relationships between their tolerances and some bioecological characteristics

    Directory of Open Access Journals (Sweden)

    TC Ulu

    2014-06-01

    Full Text Available Heat tolerances, desiccation tolerances, and effectiveness of 10 Heterorhabditis bacteriophora strains isolated from different climatic regions in Turkey were analyzed in laboratory conditions. All strains were exposed to heat and desiccation conditions to determine their tolerance levels, and different doses of the strains were applied to the host larva to detect infection capabilities. Correlations between heat and desiccation tolerances as well as effectiveness of all strains were investigated. Moreover, relationships between the tolerances and geographic origins were examined. The results showed that there was no correlation between desiccation tolerance and effectiveness as well as between heat and desiccation tolerances. However, a significant correlation was found between heat tolerance and effectiveness. Furthermore, there was a correlation between heat tolerances and origins, but no correlation existed between desiccation tolerances and origins.

  18. Proteomics of seed development, desiccation tolerance, germination and vigor.

    Science.gov (United States)

    Wang, Wei-Qing; Liu, Shu-Jun; Song, Song-Quan; Møller, Ian Max

    2015-01-01

    Proteomics, the large-scale study of the total complement of proteins in a given sample, has been applied to all aspects of seed biology mainly using model species such as Arabidopsis or important agricultural crops such as corn and rice. Proteins extracted from the sample have typically been separated and quantified by 2-dimensional polyacrylamide gel electrophoresis followed by liquid chromatography and mass spectrometry to identify the proteins in the gel spots. In this way, qualitative and quantitative changes in the proteome during seed development, desiccation tolerance, germination, dormancy release, vigor alteration and responses to environmental factors have all been studied. Many proteins or biological processes potentially important for each seed process have been highlighted by these studies, which greatly expands our knowledge of seed biology. Proteins that have been identified to be particularly important for at least two of the seed processes are involved in detoxification of reactive oxygen species, the cytoskeleton, glycolysis, protein biosynthesis, post-translational modifications, methionine metabolism, and late embryogenesis-abundant (LEA) proteins. It will be useful for molecular biologists and molecular plant breeders to identify and study genes encoding particularly interesting target proteins with the aim to improve the yield, stress tolerance or other critical properties of our crop species. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  19. Desiccation tolerance of Rhamnidium elaeocarpum Reissek (Rhamnaceae seeds

    Directory of Open Access Journals (Sweden)

    Lílian Abadia da Silva

    2015-05-01

    Full Text Available This study aimed to investigate the desiccation tolerance of Rhamnidium elaeocarpum Reissek seeds through physiological and biochemical alterations. Fruit were collected from the municipality of Jaupaci, Goias State, Brazil, when the water content of their seeds had a 37% wet basis (w.b. and the seeds were subsequently kept in a drying oven with air circulation at a temperature of 35ºC until a water content was reached of 20 to 12% (w.b.. The following parameters were evaluated: germination, germination speed index, emergence, emergence speed index, electrical conductivity and respiration rate. Furthermore, the electrophoretic profile of the isoenzymes: catalase, peroxidase and esterase, the enzymatic activities of endo-β-mannanase and α-amylase and the electrophoretic analysis of heat-resistant proteins were performed. A higher germination speed and respiratory rate was obtained for seeds with a water content of 12% w.b., and the activity of catalase isoforms was more pronounced in seeds with a higher degree of dehydration, which was in contrast to peroxidase, showed decreased activity. The seeds contained heat-resistant proteins of low molecular weight that ranged from 48.7 to 13.2 kDa. We found that the acquisition of drying tolerance in R. Elaeocarpum Reissek seeds is associated more with catalase than with esterase and peroxidase.

  20. IMPROVING ENERGY EFFICIENCY AND REDUCING COSTS IN THE DRINKING WATER SUPPLY INDUSTRY: An ENERGY STAR Resource Guide for Energy and Plant Managers

    Energy Technology Data Exchange (ETDEWEB)

    Melody, Moya; Dunham Whitehead, Camilla; Brown, Richard

    2010-09-30

    As American drinking water agencies face higher production costs, demand, and energy prices, they seek opportunities to reduce costs without negatively affecting the quality of the water they deliver. This guide describes resources for cost-effectively improving the energy efficiency of U.S. public drinking water facilities. The guide (1) describes areas of opportunity for improving energy efficiency in drinking water facilities; (2) provides detailed descriptions of resources to consult for each area of opportunity; (3) offers supplementary suggestions and information for the area; and (4) presents illustrative case studies, including analysis of cost-effectiveness.

  1. Desiccation tolerance mechanism in resurrection fern-ally Selaginella tamariscina revealed by physiological and proteomic analysis.

    Science.gov (United States)

    Wang, Xiaonan; Chen, Sixue; Zhang, Heng; Shi, Lei; Cao, Fenglin; Guo, Lihai; Xie, Yongming; Wang, Tai; Yan, Xiufeng; Dai, Shaojun

    2010-12-03

    Drought is one of the most severe limitations to plant growth and productivity. Resurrection plants have evolved a unique capability to tolerate desiccation in vegetative tissues. Fern-ally Selaginella tamariscina (Beauv.) is one of the most primitive vascular resurrection plants, which can survive a desiccated state and recover when water becomes available. To better understand the mechanism of desiccation tolerance, we have applied physiological and proteomic analysis. Samples of S. tamariscina were water-deprived for up to seven days followed by 12 h of rewatering. Our results showed that endogenous abscisic acid (ABA) increased to regulate dehydration-responsive genes/proteins and physiological processes. In the course of dehydration, the contents of osmolytes represented by soluble sugars and proline were increased to maintain cell structure integrity. The activities of four antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione reductase (GR)) also increased. In contrast, both the rate of photosynthesis and the chlorophyll content decreased, and plasma membrane integrity was lost. We identified 138 desiccation-responsive two-dimensional electrophoresis (2-DE) spots, representing 103 unique proteins. Hierarchical clustering analysis revealed that 83% of the proteins were down-regulated upon dehydration. They were mainly involved in photosynthesis, carbohydrate and energy metabolism, stress and defense, protein metabolism, signaling, membrane/transport, cell structure, and cell division. The dynamic expression changes of the desiccation-responsive proteins provide strong evidence that cell structure modification, photosynthesis reduction, antioxidant system activation, and protein post-transcriptional/translational modifications are essential to the poikilochlorophyllous fern-ally S. tamariscina in response to dehydration. In addition, our comparative analysis of dehydration-responsive proteins in vegetative tissues

  2. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological and molecular mechanisms.

    Science.gov (United States)

    Holzinger, Andreas; Karsten, Ulf

    2013-01-01

    Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological, and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. While members of the Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This aids in maintaining structural integrity in the dried state and allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics, and/or metabolomics are urgently needed to better understand the molecular

  3. A low-cost-solar liquid desiccant system for residential cooling

    Science.gov (United States)

    Ware, Joel D., III

    The use of liquid desiccants for dehumidification of heating, ventilation, and air conditioning (HVAC) process air is becoming a more promising concept as the drive for energy conservation continues to grow. Recently, liquid desiccant systems have been implemented on the commercial level in conjunction with evaporative coolers and have recorded energy savings upwards of 50%. The aim of this research is to test the potential liquid desiccant systems have on the residential level when paired with a conventional vapor compression cycle and to construct a system that would overcome some of its barriers to the residential market. A complete low-cost-solar liquid desiccant system was designed, constructed, and tested in the Off-Grid Zero Emissions Building (OGZEB) at the Florida State University. Key design characteristics include turbulent process air flow through the conditioner and airside heating in the regenerator. The system was tested in the two following ways: (1) for the energy savings while maintaining a constant temperature over a twenty four hour period and (2) for the energy savings over a single cooling cycle. The liquid desiccant system achieved a maximum energy savings of 38% over a complete day and 52% over a single cooling cycle. It was projected that the system has the potential to save 1064 kWh over the course of a year. When combined with a renewable source of heat for regeneration, liquid desiccant systems become very cost effective. The levelized cost of energy for the combination of the liquid desiccant system and solar thermal collectors was calculated to be 7.06 C/kWh with a payback period of 4.4 years. This research provides evidence of the technology's potential on the residential sector and suggests ways for it to become competitive in the market.

  4. Genes Associated with Desiccation and Osmotic Stress in Listeria monocytogenes as Revealed by Insertional Mutagenesis

    Science.gov (United States)

    Hingston, Patricia A.; Piercey, Marta J.

    2015-01-01

    Listeria monocytogenes is a foodborne pathogen whose survival in food processing environments may be associated with its tolerance to desiccation. To probe the molecular mechanisms used by this bacterium to adapt to desiccation stress, a transposon library of 11,700 L. monocytogenes mutants was screened, using a microplate assay, for strains displaying increased or decreased desiccation survival (43% relative humidity, 15°C) in tryptic soy broth (TSB). The desiccation phenotypes of selected mutants were subsequently assessed on food-grade stainless steel (SS) coupons in TSB plus 1% glucose (TSB-glu). Single transposon insertions in mutants exhibiting a change in desiccation survival of >0.5 log CFU/cm2 relative to that of the wild type were determined by sequencing arbitrary PCR products. Strain morphology, motility, and osmotic stress survival (in TSB-glu plus 20% NaCl) were also analyzed. The initial screen selected 129 desiccation-sensitive (DS) and 61 desiccation-tolerant (DT) mutants, out of which secondary screening on SS confirmed 15 DT and 15 DS mutants. Among the DT mutants, seven immotile and flagellum-less strains contained transposons in genes involved in flagellum biosynthesis (fliP, flhB, flgD, flgL) and motor control (motB, fliM, fliY), while others harbored transposons in genes involved in membrane lipid biosynthesis, energy production, potassium uptake, and virulence. The genes that were interrupted in the 15 DS mutants included those involved in energy production, membrane transport, protein metabolism, lipid biosynthesis, oxidative damage control, and putative virulence. Five DT and 14 DS mutants also demonstrated similar significantly (P < 0.05) different survival relative to that of the wild type when exposed to osmotic stress, demonstrating that some genes likely have similar roles in allowing the organism to survive the two water stresses. PMID:26025900

  5. Desiccation stress and tolerance in green algae: Consequences for ultrastructure, physiological and molecular mechanisms

    Directory of Open Access Journals (Sweden)

    Andreas eHolzinger

    2013-08-01

    Full Text Available Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. For example, Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics and/or metabolomics are urgently needed to better understand the molecular mechanisms involved in desiccation-stress physiology of

  6. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological and molecular mechanisms

    Science.gov (United States)

    Holzinger, Andreas; Karsten, Ulf

    2013-01-01

    Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological, and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. While members of the Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This aids in maintaining structural integrity in the dried state and allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics, and/or metabolomics are urgently needed to better understand the molecular

  7. Experimental study on solar desiccant cooling system. 2nd Report; Taiyonetsu kudo desiccant cooling system no jikkenteki kento. 2

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H.; Funato, H. [Fukuoka Institute of Technology, Fukuoka (Japan); Kuma, T. [Seibu Giken Co. Ltd., Fukuoka (Japan)

    1996-10-27

    Study has been made about a desiccant cleaning system using solar heated water for regenerating the dehumidifier. A dehumidifier and evaporation coolers are combined to attain a synergistic effect in dehumidifying and cooling the air in the house. The simultaneous control of humidity and temperature, however, is quite difficult. Under the circumstances, an evaporation cooler was removed from the outdoor air intake side, to leave a humidifier alone for the control of humidity only. In addition, the length of the dehumidifier was reduced into half for saving fan driving power and for downscaling the model. With only one evaporation cooler in operation that is installed at the exhaust side, the cooling effect is diminished by half. For dealing with the situation, ultrasonic atomization is performed at the exhaust side evaporation cooler for the improvement of the air cooling effect for the next sensible heat exchanger (intake side). The return air is heated by the solar heater water (approximately 60{degree}C hot), regenerates the dehumidifier, and then exhausted. The atomization process elevates the cooling effect, and the resultant cooling effect was as high as that expected from a 2-cooler setup. The dehumidification effect, however, lowers a little. Exclusion of the atomization process will enhance the dehumidification effect, but will reduce the cooling effect as well. 3 refs., 8 figs., 3 tabs.

  8. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  9. Performance Assessment of a Desiccant Cooling System in a CHP Application with an IC Engine

    Energy Technology Data Exchange (ETDEWEB)

    Jalalzadeh-Azar, A. A.; Slayzak, S.; Judkoff, R.; Schaffhauser, T.; DeBlasio, R.

    2005-04-01

    Performance of a desiccant cooling system was evaluated in the context of combined heat and power (CHP). The baseline system incorporated a desiccant dehumidifier, a heat exchanger, an indirect evaporative cooler, and a direct evaporative cooler. The desiccant unit was regenerated through heat recovery from a gas-fired reciprocating internal combustion engine. The system offered sufficient sensible and latent cooling capacities for a wide range of climatic conditions, while allowing influx of outside air in excess of what is typically required for commercial buildings. Energy and water efficiencies of the desiccant cooling system were also evaluated and compared with those of a conventional system. The results of parametric assessments revealed the importance of using a heat exchanger for concurrent desiccant post cooling and regeneration air preheating. These functions resulted in enhancement of both the cooling performance and the thermal efficiency, which are essential for fuel utilization improvement. Two approaches for mixing of the return air and outside air were examined, and their impact on the system cooling performance and thermal efficiency was demonstrated. The scope of the parametric analyses also encompassed the impact of improving the indirect evaporative cooling effectiveness on the overall cooling system performance.

  10. The effect of desiccation on the emission of volatile bromocarbons from two common temperate macroalgae

    Directory of Open Access Journals (Sweden)

    E. C. Leedham Elvidge

    2014-07-01

    Full Text Available Exposure of intertidal macroalgae during low tide has been linked to the emission of a variety of atmospherically-important trace gases into the coastal atmosphere. In recent years, several studies have investigated the role of inorganic iodine and organoiodides as antioxidants and their emission during exposure to combat oxidative stress, yet the role of organic bromine species during desiccation is less well understood. In this study the emission of dibromomethane (CH2Br2 and bromoform (CHBr3 during exposure and desiccation of two common temperate macroalgae, Fucus vesiculosus and Ulva intestinalis, is reported. Determination of the impact exposure may have on algal physiological processes is difficult as intertidal species are adapted to desiccation and may undergo varying degrees of desiccation before their physiology is affected. For this reason we include comparisons between photosynthetic capacity (Fv / Fm and halocarbon emissions during a desiccation time series. In addition, the role of rewetting with freshwater to simulate exposure to rain was also investigated. Our results show that an immediate flux of bromocarbons occurs upon exposure, followed by a decline in bromocarbon emissions. We suggest that this immediate bromocarbon pulse may be linked to volatilisation or emissions of existing bromocarbon stores from the algal surface rather than the production of bromocarbons as an antioxidant response.

  11. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

  12. Intraspecific variation in desiccation survival time of Aedes aegypti (L.) mosquito eggs of Australian origin.

    Science.gov (United States)

    Faull, Katherine J; Williams, Craig R

    2015-12-01

    Aedes aegypti (L.) mosquitoes preferentially oviposit in natural and artificial receptacles where their eggs are able to withstand drying as water levels fluctuate. Desiccation-resistant eggs also increase the potential for establishment in non-native habitats while providing logistical impediments to control programs. Viability and mean survival times of eggs stored under three dryness conditions for up to 367 days were investigated among three field-derived colonies of Australian Ae. aegypti to understand variation in desiccation survival. Further investigations compared egg survival between an established colony and its wild counterpart. Our results confirmed that Ae. aegypti eggs can withstand desiccation for extended periods of time with approximately 2-15% egg viability recorded after one year and viability remaining above 88% under all conditions through 56 days. Intraspecific variations in egg survival times were recorded, suggesting local adaptation while each of the colonies demonstrated a consistent preference for higher humidity. Egg volume varied between the populations, suggesting a relationship between egg volume and survival time, with the marginally larger eggs (Charters Towers and Innisfail) having greater desiccation resistance over the range of conditions. The strong survivorship of Charters Towers eggs in dry, warm conditions demonstrates the adaptive significance of a desiccation-resistant egg.

  13. Surviving metabolic arrest: photosynthesis during desiccation and rehydration in resurrection plants.

    Science.gov (United States)

    Challabathula, Dinakar; Puthur, Jos T; Bartels, Dorothea

    2016-02-01

    Photosynthesis is the key process that is affected by dehydration in plants. Desiccation-tolerant resurrection plants can survive conditions of very low relative water content. During desiccation, photosynthesis is not operational, but is recovered within a short period after rehydration. While homoiochlorophyllous resurrection plants retain their photosynthetic apparatus during desiccation, poikilochlorophyllous resurrection species dismantle chloroplasts and degrade chlorophyll but resynthesize them again during rehydration. Dismantling the chloroplasts avoids the photooxidative stress in poikilochlorophyllous resurrection plants, whereas it is minimized in homoiochlorophyllous plants through the synthesis of antioxidant enzymes and protective proteins or metabolites. Although the cellular protection mechanisms in both of these species vary, these mechanisms protect cells from desiccation-induced damage and restore photosynthesis upon rehydration. Several of the proteins synthesized during dehydration are localized in chloroplasts and are believed to play major roles in the protection of photosynthetic structures and in recovery in resurrection species. This review focuses on the strategies of resurrection plants in terms of how they protect their photosynthetic apparatus from oxidative stress during desiccation without membrane damage and with full recovery during rehydration. We review the role of the dehydration-induced protection mechanisms in chloroplasts and how photosynthesis is restored during rehydration.

  14. SOIL DESICCATION TECHNIQUES STRATEGIES FOR IMMOBILIZATION OF DEEP VADOSE CONTAMINANTS AT THE HANFORD CENTRAL PLATEAU

    Energy Technology Data Exchange (ETDEWEB)

    BENECKE MW; CHRONISTER GB; TRUEX MJ

    2012-01-30

    Deep vadose zone contamination poses some of the most difficult remediation challenges for the protection of groundwater at the Hanford Site where processes and technologies are being developed and tested for use in the on-going effort to remediate mobile contamination in the deep vadose zone, the area deep beneath the surface. Historically, contaminants were discharged to the soil along with significant amounts of water, which continues to drive contaminants deeper in the vadose zone toward groundwater. Soil desiccation is a potential in situ remedial technology well suited for the arid conditions and the thick vadose zone at the Hanford Site. Desiccation techniques could reduce the advance of contaminants by removing the pore water to slow the rate of contaminants movement toward groundwater. Desiccation technologies have the potential to halt or slow the advance of contaminants in unsaturated systems, as well as aid in reduction of contaminants from these same areas. Besides reducing the water flux, desiccation also establishes capillary breaks that would require extensive rewetting to resume pore water transport. More importantly, these techniques have widespread application, whether the need is to isolate radio nuclides or address chemical contaminant issues. Three different desiccation techniques are currently being studied at Hanford.

  15. Desiccation resistance reflects patterns of microhabitat choice in a Central American assemblage of wandering spiders.

    Science.gov (United States)

    Lapinski, Witold; Tschapka, Marco

    2014-08-01

    The lowland rainforest of northeastern Costa Rica harbours an assemblage of large wandering spider species belonging to three habitat subguilds: (1) semi-aquatic, (2) forest ground dwelling and (3) vegetation dwelling. We hypothesized that desiccation resistance should differ among species preferring different microhabitats and the associated microclimate. Desiccation resistance was assessed by: (1) measuring water loss rates of the spiders under relatively dry experimental conditions, and (2) recording desiccation susceptibility, i.e. the reactions of the spiders to a relatively dry environment. High water loss rates and desiccation susceptibility of the semi-aquatic and forest-ground-dwelling subguilds clearly mirrored the relatively humid microclimate of the understory. Significantly lower water loss rates and desiccation susceptibility of the vegetation-dwelling species reflected the highly variable, often dry and hot conditions of the rainforest canopy and forest edge habitats. Vegetation-dwelling wandering spiders are therefore physiologically better adapted to dry conditions than the semi-aquatic and forest-ground-dwelling species. The results illustrate the significance of physiological characteristics for explaining both species-specific habitat use and, in a larger context, niche partitioning within a community.

  16. The effect of desiccation on the emission of volatile bromocarbons from two common temperate macroalgae

    Science.gov (United States)

    Leedham Elvidge, E. C.; Phang, S.-M.; Sturges, W. T.; Malin, G.

    2015-01-01

    Exposure of intertidal macroalgae during low tide has been linked to the emission of a variety of atmospherically-important trace gases into the coastal atmosphere. In recent years, several studies have investigated the role of inorganic iodine and organoiodides as antioxidants and their emission during exposure to combat oxidative stress, yet the role of organic bromine species during desiccation is less well understood. In this study the emission of dibromomethane (CH2Br2) and bromoform (CHBr3) during exposure and desiccation of two common temperate macroalgae, Fucus vesiculosus and Ulva intestinalis, is reported. Determination of the impact exposure may have on algal physiological processes is difficult as intertidal species are adapted to desiccation and may undergo varying degrees of desiccation before their physiology is affected. For this reason we include comparisons between photosynthetic capacity (Fv/Fm) and halocarbon emissions during a desiccation time series. In addition, the role of rewetting with freshwater to simulate exposure to rain was also investigated. Our results show that an immediate flux of bromocarbons occurs upon exposure, followed by a decline in bromocarbon emissions. We suggest that this immediate bromocarbon pulse may be linked to volatilisation or emissions of existing bromocarbon stores from the algal surface rather than the production of bromocarbons as an antioxidant response.

  17. Desiccation induces accumulations of antheraxanthin and zeaxanthin in intertidal macro-alga Ulva pertusa (Chlorophyta.

    Directory of Open Access Journals (Sweden)

    Xiujun Xie

    Full Text Available For plants and algae, exposure to high light levels is deleterious to their photosynthetic machineries. It also can accelerate water evaporation and thus potentially lead to drought stress. Most photosynthetic organisms protect themselves against high light caused photodamages by xanthophyll cycle-dependent thermal energy dissipation. It is generally accepted that high light activates xanthophyll cycle. However, the relationship between xanthophyll cycle and drought stress remains ambiguous. Herein, Ulva pertusa (Chlorophyta, a representative perennial intertidal macro-algae species with high drought-tolerant capabilities and simple structures, was used to investigate the operation of xanthophyll cycle during desiccation in air. The results indicate that desiccation under dim light induced accumulation of antheraxanthin (Ax and zeaxanthin (Zx at the expense of violaxanthin (Vx. This accumulation could be arrested by dithiothreitol completely and by uncoupler (carbonyl cyanide p-trifluoromethoxyphenylhydrazone partially, implying the participation of Vx de-epoxidase in conversion of Vx to Ax and Zx. Treatment with inhibitors of electron transport along thylakoid membrane, e.g. DCMU, PG and DBMIB, did not significantly arrest desiccation-induced accumulation of Ax and Zx. We propose that for U. pertusa, besides excess light, desiccation itself could also induce accumulation of Ax and Zx. This accumulation could proceed without electron transport along thylakoid membrane, and is possibly resulting from the reduction of thylakoid lumen volume during desiccation. Considering the pleiotropic effects of Ax and Zx, accumulated Ax and Zx may function in protecting thylakoid membrane and enhancing thermal quenching during emersion in air.

  18. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

    Science.gov (United States)

    Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

    2017-01-12

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  19. Soybean performance as affected by desiccation time of Urochloa ruziziensis and grazing pressures

    Directory of Open Access Journals (Sweden)

    Julio Cezar Franchini

    Full Text Available Integrated crop-livestock farming system have demonstrated various economic and environmental advantages. However, there is lack of information on the effects of different desiccation times of Urochloa ruziziensis and grazing pressures on the soybean performance. This study aimed to evaluate the performance of three soybean cultivars, sown after different desiccation times of U. ruziziensis grazed at three heights during the 2012/13 growing season, in southern Brazil. The U. ruziziensis were continuously grazed for 6 months by 6, 4 and 2 animal units (AU per hectare, leading to average pasture heights of 15; 35; and 50 cm, respectively. Each pasture height constituted a different experiment. The experiments were laid out using randomized complete block design (RCBD with split-plot arrangement in four replications. The treatments consisted of four desiccation times (35; 28; 20; and 8 days before the soybean sowing, allocated in the main plots, and three soybean cultivars (Vmax RR; BMX Potência RR; and NA 5909 RR, distributed in the subplots. Increased interval between U. ruziziensis desiccation and soybean sowing resulted in higher soybean plant density and height, but the effects on soybean grain yields were not significant. The highest soybean grain yield was obtained when the pasture height was maintained in 35 cm, regardless of soybean cultivars. The performance of the three soybean cultivars was not influenced by the interaction between desiccation time and the pasture residue mass on the soil at soybean sowing, defined by the pasture height.

  20. Variations in desiccation tolerance in seeds of Eugenia pyriformis: dispersal at different stages of maturation

    Directory of Open Access Journals (Sweden)

    Edmir Vicente Lamarca

    Full Text Available ABSTRACT Eugenia pyriformis Cambess., known locally as uvaieira, a species of fruit-bearing tree with both pharmacological and gastronomic potential, has seeds which are sensitive to desiccation. The aim of this study was to analyse whether the degree of tolerance to desiccation of uvaieira seeds depends on the stage of maturation of the seeds at shedding. This, in turn, depends on the environmental conditions in which the seeds develop, including the accumulation of degree-days and rainfall in the period. Seeds were collected from the ripe fruit of parent plants located in the states of São Paulo and Minas Gerais, Brazil, submitted to drying and analysed for water content and germination. A completely randomised design was used in a 20 x 3 factorial scheme (source of material x level of drying. The degree of desiccation tolerance differs between region and period of collection, even for the same parent plant when the seeds are collected in different years. The water and thermal conditions of the environment during seed development modify the maturation cycle, the physiological quality and the acquisition of desiccation tolerance. In uvaieira seeds, desiccation tolerance depends on the physiological maturity of the seeds at the time of dispersal, which is associated with the environmental conditions.

  1. Do subtoxic levels of chlorate influence the desiccation tolerance of Egeria densa?

    Science.gov (United States)

    Palma, Alvaro T; Schwarz, Alex; Henríquez, Luís A; Alvarez, Ximena; Fariña, José M; Lu, Qimiao

    2013-02-01

    Among the different factors hypothesized to be responsible for the virtual disappearance of Egeria densa, once a dominant aquatic macrophyte in a southern Chile wetland ecosystem, are the negative effects of certain chemical compounds (mainly chlorate) and harsh environmental conditions (desiccation caused by prolonged atmospheric exposure). The authors performed an integrated experiment in which E. densa plants were first exposed for four weeks inside a mesocosm system to levels of chlorate that existed in the wetland at the time of the plant's demise and then exposed to desiccation conditions that also resembled those that the system had experienced. Hence, the authors tested the hypothesis that E. densa plants exposed to sublethal levels of chlorate are more susceptible to the deleterious effect of desiccation compared with plants that had not been exposed to chlorate. This hypothesis was tested by means of quantifying physiologically related parameters in plants right after the four weeks under water and then after the desiccation period of 6 h. Their results rejected this hypothesis, because all plants, regardless of their history, are equally affected by desiccation. Copyright © 2012 SETAC.

  2. Serratia entomophila bet gene induction and the impact of glycine betaine accumulation on desiccation tolerance.

    Science.gov (United States)

    Sheen, T R; O'Callaghan, M; Smalley, D J; Ronson, C W; Hurst, M R H

    2013-02-01

    The genes involved in choline transport and oxidation to glycine betaine in the biopesticidal bacterium Serratia entomophila were characterized, and the potential of osmoprotectants, coupled with increased NaCl concentrations, to improve the desiccation tolerance of this species was investigated. Serratia entomophila carries sequences similar to the Escherichia coli betTIBA genes encoding a choline transporter and dehydrogenase, a betaine aldehyde dehydrogenase and a regulatory protein. Disruption of betA abolished the ability of Ser. entomophila to utilize choline as a carbon source. Quantitative reverse-transcriptase PCR analysis revealed that betA transcription was reduced compared to that of the upstream genes in the operon, and that NaCl and choline induced bet gene expression. Glycine betaine and choline increased the NaCl tolerance of Ser. entomophila, and osmotically preconditioned cultures survived better than control cultures following desiccation and immediately after application to agricultural soil. Addition of glycine betaine and NaCl to growth medium can greatly enhance the desiccation survival of Ser. entomophila, and its initial survival in soil. Serratia entomophila is sensitive to desiccation and does not persist under low soil moisture conditions. Techniques described here for enhancing the desiccation survival of Ser. entomophila can be used to improve formulations of this bacterium, and allow its application under a wider range of environmental conditions. © 2012 AgResearch.

  3. Molecular approaches for improving desiccation tolerance: insights from the brine shrimp Artemia franciscana.

    Science.gov (United States)

    Hand, Steven C; Menze, Michael A

    2015-08-01

    We have evaluated the endogenous expression and molecular properties of selected Group 3 LEA proteins from Artemia franciscana , and the capacity of selected Groups 1 and 3 proteins transfected into various desiccation-sensitive cell lines to improve tolerance to drying. Organisms inhabiting both aquatic and terrestrial ecosystems frequently are confronted with the problem of water loss for multiple reasons--exposure to hypersalinity, evaporative water loss, and restriction of intracellular water due to freezing of extracellular fluids. Seasonal desiccation can become severe and lead to the production of tolerant propagules and entry into the state of anhydrobiosis at various stages of the life cycle. Such is the case for gastrula-stage embryos of the brine shrimp, Artemia franciscana. Physiological and biochemical responses to desiccation are central for survival and are multifaceted. This review will evaluate the impact of multiple late embryogenesis abundant proteins originating from A. franciscana, together with the non-reducing sugar trehalose, on prevention of desiccation damage at multiple levels of biological organization. Survivorship of desiccation-sensitive cells during water stress can be improved by use of the above protective agents, coupled to metabolic preconditioning and rapid cell drying. However, obtaining long-term stability of cells in the dried state at room temperature has not been accomplished and will require continued efforts on both the physicochemical and biological fronts.

  4. Group A PP2Cs evolved in land plants as key regulators of intrinsic desiccation tolerance.

    Science.gov (United States)

    Komatsu, Kenji; Suzuki, Norihiro; Kuwamura, Mayuri; Nishikawa, Yuri; Nakatani, Mao; Ohtawa, Hitomi; Takezawa, Daisuke; Seki, Motoaki; Tanaka, Maho; Taji, Teruaki; Hayashi, Takahisa; Sakata, Yoichi

    2013-01-01

    Vegetative desiccation tolerance is common in bryophytes, although this character has been lost in most vascular plants. The moss Physcomitrella patens survives complete desiccation if treated with abscisic acid (ABA). Group A protein phosphatases type 2C (PP2C) are negative regulators of abscisic acid signalling. Here we show that the elimination of Group A PP2C is sufficient to ensure P. patens survival to full desiccation, without ABA treatment, although its growth is severely hindered. Microarray analysis shows that the Group A PP2C-regulated genes exclusively overlap with genes exhibiting a high level of ABA induction. Group A PP2C disruption weakly affects ABA-activated kinase activity, indicating Group A PP2C action downstream of these kinases in the moss. We propose that Group A PP2C emerged in land plants to repress desiccation tolerance mechanisms, possibly facilitating plants propagation on land, whereas ABA releases the intrinsic desiccation tolerance from Group A PP2C regulation.

  5. Rapid reactivation of cyanobacterial photosynthesis and migration upon rehydration of desiccated marine microbial mats

    Directory of Open Access Journals (Sweden)

    Arjun eChennu

    2015-12-01

    Full Text Available Desiccated cyanobacterial mats are the dominant biological feature in the Earth's arid zones. While the response of desiccated cyanobacteria to rehydration is well documented for terrestrial systems, information about the response in marine systems is lacking. We used high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors and confocal laser microscopy to study this response in a desiccated microbial mat from Exmouth Gulf, Australia. During the initial 15 minutes after rehydration chlorophyll a concentrations increased 2-5 fold and cyanobacterial photosynthesis was re-established. Although the mechanism behind this rapid increase of chlorophyll a remains unknown, we hypothesize that it involves resynthesis from a precursor stored in desiccated cyanobacteria. The subsequent phase (15 min – 48 h involved migration of the reactivated cyanobacteria towards the mat surface, which led, together with a gradual increase in chlorophyll a, to a further increase in photosynthesis. We conclude that the response involving an increase in chlorophyll a and recovery of photosynthetic activity within minutes after rehydration is common for cyanobacteria from desiccated mats of both terrestrial and aquatic origin. However the response of upward migration and its triggering factor appears to be mat-specific and likely linked to other factors.

  6. Rapid Reactivation of Cyanobacterial Photosynthesis and Migration upon Rehydration of Desiccated Marine Microbial Mats

    KAUST Repository

    Chennu, Arjun

    2015-12-24

    Desiccated cyanobacterial mats are the dominant biological feature in the Earth’s arid zones. While the response of desiccated cyanobacteria to rehydration is well-documented for terrestrial systems, information about the response in marine systems is lacking. We used high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors, and confocal laser microscopy to study this response in a desiccated microbial mat from Exmouth Gulf, Australia. During the initial 15 min after rehydration chlorophyll a concentrations increased 2–5 fold and cyanobacterial photosynthesis was re-established. Although the mechanism behind this rapid increase of chlorophyll a remains unknown, we hypothesize that it involves resynthesis from a precursor stored in desiccated cyanobacteria. The subsequent phase (15 min–48 h) involved migration of the reactivated cyanobacteria toward the mat surface, which led, together with a gradual increase in chlorophyll a, to a further increase in photosynthesis. We conclude that the response involving an increase in chlorophyll a and recovery of photosynthetic activity within minutes after rehydration is common for cyanobacteria from desiccated mats of both terrestrial and marine origin. However, the response of upward migration and its triggering factor appear to be mat-specific and likely linked to other factors.

  7. Investigation of solar energy utilization in a novel desiccant based air conditioning system

    Energy Technology Data Exchange (ETDEWEB)

    Hurdodan, Ertac; Buyukalaca, Orhan [Department of Energy Systems Engineering, Faculty of Engineering, Osmaniye Korkut Ata University (Turkey)], email: ehurdogan@osmaniye.edu.tr, email: obuyukalaca@osmaniye.edu.tr; Yilmaz, Tuncay; Uckan, Irfan [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Cukurova University (Turkey)], email: tunyil@cu.edu.tr, email: iuckan@cu.edu.tr; Hepbasli, Arif [Department of Mechanical Engineering, College of Engineering, King Saud University (Saudi Arabia)], email: ahepbasli.c@ksu.edu.sa

    2011-07-01

    Desiccant-based air-conditioning systems are an alternative to traditional air conditioning units. They have superior humidity control and are usually used in health care facilities to reduce the airborne transmission of disease. In the present study, an innovative, desiccant-based air-conditioning system was designed and tested in Cukurova University, Adana, Turkey. A model for investigating the use of solar energy in the system was developed. Experimental temperatures throughout the cooling season of 2008 and solar radiation data, measured by the State Meteorological Affairs (DMI) over the period 1986-2006, were utilized in the model. A comparison was made between the results obtained from the model and those from the experiments and it was concluded that solar energy could be utilized in the system. Solar energy also increased the coefficient of performance (COP) of the system by between 50% and 120% and was shown to be a cost-effective way of regenerating the desiccant.

  8. An Overview of the Biology of the Desiccation-tolerant Resurrection Plant Myrothamnus flabellifolia

    Science.gov (United States)

    Moore, John P.; Lindsey, George G.; Farrant, Jill M.; Brandt, Wolf F.

    2007-01-01

    Background Myrothamnus flabellifolia is unique as the only woody resurrection plant. It is an important plant in southern Africa because of its widespread occurrence and usage in African medicine and traditional culture. Many reports have investigated facets of its biology and the mechanisms associated with its desiccation tolerance. Scope The general biology of the woody resurrection plant Myrothamnus flabellifolia is reviewed. The review focuses on the geography and ecology, systematic placement, evolution, morphology and reproductive ecology of M. flabellifolia as well as the wood anatomy and re-filling mechanism. In addition, the desiccation tolerance, ethnobotanical importance and medicinal properties of the plant are reviewed. Also, future research avenues are suggested, in particular the necessity to research the biogeography and systematics of the species and the role of the polyphenols present, as well as the molecular basis of the plant's desiccation tolerance. PMID:17218343

  9. [Functions of late embryogenesis abundant proteins in desiccation-tolerance of organisms: a review].

    Science.gov (United States)

    Liu, Yun; Liu, Guobao; Li, Ranhui; Zou, Yongdong; Zheng, Yizhi

    2010-05-01

    Late embryogenesis abundant (LEA) proteins are well associated with the desiccation tolerance in organisms. LEA proteins are categorized into at least seven groups by virtue of similarities in their deduced amino acid sequences. Most of the LEA proteins have the characteristics of high hydrophilicity and thermo-stability. The LEA proteins are in unstructured conformation in aqueous solution. However, they adopted amphiphilic alpha-helix structure during desiccation condition. LEA proteins are localized to the different organelles in the cells, i.e. cytoplasm, endoplasmic reticulum, mitochondria and nucleus. The multi-functional capacity of LEA proteins are suggested, as protein stabilization, protection of enzyme activity, membrane association and stabilization, antioxidant function, metal-ion binding or DNA protection, etc. Here, we review the structural and functional characteristics of LEA proteins to provide a reference platform to understand their protective mechanisms during the adaptive response to desiccation in organisms.

  10. Do hospital mergers reduce costs?

    Science.gov (United States)

    Schmitt, Matt

    2017-03-01

    Proponents of hospital consolidation claim that mergers lead to significant cost savings, but there is little systematic evidence backing these claims. For a large sample of hospital mergers between 2000 and 2010, I estimate difference-in-differences models that compare cost trends at acquired hospitals to cost trends at hospitals whose ownership did not change. I find evidence of economically and statistically significant cost reductions at acquired hospitals. On average, acquired hospitals realize cost savings between 4 and 7 percent in the years following the acquisition. These results are robust to a variety of different control strategies, and do not appear to be easily explained by post-merger changes in service and/or patient mix. I then explore several extensions of the results to examine (a) whether the acquiring hospital/system realizes cost savings post-merger and (b) if cost savings depend on the size of the acquirer and/or the geographic overlap of the merging hospitals. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Maintenance or collapse: responses of extraplastidic membrane lipid composition to desiccation in the resurrection plant Paraisometrum mileense.

    Directory of Open Access Journals (Sweden)

    Aihua Li

    Full Text Available Resurrection plants usually grow in specific or extreme habitats and have the capacity to survive almost complete water loss. We characterized the physiological and biochemical responses of Paraisometrum mileense to extreme desiccation and found that it is a resurrection plant. We profiled the changes in lipid molecular species during dehydration and rehydration in P. mileense, and compared these with corresponding changes in the desiccation-sensitive plant Arabidopsis thaliana. One day of desiccation was lethal for A. thaliana but not for P. mileense. After desiccation and subsequent rewatering, A. thaliana showed dramatic lipid degradation accompanied by large increases in levels of phosphatidic acid (PA and diacylglycerol (DAG. In contrast, desiccation and rewatering of P. mileense significantly decreased the level of monogalactosyldiacylglycerol and increased the unsaturation of membrane lipids, without changing the level of extraplastidic lipids. Lethal desiccation in P. mileense caused massive lipid degradation, whereas the PA content remained at a low level similar to that of fresh leaves. Neither damage nor repair processes, nor increases in PA, occurred during non-lethal desiccation in P. mileense. The activity of phospholipase D, the main source of PA, was much lower in P. mileense than in A. thaliana under control conditions, or after either dehydration or rehydration. It was demonstrated that low rates of phospholipase D-mediated PA formation in P. mileense might limit its ability to degrade lipids to PA, thereby maintaining membrane integrity following desiccation.

  12. Induction of Hsp70 by desiccation, ionising radiation and heat-shock in the eutardigrade Richtersius coronifer.

    Science.gov (United States)

    Jönsson, K Ingemar; Schill, Ralph O

    2007-04-01

    The physiology and biochemistry behind the extreme tolerance to desiccation shown by the so-called anhydrobiotic animals represents an exciting challenge to biology. The current knowledge suggests that both carbohydrates and proteins are often involved in protecting the dry cell from damage, or in the repair of induced damage. Tardigrades belong to the most desiccation-tolerant multicellular organisms, but very little research has been reported on the biochemistry behind desiccation tolerance in this group. We quantified the induction of the heat-shock protein Hsp70, a very wide-spread stress protein, in response to desiccation, ionising radiation, and heating, in the anhydrobiotic tardigrade Richtersius coronifer using an immuno-westernblot method. Elevated levels of Hsp70 were recorded after treatment of both heat and ionising radiation, and also in rehydrated tardigrades after a period of desiccation. In contrast, tardigrades in the desiccated (dry) state had reduced Hsp70 levels compared to the non-treated control group. Our results suggest that Hsp70 may be involved in the physiological and biochemical system underlying desiccation (and radiation) tolerance in tardigrades, and that its role may be connected to repair processes after desiccation rather than to biochemical stabilization in the dry state.

  13. Performance assessment and transient optimization of multi-stage solid desiccant air conditioning systems with building PV/T integration

    Science.gov (United States)

    Gadalla, Mohamed; Saghafifar, Mohammad

    2016-09-01

    One of the popular solar air conditioning technologies is desiccant air conditioning. Nonetheless, single stage desiccant air conditioning systems' coefficient of performance (COP) are relatively low. Therefore, multi-stage solid desiccant air conditioning systems are recommended. In this paper, an integrated double-stage desiccant air conditioning systems and PV/T collector is suggested for hot and humid climates such as the UAE. The results for the PV/T implementation in the double-stage desiccant cooling system are assessed against the PV/T results for a single-stage desiccant air conditioning system. In order to provide a valid comparative evaluation between the single and double stage desiccant air conditioning systems, an identical PV/T module, in terms of dimensions, is incorporated into these systems. The overall required auxiliary air heating is abated by 46.0% from 386.8 MWh to 209.0 MWh by replacing the single stage desiccant air conditioning system with the proposed double stage configuration during June to October. Moreover, the overall averaged solar share during the investigated months for the single and double stage systems are 36.5% and 43.3%.

  14. Maintenance or collapse: responses of extraplastidic membrane lipid composition to desiccation in the resurrection plant Paraisometrum mileense.

    Science.gov (United States)

    Li, Aihua; Wang, Dandan; Yu, Buzhu; Yu, Xiaomei; Li, Weiqi

    2014-01-01

    Resurrection plants usually grow in specific or extreme habitats and have the capacity to survive almost complete water loss. We characterized the physiological and biochemical responses of Paraisometrum mileense to extreme desiccation and found that it is a resurrection plant. We profiled the changes in lipid molecular species during dehydration and rehydration in P. mileense, and compared these with corresponding changes in the desiccation-sensitive plant Arabidopsis thaliana. One day of desiccation was lethal for A. thaliana but not for P. mileense. After desiccation and subsequent rewatering, A. thaliana showed dramatic lipid degradation accompanied by large increases in levels of phosphatidic acid (PA) and diacylglycerol (DAG). In contrast, desiccation and rewatering of P. mileense significantly decreased the level of monogalactosyldiacylglycerol and increased the unsaturation of membrane lipids, without changing the level of extraplastidic lipids. Lethal desiccation in P. mileense caused massive lipid degradation, whereas the PA content remained at a low level similar to that of fresh leaves. Neither damage nor repair processes, nor increases in PA, occurred during non-lethal desiccation in P. mileense. The activity of phospholipase D, the main source of PA, was much lower in P. mileense than in A. thaliana under control conditions, or after either dehydration or rehydration. It was demonstrated that low rates of phospholipase D-mediated PA formation in P. mileense might limit its ability to degrade lipids to PA, thereby maintaining membrane integrity following desiccation.

  15. A simple analytical method to estimate all exit parameters of a cross-flow air dehumidifier using liquid desiccant.

    Science.gov (United States)

    Bassuoni, M M

    2014-03-01

    The dehumidifier is a key component in liquid desiccant air-conditioning systems. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the performance results of exit parameters from an analytical model of an adiabatic cross-flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. A program performing the analytical solution is developed using the engineering equation solver software. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and -5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration, and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier. The moisture removal rate is decreased with increasing both air inlet temperature and desiccant temperature while increases with increasing air to solution mass ratio, inlet desiccant concentration, and inlet air humidity ratio.

  16. Limits of desiccation tolerance in developing embryos of Pritchardia remota (Arecaceae): the orthodox-recalcitrant seed paradigm

    Science.gov (United States)

    Orthodox and recalcitrant seeds are distinguished by the ability of embryos to survive desiccation. Seeds of many palm species do not conform to the dichotomous classification and storage physiology is considered intermediate or ambiguous. We studied the acquisition of desiccation tolerance in embr...

  17. Study of an aqueous lithium chloride desiccant system Part I: Air dehumidification

    Energy Technology Data Exchange (ETDEWEB)

    Fumo, Nelson [Universidad Nacional Experimental del Tachira, San Cristobal (Venezuela); Goswami, Yogi [University of Florida, Gainesville (United States)

    2000-07-01

    Desiccant systems have been proposed as energy saving alternative to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. For liquid-gas contact, packed towers with low pressure drop have offered good heat and mass transfer characteristics for compact designs. This paper presents the results from a study of the performance of a packed tower absorber for an aqueous lithium chloride desiccant dehumidification system. The rate of dehumidification, as well as the effectiveness of the dehumidification process were assessed under the effects of variables such as air and desiccant flow rates, air temperature and humidity, and desiccant temperature and concentration. A variation of the oeberg and Goswami mathematical model was used to predict the experimental findings given satisfactory results. [Spanish] Se han propuesto sistemas de desecacion como una alternativa de ahorro de energia para el acondicionamiento de aire mediante la compresion de vapor para manejar la carga latente. El uso de desecantes liquidos ofrece varias ventajas de diseno y de rendimiento sobre los desecantes solidos, especialmente cuando la energia solar se usa para la regeneracion. Para el contacto liquido-gas han dado buenas caracteristicas de transferencia de masa para disenos compactos las torres empacadas con baja caida de presion. Este documento presenta los resultados de un estudio del comportamiento de un absorbedor de torre empacada para una solucion acuosa de desecante de cloruro de litio como sistema de deshumidificacion. El regimen de deshumidificacion asi como tambien la eficiencia del proceso de deshumidificacion se evaluo bajo los efectos de variables tales como regimenes de flujo de aire y de desecante, temperatura del aire y humedad, y concentracion y temperatura del desecante. Se uso una variante de modelo matematico de

  18. Metabolic profiling of the resurrection plant Haberlea rhodopensis during desiccation and recovery.

    Science.gov (United States)

    Moyankova, Daniela; Mladenov, Petko; Berkov, Strahil; Peshev, Darin; Georgieva, Desislava; Djilianov, Dimitar

    2014-12-01

    Desiccation tolerance is among the most important parameters for crop improvement under changing environments. Resurrection plants are useful models for both theoretical and practical studies. We performed metabolite profiling via gas chromatography coupled with mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) and analyzed the antioxidant capacity of the endemic resurrection plant Haberlea rhodopensis at desiccation and recovery. More than 100 compounds were evaluated. Stress response included changes in both primary and secondary metabolic pathways. The high amounts of the specific glycoside myconoside and some phenolic acids - e.g. syringic and dihydrocaffeic acid under normal conditions tend to show their importance for the priming of H. rhodopensis to withstand severe desiccation and oxidative stress. The accumulation of sucrose (resulting from starch breakdown), total phenols, β-aminoisobutyric acid, β-sitosterol and α-tocopherol increased up to several times at later stages of desiccation. Extracts of H. rhodopensis showed high antioxidant capacity at stress and normal conditions. Myconoside was with the highest antioxidant properties among tested phenolic compounds. Probably, the evolution of resurrection plants under various local environments has resulted in unique desiccation tolerance with specific metabolic background. In our case, it includes the accumulation of a relatively rare compound (myconoside) that contributes alone and together with other common metabolites. Further systems biology studies on the involvement of carbohydrates, phenolic acids and glycosides in the desiccation tolerance and antioxidant capacity of H. rhodopensis will definitely help in achieving the final goal - improving crop drought tolerance. © 2014 Scandinavian Plant Physiology Society.

  19. Addition of alarm pheromone components improves the effectiveness of desiccant dusts against Cimex lectularius.

    Science.gov (United States)

    Benoit, Joshua B; Phillips, Seth A; Croxall, Travis J; Christensen, Brady S; Yoder, Jay A; Denlinger, David L

    2009-05-01

    We demonstrate that the addition of bed bug, Cimex lectularius, alarm pheromone to desiccant formulations greatly enhances their effectiveness during short-term exposure. Two desiccant formulations, diatomaceous earth (DE) and Dri-die (silica gel), were applied at the label rate with and without bed bug alarm pheromone components, (E)-2-hexenal, (E)-2-octenal, and a (E)-2-hexenal:(E)-2-octenal blend. First-instar nymphs and adult females were subjected to 10-min exposures, and water loss rates were used to evaluate the response. Optimal effectiveness was achieved with a pheromone concentration of 0.01 M. With Dri-die alone, the water loss was 21% higher than in untreated controls, and water loss increased nearly two times with (E)-2-hexenal and (E)-2-octenal and three times with the (E)-2-hexenal: (E)-2-octenal blend. This shortened survival of first-instar nymphs from 4 to 1 d, with a similar reduction noted in adult females. DE was effective only if supplemented with pheromone, resulting in a 50% increase in water loss over controls with the (E)-2-hexenal:(E)-2-octenal blend, and a survival decrease from 4 to 2 d in first-instar nymphs. Consistently, the addition of the pheromone blend to desiccant dust was more effective than adding either component by itself or by using Dri-die or DE alone. Based on observations in a small microhabitat, the addition of alarm pheromone components prompted bed bugs to leave their protective harborages and to move through the desiccant, improving the use of desiccants for control. We concluded that short exposure to Dri-die is a more effective treatment against bed bugs than DE and that the effectiveness of the desiccants can be further enhanced by incorporation of alarm pheromone. Presumably, the addition of alarm pheromone elevates excited crawling activity, thereby promoting cuticular changes that increase water loss.

  20. Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation.

    Science.gov (United States)

    Pallarés, Susana; Botella-Cruz, María; Arribas, Paula; Millán, Andrés; Velasco, Josefa

    2017-04-01

    Exposing organisms to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against the two stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress. Thus, cross-tolerance to these physiologically similar stressors could have been positively selected in insects of these regions. We used adults of the saline water beetles Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae) to test cross-tolerance responses to desiccation and salinity. In independent laboratory experiments, we evaluated the effects of (i) salinity stress on the subsequent resistance to desiccation and (ii) desiccation stress (rapid and slow dehydration) on the subsequent tolerance to salinity. Survival, water loss and haemolymph osmolality were measured. Exposure to stressful salinity improved water control under subsequent desiccation stress in both species, with a clear cross-tolerance (enhanced performance) in N. baeticus In contrast, general negative effects on performance were found under the inverse stress sequence. The rapid and slow dehydration produced different water loss and haemolymph osmolality dynamics that were reflected in different survival patterns. Our finding of cross-tolerance to salinity and desiccation in ecologically similar species from distant lineages, together with parallel responses between salinity and thermal stress previously found in several aquatic taxa, highlights the central role of adaption to salinity and co-occurring stressors in arid inland waters, having important implications for the species' persistence under climate change. © 2017. Published by The Company of Biologists Ltd.

  1. Desiccation tolerance of the tardigrade Milnesium tardigradum collected in Sapporo, Japan, and Bogor, Indonesia.

    Science.gov (United States)

    Horikawa, Daiki D; Higashi, Seigo

    2004-08-01

    A tardigrade Milnesium tardigradum showed anhydrobiotic capacity, in which the desiccation tolerance, given by the mean survival rate under desiccation at different relative humidity levels, was significantly higher in the Sapporo (Japan) population than that in the Bogor (Indonesia) population. Accordingly, the surviving tardigrades took a significantly longer time for revival in Bogor than those in Sapporo. The higher tolerance of the Sapporo population is thought to be related to the low relative humidity and low temperature such that the animals experience 41% RH in May and often -10 degrees C or lower in winter.

  2. Study on effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans

    OpenAIRE

    Sari Farah Dina; Himsar Ambarita; Farel H. Napitupulu; Hideki Kawai

    2015-01-01

    The main objective is to assess effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans. Two type of desiccants were tested, molecular sieve 13× (Na86 [(AlO2)86·(SiO2)106]·264H2O) as an adsorbent type and CaCl2 as an absorbent type. The results revealed that during sunshine hours, the maximum temperature within the drying chamber varied from 40 °C to 54 °C. In average, it was 9–12 °C higher than ambient temperature. These temperatures are very ...

  3. Experimental investigation on a solid desiccant system integrated with a R407C compression air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Fatouh, M.; Mostafa, A. [Dept. of Mechanical Power Engineering, Faculty of Engineering, El-Mattaria (Helwan Univ.), Masaken El-Helmia P.O., Cairo 11718 (Egypt); Ibrahim, Talaat A. [Dept. of Mechanical Power Engineering, Faculty of Engineering, El-Mattaria (Helwan Univ.), Masaken El-Helmia P.O., Cairo 11718 (Egypt); King Saud Univ., P.O. 70908, 11577 Riyadh (Saudi Arabia)

    2009-10-15

    In the present work, experimental performance data of a solid desiccant based hybrid air conditioning system are presented. The system consists of a packed bed solid desiccant integrated with a R407C conventional vapor compression refrigeration system. Experiments are carried out during dehumidification operation mode for various operating parameters such as; desiccant mass on shelves (5, 10 and 15 kg), air mass flow rate (7.4 and 10.2 kg/min), shelves number (1, 2 and 3) and three values of shelves span (7, 14 and 28 cm) at evaporator air inlet conditions of 28 C DBT and 66% RH, condenser air inlet volume flow rate of 850 m{sup 3}/h and temperature of 35 C. The reactivation of the desiccant at different regeneration temperatures and air flow rates as well as desiccant masses is also investigated. During the dehumidification mode, the average system coefficient of performance increases by 6.2% and 1.61% when the mass of desiccant increases from 5 to 10 kg and from 10 to 15 kg, respectively. The enhancement in the coefficient of performance is 6.2% due to increasing the air mass flow rate from 7.4 to 10.2 kg/min. Increasing both shelves number and span yields to a reduction in the adsorption rate that can be extracted by the desiccant material in the ranges of considered operating conditions. The regeneration temperature and the air flow rate of regeneration have significant effects on the reactivation process. It was found that, with increasing the mass flow rate of regenerated air from 7.4 to 10.2 kg/min produces a reduction in regeneration time by 87.5% and an augmentation in the desorption rate by 16% after 10 min of regeneration. In addition, with escalating the regeneration temperature from 45 to 55 C, the reactivation time reduces by 25%. Reported results revealed that solid desiccant based hybrid air conditioning system reduces the compressor electric power and the number of electric unit (kW h) by 10.2%. (author)

  4. Optimization analysis of high temperature heat pump coupling to desiccant wheel air conditioning system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Fang, Lei

    2014-01-01

    The high temperature heat pump and desiccant wheel (HTHP&DW) system can make full use of heat released from the condenser of heat pump for DW regeneration without additional heat. In this study, DW operation in the HTHP&DW system was investigated experimentally, and the optimization analysis....... Compared to the isosteric heat, heat accumulation in the desiccant and matrix material and heat leakage from regeneration side to process side have greater influence on the adiabatic effectiveness. Higher regeneration temperature leads to lower adiabatic effectiveness that increases more cooling load...

  5. QTLs and candidate genes for desiccation and abscisic acid content in maize kernels

    Directory of Open Access Journals (Sweden)

    Charcosset Alain

    2010-01-01

    Full Text Available Abstract Background Kernel moisture at harvest is an important trait since a low value is required to prevent unexpected early germination and ensure seed preservation. It is also well known that early germination occurs in viviparous mutants, which are impaired in abscisic acid (ABA biosynthesis. To provide some insight into the genetic determinism of kernel desiccation in maize, quantitative trait loci (QTLs were detected for traits related to kernel moisture and ABA content in both embryo and endosperm during kernel desiccation. In parallel, the expression and mapping of genes involved in kernel desiccation and ABA biosynthesis, were examined to detect candidate genes. Results The use of an intermated recombinant inbred line population allowed for precise QTL mapping. For 29 traits examined in an unreplicated time course trial of days after pollination, a total of 78 QTLs were detected, 43 being related to kernel desiccation, 15 to kernel weight and 20 to ABA content. Multi QTL models explained 35 to 50% of the phenotypic variation for traits related to water status, indicating a large genetic control amenable to breeding. Ten of the 20 loci controlling ABA content colocated with previously detected QTLs controlling water status and ABA content in water stressed leaves. Mapping of candidate genes associated with kernel desiccation and ABA biosynthesis revealed several colocations between genes with putative functions and QTLs. Parallel investigation via RT-PCR experiments showed that the expression patterns of the ABA-responsive Rab17 and Rab28 genes as well as the late embryogenesis abundant Emb5 and aquaporin genes were related to desiccation rate and parental allele effect. Database searches led to the identification and mapping of two zeaxanthin epoxidase (ZEP and five novel 9-cis-epoxycarotenoid dioxygenase (NCED related genes, both gene families being involved in ABA biosynthesis. The expression of these genes appeared independent in

  6. Freezing and desiccation tolerance in entomopathogenic nematodes: diversity and correlation of traits.

    Science.gov (United States)

    Shapiro-Ilan, David I; Brown, Ian; Lewis, Edwin E

    2014-03-01

    The ability of entomopathogenic nematodes to tolerate environmental stress such as desiccating or freezing conditions, can contribute significantly to biocontrol efficacy. Thus, in selecting which nematode to use in a particular biocontrol program, it is important to be able to predict which strain or species to use in target areas where environmental stress is expected. Our objectives were to (i) compare inter- and intraspecific variation in freeze and desiccation tolerance among a broad array of entomopathogenic nematodes, and (ii) determine if freeze and desiccation tolerance are correlated. In laboratory studies we compared nematodes at two levels of relative humidity (RH) (97% and 85%) and exposure periods (24 and 48 h), and nematodes were exposed to freezing temperatures (-2°C) for 6 or 24 h. To assess interspecific variation, we compared ten species including seven that are of current or recent commercial interest: Heterorhabditis bacteriophora (VS), H. floridensis, H. georgiana, (Kesha), H. indica (HOM1), H. megidis (UK211), Steinernema carpocapsae (All), S. feltiae (SN), S. glaseri (VS), S. rarum (17C&E), and S. riobrave (355). To assess intraspecific variation we compared five strains of H. bacteriophora (Baine, Fl1-1, Hb, Oswego, and VS) and four strains of S. carpocapsae (All, Cxrd, DD136, and Sal), and S. riobrave (355, 38b, 7-12, and TP). S. carpocapsae exhibited the highest level of desiccation tolerance among species followed by S. feltiae and S. rarum; the heterorhabditid species exhibited the least desiccation tolerance and S. riobrave and S. glaseri were intermediate. No intraspecific variation was observed in desiccation tolerance; S. carpocapsae strains showed higher tolerance than all H. bacteriophora or S. riobrave strains yet there was no difference detected within species. In interspecies comparisons, poor freeze tolerance was observed in H. indica, and S. glaseri, S. rarum, and S. riobrave whereas H. georgiana and S. feltiae exhibited the

  7. Intracellular trehalose improves osmotolerance but not desiccation tolerance in mammalian cells.

    Science.gov (United States)

    García de Castro, A; Tunnacliffe, A

    2000-12-29

    Trehalose has been shown to play a role in osmotolerance or desiccation tolerance in some microorganisms, anhydrobiotic invertebrates and resurrection plants. To test whether trehalose could improve stress responses of higher eukaryotes, a mouse cell line was genetically engineered to express bacterial trehalose synthase genes. We report that the resulting levels of intracellular trehalose ( approximately 80 mM) are able to confer increased resistance to the partial dehydration resulting from hypertonic stress, but do not enable survival of complete desiccation due to air drying.

  8. Effects of temperature on desiccant catalysis of refrigerant and lubricant decomposition. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, N.D.T.

    1998-06-01

    Accelerated aging at high temperatures (149 C) for short aging times (28 days) is effective in screening the compatibility of different materials in refrigeration systems. However, in actual applications temperatures are usually lower and operating times much longer. Therefore plots to allow for interpolation or extrapolation of experimental data to actual operating conditions are needed. In the current study, aging of refrigerant/lubricant/desiccant/metal systems was conducted at five different temperatures, and for each temperature at four different aging times. The data collected from this study provided plots relating refrigerant or lubricant decomposition to aging time, aging temperature, and type of desiccant, which can be used for interpolation or extrapolation.

  9. Desiccation of adhering and biofilm Listeria monocytogenes on stainless steel: Survival and transfer to salmon products

    DEFF Research Database (Denmark)

    Hansen, Lisbeth Truelstrup; Vogel, Birte Fonnesbech

    2011-01-01

    The foodborne bacterial pathogen, Listeria monocytogenes, commonly contaminates foods during processing, where the microorganisms are potentially subjected to low relative humidity (RH) conditions for extended periods of time. The objective of this study was to examine survival during desiccation...... (43% RH and 15°C) of biofilm L. monocytogenes N53-1 cells on stainless steel coupons and to assess subsequent transfer to salmon products. Formation of static biofilm (2days at 100% RH and 15°C) prior to desiccation for 23days significantly (P...

  10. Theoretical study on volatile organic compound removal and energy performance of a novel heat pump assisted solid desiccant cooling system

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Fang, Lei; Zhang, Ge

    2015-01-01

    A theoretical model was established for predicting the volatile organic compound (VOC) removal and energy performance of a novel heat pump assisted solid desiccant cooling system (HP-SDC). The HP-SDC was proposed based on the combination of desiccant rotor with heat pump, and was designed...... for cooling, dehumidification and indoor air cleaning in normal office, commercial or residential buildings. The desiccant rotor was used for dehumidification and indoor air cleaning; the heat pump provided sensible cooling and regeneration heat for the desiccant rotor. The theoretical model consisted of two...... sub-models. One sub-model was used to simulate the heat, moisture and VOC transfer in the desiccant rotor; the other sub-model was used to predict the energy performance of the heat pump. Combining the two sub-models, the energy performance and VOC removal effect of the HP-SDC could be simulated...

  11. Characteristics of cats sterilized through a subsidized, reduced-cost spay-neuter program in Massachusetts and of owners who had cats sterilized through this program.

    Science.gov (United States)

    Benka, Valerie A; McCobb, Emily

    2016-09-01

    OBJECTIVE To determine characteristics of cats sterilized through a subsidized, reduced-cost spay-neuter program in Massachusetts and of owners who had their cats sterilized through this program. DESIGN Cross-sectional anonymous survey and telephone interviews. SAMPLE 1,188 (anonymous surveys) and 99 (telephone interviews) cat owners. PROCEDURES Owners who had a cat sterilized at clinics held between January 2006 and December 2008 were invited to complete anonymous surveys. Semistructured telephone interviews were conducted with owners who had a cat sterilized during clinics held in 2009. RESULTS Most cats had never been seen by a veterinarian previously; "too expensive" was the most common reason for this. Total annual household income was significantly associated with the number of times the cat had been examined by a veterinarian and reason why the cat had not been spayed or neutered previously. Most cats were acquired through informal means and without actively being sought, and there was often a time lag between acquisition and sterilization. Undesirable behavior and avoiding pregnancy were primary motivations for neutering and spaying, respectively. Nearly half of owners who indicated they would have had their cat sterilized through a private veterinarian if the clinic had not been available stated that the surgery would have been delayed because of cost. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that spay-neuter decisions were related to owner income and procedure cost, that elimination of the reduced-cost spay-neuter program would likely have exacerbated the spay-delay problem, and that gradations of financial need should be considered when evaluating relationships between income and spay-neuter decisions.

  12. Light response, oxidative stress management and nucleic acid stability in closely related Linderniaceae species differing in desiccation tolerance.

    Science.gov (United States)

    Dinakar, Challabathula; Bartels, Dorothea

    2012-08-01

    In the present study, three closely related Linderniaceae species which differ in their sensitivity to desiccation are compared in response to light and oxidative stress defence. Lindernia brevidens, a desiccation-tolerant plant, displayed intense purple pigmentation in leaves under long-day conditions in contrast to Craterostigma plantagineum (desiccation tolerant) and Lindernia subracemosa (desiccation sensitive). The intense pigmentation in leaves does not affect the desiccation tolerance behaviour but seems to be related to oxidative stress protection. Green leaves of short-day and purple leaves of long-day plants provided suitable material for comparing basic photosynthetic parameters. An increase in non-photochemical quenching in purple leaves appears to prevent photoinhibition. Treatment with methyl viologen decreased the photochemical activities in both long-day and short-day plants but long-day plants which accumulate anthocyanins maintained a higher non-photochemical quenching than short-day plants. No differences were seen in the expression of desiccation-induced proteins and proteins involved in carbohydrate metabolism in short-day and long-day grown plants, whereas differences were observed in the expression of transcripts encoding chloroplast-localised stress proteins and transcripts encoding antioxidant enzymes. While the expression of genes encoding antioxidant enzymes were either constitutive or up-regulated during desiccation in C. plantagineum, the expression was down-regulated in L. subracemosa. RNA expression analysis indicated degradation of mRNA during desiccation in L. subracemosa but not in desiccation tolerant species. These results indicate that a better oxidative stress management and mRNA stability are correlated with desiccation tolerance.

  13. The survival of Listeria monocytogenes during long term desiccation is facilitated by sodium chloride and organic material.

    Science.gov (United States)

    Vogel, Birte Fonnesbech; Hansen, Lisbeth Truelstrup; Mordhorst, Hanne; Gram, Lone

    2010-06-15

    One specific DNA-subtype, as determined by RAPD, of Listeria monocytogenes persisted in a fish slaughterhouse for years, even during months with no production where the plant was cleaned and kept dry. We hypothesised that tolerance to desiccation could be a factor in explaining the persistence of L. monocytogenes in food processing environments and the purpose of the present study was to determine ability of L. monocytogenes to survive desiccation on stainless steel under simulated food processing conditions. Viable counts of eight different L. monocytogenes strains exposed to different soils and relative humidities (RHs) during desiccation decreased significantly (pDesiccation in physiological peptone saline (PPS) reduced survivors by 3-5 log units whereas bacterial cells suspended in bacteriological growth substrates (tryptone soy broth with 1% glucose, TSB-glu) or PPS with 5% NaCl only were reduced by 1-3 log units. At RHs of 2, 43 and 75%, surfaces were visibly dry after 1, 3 and 5days of incubation, respectively. The lowest RH resulted in the most significant loss of viability, however, 10(3)-10(4)CFU/cm(2) remained viable regardless of the desiccation treatment (i.e., presence of TSB-glu and/or salt). At 75% RH, the bacterial counts remained almost constant when desiccated in TSB-glu. When bacteria were grown and desiccated (15 degrees C, 43% RH) in salmon or smoked salmon juice, survivors decreased slowly resulting in low numbers (10(2)-10(3)CFU/cm(2)) from all eight strains remaining viable after 3months. Whilst conditions during desiccation had a pronounced influence on inactivation kinetics and the number of survivors, persistent L. monocytogenes were not more tolerant to desiccation than presumed non-persistent isolates. Our study shows that the ability to survive for months during desiccated conditions may be a factor explaining the ability of L. monocytogenes to persist in food processing environments. Copyright 2010 Elsevier B.V. All rights reserved.

  14. Ecological and evolutionary consequences of desiccation tolerance in tropical fern gametophytes.

    Science.gov (United States)

    Watkins, James E; Mack, Michelle C; Sinclair, Thomas R; Mulkey, Stephen S

    2007-01-01

    Ferns have radiated into the same diverse environments as spermatophytes, and have done so with an independent gametophyte that is not protected by the parent plant. The degree and extent of desiccation tolerance (DT) in the gametophytes of tropical fern species was assessed to understand mechanisms that have allowed ferns to radiate into a diversity of habitats. Species from several functional groups were subjected to a series of desiccation events, including varying degrees of intensity and multiple desiccation cycles. Measurements of chlorophyll fluorescence were used to assess recovery ability and compared with species ecology and gametophyte morphology. It is shown that vegetative DT (rare in vascular plants) is widely exhibited in fern gametophytes and the degree of tolerance is linked to species habitat preference. It is proposed that gametophyte morphology influences water-holding capacity, a novel mechanism that may help to explain how ferns have radiated into drought-prone habitats. Fern gametophytes have often been portrayed as extreme mesophytes with little tolerance for desiccation. The discovery of DT in gametophytes holds potential for improving our understanding of both the controls on fern species distribution and their evolution. It also advances a new system with which to study the evolution of DT in vascular plants.

  15. Design of Air Ventilation System for Cargo Hold Vessels Using Solar Desiccant

    Directory of Open Access Journals (Sweden)

    Alam Baheramsyah

    2017-09-01

    Full Text Available One of the facilities and infrastructure of the vessel is the ventilation system in the cargo hold to maintain the quality. One attempt to avoid high moisture ratios is to provide a dry air supply by using desiccants. The purpose of this thesis is to design the system of air ventilation with solar desiccant by analysis the calculation with decrease air humidity ratio after passing desiccant rotor as well as fulfillment needs of heater and cooling system using heat of exhaust gas and seawater as well as fulfillment of electricity need using solar energy. From the result of analysis obtain to provide air supply in the cargo hold of 437.5 m3 / hour, the specification of rotor desiccant has a diameter of 550 mm with thickness 200 mm to decrease ratio of outside air humidity equal to 83.1% become 46.5%. Dehumidification air temperature of 47.7oC will be lowered to 35oC by using the sea water cooling media. As for the reactivation air heater requirement of 24.292 kW would be to fulfilled by utilizing the exhaust power of 498.12 kW. And for the electric power needs of the syetm is 34,488 wp will be supplied from the total solar module is 33 units with 345 wp per-capacity.

  16. Study on effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans

    Directory of Open Access Journals (Sweden)

    Sari Farah Dina

    2015-03-01

    Full Text Available The main objective is to assess effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans. Two type of desiccants were tested, molecular sieve 13× (Na86 [(AlO286·(SiO2106]·264H2O as an adsorbent type and CaCl2 as an absorbent type. The results revealed that during sunshine hours, the maximum temperature within the drying chamber varied from 40 °C to 54 °C. In average, it was 9–12 °C higher than ambient temperature. These temperatures are very suitable for drying cocoa beans. During off-sunshine hours, humidity of air inside the drying chamber was lower than ambient because of the desiccant thermal storage. Drying times for intermittent directs sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorbent were 55 h, 41 h, and 30 h, respectively. Specific energy consumptions for direct sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorber were 60.4 MJ/kg moist, 18.94 MJ/kg moist, and 13.29 MJ/kg moist, respectively. The main conclusion can be drawn here is that a solar dryer integrated with desiccant thermal storage makes drying using solar energy more effective in term of drying time and specific energy consumption.

  17. Parametric Analysis of a Rotary Type Liquid Desiccant Air Conditioning System

    Directory of Open Access Journals (Sweden)

    M. Mujahid Rafique

    2016-04-01

    Full Text Available Now days, air conditioning systems are a must for almost every commercial and residential building to achieve comfortable indoor conditions. The increasing energy demand, and increasing oil prices and pollution levels raise the need for alternative air conditioning systems which can efficiently utilize renewable energy resources. The liquid desiccant-based air conditioning method is pollution free and thermal energy-based cooling techniques can use low grade thermal energy resources like solar energy, waste heat, etc. These systems have an additional advantage of cleaning bacteria and fungi from the air. In this paper, a newly proposed rotary liquid desiccant air conditioning system has been investigated theoretically. Most direct contact liquid desiccant cooling systems have the problem of desiccant carryover which can be eliminated using the proposed system. The effects of various key parameters and climatic conditions on the performance of the system have been evaluated. The results showed that if the key parameters of the system are controlled effectively, the proposed cooling system has the ability to achieve the desired supply air conditions. The system can achieve high coefficient of performance (COP under different conditions. The dehumidifier has a sensible heat ratio (SHR in the range of 0.3–0.6 for different design, climatic, and operating conditions. The system can remove latent load efficiently in applications which require good humidity control.

  18. Biofilm resilience to desiccation in groundwater aquifers: a laboratory and field study.

    Science.gov (United States)

    Weaver, L; Webber, J B; Hickson, A C; Abraham, P M; Close, M E

    2015-05-01

    Groundwater is used as a precious resource for drinking water worldwide. Increasing anthropogenic activity is putting increasing pressure on groundwater resources. One impact of increased groundwater abstraction coupled with increasing dry weather events is the lowering of groundwater levels within aquifers. Biofilms within groundwater aquifers offer protection to the groundwater by removing contaminants entering the aquifer systems from land use activities. The study presented investigated the impact of desiccation events on the biofilms present in groundwater aquifers using field and laboratory experiments. In both field and laboratory experiments a reduction in enzyme activity (glucosidase, esterase and phosphatase) was seen during desiccation compared to wet controls. However, comparing all the data together no significant differences were seen between either wet or desiccated samples or between the start and end of the experiments. In both field and laboratory experiments enzyme activity recovered to start levels after return to wet conditions. The study shows that biofilms within groundwater systems are resilient and can withstand periods of desiccation (4 months).

  19. Adsorption/Desorption Behavior of Water Vapor in an Adsorbent Desiccant Rotor

    Science.gov (United States)

    Tsujiguchi, Takuya; Kodama, Akio

    To clarify the operating and design concept of desiccant rotor, which is a most important component of an adsorptive desiccant cooling process, adsorption / desorption behavior of water vapor in a desiccant rotor has been investigated by means of computer simulation. Mass transfer coefficient in the mathematical model could be related to cycle time by applying the penetration theory. Considering this relationship, influences of the rotation speed of the desiccant rotor, process / regeneration air velocity and their velocity ratio were investigated. It was found that the optimum rotation speed tended to disappear when the regeneration air temperature was low and its humidity was considerably small compared to the process inlet air, since the product air condition approached to regeneration air condition as the rotation speed increased. Decrease of the dehumidifying performance was observed at higher air velocity and the corresponding higher rotation speed since the adsorbent rotor was not fully regenerated due to shorter regeneration time and shorter residence time of process / regeneration air in the adsorbent rotor prevented the mass transfer between air and adsorbent. It was also found that the dehumidifying performance was not improved even though the adsorbent was fully regenerated by higher regeneration air velocity as the sensible heat transferred from the regeneration zone via adsorbent itself increased and disturbed adsorption.

  20. Photosynthesis during desiccation in an intertidal alga and a land plant.

    Science.gov (United States)

    Kawamitsu, Y; Driscoll, T; Boyer, J S

    2000-03-01

    This study was undertaken to determine how photosynthesis tolerates desiccation in an intertidal alga Fucus vesiculosus L. and a terrestrial sunflower Helianthus annuus L. Photosynthetic O2 evolution generally was inhibited at low water potentials (psiw) but more in sunflower leaves than in Fucus fronds at the same psiw. As psiw decreased, less carbon accumulated in an organic carbon store in Fucus. The inhibition of photosynthesis appeared to be mostly biochemical because it could not be prevented by supplying additional CO2 or by supplying CO2 from the internal organic carbon store. The inhibition of photosynthesis and carbon storage occurred after turgor disappeared and thus when solute concentrations were increasing in the cells. Solute concentrations were much higher in Fucus than in sunflower. After desiccation to the air-dry state (psiw below - 10 MPa), photosynthesis could not recover in sunflower but it recovered rapidly when Fucus was exposed to seawater. The lack of recovery in sunflower was associated with inability to recover turgor probably because of breaks in cell membranes. The ability to recover in Fucus was gradually lost during 1.5 d of desiccation at 45% relative humidity. At lower humidities, recovery was lost sooner as small amounts of water were removed. We conclude that photosynthesis tolerated desiccation more in Fucus than in sunflower because of differences in the molecular environment around the photosynthetic enzymes. Important aspects of this environment were features that prevented membrane breakage but promoted the retention of small amounts of water that were critical for viability.

  1. Apparent light requirement for activation of photosynthesis upon rehydration of desiccated beachrock microbial mats

    DEFF Research Database (Denmark)

    Schreiber, Ulrich; Gademann, Rolf; Bird, Paul

    2002-01-01

    excitation. Even after desiccation for long time periods under full sunlight, beachrock showed rapid recovery of photosynthesis after rehydration in the light (t1/2~ 15 min). However, when rehydrated in the dark, the quantum yield of energy conversion of PSII remained zero over extended periods of time...

  2. Desiccant dehumidification in decentralized air conditioning systems; Einsatz der Sorptionstechnik in der dezentralen Klimatisierung von Gebaeuden

    Energy Technology Data Exchange (ETDEWEB)

    Busweiler, Ulrich [Fachhochschule Giessen-Friedberg (Germany)

    2009-01-15

    Dehumidification of supply air with adsorption wheels, which is known from desiccant cooling systems, is now applied to small air handling units which condition the air of one single room. There is an increase in comfort in winter by recovery of moisture. In summer, dehumidification and cooling of air are ensured by an absolutely dry process without any hygienic risk. (orig.)

  3. C4 grasses prosper as carbon dioxide eliminates desiccation in warmed semi-arid grassland.

    Science.gov (United States)

    Morgan, Jack A; LeCain, Daniel R; Pendall, Elise; Blumenthal, Dana M; Kimball, Bruce A; Carrillo, Yolima; Williams, David G; Heisler-White, Jana; Dijkstra, Feike A; West, Mark

    2011-08-03

    Global warming is predicted to induce desiccation in many world regions through increases in evaporative demand. Rising CO(2) may counter that trend by improving plant water-use efficiency. However, it is not clear how important this CO(2)-enhanced water use efficiency might be in offsetting warming-induced desiccation because higher CO(2) also leads to higher plant biomass, and therefore greater transpirational surface. Furthermore, although warming is predicted to favour warm-season, C(4) grasses, rising CO(2) should favour C(3), or cool-season plants. Here we show in a semi-arid grassland that elevated CO(2) can completely reverse the desiccating effects of moderate warming. Although enrichment of air to 600 p.p.m.v. CO(2) increased soil water content (SWC), 1.5/3.0 °C day/night warming resulted in desiccation, such that combined CO(2) enrichment and warming had no effect on SWC relative to control plots. As predicted, elevated CO(2) favoured C(3) grasses and enhanced stand productivity, whereas warming favoured C(4) grasses. Combined warming and CO(2) enrichment stimulated above-ground growth of C(4) grasses in 2 of 3 years when soil moisture most limited plant productivity. The results indicate that in a warmer, CO(2)-enriched world, both SWC and productivity in semi-arid grasslands may be higher than previously expected.

  4. Developments in solar drying using forced ventilation and solar regenerated desiccant materials

    Energy Technology Data Exchange (ETDEWEB)

    Thoruwa, T.F.N. [Kenyatta University, Nairobi (Kenya). Mechanical Engineering Dept.; Smith, J.E. [Strathclyde University, Glasgow (United Kingdom). Dept. of Bioscience and Biotechnology; Johnstone, C.M. [Strathclyde Univ., Glasgow (United Kingdom). Energy Simulation Research Unit

    1996-09-01

    In many countries, grains are naturally sun dried in the field, resulting in large-scale spoilage. Purpose-built solar grain dryers are being introduced with some success, but to be effective, their performance must be carefully controlled to prevent cracking of grains, fungal growth and aflatoxin production during storage. This paper describes some of the performance aspects of an autonomous solar desiccant maize dryer developed for village use in Kenya. Since most commercial desiccants are expensive, a low cost solid desiccant was fabricated from bentonite clay and calcium chloride materials. This desiccant is capable of regeneration at 45{sup o}C, has high moisture sorption of 45% (dwb), significantly extends the drying process at night and reduces aflatoxin contamination of the grain. Laboratory and field testing took place to determine the drying performance and allow conclusions to be drawn. This showed the prototype dryer had the capability of drying 90kg of fresh maize from 38% (dwb) to 15% (dwb) within 24 hours. (Author)

  5. Characterization of a Functional Role of the Bradyrhizobium japonicum Isocitrate Lyase in Desiccation Tolerance

    Directory of Open Access Journals (Sweden)

    Jeong-Min Jeon

    2015-07-01

    Full Text Available Bradyrhizobium japonicum is a nitrogen-fixing symbiont of soybean. In previous studies, transcriptomic profiling of B. japonicum USDA110, grown under various environmental conditions, revealed the highly induced gene aceA, encoding isocitrate lyase (ICL. The ICL catalyzes the conversion of isocitrate to succinate and glyoxylate in the glyoxylate bypass of the TCA cycle. Here, we evaluated the functional role of B. japonicum ICL under desiccation-induced stress conditions. We purified AceA (molecular mass = 65 kDa from B. japonicum USDA110, using a His-tag and Ni-NTA column approach, and confirmed its ICL enzyme activity. The aceA mutant showed higher sensitivity to desiccation stress (27% relative humidity (RH, compared to the wild type. ICL activity of the wild type strain increased approximately 2.5-fold upon exposure to 27% RH for 24 h. The aceA mutant also showed an increased susceptibility to salt stress. Gene expression analysis of aceA using qRT-PCR revealed a 148-fold induction by desiccation, while other genes involved in the glyoxylate pathway were not differentially expressed in this condition. Transcriptome analyses revealed that stress-related genes, such as chaperones, were upregulated in the wild-type under desiccating conditions, even though fold induction was not dramatic (ca. 1.5–2.5-fold.

  6. The role of recovery of mitochondrial structure and function in desiccation tolerance of pea seeds

    DEFF Research Database (Denmark)

    Wang, Wei-Qing; Cheng, Hong-Yan; Møller, Ian Max;

    2012-01-01

    Mitochondrial repair is of fundamental importance for seed germination. When mature orthodox seeds are imbibed and germinated, they lose their desiccation tolerance in parallel. To gain a better understanding of this process, we studied the recovery of mitochondrial structure and function in pea...

  7. Membrane-based air conditioning. Decentral desiccant cooling; Membranbasierte Raumklimatisierung. Dezentrale sorptionsgestuetzte Klimatisierung

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbaum, Hannes [Institut fuer Luft- und Kaeltetechnik gGmbH, Dresden (Germany)

    2012-04-15

    Semipermeable membranes have a considerable potential use in air conditioning systems due to their properties. As water resistant but water vapor permeable functional separation layers, they allow desiccant air-conditioning processes in decentral air conditioning systems and a condensate-free air dehumidification at cooling ceiling elements. (orig.)

  8. Experimental performance study of a proposed desiccant based air conditioning system.

    Science.gov (United States)

    Bassuoni, M M

    2014-01-01

    An experimental investigation on the performance of a proposed hybrid desiccant based air conditioning system referred as HDBAC is introduced in this paper. HDBAC is mainly consisted of a liquid desiccant dehumidification unit integrated with a vapor compression system (VCS). The VCS unit has a cooling capacity of 5.27 kW and uses 134a as refrigerant. Calcium chloride (CaCl2) solution is used as the working desiccant material. HDBAC system is used to serve low sensible heat factor applications. The effect of different parameters such as, process air flow rate, desiccant solution flow rate, evaporator box and condenser box solution temperatures, strong solution concentration and regeneration temperature on the performance of the system is studied. The performance of the system is evaluated using some parameters such as: the coefficient of performance (COPa), specific moisture removal and energy saving percentage. A remarkable increase of about 54% in the coefficient of performance of the proposed system over VCS with reheat is achieved. A maximum overall energy saving of about 46% is observed which emphasizes the use of the proposed system as an energy efficient air conditioning system.

  9. Experimental performance study of a proposed desiccant based air conditioning system

    Directory of Open Access Journals (Sweden)

    M.M. Bassuoni

    2014-01-01

    Full Text Available An experimental investigation on the performance of a proposed hybrid desiccant based air conditioning system referred as HDBAC is introduced in this paper. HDBAC is mainly consisted of a liquid desiccant dehumidification unit integrated with a vapor compression system (VCS. The VCS unit has a cooling capacity of 5.27 kW and uses 134a as refrigerant. Calcium chloride (CaCl2 solution is used as the working desiccant material. HDBAC system is used to serve low sensible heat factor applications. The effect of different parameters such as, process air flow rate, desiccant solution flow rate, evaporator box and condenser box solution temperatures, strong solution concentration and regeneration temperature on the performance of the system is studied. The performance of the system is evaluated using some parameters such as: the coefficient of performance (COPa, specific moisture removal and energy saving percentage. A remarkable increase of about 54% in the coefficient of performance of the proposed system over VCS with reheat is achieved. A maximum overall energy saving of about 46% is observed which emphasizes the use of the proposed system as an energy efficient air conditioning system.

  10. Egg hatching, larval movement and larval survival of the malaria vector Anopheles gambiae in desiccating habitats

    NARCIS (Netherlands)

    Koenraadt, C.J.M.; Paaijmans, K.P.; Githeko, A.K.; Knols, B.G.J.; Takken, W.

    2003-01-01

    Background - Although the effects of rainfall on the population dynamics of the malaria vector Anopheles gambiae have been studied in great detail, the effects of dry periods on its survival remain less clear. Methods - The effects of drying conditions were simulated by creating desiccated habitats,

  11. Solar-Powered, Liquid-Desiccant Air Conditioner for Low-Electricity Humidity Control

    Science.gov (United States)

    2012-11-01

    energy penalty in fan power and requires frequent maintenance to remain effective. Alternatively, the low-flow liquid desiccant uses minimal mist ...65 8.3.4 LDAC Fans and Pumps...27 Table 9. LDAC System Pump and Fan Motor Schedule

  12. A realistic appraisal of methods to enhance desiccation tolerance of entomopathogenic nematodes.

    Science.gov (United States)

    Perry, Roland N; Ehlers, Ralf-Udo; Glazer, Itamar

    2012-06-01

    Understanding the desiccation survival attributes of infective juveniles of entomopathogenic nematodes (EPN) of the genera Steinernema and Heterorhabditis, is central to evaluating the reality of enhancing the shelf-life and field persistence of commercial formulations. Early work on the structural and physiological aspects of desiccation survival focused on the role of the molted cuticle in controlling the rate of water loss and the importance of energy reserves, particularly neutral lipids. The accumulation of trehalose was also found to enhance desiccation survival. Isolation of natural populations that can survive harsh environments, such as deserts, indicated that some populations have enhanced abilities to survive desiccation. However, survival abilities of EPN are limited compared with those of some species of plant-parasitic nematodes inhabiting aerial parts of plants. Research on EPN stress tolerance has expanded on two main lines: i) to select strains of species, currently in use commercially, which have increased tolerance to environmental extremes; and ii) to utilize molecular information, including expressed sequence tags and genome sequence data, to determine the underlying genetic factors that control longevity and stress tolerance of EPN. However, given the inherent limitations of EPN survival ability, it is likely that improved formulation will be the major factor to enhance EPN longevity and, perhaps, increase the range of applications.

  13. A new microscopic method to analyse desiccation-induced volume changes in aeroterrestrial green algae.

    Science.gov (United States)

    Lajos, K; Mayr, S; Buchner, O; Blaas, K; Holzinger, A

    2016-08-01

    Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED ) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants.

  14. Shrinkage-reducing admixtures and early-age desiccation in cement pastes and mortars

    DEFF Research Database (Denmark)

    Bentz, D. P.; Geiker, Mette Rica; Hansen, Kurt Kielsgaard

    2001-01-01

    Fundamental studies of the early-age desiccation of cement-based materials with and without a shrinkage-reducing admixture (SRA) have been performed. Studies have been conducted under both sealed and drying conditions. Physical measurements include mass loss, surface tension, X-ray absorption...

  15. The competence to acquire cellular desiccation tolerance is not dependent on seed morphological development

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.; Aelst, van A.C.

    2001-01-01

    Acquisition of desiccation tolerance and the related changes at the cellular level in wheat (Triticum aestivum cv. Priokskaya) kernels during normal development and premature drying on the ear were studied using a spin probe technique and low temperature scanning electron microscopy. During normal d

  16. The impact of land use on water loss and soil desiccation in the soil profile

    Science.gov (United States)

    Zhang, Jing; Wang, Li

    2017-08-01

    Farmlands have gradually been replaced by apple orchards in Shaanxi province, China, and there will be a risk of severe soil-water-storage deficit with the increasing age of the apple trees. To provide a theoretical basis for the sustainable development of agriculture and forestry in the Loess Plateau, soil water content in a 19-year-old apple orchard, a 9-year-old apple orchard, a cornfield and a wheat field in the Changwu Tableland was investigated at different depths from January to October 2014. The results showed that: (1) the soil moisture content is different across the soil profile—for the four plots, the soil moisture of the cornfield is the highest, followed by the 9-year-old apple orchard and the wheat field, and the 19-year-old apple orchard has the lowest soil moisture. (2) There are varying degrees of soil desiccation in the four plots: the most serious degree of desiccation is in the 19-year-old apple orchard, followed by the wheat field and the cornfield, with the least severe desiccation occurring in the 9-year-old apple orchard. Farmland should replace apple orchards for an indefinite period while there is an extremely desiccated soil layer in the apple orchard so as to achieve the purpose of sustainable development. It will be necessary to reduce tree densities, and to carry out other research, if development of the economy and ecology of Changwu is to be sustainable.

  17. The response of Asterochloris erici (Ahmadjian) Skaloud et Peksa to desiccation: a proteomic approach

    Science.gov (United States)

    The study of desiccation tolerance of lichens, and of their photobionts in particular, has frequently focused on the antioxidant system that protects the cell against photo-oxidative stress during dehydration/rehydration cycles. Thus, in this work we carried out proteomic and transcript analyses of ...

  18. Some thoughts about the desiccation tolerance continuum and the basis for “intermediate” seed physiologies

    Science.gov (United States)

    Desiccation-sensitive seeds succumb when dried below a critical water content. Critical water contents range widely among species and with experimental conditions, implying a continuum in the amount of water that can be non-lethally removed from diverse cells. However, water potentials correspondi...

  19. Induction of desiccation tolerance in plant somatic embryos : how exclusive is the protective role of sugars?

    NARCIS (Netherlands)

    Hoekstra, F.A.; Golovina, E.A.; Tetteroo, F.A.A.; Wolkers, W.F.

    2001-01-01

    Plant somatic embryos usually lack desiccation tolerance. They may acquire such a tolerance upon preculture in the presence of abscisic acid (ABA), followed by slow drying, but not fast drying. ABA causes torpedo-shaped somatic embryos to lose their chlorophyll, suspend growth, exhibit low rates of

  20. Abscisic acid (ABA) sensitivity regulates desiccation tolerance in germinated Arabidopsis seeds.

    Science.gov (United States)

    Maia, Julio; Dekkers, Bas J W; Dolle, Miranda J; Ligterink, Wilco; Hilhorst, Henk W M

    2014-07-01

    During germination, orthodox seeds lose their desiccation tolerance (DT) and become sensitive to extreme drying. Yet, DT can be rescued, in a well-defined developmental window, by the application of a mild osmotic stress before dehydration. A role for abscisic acid (ABA) has been implicated in this stress response and in DT re-establishment. However, the path from the sensing of an osmotic cue and its signaling to DT re-establishment is still largely unknown. Analyses of DT, ABA sensitivity, ABA content and gene expression were performed in desiccation-sensitive (DS) and desiccation-tolerant Arabidopsis thaliana seeds. Furthermore, loss and re-establishment of DT in germinated Arabidopsis seeds was studied in ABA-deficient and ABA-insensitive mutants. We demonstrate that the developmental window in which DT can be re-established correlates strongly with the window in which ABA sensitivity is still present. Using ABA biosynthesis and signaling mutants, we show that this hormone plays a key role in DT re-establishment. Surprisingly, re-establishment of DT depends on the modulation of ABA sensitivity rather than enhanced ABA content. In addition, the evaluation of several ABA-insensitive mutants, which can still produce normal desiccation-tolerant seeds, but are impaired in the re-establishment of DT, shows that the acquisition of DT during seed development is genetically different from its re-establishment during germination. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  1. Physiological history may mask the inherent inducible desiccation tolerance strategy of the desert moss Crossidium crassinerve.

    Science.gov (United States)

    Stark, L R; Greenwood, J L; Brinda, J C; Oliver, M J

    2014-09-01

    Shoots of bryophytes collected in the desiccated state from the field are likely to be hardened to desiccation tolerance (DT) to varying degrees. To account for this, most studies on DT include a relatively short deacclimation period. However, no study has experimentally determined the appropriate deacclimation time for any bryophyte species. Our purposes are to (i) determine if 'field effects' are biologically relevant to DT studies and how long a deacclimation period is required to remove them; and (ii) utilise field versus cultured shoot responses within the context of a deacclimation period to elucidate the ecological strategy of DT. Our hypothesis (based on an extensive literature on DT) is that a deacclimation period from 24 to 72 h should be sufficient to eliminate historical stress effects on the physiology of the shoots and allow an accurate determination of the inherent ecological DT strategy (constitutive or inducible). We determined, however, using chlorophyll fluorescence and visual estimates of shoot damage, that field-collected shoots of the desert moss Crossidium crassinerve required an experimental deacclimation period of >7 days before field effects were removed, and revealed an ecological DT strategy of inducible DT. If the deacclimation period was desiccation tolerance exhibited by the species, and this translates into a need to re-evaluate previous mechanistic and ecological studies of desiccation tolerance in plants. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. Desiccation tolerance in diapausing spider mites Tetranychus urticae and T. kanzawai (Acari: Tetranychidae).

    Science.gov (United States)

    Ghazy, Noureldin Abuelfadl; Suzuki, Takeshi

    2014-05-01

    We investigated the effects of changes in vapor pressure deficit (VPD) on the survival of diapausing (winter form) and non-diapausing (summer form) spider mites Tetranychus urticae Koch and Tetranychus kanzawai Kishida (Acari: Tetranychidae). Adult females of both species were kept without food at VPDs of 0.0, 0.4, 0.7, 1.5, 1.9, or 2.7 kPa for 3, 6, 9, 12, or 15 days at 25 °C. Diapausing females of both species kept at a VPD of ≥0.4 kPa for ≥6 days clearly tolerated desiccation. Under water-saturated conditions (VPD = 0.0 kPa), in which no desiccation occurred, diapausing females showed high starvation tolerance: 90 % survived for up to 15 days. No interspecific differences in tolerance to desiccation or starvation were observed under most conditions. These results indicate that diapause functions increase tolerance to desiccation and starvation. Such multiple tolerances to harsh environments might support winter survival in spider mites.

  3. Understanding Vegetative Desiccation Tolerance using Integrated Functional Genomics Approaches within a Comparative Evolutionary Framework

    Science.gov (United States)

    Desiccation tolerance (DT) is defined as the equilibration of protoplasmic water potential with that of the surrounding air (generally dry) without loss of viability upon rehydration. Vegetative DT is widespread amongst mosses and lichens, but is relatively rare in vascular plants (0.15%). Recent st...

  4. The competence to acquire cellular desiccation tolerance is not dependent on seed morphological development

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.; Aelst, van A.C.

    2001-01-01

    Acquisition of desiccation tolerance and the related changes at the cellular level in wheat (Triticum aestivum cv. Priokskaya) kernels during normal development and premature drying on the ear were studied using a spin probe technique and low temperature scanning electron microscopy. During normal d

  5. Soil moisture deficit selects for desiccation tolerant Rhizobium leguminosarum bv. trifolii

    NARCIS (Netherlands)

    Ham, van Robert; O'Callaghan, Maureen; Geurts, Rene; Ridgway, Hayley J.; Ballard, Ross; Noble, Alasdair; Macara, Gregor; Wakelin, Steven A.

    2016-01-01

    Tolerance to desiccation is a highly desirable attribute for Rhizobium spp., which are widely used as symbionts of pasture legumes. Poor survival of Rhizobium spp. is of particular concern during the commercial formulation and seed application phase, but also when sown into dry fields and during sap

  6. Desiccation sensitivity and tolerance in the moss Physcomitrella patens: assessing limits and damage.

    Science.gov (United States)

    The moss Physcomitrella patens is becoming the model of choice for functional genomic studies at the cellular level. Studies report that P. patens survives moderate osmotic and salt stress, and that desiccation tolerance can be induced by exogenous ABA. Our goal was to quantify the extent of dehydr...

  7. Loss of desiccation tolerance in Copaifera langsdorffii Desf. seeds during germination.

    Science.gov (United States)

    Pereira, W V S; Faria, J M R; Tonetti, O A O; Silva, E A A

    2014-05-01

    This study evaluated the loss of desiccation tolerance in C. langsdorffii seeds during the germination process. Seeds were imbibed for 24, 48, 72, 96, 120 and 144 hours and dried to the initial moisture content, kept in this state for 3 days after which they were submitted to pre-humidification and rehydration. Ultraestructural evaluations were done aiming to observe the cell damage caused by the dry process. Desiccation tolerance was evaluated in terms of the percentage of normal seedlings. Seeds not submitted to the drying process presented 61% of normal seedlings, and after 24 hours of imbibition, followed by drying, the seeds presented the same percentage of survival. However, after 48 hours of imbibition, seeds started to lose the desiccation tolerance. There was twenty six percent of normal seedlings formed from seeds imbibed for 96 hours and later dried and rehydrated. Only 5% of seeds imbibed for 144 hours, dried and rehydrated formed normal seedlings. At 144 hours of imbibition followed the dry process, there was damage into the cell structure, indicating that the seeds were unable to keep the cell structure during the drying process. Copaifera langsdorffii seeds loses the desiccation tolerance at the start of Phase 2 of imbibition.

  8. The evolution of desiccation-tolerance in angiosperm plants, a rare yet common phenomenon!

    Science.gov (United States)

    In a minute proportion of angiosperm species, rehydrating foliage can revive from airdryness or even from equilibration with air of ~0% relative humidity. Such desiccation tolerance is known from vegetative cells of some species of algae and of major groups close to the evolutionary path of the angi...

  9. Characterization of a Functional Role of the Bradyrhizobium japonicum Isocitrate Lyase in Desiccation Tolerance.

    Science.gov (United States)

    Jeon, Jeong-Min; Lee, Hae-In; Sadowsky, Michael J; Sugawara, Masayuki; Chang, Woo-Suk

    2015-07-22

    Bradyrhizobium japonicum is a nitrogen-fixing symbiont of soybean. In previous studies, transcriptomic profiling of B. japonicum USDA110, grown under various environmental conditions, revealed the highly induced gene aceA, encoding isocitrate lyase (ICL). The ICL catalyzes the conversion of isocitrate to succinate and glyoxylate in the glyoxylate bypass of the TCA cycle. Here, we evaluated the functional role of B. japonicum ICL under desiccation-induced stress conditions. We purified AceA (molecular mass = 65 kDa) from B. japonicum USDA110, using a His-tag and Ni-NTA column approach, and confirmed its ICL enzyme activity. The aceA mutant showed higher sensitivity to desiccation stress (27% relative humidity (RH)), compared to the wild type. ICL activity of the wild type strain increased approximately 2.5-fold upon exposure to 27% RH for 24 h. The aceA mutant also showed an increased susceptibility to salt stress. Gene expression analysis of aceA using qRT-PCR revealed a 148-fold induction by desiccation, while other genes involved in the glyoxylate pathway were not differentially expressed in this condition. Transcriptome analyses revealed that stress-related genes, such as chaperones, were upregulated in the wild-type under desiccating conditions, even though fold induction was not dramatic (ca. 1.5-2.5-fold).

  10. The response of foodborne pathogens to osmotic and desiccation stresses in the food chain

    DEFF Research Database (Denmark)

    Burgess, Catherine M.; Gianotti, Andrea; Gruzdev, Nadia;

    2016-01-01

    In combination with other strategies, hyperosmolarity and desiccation are frequently used by the food processing industry as a means to prevent bacterial proliferation, and particularly that of foodborne pathogens, in food products. However, it is increasingly observed that bacteria, including hu...

  11. Potential Evaluation of Solar Heat Assisted Desiccant Hybrid Air Conditioning System

    Science.gov (United States)

    Tran, Thien Nha; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    The solar thermal driven desiccant dehumidification-absorption cooling hybrid system has superior advantage in hot-humid climate regions. The reasonable air processing of desiccant hybrid air conditioning system and the utility of clean and free energy make the system environment friendly and energy efficient. The study investigates the performance of the desiccant dehumidification air conditioning systems with solar thermal assistant. The investigation is performed for three cases which are combinations of solar thermal and absorption cooling systems with different heat supply temperature levels. Two solar thermal systems are used in the study: the flat plate collector (FPC) and the vacuum tube with compound parabolic concentrator (CPC). The single-effect and high energy efficient double-, triple-effect LiBr-water absorption cooling cycles are considered for cooling systems. COP of desiccant hybrid air conditioning systems are determined. The evaluation of these systems is subsequently performed. The single effect absorption cooling cycle combined with the flat plate collector solar system is found to be the most energy efficient air conditioning system.

  12. Food availability determines the response to pond desiccation in anuran tadpoles.

    Science.gov (United States)

    Enriquez-Urzelai, Urtzi; San Sebastián, Olatz; Garriga, Núria; Llorente, Gustavo A

    2013-09-01

    Food availability and pond desiccation are two of the most studied factors that condition amphibian metamorphosis. It is well known that, when food is abundant, organisms undergo metamorphosis early and when they are relatively large. The capability of anurans to accelerate their developmental rate in response to desiccation is also common knowledge. These two variables must act together in nature, since we know that, as a pond dries, the per capita resources decrease. We conduct an experiment to evaluate the effects of desiccation and food availability separately and in combination in tadpoles of the painted frog (Discoglossus pictus). We demonstrate that food deprivation leads to slow growth rates, which delay metamorphosis and produce smaller size and weight. The capability to accelerate metamorphosis when facing a drying pond is also confirmed, but, nevertheless, with factor interaction (when the pool is drying and resources are scarce) the capacity to respond to desiccation is lost. In addition, slow drying rates are shown to be stressful situations, but not enough to provoke a shortening of the larval period; in fact, the larval period becomes longer. We also demonstrate that the interaction of these factors changes the allometric relationship of different parts of the hind limb, which has implications for the biomechanics of jumping. Due to low mortality rates and an adequate response to both environmental factors, we expect D. pictus to have a great invasive potential in its new Mediterranean distribution area, where lots of temporary and ephemeral ponds are present.

  13. SEED DESICCATION TOLERANCE AND CRYOPRESERVATION OF PHILIPPINE CALAMANSI [x Citrofortunella microcarpa (BUNGE) WIJNANDS].

    Science.gov (United States)

    Damasco, O L; Refuerzo, L C

    The traditional on farm conservation of Calamansi [x Citrofortunella microcarpa (Bunge) Wijnands], an important indigenous Citrus species in the Philippines, is now being threatened by shifting agricultural crop production, climate change, and increasing biotic and abiotic stresses. The study aimed to characterize the desiccation and cryopreservation tolerance of seeds as the basis for complementary long term ex situ conservation. Intact seeds were desiccated in an airtight container filled with activated silica gel for 0-96 h. Seeds placed in cryotubes were subjected to rapid freezing in liquid nitrogen, rapid thawing in a water bath at 50 degree C for 3 min, and cultured on MS basal medium for seedling recovery and growth. Recovered seedlings were potted out in plastic bags filled with coir dust: garden soil mixture (1:1 v/v) and maintained in the nursery. Significant reduction in percentage germination was obtained at in a moisture content (MC) window between 24.3% and 4.2% and complete loss of viability at below 3.2%. The number of germinated embryos per seed was significantly reduced following desiccation from a mean of 4.2 embryos per seed for the untreated control to 1.2 to 1.02 embryos per seed at 33.3-4.2% MC, respectively. Recovery and germination of seeds after cryopreservation were obtained in a MC window between 24.3% and 4.2% with the maximum seed germination (27%) obtained at 13.4%. Germination abnormalities such as incomplete germination, greening and or enlargement of cotyledon without shoot emergence were observed in both desiccated and cryopreserved seeds. Variations in response to seed desiccation and cryopreservation were observed among Calamansi accessions tested. Maximum seedling recovery after liquid nitrogen storage varied between 12.5% and 61.5%. Recovered seedlings from desiccation and cryopreservation treatments survived ex vitro establishment and showed normal growth and similar morphology with the non-treated control seedlings. The

  14. Nitric oxide enhances desiccation tolerance of recalcitrant Antiaris toxicaria seeds via protein S-nitrosylation and carbonylation.

    Directory of Open Access Journals (Sweden)

    Xuegui Bai

    Full Text Available The viability of recalcitrant seeds is lost following stress from either drying or freezing. Reactive oxygen species (ROS resulting from uncontrolled metabolic activity are likely responsible for seed sensitivity to drying. Nitric oxide (NO and the ascorbate-glutathione cycle can be used for the detoxification of ROS, but their roles in the seed response to desiccation remain poorly understood. Here, we report that desiccation induces rapid accumulation of H(2O(2, which blocks recalcitrant Antiaris toxicaria seed germination; however, pretreatment with NO increases the activity of antioxidant ascorbate-glutathione pathway enzymes and metabolites, diminishes H(2O(2 production and assuages the inhibitory effects of desiccation on seed germination. Desiccation increases the protein carbonylation levels and reduces protein S-nitrosylation of these antioxidant enzymes; these effects can be reversed with NO treatment. Antioxidant protein S-nitrosylation levels can be further increased by the application of S-nitrosoglutathione reductase inhibitors, which further enhances NO-induced seed germination rates after desiccation and reduces desiccation-induced H(2O(2 accumulation. These findings suggest that NO reinforces recalcitrant seed desiccation tolerance by regulating antioxidant enzyme activities to stabilize H(2O(2 accumulation at an appropriate concentration. During this process, protein carbonylation and S-nitrosylation patterns are used as a specific molecular switch to control antioxidant enzyme activities.

  15. Nitric oxide enhances desiccation tolerance of recalcitrant Antiaris toxicaria seeds via protein S-nitrosylation and carbonylation.

    Science.gov (United States)

    Bai, Xuegui; Yang, Liming; Tian, Meihua; Chen, Jinhui; Shi, Jisen; Yang, Yongping; Hu, Xiangyang

    2011-01-01

    The viability of recalcitrant seeds is lost following stress from either drying or freezing. Reactive oxygen species (ROS) resulting from uncontrolled metabolic activity are likely responsible for seed sensitivity to drying. Nitric oxide (NO) and the ascorbate-glutathione cycle can be used for the detoxification of ROS, but their roles in the seed response to desiccation remain poorly understood. Here, we report that desiccation induces rapid accumulation of H(2)O(2), which blocks recalcitrant Antiaris toxicaria seed germination; however, pretreatment with NO increases the activity of antioxidant ascorbate-glutathione pathway enzymes and metabolites, diminishes H(2)O(2) production and assuages the inhibitory effects of desiccation on seed germination. Desiccation increases the protein carbonylation levels and reduces protein S-nitrosylation of these antioxidant enzymes; these effects can be reversed with NO treatment. Antioxidant protein S-nitrosylation levels can be further increased by the application of S-nitrosoglutathione reductase inhibitors, which further enhances NO-induced seed germination rates after desiccation and reduces desiccation-induced H(2)O(2) accumulation. These findings suggest that NO reinforces recalcitrant seed desiccation tolerance by regulating antioxidant enzyme activities to stabilize H(2)O(2) accumulation at an appropriate concentration. During this process, protein carbonylation and S-nitrosylation patterns are used as a specific molecular switch to control antioxidant enzyme activities.

  16. Identification by phenotypic and genetic approaches of an indigenous Saccharomyces cerevisiae wine strain with high desiccation tolerance.

    Science.gov (United States)

    Zambuto, Marianna; Romaniello, Rossana; Guaragnella, Nicoletta; Romano, Patrizia; Votta, Sonia; Capece, Angela

    2017-07-21

    During active dry yeast (ADY) production process, cells are exposed to multiple stresses, such as thermal, oxidative and hyperosmotic shock. Previously, by analysing cells in exponential growth phase, we selected an indigenous Saccharomyces cerevisiae wine strain, namely CD-6Sc, for its higher tolerance to desiccation and higher expression of specific desiccation stress-related genes in comparison to other yeast strains. In this study, we performed a desiccation treatment on stationary phase cells by comparing the efficacy of two different methods: a 'laboratory dry test' on a small scale (mild stress) and a treatment by spray-drying (severe stress), one of the most appropriate preservation method for yeasts and other micro-organisms. The expression of selected desiccation-related genes has been also assessed in order to validate predictive markers for desiccation tolerance. Our data demonstrate that the 'mild' and the 'severe' desiccation treatments give similar results in terms of cell recovery, but the choice of marker genes strictly depends on the growth phase in which cells undergo desiccation. The indigenous CD-6Sc was ultimately identified as a high dehydration stress-tolerant indigenous strain suitable for ADY production. This study highlights the exploitation of natural yeast biodiversity as a source of hidden technological features and as an alternative approach to strain improvement by genetic modifications. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  17. Trehalose as an indicator of desiccation stress in Drosophila melanogaster larvae: A potential marker of anhydrobiosis

    Energy Technology Data Exchange (ETDEWEB)

    Thorat, Leena J. [Centre for Advanced Studies, Department of Zoology, University of Pune, Pune 411007 (India); Gaikwad, Sushama M. [Division of Biochemical Sciences, National Chemical Laboratory, Pune 411008 (India); Nath, Bimalendu B., E-mail: bbnath@unipune.ac.in [Centre for Advanced Studies, Department of Zoology, University of Pune, Pune 411007 (India)

    2012-03-23

    Highlights: Black-Right-Pointing-Pointer First report confirming anhydrobiosis in Drosophila melanogaster larvae. Black-Right-Pointing-Pointer Trehalose synthesis and accumulation in larvae that hydrolyzed on rehydration. Black-Right-Pointing-Pointer Trehalose synthesis in concert with the enzymes involved in trehalose metabolism. Black-Right-Pointing-Pointer Inhibition of trehalose hydrolysis in presence of a specific trehalase inhibitor. Black-Right-Pointing-Pointer Trehalose proposed as a reliable marker for biomonitoring of climate change studies. -- Abstract: In the current scenario of global climate change, desiccation is considered as one of the major environmental stressors for the biota exposed to altered levels of ambient temperature and humidity. Drosophila melanogaster, a cosmopolitan terrestrial insect has been chosen as a humidity-sensitive bioindicator model for the present study since its habitat undergoes frequent stochastic and/or seasonally aggravated dehydration regimes. We report here for the first time the occurrence of anhydrobiosis in D. melanogaster larvae by subjecting them to desiccation stress under laboratory conditions. Larvae desiccated for ten hours at <5% relative humidity could enter anhydrobiosis and could revive upon rehydration followed by resumption of active metabolism. As revealed by FTIR and HPLC analyzes, our findings strongly indicated the synthesis and accumulation of trehalose in the desiccating larvae. Biochemical measurements pointed out the desiccation-responsive trehalose metabolic pathway that was found to be coordinated in concert with the enzymes trehalose 6-phosphate synthase and trehalase. Further, an inhibitor-based experimental approach using deoxynojirimycin, a specific trehalase inhibitor, demonstrated the pivotal role of trehalose in larval anhydrobiosis of D. melanogaster. We therefore propose trehalose as a potential marker for the assessment of anhydrobiosis in Drosophila. The present findings thus add

  18. Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions

    Science.gov (United States)

    Frösler, Jan; Panitz, Corinna; Wingender, Jost; Flemming, Hans-Curt; Rettberg, Petra

    2017-05-01

    Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions. The effect of sulfatic Mars regolith simulant on cell viability during stress was investigated separately. The EPS produced by the biofilm cells contained mainly polysaccharides and proteins. To detect viable but nonculturable (VBNC) cells, cultivation-independent viability indicators (membrane integrity, ATP, 16S rRNA) were determined in addition to colony counts. Desiccation for 2 months resulted in a decrease of culturability with minor changes of membrane integrity in biofilm cells and major loss of membrane integrity in planktonic bacteria. Temperatures between -25°C and +60°C, vacuum, and Mars atmosphere affected neither culturability nor membrane integrity in both phenotypes. Monochromatic (254 nm; ≥1 kJ m-2) and polychromatic (200-400 nm; >5.5 MJ m-2 for planktonic cells and >270 MJ m-2 for biofilms) UV irradiation significantly reduced the culturability of D. geothermalis but did not affect cultivation-independent viability markers, indicating the induction of a VBNC state in UV-irradiated cells. In conclusion, a substantial proportion of the D. geothermalis population remained viable under

  19. Genome-wide transcriptional analysis of genes associated with acute desiccation stress in Anopheles gambiae.

    Directory of Open Access Journals (Sweden)

    Mei-Hui Wang

    Full Text Available Malaria transmission in sub-Saharan Africa varies seasonally in intensity. Outbreaks of malaria occur after the beginning of the rainy season, whereas, during the dry season, reports of the disease are less frequent. Anopheles gambiae mosquitoes, the main malaria vector, are observed all year long but their densities are low during the dry season that generally lasts several months. Aestivation, seasonal migration, and local adaptation have been suggested as mechanisms that enable mosquito populations to persist through the dry season. Studies of chromosomal inversions have shown that inversions 2La, 2Rb, 2Rc, 2Rd, and 2Ru are associated with various physiological changes that confer aridity resistance. However, little is known about how phenotypic plasticity responds to seasonally dry conditions. This study examined the effects of desiccation stress on transcriptional regulation in An. gambiae. We exposed female An. gambiae G3 mosquitoes to acute desiccation and conducted a genome-wide analysis of their transcriptomes using the Affymetrix Plasmodium/Anopheles Genome Array. The transcription of 248 genes (1.7% of all transcripts was significantly affected in all experimental conditions, including 96 with increased expression and 152 with decreased expression. In general, the data indicate a reduction in the metabolic rate of mosquitoes exposed to desiccation. Transcripts accumulated at higher levels during desiccation are associated with oxygen radical detoxification, DNA repair and stress responses. The proportion of transcripts within 2La and 2Rs (2Rb, 2Rc, 2Rd, and 2Ru (67/248, or 27% is similar to the percentage of transcripts located within these inversions (31%. These data may be useful in efforts to elucidate the role of chromosomal inversions in aridity tolerance. The scope of application of the anopheline genome demonstrates that examining transcriptional activity in relation to genotypic adaptations greatly expands the number of

  20. Genetic background of enhanced radioresistance in an anhydrobiotic insect: transcriptional response to ionizing radiations and desiccation.

    Science.gov (United States)

    Ryabova, Alina; Mukae, Kyosuke; Cherkasov, Alexander; Cornette, Richard; Shagimardanova, Elena; Sakashita, Tetsuya; Okuda, Takashi; Kikawada, Takahiro; Gusev, Oleg

    2017-01-01

    It is assumed that resistance to ionizing radiation, as well as cross-resistance to other abiotic stresses, is a side effect of the evolutionary-based adaptation of anhydrobiotic animals to dehydration stress. Larvae of Polypedilum vanderplanki can withstand prolonged desiccation as well as high doses of ionizing radiation exposure. For a further understanding of the mechanisms of cross-tolerance to both types of stress exposure, we profiled genome-wide mRNA expression patterns using microarray techniques on the chironomid larvae collected at different stages of desiccation and after exposure to two types of ionizing radiation-70 Gy of high-linear energy transfer (LET) ions ((4)He) and the same dose of low-LET radiation (gamma rays). In expression profiles, a wide transcriptional response to desiccation stress that much exceeded the amount of up-regulated transcripts to irradiation exposure was observed. An extensive group of coincidently up-regulated overlapped transcripts in response to desiccation and ionizing radiation was found. Among this, overlapped set of transcripts was indicated anhydrobiosis-related genes: antioxidants, late embryogenesis abundant (LEA) proteins, and heat-shock proteins. The most overexpressed group was that of protein-L-isoaspartate/D-aspartate O-methyltransferase (PIMT), while probes, corresponding to LEA proteins, were the most represented. Performed functional analysis showed strongly enriched gene ontology terms associated with protein methylation. In addition, active processes of DNA repair were detected. We assume that the cross-tolerance of the sleeping chironomid to both desiccation and irradiation exposure comes from a complex mechanism of adaptation to anhydrobiosis.

  1. PCR detection of malaria parasites in desiccated Anopheles mosquitoes is uninhibited by storage time and temperature

    Directory of Open Access Journals (Sweden)

    Rider Mark A

    2012-06-01

    Full Text Available Abstract Background Reliable methods to preserve mosquito vectors for malaria studies are necessary for detecting Plasmodium parasites. In field settings, however, maintaining a cold chain of storage from the time of collection until laboratory processing, or accessing other reliable means of sample preservation is often logistically impractical or cost prohibitive. As the Plasmodium infection rate of Anopheles mosquitoes is a central component of the entomological inoculation rate and other indicators of transmission intensity, storage conditions that affect pathogen detection may bias malaria surveillance indicators. This study investigated the effect of storage time and temperature on the ability to detect Plasmodium parasites in desiccated Anopheles mosquitoes by real-time polymerase chain reaction (PCR. Methods Laboratory-infected Anopheles stephensi mosquitoes were chloroform-killed and stored over desiccant for 0, 1, 3, and 6 months while being held at four different temperatures: 28, 37, -20 and -80°C. The detection of Plasmodium DNA was evaluated by real-time PCR amplification of a 111 base pair region of block 4 of the merozoite surface protein. Results Varying the storage time and temperature of desiccated mosquitoes did not impact the sensitivity of parasite detection. A two-way factorial analysis of variance suggested that storage time and temperature were not associated with a loss in the ability to detect parasites. Storage of samples at 28°C resulted in a significant increase in the ability to detect parasite DNA, though no other positive associations were observed between the experimental storage treatments and PCR amplification. Conclusions Cold chain maintenance of desiccated mosquito samples is not necessary for real-time PCR detection of parasite DNA. Though field-collected mosquitoes may be subjected to variable conditions prior to molecular processing, the storage of samples over an inexpensive and logistically

  2. Development of desiccation tolerance and vitrification by preculture treatment in suspension-cultured cells of the liverwort Marchantia polymorpha.

    Science.gov (United States)

    Hatanaka, Rie; Sugawara, Yasutake

    2010-03-01

    Some cultured plant cells are able to acquire tolerance to various stresses when they are cultured under suitably controlled conditions. Induction of a high level of desiccation tolerance in suspension-cultured cells of the liverwort Marchantia polymorpha was examined for studying the mechanisms of desiccation tolerance and vitrification at the cellular level. Desiccation tolerance level of cells was very low and the survival rate was less than 10% after exposure to drying below 0.1 g H(2)O g(-1) dry weight (DW). Preculture treatment in 0.5 M sucrose medium was the most effective method for inducing a high level of desiccation tolerance in cells and the survival rate was 87% even after being desiccated to below 0.1 g H(2)O g(-1) DW. Preculture treatment caused alteration of cell structures and accumulation of a large amount of sucrose and newly synthesized proteins in cells. Abundant sucrose and preculture-induced proteins were necessary for full development of desiccation tolerance in the cells. When water content decreased to below 0.1 g H(2)O g(-1) DW, desiccation-tolerant cells that had been precultured were vitrified above 0 degrees C and maintained stable viability. We have succeeded in the induction of desiccation tolerance that allows formation of intracellular glass with cell viability at ambient temperatures by controlling culture conditions, and our results suggest that suspension-cultured cells of M. polymorpha are useful for studying cellular mechanisms for the development of desiccation tolerance and the stabilization of vitrified cells.

  3. Desiccant Enhanced Evaporative Air-Conditioning (DEVap): Evaluation of a New Concept in Ultra Efficient Air Conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.; Woods, J.; Burch, J.; Boranian, A.; Merrigan, T.

    2011-01-01

    NREL has developed the novel concept of a desiccant enhanced evaporative air conditioner (DEVap) with the objective of combining the benefits of liquid desiccant and evaporative cooling technologies into an innovative 'cooling core.' Liquid desiccant technologies have extraordinary dehumidification potential, but require an efficient cooling sink. DEVap's thermodynamic potential overcomes many shortcomings of standard refrigeration-based direct expansion cooling. DEVap decouples cooling and dehumidification performance, which results in independent temperature and humidity control. The energy input is largely switched away from electricity to low-grade thermal energy that can be sourced from fuels such as natural gas, waste heat, solar, or biofuels.

  4. Variations in biofilm formation, desiccation resistance and Benzalkonium chloride susceptibility among Listeria monocytogenes strains isolated in Canada

    DEFF Research Database (Denmark)

    Piercey, Marta J.; C. Ells, Timothy; Macintosh, Andrew J.

    2017-01-01

    of the SSI-1 (Stress Survival Islet) and LGI1/CC8 (Listeria Genomic Island 1 in a clonal complex 8 background) genetic markers. Genetic sequences from four strains representing different phenotypes were also probed for predicted amino acid differences in biofilm, desiccation, and membrane related genes....... The water isolates were among the most desiccation susceptible strains, while strains exhibiting desiccation resistance harboured SSI-1 or both the SSI-1 and LGI1/CC8 markers. BAC resistance was greatest in planktonic LGI1/CC8 cells (relative to non-LGI1/CC8 cells), and higher BAC concentrations were also...

  5. The survival of Listeria monocytogenes during long term desiccation is facilitated by sodium chloride and organic material

    DEFF Research Database (Denmark)

    Vogel, Birte Fonnesbech; Hansen, Lisbeth Truelstrup; Mordhorst, Hanne

    2010-01-01

    One specific DNA-subtype, as determined by RAPD, of Listeria monocytogenes persisted in a fish slaughterhouse for years, even during months with no production where the plant was cleaned and kept dry. We hypothesised that tolerance to desiccation could be a factor in explaining the persistence of L...... monocytogenes in food processing environments and the purpose of the present study was to determine ability of L monocytogenes to survive desiccation on stainless steel under simulated food processing conditions. Viable counts of eight different L. monocytogenes strains exposed to different soils and relative...... humidities (RHs) during desiccation decreased significantly (p...

  6. Desiccant wheels as gas-phase absorption (GPA) air cleaners: evaluation by PTR-MS and sensory assessment

    DEFF Research Database (Denmark)

    Fang, Lei; Zhang, G.; Wisthaler, A.

    2008-01-01

    Two experiments were conducted to investigate the use of the co-sorption effect of a desiccant wheel for improving indoor air quality. One experiment was conducted in a climate chamber to investigate the co-sorption effect of a desiccant wheel on the chemical removal of indoor air pollutants......; another experiment was conducted in an office room to investigate the resulting effect on perceived air quality. A dehumidifier with a silica-gel desiccant wheel was installed in the ventilation system of the test chamber and office room to treat the recirculation airflow. Human subjects, flooring...

  7. Desiccation sensitivity and cryopreservation of excised embryonic axes of Citrus suhuiensis cv. limau madu, Citrumelo [Citrus paradisi macf. × Poncirus trifoliata (l.) raf.] and Fortunella polyandra.

    Science.gov (United States)

    Al Zoubi, O M; Normah, M N

    2012-01-01

    Excised embryonic axes from seeds of three taxa, namely, Citrus suhuiensis cv. limau madu, Citrumelo (Citrus paradisi x Poncirus trifoliate) and Fortunella polyandra, were desiccated in a laminar airflow, over silica gel, and ultra-rapidly. Desiccation sensitivity (WC50) was estimated for each taxon using the quantal response model. High desiccation tolerance (WC50 = 0.11 g water per g dry mass. g/gdw) was observed for limau madu embryonic axes desiccated in a laminar airflow and ultra-rapidly (WC50 =0.10 g/gdw). Desiccation tolerance was substantially lower (WC50 = 0.19 g/gdw) for silica gel dehydration. Similarly, high desiccation tolerance (WC50 = 0.15 g/gdw) was associated with F. polyandra embryonic axes when desiccated in a laminar airflow, while a lower desiccation tolerance (WC50 = 0.17 g/gdw) was observed with silica gel dehydration. Ultra-rapid desiccation led to the highest desiccation tolerance (WC50 = 0.14 g/gdw). The dehydration rate, however, had no influence on desiccation tolerance (WC50 ~ 0.14 g/gdw) for Citrumelo embryonic axes. After each desiccation period, embryonic axes were directly immersed in liquid nitrogen (LN) followed by rapid rewarming. Normal seedling recovery of 80 to 83% for excised embryonic axes of limau madu was observed for laminar airflow and ultra-rapid dehydration, but for silica gel dehydration, 57% recovery was obtained. Similarly, for Citrumelo, high recoveries of 100% and 97% were obtained from axes desiccated in a laminar airflow and using ultra-rapid dehydration, respectively, whereas a lower value was associated with silica gel dehydration (80%). For F. polyandra, 50% recovery was obtained both for laminar airflow and ultra-rapid dehydration, while much lower recovery (43%) was associated with silica gel dehydration. Regardless of the drying method employed, axis survival percentages following exposure to LN were commensurate with the desiccation sensitivity pattern.

  8. Desiccation tolerance of Hymenophyllacea filmy ferns is mediated by constitutive and non-inducible cellular mechanisms.

    Science.gov (United States)

    Garcés Cea, Marcelo; Claverol, Stephan; Alvear Castillo, Carla; Rabert Pinilla, Claudia; Bravo Ramírez, León

    2014-04-01

    The Hymenophyllaceae is a primitive family within the Filicopsidae. One of the most exceptional features of this family of ferns is the presence of fronds with one or just a few cell layers (hence their name of filmy ferns), and the absence of stomata. Hymenophyllum caudiculatum and Hymenophyllum dentatum are able to lose more than 82% of their fully hydrated water content, to remain dry for extended periods of time (days or weeks), and to survive and remain viable following rehydration. The aim of this work was to understand whether the adaptive strategy of the Hymenophyllaceae for desiccation tolerance is constitutive or inducible. A proteomic approach was adopted in combination with physiological parameters to assess whether there were changes in the protein content during dehydration and following rehydration. Detached fronds were used to monitor the rates of photosynthesis in desiccation experiments, sugar accumulation, and high-resolution 2-DE to analyze proteome variation during a desiccation-rehydration cycle. The analyzed proteome exhibited little variation (3-4%) between hydrated and desiccated states, while variation was greater between the desiccated and rehydrated states (8.7-10%). Eighty-two discrete proteins were analyzed by MS/MS, and 65 were identified. About 21% of the analyzed proteins (17) were mixtures of two or more different polypeptides. Of the identified proteins, more than a half (33 spots, 55%) had functions related to energy-photosynthesis. The second largest category with known function (five spots, 8%) was related to cell rescue, defense, and virulence. More than one in every four proteins analyzed belonged to a group of hypothetical proteins (18 spots, 28%). The results suggest that the Hymenophyllaceae represent an example of a change in adaptive strategy from a typical vascular to the poikilohydric homoiochlorophyllous adaptation, which they share with the bryophytes that grow in profusion in the same habitats. The speed at which

  9. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds

    NARCIS (Netherlands)

    Buitink, J.; Leprince, O.; Hoekstra, F.A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumb

  10. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds

    NARCIS (Netherlands)

    Buitink, J.; Leprince, O.; Hoekstra, F.A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumb

  11. Advanced manufacturing technologies for reduced cost and weight in portable ruggedized VIS-IR and multi-mode optical systems for land, sea, and air

    Science.gov (United States)

    Sweeney, Michael; Spinazzola, Robert; Morrison, Donald; Macklin, Dennis; Marion, Jared

    2011-06-01

    Homeland security systems, special forces, unmanned aerial vehicles (UAV), and marine patrols require low cost, high performance, multi-mode visible through infrared (VIS-IR) wavelength optical systems to identify and neutralize potential threats that often arise at long ranges and under poor visibility conditions. Long range and wide spectral performance requirements favor reflective optical system design solutions. The limited field of view of such designs can be significantly enhanced by the use of catadioptric optical solutions that utilize molded or diamond point machined VIS-IR lenses downstream from reflective objective optics. A common optical aperture that services multiple modes of field-of-view, operating wavelength, and includes laser ranging and spotting, provides the highest utility and is most ideal for size and weight. Such a design also often requires fast, highly aspheric, reflective, refractive, and sometimes diffractive surfaces using high performance and aggressively light-weighted materials that demand the finest of manufacturing technologies. Visible wavelength performance sets the bar for component optical surface irregularity on the order of 20 nm RMS and surface finishes less than 3.0 nm RMS. Aluminum mirrors and structures can also be precision machined to yield "snap together alignment" or limited compensation assembly approaches to reduce cost and enhance interchangeability. Diamond point turning, die cast and investment cast mirror substrates and structures, computerized optical polishing, mirror replication, lens molding and other advanced manufacturing technologies can all be used to minimize the cost of this type of optical equipment. This paper discusses the tradeoffs among materials and process selection for catadioptric, multi-mode systems that are under development for a variety of DoD and Homeland Security applications. Several examples are profiled to illuminate the confluence of applicable design and manufacturing

  12. Synergistic interaction between the fungus Beauveria bassiana and desiccant dusts applied against poultry red mites (Dermanyssus gallinae)

    DEFF Research Database (Denmark)

    Steenberg, Tove; Kilpinen, Ole Østerlund

    2014-01-01

    The poultry red mite, Dermanyssus gallinae, is a major pest in egg production, feeding on laying hens. Widely used non-chemical control methods include desiccant dusts, although their persistence under field conditions is often short. Entomopathogenic fungi may also hold potential for mite control...... weeks. Overall, combinations of desiccant dusts and fungus conidia seem to hold considerable promise for future non-chemical control of poultry red mites....

  13. Towards clarifying what distinguishes cyanobacteria able to resurrect after desiccation from those that cannot: The photosynthetic aspect.

    Science.gov (United States)

    Raanan, Hagai; Oren, Nadav; Treves, Haim; Keren, Nir; Ohad, Itzhak; Berkowicz, Simon M; Hagemann, Martin; Koch, Moriz; Shotland, Yoram; Kaplan, Aaron

    2016-06-01

    Organisms inhabiting biological soil crusts (BSCs) are able to cope with extreme environmental conditions including daily hydration/dehydration cycles, high irradiance and extreme temperatures. The photosynthetic machinery, potentially the main source of damaging reactive oxygen species during cessation of CO(2) fixation in desiccating cells, must be protected to avoid sustained photodamage. We compared certain photosynthetic parameters and the response to excess light of BCS-inhabiting, desiccation-tolerant cyanobacteria Leptolyngbya ohadii and Nostoc reinholdii with those observed in the "model" organisms Nostoc sp. PCC 7120, able to resurrect after mild desiccation, and Synechococcus elongatus PCC 7942 and Synechocystis sp. PCC 6803 that are unable to recover from dehydration. Desiccation-tolerant strains exhibited a transient decline in the photosynthetic rate at light intensities corresponding to the inflection point in the PI curve relating the O(2) evolution rate to light intensity. They also exhibited a faster and larger loss of variable fluorescence and profoundly faster Q(A)(-) re-oxidation rates after exposure to high illumination. Finally, a smaller difference was found in the temperature of maximal thermoluminescence signal in the absence or presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) than observed in "model" cyanobacteria. These parameters indicate specific functional differences of photosystem II (PSII) between desiccation tolerant and sensitive cyanobacteria. We propose that exposure to excess irradiation activates a non-radiative electron recombination route inside PSII that minimizes formation of damaging singlet oxygen in the desiccation-tolerant cyanobacteria and thereby reduces photodamage.

  14. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds.

    Science.gov (United States)

    Buitink, J; Leprince, O; Hoekstra, F A

    2000-11-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumber (Cucumis sativa) seeds. Survival following drying and a membrane integrity assay indicated that desiccation tolerance was present during early imbibition and lost in germinated radicles. In germinated cucumber radicles, desiccation tolerance could be re-induced by an incubation in polyethylene glycol (PEG) before drying. In desiccation-intolerant radicles, partitioning of spin probes into lipids during dehydration occurred at higher water contents compared with tolerant and PEG-induced tolerant radicles. The difference in partitioning behavior between desiccation-tolerant and -intolerant tissues could not be explained by the loss of water. Consequently, using a two-phase model system composed of sunflower or cucumber oil and water, physical properties of the aqueous solvent that may affect the partitioning of amphiphilic spin probes were investigated. A significant relationship was found between the partitioning of spin probes and the viscosity of the aqueous solvent. Moreover, in desiccation-sensitive radicles, the rise in cellular microviscosity during drying commenced at higher water contents compared with tolerant or PEG-induced tolerant radicles, suggesting that the microviscosity of the cytoplasm may control the partitioning behavior in dehydrating seeds.

  15. Expression of a GALACTINOL SYNTHASE gene is positively associated with desiccation tolerance of Brassica napus seeds during development.

    Science.gov (United States)

    Li, Xu; Zhuo, Jiajin; Jing, Yin; Liu, Xiao; Wang, Xiaofeng

    2011-10-15

    Desiccation tolerance of seeds is positively correlated with raffinose family oligosaccharides (RFOs). However, RFOs' role in desiccation tolerance is still a matter of controversy. The aim of this work was to monitor the accumulation of RFO during acquisition of desiccation tolerance in rapeseed (Brassica napus L.). Rapeseeds become desiccation tolerant at 21-24d after flowering (DAF), and the time was coincident with an accumulation of raffinose and stachyose. A gene encoding galactinol synthase (GolS; EC2.4.1.123), involved in RFO biosynthesis, was cloned and functionally characterized. Enzymatic properties of recombinant galactinol synthase were also determined. Accumulation of BnGOLS-1 mRNA in developing rapeseeds was concomitant with dry weight deposition and the acquisition of desiccation tolerance, and was concurrent with the formation of raffinose and stachyose. The physiological implications of BnGOLS-1 expression patterns in developing seeds are discussed in light of the hypothesized role of RFOs in seed desiccation tolerance. Copyright © 2011 Elsevier GmbH. All rights reserved.

  16. Dehydration-Induced Redistribution of Amphiphilic Molecules between Cytoplasm and Lipids Is Associated with Desiccation Tolerance in Seeds1

    Science.gov (United States)

    Buitink, Julia; Leprince, Olivier; Hoekstra, Folkert A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumber (Cucumis sativa) seeds. Survival following drying and a membrane integrity assay indicated that desiccation tolerance was present during early imbibition and lost in germinated radicles. In germinated cucumber radicles, desiccation tolerance could be re-induced by an incubation in polyethylene glycol (PEG) before drying. In desiccation-intolerant radicles, partitioning of spin probes into lipids during dehydration occurred at higher water contents compared with tolerant and PEG-induced tolerant radicles. The difference in partitioning behavior between desiccation-tolerant and -intolerant tissues could not be explained by the loss of water. Consequently, using a two-phase model system composed of sunflower or cucumber oil and water, physical properties of the aqueous solvent that may affect the partitioning of amphiphilic spin probes were investigated. A significant relationship was found between the partitioning of spin probes and the viscosity of the aqueous solvent. Moreover, in desiccation-sensitive radicles, the rise in cellular microviscosity during drying commenced at higher water contents compared with tolerant or PEG-induced tolerant radicles, suggesting that the microviscosity of the cytoplasm may control the partitioning behavior in dehydrating seeds. PMID:11080316

  17. Seed storage proteins of spermatophytes share a common ancestor with desiccation proteins of fungi.

    Science.gov (United States)

    Bäumlein, H; Braun, H; Kakhovskaya, I A; Shutov, A D

    1995-12-01

    The legumin- and vicilin-like seed storage globulins of spermatophytes are specifically accumulated during embryogenesis and seed development. Previous studies have shown that a precursor common to both legumin and vicilin genes might have evolved by duplication from a single-domain ancestral gene. We here report that amino acid sequences of legumin and vicilin domains share statistically significant similarity to the germination-specific germins of wheat as well as to the spherulation-specific spherulins of myxomycetes. This conclusion is further supported by the derived intron-exon structure of a spherulin gene. Spherulins are thought to be involved in tissue desiccation or hydration. It is suggested that the present-day seed globulins of spermatophytes have evolved from a group of ancient proteins functional in cellular desiccation/hydration processes.

  18. Arabinose-rich polymers as an evolutionary strategy to plasticize resurrection plant cell walls against desiccation

    DEFF Research Database (Denmark)

    Moore, John P.; Nguema-Ona, Eric E.; Vicré-Gibouin, Mäite

    2013-01-01

    A variety of Southern African resurrection plants were surveyed using high-throughput cell wall profiling tools. Species evaluated were the dicotyledons, Myrothamnus flabellifolia and Craterostigma plantagineum; the monocotyledons, Xerophyta viscosa, Xerophyta schlecterii, Xerophyta humilis...... and comprehensive microarray polymer profiling in combination with multivariate data analysis. The data obtained suggest that three main functional strategies appear to have evolved to prepare plant cell walls for desiccation. Arabinan-rich pectin and arabinogalactan proteins are found in the resurrection fern M......-like Xerophyta spp. and the resurrection grass E. nindensis were found to contain highly arabinosylated xylans and arabinogalactan proteins. These data support a general mechanism of ‘plasticising’ the cell walls of resurrection plants to desiccation and implicate arabinose-rich polymers (pectin...

  19. Development of a solar-desiccant dehumidifier. Phase II second technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, J.

    1981-10-16

    The solar desiccant air conditioner (SODAC) system and its operation are described, including the characteristics of the major components, the performance at design conditions, and the control schemes for optimum operation in various climates. The system uses granular silica gel as a desiccant. It may operate in either a recirculated mode (no air exchange between the outside and the conditioned space) or a ventilated mode (air exchanged between outside and conditioned space). The test data in the ventilated mode at design flow rates are presented. Data include outdoor and indoor inlet wet and dry bulb temperatures, indoor outlet dry and wet bulb temperatures, capacity, coefficient of performance, air flow rates, hot water temperature, and solar heat used. The effects of indoor, outdoor, and hot water temperatures on the capacity and coefficient of performance are shown graphically, and the recirculated and ventilated modes, performances are compared. (LEW)

  20. Modeling of a regenerative indirect evaporative cooler for a desiccant cooling system

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Reinholdt, Lars O.;

    This paper presents a numerical study of a regenerative indirect evaporative cooler, the so-called Dew Point Cooler (DPC), which is part of a Desiccant Cooling system that may both dehumidify and cool humid air. The DPC model is based on first principles using a 1D finite volume scheme and determ......This paper presents a numerical study of a regenerative indirect evaporative cooler, the so-called Dew Point Cooler (DPC), which is part of a Desiccant Cooling system that may both dehumidify and cool humid air. The DPC model is based on first principles using a 1D finite volume scheme...... and determines the steady state working conditions for the component. A sensitivity analysis of the DPC performance is carried out based on the air inlet conditions, air flow rate and recirculation fraction. A recirculation fraction around 0.3 maximizes the DPC net cooling capacity. The supply temperature...

  1. Contrasting assembly processes in a bacterial metacommunity along a desiccation gradient

    Directory of Open Access Journals (Sweden)

    Angel eValverde

    2014-12-01

    Full Text Available Understanding the relative influence of deterministic and stochastic processes in driving community assembly is a major goal in microbial ecology. Here, we have investigated the influence of these processes on bacterial community assembly in the lateral sediments of a salt pan along a desiccation gradient over a three-year period. We show that the role of deterministic processes increases in communities distant from the water line (shaped by drought, probably as a result of the interplay between abiotic and biotic factors. By contrast, the influence of stochastic processes on bacterial community assembly was higher in the sediments closest to the water line, more likely due to lower levels of abiotic stress. Our results demonstrate that both deterministic and stochastic processes influence bacterial community assembly in salt pan sediments, and that their relative influence varies along a desiccation gradient.

  2. Development and construction of the novel solar thermal desiccant cooling system incorporating hot water production

    Energy Technology Data Exchange (ETDEWEB)

    Enteria, Napoleon; Yoshino, Hiroshi; Mochida, Akashi; Takaki, Rie [Faculty of Engineering, Tohoku University, Sendai 980-8579 (Japan); Satake, Akira [Technical Research Institute, Maeda Corporation, Tokyo 179-8914 (Japan); Yoshie, Ryuichiro [Faculty of Engineering, Tokyo Polytechnic University, Atsugi 243-0297 (Japan); Baba, Seizo [Earth Clean Tohoku Co. Ltd., Sendai 984-0038 (Japan)

    2010-02-15

    This paper reports the development and construction of the novel solar cooling and heating system. The system consists of the thermal energy subsystem and the desiccant cooling subsystem. The system utilizes both the cheaper nighttime electric energy and the free daytime solar energy. The system is conceptualized to produce both cooling during summer daytime and hot water production during winter. Testing and evaluation of the system had been done to determine its operational procedure and performance. Based on the results, the thermal energy subsystem functioned to its expected performance in solar energy collection and thermal storage. The desiccant cooling subsystem reduced both the temperature and the humidity content of the air using solar energy with a minimal amount of back-up electric energy. The system however, needs further investigation under real conditions. (author)

  3. Plant Drought Tolerance Enhancement by Trehalose Production of Desiccation-Tolerant Microorganisms

    Science.gov (United States)

    Vílchez, Juan I.; García-Fontana, Cristina; Román-Naranjo, Desireé; González-López, Jesús; Manzanera, Maximino

    2016-01-01

    A collection of desiccation-tolerant xeroprotectant-producing microorganisms was screened for their ability to protect plants against drought, and their role as plant growth-promoting rhizobacteria was investigated in two different crops (tomato and pepper). The most commonly described biochemical mechanisms for plant protection against drought by microorganisms including the production of phytohormones, antioxidants and xeroprotectants were analyzed. In particular, the degree of plant protection against drought provided by these microorganisms was characterized. After studying the findings and comparing them with results of the closest taxonomic relatives at the species and strain levels, we propose that trehalose produced by these microorganisms is correlated with their ability to protect plants against drought. This proposal is based on the increased protection of plants against drought by the desiccation-sensitive microorganism Pseudomonas putida KT2440, which expresses the otsAB genes for trehalose biosynthesis in trans.

  4. Liquid-Desiccant Vapor Separation Reduces the Energy Requirements of Atmospheric Moisture Harvesting.

    Science.gov (United States)

    Gido, Ben; Friedler, Eran; Broday, David M

    2016-08-02

    An innovative atmospheric moisture harvesting system is proposed, where water vapor is separated from the air prior to cooling and condensation. The system was studied using a model that simulates its three interconnected cycles (air, desiccant, and water) over a range of ambient conditions, and optimal configurations are reported for different operation conditions. Model results were compared to specifications of commercial atmospheric moisture harvesting systems and found to represent saving of 5-65% of the electrical energy requirements due to the vapor separation process. We show that the liquid desiccant separation stage that is integrated into atmospheric moisture harvesting systems can work under a wide range of environmental conditions using low grade or solar heating as a supplementary energy source, and that the performance of the combined system is superior.

  5. Recent Advances and Future Direction in Lyophilisation and Desiccation of Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Akalabya Bissoyi

    2016-01-01

    Full Text Available Mesenchymal Stem Cells (MSCs are a promising mammalian cell type as they can be used for the reconstruction of human tissues and organs. MSCs are shown to form bone, cartilage, fat, and muscle-like cells under specific cultivation conditions. Current technology of MSCs cryopreservation has significant disadvantages. Alternative technologies of mammalian cells preservation through lyophilisation or desiccation (air-drying are among the upcoming domains of investigation in the field of cryobiology. Different protectants and their combinations were studied in this context. Loading of the protectant in the live cell can be a challenging issue but recent studies have shown encouraging results. This paper deals with a review of the protectants, methods of their delivery, and physical boundary conditions adopted for the desiccation and lyophilisation of mammalian cells, including MSCs. A hybrid technique combining both methods is also proposed as a promising way of MSCs dry preservation.

  6. Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, Eric Joseph

    2016-12-13

    An indirect evaporative cooler for cooling inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air. The cooler includes a first flow channel for inlet supply air and a second flow channel adjacent the first for exhaust air. The first and second flow channels are defined in part by sheets of a membrane permeable to water vapor such that mass is transferred as a vapor through the membrane from the inlet supply air to a contained liquid desiccant for dehumidification and also to the exhaust air as heat is transferred from the inlet supply air to the liquid coolant. A separation wall divides the liquid desiccant and the coolant but allows heat to be transferred from the supply air to the coolant which releases water vapor to the counter or cross flowing exhaust air.

  7. Plant Drought Tolerance Enhancement by Trehalose Production of Desiccation-Tolerant Microorganisms

    Directory of Open Access Journals (Sweden)

    Juan Ignacio Vilchez Morillas

    2016-09-01

    Full Text Available A collection of desiccation-tolerant xeroprotectant-producing microorganisms was screened for their ability to protect plants against drought, and their role as plant growth-promoting rhizobacteria was investigated in two different crops (tomato and pepper. The most commonly described biochemical mechanisms for plant protection against drought by microorganisms including the production of phytohormones, antioxidants and xeroprotectants were analyzed. In particular, the degree of plant protection against drought provided by these microorganisms was characterized. After studying the findings and comparing them with results of the closest taxonomic relatives at the species and strain levels, we propose that trehalose produced by these microorganisms is correlated with their ability to protect plants against drought. This proposal is based on the increased protection of plants against drought by the desiccation-sensitive microorganism Pseudomonas putida KT2440, which expresses the otsAB genes for trehalose biosynthesis in trans.

  8. Impact-driven planetary desiccation: The origin of the dry Venus

    CERN Document Server

    Kurosawa, Kosuke

    2015-01-01

    The fate of surface water on Venus is one of the most important outstanding problems in comparative planetology. Here a new concept is proposed to explain water removal on a steam-covered proto Venus, referred to as impact-driven planetary desiccation. Since a steam atmosphere is photochemically unstable, water vapor dissociates into hydrogen and oxygen. Then, hydrogen escapes easily into space through hydrodynamic escape driven by strong extreme ultraviolet radiation from the young Sun. The focus is on the intense impact bombardment during the terminal stage of planetary accretion as generators of a significant amount of reducing agent. The fine-grained ejecta remove the residual oxygen, the counter part of escaped hydrogen, via the oxidation of iron-bearing rocks in a hot atmosphere. Thus, hypervelocity impacts cause net desiccation of the planetary surface. I constructed a stochastic cratering model using a Monte Carlo approach to investigate the cumulative mass of nonoxidized, ejected rocks due to the int...

  9. Microbial biosynthesis of wax esters during desiccation: an adaptation for colonization of the earliest terrestrial environments?

    Science.gov (United States)

    Finkelstein, D. B.; Brassell, S. C.; Pratt, L. M.

    2008-12-01

    Biosynthesis of wax esters (WE) by prokaryotes in natural systems, notably bacteria from hot springs and marine phytoplankton, is poorly documented, primarily because saponification is a routine step in the analysis of microbial mat lipids. Use of this preparative procedure, critical for characterization of the diagnostic distributions of carboxylic acids in phospholipids, precludes recovery of intact WE. Examination of non-saponified lipids in emergent and desiccated mats with comparable microbial communities from the Warner Lake region, Oregon, reveals increases in the relative abundance (18.6 to 59.9μg/g Corg) and average chain length (C38 to C46) of WE in the latter, combined with assimilation of phytol and tocopherol moieties. Prokaryotes can accumulate WE as storage lipids in vitro, notably at elevated temperature or under nitrogen limiting conditions, but we propose that biosynthesis of long-chain WE that have a low solubility and are resistant to degradation/oxidation may represent an evolutionary strategy to survive desiccation in evaporative environments. Moreover, aeolian transport of desiccated mat-rip-ups between lake flats allows for migration of microbial communities within and between lake flats and basins during arid conditions. Subsequent rehydration within an alkaline environment would naturally saponify WE, and thereby regenerate alcohol and acid moieties that could serve as membrane lipids for the next viable microbial generation. The evolutionary cradle of WE was likely abiotic generation under hydrothermal conditions, which is consistent with the antiquity of the ester linkage necessitated by its integral role in the membranes of Eubacteria (though not Archaea) and in bacteriochlorophyll. The subsequent capability of microbes to biosynthesize WE may have facilitated their survival when nutrients were limiting, and production of long-chain WE (>C40) may represent a further critical evolutionary threshold that enabled their persistence through

  10. Moving Advanced Desiccant Materials into Mainstream Non-CFC Cooling Products

    Energy Technology Data Exchange (ETDEWEB)

    Sand, J. R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grossman, T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rice, C. K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fairchild, P. D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gross, I. L. [Engelhard/ICC, Hatboro, PA (United States). Fresh Air Solutions

    2004-12-30

    Desiccant dehumidification technology is emerging as a technically viable alternative for comfort conditioning in many commercial and institutional buildings. Attempts to improve the indoor air quality of buildings has resulted in increasingly stringent guidelines for occupant outdoor air ventilation rates. Additionally, revised building heating, ventilating, and air-conditioning (HVAC) design criteria based on regional peak dew point data highlight the important of the latent (moisture removal) building load relative to the sensible (temperature) building load.

  11. Performance of a solar liquid desiccant air conditioner - An experimental and theoretical approach

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Shahab [Queensland University of Technology, Faculty of Built Environment and Engineering, GPO Box 2434, Brisbane 4001 (Australia)

    2008-06-15

    In this paper the results of testing a solar liquid desiccant air conditioner (LDAC) in the tropical climate of Queensland, Australia have been presented. The system uses polymer plate heat exchanger (PPHE) for dehumidification/indirect evaporative cooling, and a cooling pad as the direct evaporative cooler for the dry air leaving the PPHE. Lithium chloride, which is an effective desiccant in air dehumidification, was used in the experiments and a scavenger air regenerator concentrates the dilute solution from the dehumidifier using hot water from flat plate solar collectors. The data obtained from performance monitoring of the solar LDAC operating on a commercial site in Brisbane was compared with a previously developed model for the PPHE. The comparison reveals that good agreement exists between the experiments and model predictions. The inaccuracies are well within the measuring errors of the temperature, humidity and the air and solution flow rates. The above tests further indicate a satisfactory performance of the unit by independently controlling the air temperature and humidity inside the conditioned space. In order to prevent carryover of the solution particles into the environment, eliminators are used at outlet of the absorber unit and the regenerator. An alternative method in preventing the carryover is the use of indirect cooling, in which the supply air does not contact the solution. The method can be used to produce potable water from the atmospheric air in remote areas. The liquid desiccant system can be used in the HVAC industry, either as a packaged roof-top air conditioner, or as an air handler unit for commercial applications. The system could also be used for space heating in winter due to the property of desiccants to provide heat when wetted. (author)

  12. Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis.

    Science.gov (United States)

    Gechev, Tsanko S; Benina, Maria; Obata, Toshihiro; Tohge, Takayuki; Sujeeth, Neerakkal; Minkov, Ivan; Hille, Jacques; Temanni, Mohamed-Ramzi; Marriott, Andrew S; Bergström, Ed; Thomas-Oates, Jane; Antonio, Carla; Mueller-Roeber, Bernd; Schippers, Jos H M; Fernie, Alisdair R; Toneva, Valentina

    2013-02-01

    Haberlea rhodopensis is a resurrection plant with remarkable tolerance to desiccation. Haberlea exposed to drought stress, desiccation, and subsequent rehydration showed no signs of damage or severe oxidative stress compared to untreated control plants. Transcriptome analysis by next-generation sequencing revealed a drought-induced reprogramming, which redirected resources from growth towards cell protection. Repression of photosynthetic and growth-related genes during water deficiency was concomitant with induction of transcription factors (members of the NAC, NF-YA, MADS box, HSF, GRAS, and WRKY families) presumably acting as master switches of the genetic reprogramming, as well as with an upregulation of genes related to sugar metabolism, signaling, and genes encoding early light-inducible (ELIP), late embryogenesis abundant (LEA), and heat shock (HSP) proteins. At the same time, genes encoding other LEA, HSP, and stress protective proteins were constitutively expressed at high levels even in unstressed controls. Genes normally involved in tolerance to salinity, chilling, and pathogens were also highly induced, suggesting a possible cross-tolerance against a number of abiotic and biotic stress factors. A notable percentage of the genes highly regulated in dehydration and subsequent rehydration were novel, with no sequence homology to genes from other plant genomes. Additionally, an extensive antioxidant gene network was identified with several gene families possessing a greater number of antioxidant genes than most other species with sequenced genomes. Two of the transcripts most abundant during all conditions encoded catalases and five more catalases were induced in water-deficient samples. Using the pharmacological inhibitor 3-aminotriazole (AT) to compromise catalase activity resulted in increased sensitivity to desiccation. Metabolome analysis by GC or LC-MS revealed accumulation of sucrose, verbascose, spermidine, and γ-aminobutyric acid during drought, as

  13. Desiccation tolerance, longevity and seed-siring ability of entomophilous pollen from UK native orchid species.

    Science.gov (United States)

    Marks, Timothy R; Seaton, Philip T; Pritchard, Hugh W

    2014-09-01

    Pollinator-limited seed-set in some terrestrial orchids is compensated for by the presence of long-lived flowers. This study tests the hypothesis that pollen from these insect-pollinated orchids should be desiccation tolerant and relatively long lived using four closely related UK terrestrial species; Anacamptis morio, Dactylorhiza fuchsii, D. maculata and Orchis mascula. Pollen from the four species was harvested from inflorescences and germinated in vitro, both immediately and also after drying to simulate interflower transit. Their tolerance to desiccation and short-term survival was additionally assessed after 3 d equilibration at a range of relative humidities (RHs), and related to constructed sorption isotherms (RH vs. moisture content, MC). Ageing of D. fuchsii pollen was further tested over 2 months against temperature and RH, and the resultant survival curves were subjected to probit analysis, and the distribution of pollen death in time (σ) was determined. The viability and siring ability, following artificial pollinations, were determined in D. fuchsii pollen following storage for 6 years at -20 °C. The pollen from all four species exhibited systematic increases in germinability and desiccation tolerance as anthesis approached, and pollen from open flowers generally retained high germinability. Short-term storage revealed sensitivity to low RH, whilst optimum survival occurred at comparable RHs in all species. Similarly, estimated pollen life spans (σ) at differing temperatures were longest under the dry conditions. Despite a reduction in germination and seeds per capsule, long-term storage of D. fuchsii pollen did not impact on subsequent seed germination in vitro. Substantial pollen desiccation tolerance and life span of the four entomophilous orchids reflects a resilient survival strategy in response to unpredictable pollinator visitation, and presents an alternative approach to germplasm conservation. © The Author 2014. Published by Oxford

  14. Desiccation tolerance and lichenization: a case study with the aeroterrestrial microalga Trebouxia sp. (Chlorophyta).

    Science.gov (United States)

    Candotto Carniel, Fabio; Zanelli, Davide; Bertuzzi, Stefano; Tretiach, Mauro

    2015-08-01

    A comparative study of isolated vs. lichenized Trebouxia sp. showed that lichenization does not influence the survival capability of the alga to the photo-oxidative stress derived from prolonged desiccation. Coccoid algae in the Trebouxia genus are the most common photobionts of chlorolichens but are only sporadically found in soil or bark outside of a lichen. They all appear to be desiccation tolerant, i.e. they can survive drying to water contents of below 10%. However, little is known about their longevity in the dry state and to which extent lichenization can influence it. Here, we studied the longevity in the dry state of the lichenized alga (LT) Trebouxia sp. in the lichen Parmotrema perlatum, in comparison with axenically grown cultures (CT) isolated from the same lichen. We report on chlorophyll fluorescence emission and reactive oxygen species (ROS) production before desiccation, after 15-45 days in the dry state under different combinations of light and air humidity and after recovery for 1 or 3 days in fully hydrated conditions. Both the CT and the LT were able to withstand desiccation under high light (120 µmol photons m(-2) s(-1) for 14 h per day), but upon recovery after 45 days in the dry state the performance of the CT was better than that of the LT. By contrast, the quenching of excess light energy was more efficient in the LT, at high relative humidities especially. ROS production in the LT was influenced mostly by light exposure, whereas the CT showed an oxidative burst independent of the light conditions. Although lichenization provides benefits that are essential for the survival of the photobiont in high-light habitats, Trebouxia sp. can withstand protracted periods of photo-oxidative stress even outside of a lichen thallus.

  15. Contrasting strategies of resistance vs. tolerance to desiccation in two polar dipterans

    Directory of Open Access Journals (Sweden)

    M.J. Everatt

    2014-05-01

    Full Text Available Low water availability is one of the principal stressors for terrestrial invertebrates in the polar regions, determining the survival of individuals, the success of species and the composition of communities. The Arctic and Antarctic dipterans Heleomyza borealis and Eretmoptera murphyi spend the majority of their biennial life cycles as larvae, and so are exposed to the full range of environmental conditions, including low water availability, over the annual cycle. In the current study, the desiccation resistance and desiccation tolerance of larvae were investigated, as well as their capacity for cross-tolerance to temperature stress. Larvae of H. borealis showed high levels of desiccation resistance, only losing 6.9% of their body water after 12 days at 98.2% relative humidity (RH. In contrast, larvae of E. murphyi lost 46.7% of their body water after 12 days at the same RH. Survival of E. murphyi larvae remained high in spite of this loss (>80% survival. Following exposure to 98.2% RH, larvae of E. murphyi showed enhanced survival at −18°C for 2 h. The supercooling point of larvae of both species was also lowered following prior treatment at 98.2% RH. Cross-tolerance to high temperatures (37 or 38.5°C was not noted following desiccation in E. murphyi, and survival even fell at 37°C following a 12-day pre-treatment. The current study demonstrates two different strategies of responding to low water availability in the polar regions and indicates the potential for cross-tolerance, a capacity which is likely to be beneficial in the ever-changing polar climate.

  16. Trehalose biosynthesis in Rhizobium leguminosarum bv. trifolii and its role in desiccation tolerance.

    Science.gov (United States)

    McIntyre, Helen J; Davies, Holiday; Hore, Timothy A; Miller, Simon H; Dufour, Jean-Pierre; Ronson, Clive W

    2007-06-01

    Rhizobium leguminosarum bv. trifolii forms nitrogen-fixing root nodules on the pasture legume Trifolium repens, and T. repens seed is often coated with a compatible R. leguminosarum bv. trifolii strain prior to sowing. However, significant losses in bacterial viability occur during the seed-coating process and during storage of the coated seeds, most likely due to desiccation stress. The disaccharide trehalose is known to function as an osmoprotectant, and trehalose accumulation due to de novo biosynthesis is a common response to desiccation stress in bacteria. In this study we investigated the role of endogenous trehalose synthesis in desiccation tolerance in R. leguminosarum bv. trifolii strain NZP561. Strain NZP561 accumulated trehalose as it entered the stationary phase due to the combined actions of the TreYZ and OtsAB pathways. Mutants deficient in either pathway showed near-wild-type levels of trehalose accumulation, but double otsA treY mutants failed to accumulate any trehalose. The double mutants were more sensitive to the effects of drying, and their survival was impaired compared to that of the wild type when glass beads were coated with the organisms and stored at relative humidities of 5 and 32%. The otsA treY mutants were also less competitive for nodule occupancy. Gene expression studies showed that the otsA and treY genes were expressed constitutively and that expression was not influenced by the growth phase, suggesting that trehalose accumulation is controlled at the posttranscriptional level or by control of trehalose breakdown rates. Our results indicate that accumulated trehalose plays an important role in protecting R. leguminosarum bv. trifolii cells against desiccation stress and against stress encountered during nodulation.

  17. Effect of desiccation and salinity stress on seed germination and initial plant growth of Cucumis melo

    OpenAIRE

    Sohrabikertabad,S.; A. Ghanbari; Mohassel, Mohamad,H.R.; Mahalati,M.N.; Gherekhloo, J.

    2013-01-01

    Smellmelon, an annual invasive weed of soybean production fields in the north of Iran, reproduces and spreads predominately through seed production. This makes seed bank survival and successful germination essential steps in the invasive process. To evaluate the potential of Smellmelon to invade water-stressed environments, laboratory studies were conducted to investigate the effect of desiccation and salinity at different temperatures on seed germination and seedling growth of Cucumis melo. ...

  18. Protective mechanism of desiccation tolerance in Reaumuria soongorica: Leaf abscission and sucrose accumulation in the stem

    Institute of Scientific and Technical Information of China (English)

    LIU YuBing; ZHANG TengGuo; LI XingRong; WANG Gang

    2007-01-01

    Reaumuria soongorica (Pall.) Maxim., a perennial semi-shrub, is widely found in semi-arid areas in northwestern China and can survive severe desiccation of its vegetative organs. In order to study the protective mechanism of desiccation tolerance in R. Soongorica, diurnal patterns of net photosynthetic rate (Pn), water use efficiency (WUE) and chlorophyll fluorescence parameters of Photosystem II (PSII), and sugar content in the source leaf and stem were investigated in 6-year-old plants during progressive soil drought imposed by the cessation of watering. The results showed that R. Soongorica was characterized by very low leaf water potential, high WUE, photosynthesis and high accumulation of sucrose in the stem and leaf abscission under desiccation. The maximum Pn increased at first and then declined during drought, but intrinsic WUE increased remarkably in the morning with increasing drought stress. The maximal photochemical efficiency of PSII (Fv/Fm) and the quantum efficiency of noncyclic electric transport of PSII(Φpsii) decreased significantly under water stress and exhibited an obvious phenomenon of photoinhibition at noon. Drought stressed plants maintained a higher capacity of dissipation of the excitation energy (measured as NPQ) with the increasing intensity of stress. Conditions of progressive drought promoted sucrose and starch accumulation in the stems but not in the leaves. However, when leaf water potential was less than -21.3 Mpa, the plant leaves died and then abscised. But the stem photosynthesis remained and, afterward the plants entered the dormant state. Upon rewatering, the shoots reactivated and the plants developed new leaves. Therefore, R. Soongorica has the ability to reduce water loss through leaf abscission and maintain the vigor of the stem cells to survive desiccation.

  19. Protective mechanism of desiccation tolerance in Reaumuria soongorica: Leaf abscission and sucrose accumulation in the stem

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Reaumuria soongorica (Pall.) Maxim., a perennial semi-shrub, is widely found in semi-arid areas in northwestern China and can survive severe desiccation of its vegetative organs. In order to study the protective mechanism of desiccation tolerance in R. soongorica, diurnal patterns of net photosynthetic rate (Pn), water use efficiency (WUE) and chlorophyll fluorescence parameters of Photosystem II (PSII), and sugar content in the source leaf and stem were investigated in 6-year-old plants during progressive soil drought imposed by the cessation of watering. The results showed that R. soongorica was char-acterized by very low leaf water potential, high WUE, photosynthesis and high accumulation of sucrose in the stem and leaf abscission under desiccation. The maximum Pn increased at first and then de-clined during drought, but intrinsic WUE increased remarkably in the morning with increasing drought stress. The maximal photochemical efficiency of PSII (Fv/Fm) and the quantum efficiency of noncyclic electric transport of PSII(ΦPSII) decreased significantly under water stress and exhibited an obvious phenomenon of photoinhibition at noon. Drought stressed plants maintained a higher capacity of dis-sipation of the excitation energy (measured as NPQ) with the increasing intensity of stress. Conditions of progressive drought promoted sucrose and starch accumulation in the stems but not in the leaves. However, when leaf water potential was less than –21.3 MPa, the plant leaves died and then abscised. But the stem photosynthesis remained and, afterward the plants entered the dormant state. Upon re-watering, the shoots reactivated and the plants developed new leaves. Therefore, R. soongorica has the ability to reduce water loss through leaf abscission and maintain the vigor of the stem cells to survive desiccation.

  20. Taken to the limit--Is desiccation stress causing precocious encystment of trematode parasites in snails?

    Science.gov (United States)

    O'Dwyer, Katie; Poulin, Robert

    2015-12-01

    When hosts experience environmental stress, the quantity and quality of resources they provide for parasites may be diminished, and host longevity may be decreased. Under stress, parasites may adopt alternative strategies to avoid fitness reductions. Trematode parasites typically have complex life cycles, involving asexual reproduction in a gastropod first intermediate host. A rare phenomenon, briefly mentioned in the literature, and termed 'precocious encystment' involves the next stage in the parasites' life cycle (metacercarial cyst) forming within the preceding stage (redia), while still inside the snail. In the trematode Parorchis sp. NZ using rocky shore snails exposed to long periods outside water, we hypothesised that this might be an adaptive strategy against desiccation, preventing parasite emergence from the snail. To test this, we first investigated the effect of prolonged desiccation on the survival of two species of high intertidal snails. Secondly, we measured the reproductive output (cercarial production) of the parasite under wet and dry conditions. Finally, we quantified the influence of desiccation stress on the occurrence of precocious encystment. Snail mortality was higher under dry conditions, indicating stress, and it was somewhat exacerbated for infected snails. Parasite reproductive output differed between wet and dry conditions, with parasites of snails kept in dry conditions producing more cercariae when placed in water. Little variation was observed in the occurrence of precocious encystment, although some subtle patterns emerged. Given the stresses associated with living in high intertidal environments, we discuss precocious encystment as a possible stress response in this trematode parasite.

  1. Polypropylene Fiber Amendments to Alleviate Initiation and Evolution of Desiccation Cracks in Bentonite Liners

    Science.gov (United States)

    Tuller, M.; Gebrenegus, T. B.

    2009-12-01

    Sodium saturated bentonite is a major constituent of compacted and geosynthetic liners and covers for hydraulic isolation of hazardous waste, playing a crucial role in protecting groundwater and other environmental resources from harmful landfill leachates. Due to favorable hydraulic properties (i.e., low permeability), large surface area and associated adsorption capacity for particular contaminants, and relative abundance and low cost, bentonite is the material of choice in many modern waste containment systems. However, long-term interactions between bentonite and waste leachate and exposure of bentonite to desiccative conditions may significantly deteriorate liner or cover performance and ultimately lead to failure of containment systems. In the presented study, the potential usefulness of polypropylene fiber amendments for preventing initiation and evolution of desiccation cracks, while maintaining acceptably low permeability under saturated conditions was investigated. Well-controlled desiccation experiments were conducted using initially saturated bentonite-sand mixtures that contained varying amounts of polypropylene fibers. Initiation and evolution of surface cracks were observed by means of X-Ray Computed Tomography (CT). Advanced image analysis techniques were employed to characterize and quantify 2-D and 3-D features of the evolving crack networks. Potential negative effects of employed additives on saturated hydraulic conductivity were determined with fully-automated Flexible Wall Permeametry (FWP).

  2. Global Lysine Acetylome Analysis of Desiccated Somatic Embryos of Picea asperata

    Science.gov (United States)

    Xia, Yan; Jing, Danlong; Kong, Lisheng; Zhang, Jianwei; OuYang, Fangqun; Zhang, Hanguo; Wang, Junhui; Zhang, Shougong

    2016-01-01

    Partial desiccation treatment (PDT) promotes the germination capacity of conifer somatic embryos. Lysine acetylation (LysAc) is a dynamic and reversible post-translational modification that plays a key role in many biological processes including metabolic pathways and stress response. To investigate the functional impact of LysAc in the response of Picea asperata somatic embryos to PDT, we performed a global lysine acetylome analysis. Here, combining antibody-based affinity enrichment and high-resolution mass spectrometry, we identified and validated 1079 acetylation sites in 556 acetylated proteins from P. asperata somatic embryos during PDT. These data represent a novel large-scale dataset of lysine-acetylated proteins from the conifer family. Intensive bioinformatics analysis of the Gene Ontology of molecular functions demonstrated that lysine-acetylated proteins were mainly associated with binding, catalytic activities, and structural molecular activities. Functional characterization of the acetylated proteins revealed that in the desiccated somatic embryos, LysAc is mainly involved in the response to stress and central metabolism. Accordingly, the majority of these interacting proteins were also highly enriched in ribosome, proteasome, spliceosome, and carbon metabolism clusters. This work provides the most comprehensive profile of LysAc for a coniferous species obtained to date and facilitates the systematic study of the physiological role of LysAc in desiccated somatic embryos of P. asperata. PMID:28066480

  3. Performance analysis of four-partition desiccant wheel and hybrid dehumidification air-conditioning system

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jongsoo; Yamaguchi, Seiichi; Saito, Kiyoshi; Kawai, Sunao [Department of Applied Mechanics and Aerospace Engineering, School of Fundamental Science and Engineering, Waseda University, 3-4-1-58-210 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2010-05-15

    A desiccant dehumidification system with air can decrease energy consumption because it can be driven by low-grade waste heat below 80 C. If this system can be driven by low-temperature heat sources whose temperature is below 50 C, exhausted heat from fuel cells or air conditioners that exist everywhere can be used as heat sources. This could lead to considerable energy saving. This study provides a detailed evaluation of the performance of a four-partition desiccant wheel to make a low-temperature driving heat source possible and achieve considerable energy saving by the simulation and experiment. Further, the study investigates the in-depth performance of a hybrid air-conditioning system with a four-partition desiccant wheel by simulation. As a result, it was clear that there exists an optimum rotational speed to maximize the dehumidification performance and that the hybrid air-conditioning system improves COP by approximately 94% as compared to the conventional vapour compression-type refrigerator. (author)

  4. Effects of leachate infiltration and desiccation cracks on hydraulic conductivity of compacted clay

    Directory of Open Access Journals (Sweden)

    Jun HE

    2015-04-01

    Full Text Available Both cracks in clay liner and the complex composition of landfill leachate might have effects on the hydraulic conductivity of a compacted clay liner. In this study, the hydraulic conductivities of natural clay and bentonite-modified clay with and without desiccation cracks were measured, respectively, using three types of liquids as permeating liquid: 2 500 mg/L acetic acid solution, 0.5 mol/L CaCl2 solution, and tap water. When tap water was adopted as the permeating liquid, desiccation cracks resulted in increases in the average value of hydraulic conductivity: a 25-fold increase for the natural clay and a 5.7-fold increase for the bentonite-modified clay. It was also found out that the strong self-healing capability of bentonite helped to reduce the adverse impact of cracks on hydraulic performance. In contrast to tap water, simulated leachates (acetic acid and CaCl2 solutions show no adverse effect on the hydraulic conductivities of natural and bentonite-modified clays. It is concluded that desiccation cracks and bentonite have more significant effects on hydraulic performance than simulated leachates.

  5. Evolution and plasticity of anuran larval development in response to desiccation. A comparative analysis.

    Science.gov (United States)

    Richter-Boix, Alex; Tejedo, Miguel; Rezende, Enrico L

    2011-09-01

    Anurans breed in a variety of aquatic habitats with contrasting levels of desiccation risk, which may result in selection for faster development during larval stages. Previous studies suggest that species in ephemeral ponds reduce their developmental times to minimize desiccation risks, although it is not clear how variation in desiccation risk affects developmental strategies in different species. Employing a comparative phylogenetic approach including data from published and unpublished studies encompassing 62 observations across 30 species, we tested if species breeding in ephemeral ponds (High risk) develop faster than those from permanent ponds (Low risk) and/or show increased developmental plasticity in response to drying conditions. Our analyses support shorter developmental times in High risk, primarily by decreasing body mass at metamorphosis. Plasticity in developmental times was small and did not differ between groups. However, accelerated development in High risk species generally resulted in reduced sizes at metamorphosis, while some Low risk species were able compensate this effect by increasing mean growth rates. Taken together, our results suggest that plastic responses in species breeding in ephemeral ponds are constrained by a general trade-off between development and growth rates.

  6. Arabinose-rich polymers as an evolutionary strategy to plasticize resurrection plant cell walls against desiccation.

    Science.gov (United States)

    Moore, John P; Nguema-Ona, Eric E; Vicré-Gibouin, Mäite; Sørensen, Iben; Willats, William G T; Driouich, Azeddine; Farrant, Jill M

    2013-03-01

    A variety of Southern African resurrection plants were surveyed using high-throughput cell wall profiling tools. Species evaluated were the dicotyledons, Myrothamnus flabellifolia and Craterostigma plantagineum; the monocotyledons, Xerophyta viscosa, Xerophyta schlecterii, Xerophyta humilis and the resurrection grass Eragrostis nindensis, as well as a pteridophyte, the resurrection fern, Mohria caffrorum. Comparisons were made between hydrated and desiccated leaf and frond material, with respect to cell wall composition and polymer abundance, using monosaccharide composition analysis, FT-IR spectroscopy and comprehensive microarray polymer profiling in combination with multivariate data analysis. The data obtained suggest that three main functional strategies appear to have evolved to prepare plant cell walls for desiccation. Arabinan-rich pectin and arabinogalactan proteins are found in the resurrection fern M. caffrorum and the basal angiosperm M. flabellifolia where they appear to act as 'pectic plasticizers'. Dicotyledons with pectin-rich walls, such as C. plantagineum, seem to use inducible mechanisms which consist of up-regulating wall proteins and osmoprotectants. The hemicellulose-rich walls of the grass-like Xerophyta spp. and the resurrection grass E. nindensis were found to contain highly arabinosylated xylans and arabinogalactan proteins. These data support a general mechanism of 'plasticising' the cell walls of resurrection plants to desiccation and implicate arabinose-rich polymers (pectin-arabinans, arabinogalactan proteins and arabinoxylans) as the major contributors in ensuring flexibility is maintained and rehydration is facilitated in these plants.

  7. Understanding desiccation tolerance using the resurrection plant Boea hygrometrica as a model system.

    Science.gov (United States)

    Mitra, Jayeeta; Xu, Guanghui; Wang, Bo; Li, Meijing; Deng, Xin

    2013-01-01

    Vegetative tissues of Boea hygrometrica, a member of the Gesneriaceae family, can tolerate severe water loss to desiccated state and fully recover upon rehydration. Unlike many other so called "resurrection plants," the detached leaves of B. hygrometrica also possess the same level of capacity for desiccation tolerance (DT) as that of whole plant. B. hygrometrica is distributed widely from the tropics to northern temperate regions in East Asia and grows vigorously in areas around limestone rocks, where dehydration occurs frequently, rapidly, and profoundly. The properties of detached B. hygrometrica leaves and relative ease of culture have made it a useful system to study the adaptive mechanisms of DT. Extensive studies have been conducted to identify the physiological, cellular, and molecular mechanisms underlying DT in the last decade, including specific responses to water stress, such as cell wall folding and pigment-protein complex stabilizing in desiccated leaves. In this review, the insight into the structural, physiological, and biochemical, and molecular alterations that accompany the acquisition of DT in B. hygrometrica is described. Finally a future perspective is proposed, with an emphasis on the emerging regulatory roles of retroelements and histone modifications in the acquisition of DT, and the need of establishment of genome sequence database and high throughput techniques to identify novel regulators for fully understanding of the matrix of DT.

  8. Desiccation tolerance of Muellerius cf. capillaris (Nematoda: Protostrongylidae) first-stage larvae.

    Science.gov (United States)

    Solomon, A; Ilan, P; Itamar, G

    1998-08-01

    Muellerius cf. capillaris is the most common lung worm of wild Nubian ibex (Capra ibex nubiana) in the northern Negev desert, Israel. The capacity of the free-living stages (L1) of the parasite to survive extreme desiccation was tested under 2 different dehydration regimes at 23 C: rapid dehydration through direct exposure to 0% relative humidity (RH), and a slow dehydration regime of preconditioning at 33% RH for 7 days prior to exposure to 0% RH for a further 21 days. In direct exposures to 0% and 33% RH, by day 11 survival rates of L1 were significantly higher than when stored in water and in 97% RH (P 0.1). L1 surviving after 21 days of desiccation at 0% RH were, on the other hand, less infective to T. pisana. The percentage of such postdesiccated L1 reaching infective stage (L3) was, however, the same as that of the control group. The ability of M. cf. capillaris L1 to survive anhydrobiosis and retain infectivity to land snails after extreme desiccation enables their coexistence with the Nubian ibex in desert habitat.

  9. Design and development of desiccant seed dryer with airflow inversion and recirculation.

    Science.gov (United States)

    Gill, R S; Singh, Sukhmeet; Singh, Parm Pal

    2014-11-01

    A desiccant seed dryer has been developed to dry seed in deep bed at safe temperatures for good shelf life and germination. The dryer consists of two chambers viz., air conditioning control unit and seed drying chamber. It operates in seed drying mode and desiccant regeneration mode. It has provision for recirculation of the drying air to minimise the moisture removal from drying air. Also, it has provision of airflow inversion through deep seed bed for uniform drying. Moisture removal from drying air has been done using silica gel desiccant. Chilly 'Punjab Surakh', Chilly 'Punjab Guchhedaar', Paddy, Coriander, Fenugreek and Radish seeds was dried with hot air at 38 °C from initial moisture content of 26.9 to 5 % (wb) in 2 h, 46.52 to 4.19 % (wb) in 4.25 h, 13.3 to 2.61 % (wb) in 4 h, 13.4 to 10.08 % (wb) in 3 h, 12.4 to 8.22 % (wb) in 4¼ h and 10.6 to 6.08 % (wb) in 4 h respectively. The statistical analysis based on paired t-test showed that seed drying in this dryer has no adverse effect on seed germination.

  10. Late embryogenesis abundant proteins protect human hepatoma cells during acute desiccation.

    Science.gov (United States)

    Li, Shumin; Chakraborty, Nilay; Borcar, Apurva; Menze, Michael A; Toner, Mehmet; Hand, Steven C

    2012-12-18

    Expression of late embryogenesis abundant (LEA) proteins is highly correlated with desiccation tolerance in anhydrobiotic animals, selected land plants, and bacteria. Genes encoding two LEA proteins, one localized to the cytoplasm/nucleus (AfrLEA2) and one targeted to mitochondria (AfrLEA3m), were stably transfected into human HepG2 cells. A trehalose transporter was used for intracellular loading of this disaccharide. Cells were rapidly and uniformly desiccated to low water content (spin-drying technique. Immediately on rehydration, control cells without LEA proteins or trehalose exhibited 0% membrane integrity, compared with 98% in cells loaded with trehalose and expressing AfrLEA2 or AfrLEA3m; surprisingly, AfrLEA3m without trehalose conferred 94% protection. Cell proliferation across 7 d showed an 18-fold increase for cells dried with AfrLEA3m and trehalose, compared with 27-fold for nondried controls. LEA proteins dramatically enhance desiccation tolerance in mammalian cells and offer the opportunity for engineering biostability in the dried state.

  11. Re-induction of desiccation tolerance after germination of Cedrela fissilis Vell. seeds.

    Science.gov (United States)

    Masetto, Tathiana E; Faria, Jose M; Fraiz, Ana C R

    2014-09-01

    This work aimed to characterize the re-induction of desiccation tolerance (DT) in germinated seeds, using polyethylene glycol (PEG 8000). Cell changes were investigated through cytological assays (cell viability and transmission electronic microscopy) as well as DNA integrity during loss and re-establishment of DT. The loss of DT was characterized by drying germinated seeds with different radicle lengths (1, 2, 3, 4 and 5 mm) in silica gel, decreasing the moisture content to ten percentage points intervals, followed by pre-humidification (100% RH / 24 h) and rehydration. To re-induce DT, germinated seeds were treated for 72 h with PEG (-2.04 MPa) and PEG (-2.04 MPa) + ABA (100 µM) before dehydration. Germinated seeds did not tolerate desiccation to 10% moisture content, irrespectively of the radicle length. However, when incubated in PEG, those with 1 and 2 mm long radicle attained 71% and 29% survival, respectively. The PEG+ABA treatment was efficient to re-establish DT in seeds with 1 mm long radicles (100% survival). The ultrastructural assays of the cells of germinated seeds with 2 and 5 mm length confirmed the obtained physiological results. Germinated seeds of C. fissilis constitute a useful tool for desiccation tolerance investigations.

  12. Acquisition and loss of desiccation tolerance in seeds: from experimental model to biological relevance.

    Science.gov (United States)

    Dekkers, Bas J W; Costa, Maria Cecilia D; Maia, Julio; Bentsink, Leónie; Ligterink, Wilco; Hilhorst, Henk W M

    2015-03-01

    Besides being an important model to study desiccation tolerance, the induction of desiccation tolerance in germinated seeds may also play an ecological role in seedling establishment. Desiccation tolerance (DT) is the ability of certain organisms to survive extreme water losses without accumulation of lethal damage. This was a key feature in the conquering of dry land and is currently found in all taxa including bacteria, fungi, roundworms and plants. Not surprisingly, studies in various fields have been performed to unravel this intriguing phenomenon. In flowering plants, DT is rare in whole plants (vegetative tissues), yet is common in seeds. In this review, we present our current understanding of the evolution of DT in plants. We focus on the acquisition of DT in seeds and the subsequent loss during and after germination by highlighting and comparing research in two model plants Medicago truncatula and Arabidopsis thaliana. Finally, we discuss the ability of seeds to re-establish DT during post-germination, the possible ecological meaning of this phenomenon, and the hypothesis that DT, in combination with dormancy, optimizes seedling establishment.

  13. Effect of wetting-drying cycles on soil desiccation cracking behaviour

    Directory of Open Access Journals (Sweden)

    Tang Chao-Sheng

    2016-01-01

    Full Text Available Better understanding the desiccation cracking process is essential in analysing drought effects on soil hydraulic and mechanical properties through consideration of the atmosphere-ground interaction. Laboratory tests were conducted to investigate the consequence of wetting-drying cycles on the initiation and propagation characteristics of desiccation cracks on soil surface. Initially saturated slurry specimens were prepared and subjected to five subsequent wetting-drying cycles. Image processing technique was employed to quantitatively analyze the morphology characteristics of crack patterns formed during each drying path. The results show that the desiccation cracking behaviour of soil is significantly affected by the wetting-drying cycles. Before the third wetting-drying cycle is reached, the surface crack ratio and the average crack width increases while the average clod area decreases with increasing the number of wetting-drying cycles. The number of intersections and crack segments per unit area reaches the peak values after the second wetting-drying cycle. After the third wetting-drying cycle is reached, the effect of increasing wetting-drying cycles on crack patterns is insignificant. Moreover, it is observed that the applied wetting-drying cycles are accompanied by a continual reconstruction of soil structure. The initial homogenous slurry structure is completely replaced with aggregated structure after the third cycles, and a significant increase in the inter-aggregate porosity can be observed.

  14. Influence of pretreatment and desiccation on the germination of Laurus nobilis L. seeds.

    Science.gov (United States)

    Tilki, Fahrettin

    2004-04-01

    The effects of moist stratification, gibberellic acid (GA3) in combination with cold-moist stratification and desiccation on the germination of bay laurel (Laurus nobilis L.) seeds were studied. It was found that the external fleshy pericarp caused dormancy. There was also embryo dormancy and it was broken in seeds lacking pericarp either warm-moist stratification (20 degrees C day/4 degrees C night) or cold-moist stratification (4 degrees C) for 8 and 10 weeks, respectively. Gibberellic acid had little effect on germination percent and germination value of seeds without pericarp when used alone but significantly increased overall germination performance when used with cold-moist stratification. The viability of seeds dropped when the moisture content of the seeds was reduced by desiccation, and the time required to reach the critical moisture levels in the seeds differed in the different desiccation temperatures. The critical minimum seed moisture content for bay laurel was around 15% and the seeds showed the typical behavior of recalcitrant seeds.

  15. Optimization of Design of Aquifer Storage and Recovery System (ASTR) for Enhanced Infiltration Rate with Reduced Cost at the Coastal Aquifers of South-Western Bangladesh

    Science.gov (United States)

    Nawrin, N.; Ahmed, K. M.; Rahman, M. M.

    2016-12-01

    Increasing salinity of natural drinking water sources has been reported as one of the many problems that affect low-income countries. Safe potable water sources in coastal Bangladesh have become contaminated by varying degrees of salinity due to saltwater intrusion, cyclone and storm surges and increased shrimp and crab farming along the coastal areas. This crisis is also exacerbated owing to climate change. The problem of salinity can have serious implications to public health. Here Managed Aquifer Recharge (MAR) has been ascertained as a better solution to overcome the fresh water shortage in the coastal belt of Bangladesh in terms of groundwater quality improvement and supply fresh water even during the dry period. 19 MAR systems have been built and tested in the area for providing community water supply by way of creating freshwater buffer zone in the brackish aquifers through artificial recharge of pond or rooftop rainwater. These existing ASTR schemes consist of sand filtration tank with 4 to 6 large diameter infiltration wells filled with sorted gravel. These larger diameter recharge wells make the construction and maintenance expensive and little difficult for the rural communities. Therefore, modification of design is required for enhancing infiltration rates with reduced costs. As the design of the existing MAR system have confronted some problems, the details of design, construction and performance have been studied from previous investigations and a new modified ASTR scheme has been demonstrated to amplify the infiltration rate along with monitoring scheme. Smaller 4 inch diameter empty recharge wells and PVC screen have been used in the newly developed design. Daily infiltration rate has been increased to 8 to 10 m3/d compared to 4 to 6 m3/d in the old design. Three layered sand filtration tank has been prepared by modification of an abandoned PSF. Time needed for lowering EC to acceptable limits has been found to be significantly lower than the pre

  16. Does NGAL reduce costs? A cost analysis of urine NGAL (uNGAL) & serum creatinine (sCr) for acute kidney injury (AKI) diagnosis.

    Science.gov (United States)

    Parikh, Amay; Rizzo, John A; Canetta, Pietro; Forster, Catherine; Sise, Meghan; Maarouf, Omar; Singer, Eugenia; Elger, Antje; Elitok, Saban; Schmidt-Ott, Kai; Barasch, Jonathon; Nickolas, Thomas L

    2017-01-01

    Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a sensitive and specific diagnostic test for acute kidney injury (AKI) in the Emergency Department (ED), but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr) would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone. A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs. uNGAL plus sCr (uNGAL+sCr). A cost minimization analysis was performed to determine total expected costs for patients with AKI. uNGAL test characteristics were validated with eight-hundred forty-nine patients with sCr ≥1.5 from a completed study of 1635 patients recruited from EDs at two U.S. hospitals from 2007-8. Biomarker test, AKI work-up, and diagnostic imaging costs were incorporated. For a hypothetical cohort of 10,000 patients, the model predicted that the expected costs were $900 per patient (pp) in the sCr arm and $950 in the uNGAL+sCr arm. uNGAL+sCr resulted in 1,578 fewer patients with delayed diagnosis and treatment than sCr alone (2,013 vs. 436 pts) at center 1 and 1,973 fewer patients with delayed diagnosis and treatment than sCr alone at center 2 (2,227 vs. 254 patients). Although initial evaluation costs at each center were $50 pp higher in with uNGAL+sCr, total costs declined by $408 pp at Center 1 and by $522 pp at Center 2 due to expected reduced delays in diagnosis and treatment. Sensitivity analyses confirmed savings with uNGAL + sCr for a range of cost inputs. Using uNGAL with sCr as a clinical diagnostic test for AKI may improve patient management and reduce expected costs. Any cost savings would likely result from avoiding delays in diagnosis and treatment and from avoidance of unnecessary testing in patients given a false positive AKI diagnosis by use of sCr alone.

  17. Wheat seedlings as a model to understand desiccation tolerance and sensitivity.

    Science.gov (United States)

    Farrant, Jill M.; Bailly, Christophe; Leymarie, Juliette; Hamman, Brigitte; Côme, Daniel; Corbineau, Françoise

    2004-04-01

    The coleoptiles of wheat (Triticum aestivum L.) seedlings of cultivar Trémie are desiccation tolerant when 3 days old, although the roots are not. Cutting some of the coleoptiles open prior to dehydration rapidly increased the drying rate. This rendered the coleoptiles sensitive to desiccation, providing a useful model with which to study desiccation tolerance. Both sensitive and tolerant seedlings were dehydrated to 0.3 g H(2)O g(-1) dry mass (g.g) and thereafter rehydrated. Sensitive tissues accr- ued the lipid peroxidation products H(2)O(2)and MDA, and substantial subcellular damage was evident in dry tissues. H(2)O(2) and MDA accumulated slightly only in dry tolerant coleoptiles and no subcellular damage was evident. The activity of antioxidant enzymes glutathione reductase (EC1.6.2.4), superoxide dismutase (EC 1.14.1.1) and catalase (EC 1.11.1.6) increased on drying in both tolerant and sensitive tissues, but were sustained on rehydration in only the tolerant tissues. It is proposed that free radical damage sustained during rapid drying exceeded the ameliorating capacity of antioxidant systems, allowed accrual of lethal subcellular damage. Slow drying enabled sufficient detoxification by antioxidants to minimize damage and allow tolerance to drying. Three LEA- (p11 and Asp 52) and dehydrin- (XV8) like proteins were detected by western blots in tolerant coleoptiles dried to 3.0 g.g and below. Only one (Asp 52) was induced at low water content in rapidly dried sensitive coleoptiles. None were present in root tissues. XV8 RNA (northern analyses) was induced on drying only in tolerant coleoptiles and correlated with protein expression. These stress-putative protein protectants (and XV8 transcripts) appear to be down-regulated during germination but wheat seedlings temporarily retain the ability to reproduce them if drying is slow. Sucrose accumulation during dehydration was similar for both sensitive and tolerant tissues, suggesting that this sugar has little

  18. In vivo Characterization of the Effects of Abscisic Acid and Drying Protocols Associated with the Acquisition of Desiccation Tolerance in Alfalfa (Medicago sativa L.) Somatic Embryos

    OpenAIRE

    SREEDHAR, LEKHA; Wolkers, Willem F.; Hoekstra, Folkert A.; BEWLEY, J. DEREK

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 μm abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination. Compared with fast drying, slow drying of the ABA‐treated embryos improved desiccation tolerance. However, slow drying of non‐ABA‐treated embryos led to the complete loss of germination capacity, w...

  19. High Efficiency Liquid-Desiccant Regenerator for Air Conditioning and Industrial Drying

    Energy Technology Data Exchange (ETDEWEB)

    Andrew Lowenstein

    2005-12-19

    Over 2 quads of fossil fuels are used each year for moisture removal. This includes industrial and agricultural processes where feedstocks and final products must be dried, as well as comfort conditioning of indoor spaces where the control of humidity is essential to maintaining healthy, productive and comfortable working conditions. Desiccants, materials that have a high affinity for water vapor, can greatly reduce energy use for both drying and dehumidification. An opportunity exists to greatly improve the competitiveness of advanced liquid-desiccant systems by increasing the efficiency of their regenerators. It is common practice within the chemical process industry to use multiple stage boilers to improve the efficiency of thermal separation processes. The energy needed to regenerate a liquid desiccant, which is a thermal separation process, can also be reduced by using a multiple stage boiler. In this project, a two-stage regenerator was developed in which the first stage is a boiler and the second stage is a scavenging-air regenerator. The only energy input to this regenerator is the natural gas that fires the boiler. The steam produced in the boiler provides the thermal energy to run the second-stage scavenging-air regenerator. This two-stage regenerator is referred to as a 1?-effect regenerator. A model of the high-temperature stage of a 1?-effect regenerator for liquid desiccants was designed, built and successfully tested. At nominal operating conditions (i.e., 2.35 gpm of 36% lithium chloride solution, 307,000 Btu/h firing rate), the boiler removed 153 lb/h of water from the desiccant at a gas-based efficiency of 52.9 % (which corresponds to a COP of 0.95 when a scavenging-air regenerator is added). The steam leaving the boiler, when condensed, had a solids concentration of less than 10 ppm. This low level of solids in the condensate places an upper bound of about 6 lb per year for desiccant loss from the regenerator. This low loss will not create

  20. Large-scale proteome analysis of abscisic acid and ABSCISIC ACID INSENSITIVE3-dependent proteins related to desiccation tolerance in Physcomitrella patens

    Energy Technology Data Exchange (ETDEWEB)

    Yotsui, Izumi, E-mail: izumi.yotsui@riken.jp [Department of BioScience, Tokyo University of Agriculture 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 (Japan); Serada, Satoshi, E-mail: serada@nibiohn.go.jp [Laboratory of Immune Signal, National Institute of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085 (Japan); Naka, Tetsuji, E-mail: tnaka@nibiohn.go.jp [Laboratory of Immune Signal, National Institute of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085 (Japan); Saruhashi, Masashi, E-mail: s13db001@mail.saitama-u.ac.jp [Department of BioScience, Tokyo University of Agriculture 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 (Japan); Taji, Teruaki, E-mail: t3teruak@nodai.ac.jp [Department of BioScience, Tokyo University of Agriculture 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 (Japan); Hayashi, Takahisa, E-mail: t4hayash@nodai.ac.jp [Department of BioScience, Tokyo University of Agriculture 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 (Japan); Quatrano, Ralph S., E-mail: rsq@wustl.edu [Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130-4899 (United States); Sakata, Yoichi, E-mail: sakata@nodai.ac.jp [Department of BioScience, Tokyo University of Agriculture 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 (Japan)

    2016-03-18

    Desiccation tolerance is an ancestral feature of land plants and is still retained in non-vascular plants such as bryophytes and some vascular plants. However, except for seeds and spores, this trait is absent in vegetative tissues of vascular plants. Although many studies have focused on understanding the molecular basis underlying desiccation tolerance using transcriptome and proteome approaches, the critical molecular differences between desiccation tolerant plants and non-desiccation plants are still not clear. The moss Physcomitrella patens cannot survive rapid desiccation under laboratory conditions, but if cells of the protonemata are treated by the phytohormone abscisic acid (ABA) prior to desiccation, it can survive 24 h exposure to desiccation and regrow after rehydration. The desiccation tolerance induced by ABA (AiDT) is specific to this hormone, but also depends on a plant transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3). Here we report the comparative proteomic analysis of AiDT between wild type and ABI3 deleted mutant (Δabi3) of P. patens using iTRAQ (Isobaric Tags for Relative and Absolute Quantification). From a total of 1980 unique proteins that we identified, only 16 proteins are significantly altered in Δabi3 compared to wild type after desiccation following ABA treatment. Among this group, three of the four proteins that were severely affected in Δabi3 tissue were Arabidopsis orthologous genes, which were expressed in maturing seeds under the regulation of ABI3. These included a Group 1 late embryogenesis abundant (LEA) protein, a short-chain dehydrogenase, and a desiccation-related protein. Our results suggest that at least three of these proteins expressed in desiccation tolerant cells of both Arabidopsis and the moss are very likely to play important roles in acquisition of desiccation tolerance in land plants. Furthermore, our results suggest that the regulatory machinery of ABA- and ABI3-mediated gene expression for desiccation

  1. Gene induction by desiccation stress in the entomopathogenic nematode Steinernema carpocapsae reveals parallels with drought tolerance mechanisms in plants.

    Science.gov (United States)

    Tyson, Trevor; Reardon, Wesley; Browne, John A; Burnell, Ann M

    2007-06-01

    The dauer juvenile (DJ) stage of the insect parasitic nematode Steinernema carpocapsae is the only stage in the life cycle which is capable of surviving outside its host and it is adapted for tolerating environmental stresses and for host finding. We have isolated 45 unique expressed sequence tags (ESTs) that are up-regulated in response to desiccation in S. carpocapsae DJs. The majority of these ESTs were co-expressed in response to desiccation and osmotic stress and were generally not induced in response to heat and cold stress. Thirty-two ESTs showed similarity to known sequences. Among these were sequences which encode putative signalling molecules or transcription factors, sequences which detoxify reactive oxygen species, two C-type lectin sequences, ESTs which encode membrane-associated proteins and seven distinct late embryogenic abundant (LEA) sequences. We also isolated 13 novel ESTs. These data show that the molecular response to desiccation stress in entomopathogenic nematode DJs is complex and parallels many of the adaptive changes which occur in drought tolerant plants during exposure to desiccation and osmotic stress. A notable feature of the desiccation response of plants is the number and diversity of hydrophilic LEA proteins synthesised in response to desiccation. All of the LEA sequences detected in animals to date, including those reported in this study, belong to LEA3 group. We show that S. carpocapsae expresses several novel sequences which encode putative hydrophilic and natively unfolded proteins. It is likely that these novel and putative proteins play an important role in desiccation tolerance, possibly by carrying out analogous roles in nematodes to those carried out by the other LEA protein classes in plants.

  2. Influence of Protoplasmic Water Loss on the Control of Protein Synthesis in the Desiccation-Tolerant Moss Tortula ruralis 1

    Science.gov (United States)

    Oliver, Melvin J.

    1991-01-01

    Desiccation tolerance of the moss Tortula ruralis is characterized by a desiccation-induced change in gene expression that becomes evident upon rehydration. As reported earlier, this change in gene expression is apparently brought about by a change in the control of translation and does not include a major shift in mRNA abundance. A full qualitative and quantitative analysis of the alteration in gene expression, which is characterized by the loss of (or greater than fivefold decrease in) the synthesis of 25 hydration (h) proteins and initiation (or greater than fivefold increase) of the synthesis of 74 rehydration (r) proteins, is given in this report. Exposure to a desiccating atmosphere, for times that result in varying levels of water loss, enabled the determination that the control of synthesis of r proteins is different from the control of synthesis of h proteins. The r and h protein synthesis responses are internally coordinate, however. Similarly, the return to normal levels of h protein synthesis differs from that of the r proteins. The return to normal synthetic levels for all h proteins is synchronous, but the rate of loss of r protein synthesis varies with each individual r protein. Run-off translation of polysomes isolated from gametophytes during the drying phase demonstrates that there are no novel mRNAs recruited and no particular mRNA is favored for translation during desiccation. These findings add credence to the argument that translational control is the major component of the desiccation-induced alteration in gene expression in this plant, as discussed. Aspects of the response of protein synthesis to desiccation are consistent with the hypothesis that T. ruralis exhibits a repair-based mechanism of desiccation tolerance. ImagesFigure 2Figure 3Figure 5Figure 6Figure 7 PMID:16668577

  3. Desiccation tolerance in the chlorophyte green alga Ulva compressa: does cell wall architecture contribute to ecological success?

    Science.gov (United States)

    Holzinger, Andreas; Herburger, Klaus; Kaplan, Franziska; Lewis, Louise A

    2015-08-01

    Desiccation leads to structural changes of the inner pectic cell wall layers in Ulva compressa. This contributes to protection against mechanical damage due to desiccation-rehydration cycles. Ulva compressa, characterized by rbcL phylogeny, is a common species in the Mediterranean Sea. Ulva as an intertidal species tolerates repeated desiccation-rehydration cycles in nature; the physiological and structural basis were investigated under experimental conditions here. Desiccation to 73% relative water content (RWC) led to a significant decrease of the maximum quantum yield of photosystem II (F v/F m) to about half of the initial value. A reduction to 48 or 27% RWC caused a more drastic effect and thalli were only able to recover fully from desiccation to 73% RWC. Relative electron transport rates were stimulated at 73% RWC, but decreased significantly at 48 and 27% RWC, respectively. Imaging-PAM analysis demonstrated a homogenous desiccation process within individual thallus discs. The different cell wall layers of U. compressa were characterized by standard staining procedures, i.e. calcofluor white and aniline blue for structural components (cellulose, callose), ruthenium red for pectins and toluidine blue for acidic polysaccharides. Already a reduction to 73% RWC caused severe changes of the cell walls. The inner pectin-rich layers followed the shrinkage process of the cytoplasm, while the outer denser fibrillar layers maintained their shape. In this way, the thalli were not plasmolyzed during water loss, and upon recovery not negatively influenced by any mechanical damage. Transmission electron microscopy corroborated the arrangement of the different layers clearly distinguishable by their texture and electron density. We suggest the flexibility of the pectin-rich cell wall layers as a major contribution to desiccation tolerance in Ulva.

  4. The role of lipid metabolism in the acquisition of desiccation tolerance in Craterostigma plantagineum: a comparative approach.

    Science.gov (United States)

    Gasulla, Francisco; Vom Dorp, Katharina; Dombrink, Isabel; Zähringer, Ulrich; Gisch, Nicolas; Dörmann, Peter; Bartels, Dorothea

    2013-09-01

    Dehydration leads to different physiological and biochemical responses in plants. We analysed the lipid composition and the expression of genes involved in lipid biosynthesis in the desiccation-tolerant plant Craterostigma plantagineum. A comparative approach was carried out with Lindernia brevidens (desiccation tolerant) and two desiccation-sensitive species, Lindernia subracemosa and Arabidopsis thaliana. In C. plantagineum the total lipid content remained constant while the lipid composition underwent major changes during desiccation. The most prominent change was the removal of monogalactosyldiacylglycerol (MGDG) from the thylakoids. Analysis of molecular species composition revealed that around 50% of 36:x (number of carbons in the acyl chains: number of double bonds) MGDG was hydrolysed and diacylglycerol (DAG) used for phospholipid synthesis, while another MGDG fraction was converted into digalactosyldiacylglycerol via the DGD1/DGD2 pathway and subsequently into oligogalactolipids by SFR2. 36:x-DAG was also employed for the synthesis of triacylglycerol. Phosphatidic acid (PA) increased in C. plantagineum, L. brevidens, and L. subracemosa, in agreement with a role of PA as an intermediate of lipid turnover and of phospholipase D in signalling during desiccation. 34:x-DAG, presumably derived from de novo assembly, was converted into phosphatidylinositol (PI) in C. plantagineum and L. brevidens, but not in desiccation-sensitive plants, suggesting that PI is involved in acquisition of desiccation tolerance. The accumulation of oligogalactolipids and PI in the chloroplast and extraplastidial membranes, respectively, increases the concentration of hydroxyl groups and enhances the ratio of bilayer- to non-bilayer-forming lipids, thus contributing to protein and membrane stabilization. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  5. LEA polypeptide profiling of recalcitrant and orthodox legume seeds reveals ABI3-regulated LEA protein abundance linked to desiccation tolerance.

    Science.gov (United States)

    Delahaie, Julien; Hundertmark, Michaela; Bove, Jérôme; Leprince, Olivier; Rogniaux, Hélène; Buitink, Julia

    2013-11-01

    In contrast to orthodox seeds that acquire desiccation tolerance during maturation, recalcitrant seeds are unable to survive drying. These desiccation-sensitive seeds constitute an interesting model for comparative analysis with phylogenetically close species that are desiccation tolerant. Considering the importance of LEA (late embryogenesis abundant) proteins as protective molecules both in drought and in desiccation tolerance, the heat-stable proteome was characterized in cotyledons of the legume Castanospermum australe and it was compared with that of the orthodox model legume Medicago truncatula. RNA sequencing identified transcripts of 16 homologues out of 17 LEA genes for which polypeptides are detected in M. truncatula seeds. It is shown that for 12 LEA genes, polypeptides were either absent or strongly reduced in C. australe cotyledons compared with M. truncatula seeds. Instead, osmotically responsive, non-seed-specific dehydrins accumulated to high levels in the recalcitrant cotyledons compared with orthodox seeds. Next, M. truncatula mutants of the abscisic acid insensitive3 (ABI3) gene were characterized. Mature Mtabi3 seeds were found to be desiccation sensitive when dried below a critical water content of 0.4 g H2O g DW(-1). Characterization of the LEA proteome of the Mtabi3 seeds revealed a subset of LEA proteins with severely reduced abundance that were also found to be reduced or absent in C. australe cotyledons. Transcripts of these genes were indeed shown to be ABI3 responsive. The results highlight those LEA proteins that are critical to desiccation tolerance and suggest that comparable regulatory pathways responsible for their accumulation are missing in both desiccation-sensitive genotypes, revealing new insights into the mechanistic basis of the recalcitrant trait in seeds.

  6. Synergistic interaction between the fungus Beauveria bassiana and desiccant dusts applied against poultry red mites (Dermanyssus gallinae).

    Science.gov (United States)

    Steenberg, Tove; Kilpinen, Ole

    2014-04-01

    The poultry red mite, Dermanyssus gallinae, is a major pest in egg production, feeding on laying hens. Widely used non-chemical control methods include desiccant dusts, although their persistence under field conditions is often short. Entomopathogenic fungi may also hold potential for mite control, but these fungi often take several days to kill mites. Laboratory experiments were carried out to study the efficacy of 3 types of desiccant dusts, the fungus Beauveria bassiana and combinations of the two control agents against D. gallinae. There was significant synergistic interaction between each of the desiccant dusts and the fungus, with observed levels of mite mortality significantly higher than those expected for an additive effect (up to 38 % higher). Synergistic interaction between desiccant dust and fungus was found also when different application methods were used for the fungus and at different levels of relative humidity. Although increased levels of mortality were reached due to the synergistic interaction, the speed of lethal action was not influenced by combining the two components. The persistence of the control agents applied separately or in combination did not change over a period of 4 weeks. Overall, combinations of desiccant dusts and fungus conidia seem to hold considerable promise for future non-chemical control of poultry red mites.

  7. Effect of transparent film desiccant on the lifetime of top-emitting active matrix organic light emitting diodes

    Science.gov (United States)

    Lee, Byoung Duk; Cho, Yoon-Hyung; Kim, Won-Jong; Oh, Min Ho; Lee, Jong Hyuk; Zang, Dong Sik

    2007-03-01

    The effects of a transparent film desiccant on the lifetime of top-emitting active matrix organic light emitting diodes (AMOLEDs) were investigated. The transparent film desiccants were prepared by mixing solutions dispersed with calcium oxide powders and ultraviolet-curable resins. As the solid content in the solutions increased from 15to30wt%, the average particle size increased from 107to240nm, whereas the transmittance of the films decreased from 98% to 80% in the visible range. The devices encapsulated with the transparent film desiccants which contained 20wt% CaO exhibited no dark spots and 97% of the initial luminance, even after being stored for over 500h at 70°C and 90% relative humidity. Also, the operational lifetime of these devices was 1850h, ten times longer than that of a device without desiccant. These results confirmed that the transparent film desiccants, which absorbed the moisture that penetrated into the devices, could be applied to the encapsulation of top-emitting AMOLEDs.

  8. Transcriptomic analysis reveals numerous diverse protein kinases and transcription factors involved in desiccation tolerance in the resurrection plant Myrothamnus flabellifolia.

    Science.gov (United States)

    Ma, Chao; Wang, Hong; Macnish, Andrew J; Estrada-Melo, Alejandro C; Lin, Jing; Chang, Youhong; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The woody resurrection plant Myrothamnus flabellifolia has remarkable tolerance to desiccation. Pyro-sequencing technology permitted us to analyze the transcriptome of M. flabellifolia during both dehydration and rehydration. We identified a total of 8287 and 8542 differentially transcribed genes during dehydration and rehydration treatments respectively. Approximately 295 transcription factors (TFs) and 484 protein kinases (PKs) were up- or down-regulated in response to desiccation stress. Among these, the transcript levels of 53 TFs and 91 PKs increased rapidly and peaked early during dehydration. These regulators transduce signal cascades of molecular pathways, including the up-regulation of ABA-dependent and independent drought stress pathways and the activation of protective mechanisms for coping with oxidative damage. Antioxidant systems are up-regulated, and the photosynthetic system is modified to reduce ROS generation. Secondary metabolism may participate in the desiccation tolerance of M. flabellifolia as indicated by increases in transcript abundance of genes involved in isopentenyl diphosphate biosynthesis. Up-regulation of genes encoding late embryogenesis abundant proteins and sucrose phosphate synthase is also associated with increased tolerance to desiccation. During rehydration, the transcriptome is also enriched in transcripts of genes encoding TFs and PKs, as well as genes involved in photosynthesis, and protein synthesis. The data reported here contribute comprehensive insights into the molecular mechanisms of desiccation tolerance in M. flabellifolia.

  9. Desiccation tolerance of the resurrection plant Ramonda serbica is associated with dehydration-dependent changes in levels of proteolytic activities.

    Science.gov (United States)

    Kidrič, Marjetka; Sabotič, Jerica; Stevanović, Branka

    2014-07-15

    The unique response of desiccation-tolerant, or resurrection plants, to extreme drought is accompanied by major changes in the protein pool, raising the possibility of the involvement of proteases. We detected and characterized proteases present in their active state in leaf extracts of desiccated Ramonda serbica Panč., a resurrection plant from the Balkan Peninsula. Plants desiccated under laboratory conditions and maintained in anhydrobiosis for 4 and 14 months revived upon rehydration. Protease activities were determined spectrophotometrically in solution and by zymography on gels. Several endo- and aminopeptidases were detected and characterized by their pH profiles. Their enzyme class was determined using specific inhibitors. Those with higher activities were a serine endopeptidase active against Bz-Arg-pNA with a pH optimum around 9, and aminopeptidases optimally active at pHs from 7 to 9 against Leu-pNA, Met-pNA, Phe-pNA, Pro-pNA and Ala-pNA. The levels of their activities in leaf extracts from desiccated plants were significantly higher than those from rehydrated plants and from regularly watered plants, implying their involvement in the recovery of vegetative tissues from desiccation. Copyright © 2014 Elsevier GmbH. All rights reserved.

  10. Proteomic analysis of oil body membrane proteins accompanying the onset of desiccation phase during sunflower seed development.

    Science.gov (United States)

    Thakur, Anita; Bhatla, Satish C

    2015-01-01

    A noteworthy metabolic signature accompanying oil body (OB) biogenesis during oilseed development is associated with the modulation of the oil body membranes proteins. Present work focuses on 2-dimensional polyacrylamide gel electrophoresis (2-D PAGE)-based analysis of the temporal changes in the OB membrane proteins analyzed by LC-MS/MS accompanying the onset of desiccation (20-30 d after anthesis; DAA) in the developing seeds of sunflower (Helianthus annuus L.). Protein spots unique to 20-30 DAA stages were picked up from 2-D gels for identification and the identified proteins were categorized into 7 functional classes. These include proteins involved in energy metabolism, reactive oxygen scavenging, proteolysis and protein turnover, signaling, oleosin and oil body biogenesis-associated proteins, desiccation and cytoskeleton. At 30 DAA stage, exclusive expressions of enzymes belonging to energy metabolism, desiccation and cytoskeleton were evident which indicated an increase in the metabolic and enzymatic activity in the cells at this stage of seed development (seed filling). Increased expression of cruciferina-like protein and dehydrin at 30 DAA stage marks the onset of desiccation. The data has been analyzed and discussed to highlight desiccation stage-associated metabolic events during oilseed development.

  11. Comparative study of Saccharomyces cerevisiae wine strains to identify potential marker genes correlated to desiccation stress tolerance.

    Science.gov (United States)

    Capece, Angela; Votta, Sonia; Guaragnella, Nicoletta; Zambuto, Marianna; Romaniello, Rossana; Romano, Patrizia

    2016-05-01

    The most diffused formulation of starter for winemaking is active dry yeast (ADY). ADYs production process is essentially characterized by air-drying stress, a combination of several stresses, including thermal, hyperosmotic and oxidative and cell capacity to counteract such multiple stresses will determine its survival. The molecular mechanisms underlying cell stress response to desiccation have been mostly studied in laboratory and commercial yeast strains, but a growing interest is currently developing for indigenous yeast strains which represent a valuable and alternative source of genetic and molecular biodiversity to be exploited. In this work, a comparative study of different Saccharomyces cerevisiae indigenous wine strains, previously selected for their technological traits, has been carried out to identify potentially relevant genes involved in desiccation stress tolerance. Cell viability was evaluated along desiccation treatment and gene expression was analyzed by real-time PCR before and during the stress. Our data show that the observed differences in individual strain sensitivity to desiccation stress could be associated to specific gene expression over time. In particular, either the basal or the stress-induced mRNA levels of certain genes, such as HSP12, SSA3, TPS1, TPS2, CTT1 and SOD1, result tightly correlated to the strain survival advantage. This study provides a reliable and sensitive method to predict desiccation stress tolerance of indigenous wine yeast strains which could be preliminary to biotechnological applications. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Surviving extreme polar winters by desiccation: clues from Arctic springtail (Onychiurus arcticus EST libraries

    Directory of Open Access Journals (Sweden)

    Kube Michael

    2007-12-01

    Full Text Available Abstract Background Ice, snow and temperatures of -14°C are conditions which most animals would find difficult, if not impossible, to survive in. However this exactly describes the Arctic winter, and the Arctic springtail Onychiurus arcticus regularly survives these extreme conditions and re-emerges in the spring. It is able to do this by reducing the amount of water in its body to almost zero: a process that is called "protective dehydration". The aim of this project was to generate clones and sequence data in the form of ESTs to provide a platform for the future molecular characterisation of the processes involved in protective dehydration. Results Five normalised libraries were produced from both desiccating and rehydrating populations of O. arcticus from stages that had previously been defined as potentially informative for molecular analyses. A total of 16,379 EST clones were generated and analysed using Blast and GO annotation. 40% of the clones produced significant matches against the Swissprot and trembl databases and these were further analysed using GO annotation. Extraction and analysis of GO annotations proved an extremely effective method for identifying generic processes associated with biochemical pathways, proving more efficient than solely analysing Blast data output. A number of genes were identified, which have previously been shown to be involved in water transport and desiccation such as members of the aquaporin family. Identification of these clones in specific libraries associated with desiccation validates the computational analysis by library rather than producing a global overview of all libraries combined. Conclusion This paper describes for the first time EST data from the arctic springtail (O. arcticus. This significantly enhances the number of Collembolan ESTs in the public databases, providing useful comparative data within this phylum. The use of GO annotation for analysis has facilitated the identification of a

  13. A molecular physiological review of vegetative desiccation tolerance in the resurrection plant Xerophyta viscosa (Baker).

    Science.gov (United States)

    Farrant, Jill M; Cooper, Keren; Hilgart, Amelia; Abdalla, Kamal O; Bentley, Joanne; Thomson, Jennifer A; Dace, Halford J W; Peton, Nashied; Mundree, Sagadevan G; Rafudeen, Mohamed S

    2015-08-01

    Provides a first comprehensive review of integrated physiological and molecular aspects of desiccation tolerance Xerophyta viscosa. A synopsis of biotechnological studies being undertaken to improve drought tolerance in maize is given. Xerophyta viscosa (Baker) is a monocotyledonous resurrection plant from the family Vellociacea that occurs in summer-rainfall areas of South Africa, Lesotho and Swaziland. It inhabits rocky terrain in exposed grasslands and frequently experiences periods of water deficit. Being a resurrection plant it tolerates the loss of 95% of total cellular water, regaining full metabolic competency within 3 days of rehydration. In this paper, we review some of the molecular and physiological adaptations that occur during various stages of dehydration of X. viscosa, these being functionally grouped into early and late responses, which might be relevant to the attainment of desiccation tolerance. During early drying (to 55% RWC) photosynthesis is shut down, there is increased presence and activity of housekeeping antioxidants and a redirection of metabolism to the increased formation of sucrose and raffinose family oligosaccharides. Other metabolic shifts suggest water replacement in vacuoles proposed to facilitate mechanical stabilization. Some regulatory processes observed include increased presence of a linker histone H1 variant, a Type 2C protein phosphatase, a calmodulin- and an ERD15-like protein. During the late stages of drying (to 10% RWC) there was increased expression of several proteins involved in signal transduction, and retroelements speculated to be instrumental in gene silencing. There was induction of antioxidants not typically found in desiccation-sensitive systems, classical stress-associated proteins (HSP and LEAs), proteins involved in structural stabilization and those associated with changes in various metabolite pools during drying. Metabolites accumulated in this stage are proposed, inter alia, to facilitate subcellular

  14. Facing the Heat: Does Desiccation and Thermal Stress Explain Patterns of Orientation in an Intertidal Invertebrate?

    Directory of Open Access Journals (Sweden)

    Clarissa M L Fraser

    Full Text Available A key challenge for ecologists is to quantify, explain and predict the ecology and behaviour of animals from knowledge of their basic physiology. Compared to our knowledge of many other types of distribution and behaviour, and how these are linked to individual function, we have a poor level of understanding of the causal basis for orientation behaviours. Most explanations for patterns of animal orientation assume that animals will modify their exposure to environmental factors by altering their orientation. We used a keystone grazer on rocky shores, the limpet Cellana tramoserica, to test this idea. Manipulative experiments were done to evaluate whether orientation during emersion affected limpet desiccation or body temperature. Body temperature was determined from infrared thermography, a technique that minimises disturbance to the test organism. No causal relationships were found between orientation and (i level of desiccation and (ii their body temperature. These results add to the growing knowledge that responses to desiccation and thermal stress may be less important in modifying the behaviour of intertidal organisms than previously supposed and that thermoregulation does not always reflect patterns of animal orientation. Much of what we understand about orientation comes from studies of animals able to modify orientation over very short time scales. Our data suggests that for animals whose location is less flexible, orientation decisions may have less to do with responses to environmental factors and more to do with structural habitat properties or intrinsic individual attributes. Therefore we suggest future studies into processes affecting orientation must include organisms with differing levels of behavioural plasticity.

  15. Open-cycle desiccant air conditioning as an alternative to vapor compression cooling in residential applications

    Energy Technology Data Exchange (ETDEWEB)

    Jurinak, J.J.; Beckman, W.A.; Mitchell, J.W.

    1984-08-01

    The performance of open-cycle desiccant air conditioners for residential applications is evaluated. The performance of these systems is compared to that of vapor compression air conditioners on the basis of primary energy use and cost. Systems with improved dehumidifiers can achieve seasonal COP's on the order of 1.1. These systems, when coupled with a solar energy system to supply regeneration energy, are significantly better than conventional air conditioners on a primary energy basis, but are not presently cost-competitive.

  16. Gas-fired desiccant dehumidification system field evaluation in a quick-service restaurant. Final report, October 1989

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, R.N.; Marciniak, T.J.

    1989-10-01

    This report describes the results of a field evaluation of state-of-art desiccant dehumidification equipment in Houston, TX. The evaluation demonstrated that comfort control in a quick-service restaurant could be improved dramatically. However, available gas-fired desiccant dehumidification equipment is too expensive, inefficient, and unreliable to be considered for wide application in the restaurant industry. Results of a technical and economic analysis of four HVAC options in four U.S. cities indicated that improved comfort control could be achieved with only a modest increase in operating costs with an advanced system. This, coupled with the economic benefits achieved through lower indoor humidity such as improved crew performance and reduced maintenance costs, could justify the introduction of an advanced, integrated, HVAC system using desiccant technology which has an installed cost similar to current equipment.

  17. Effect of exogenous extracellular polysaccharides on the desiccation and freezing tolerance of rock-inhabiting phototrophic microorganisms.

    Science.gov (United States)

    Knowles, Emily J; Castenholz, Richard W

    2008-11-01

    Two major stresses that threaten rock-inhabiting microbial communities are desiccation and freezing; both result in a loss of liquid water in the cells. The mechanisms necessary to tolerate these extremes may be similar, but are not well understood. In both cases extracellular polysaccharides (EPS) seem to play an important role. This study examines whether the EPS released by a rock-inhabiting phototroph can have a protective effect on other members of similar and neighboring microbial communities. This interaction was modeled by adding EPS isolated from the cryptoendolithic cyanobacterium Nostoc sp. to cells of the cryptoendolithic green alga Chlorella sp. and to cells of the epilithic cyanobacterium Chroococcidiopsis sp. The cells were then subjected to desiccation and freezing and the survival rates were determined by vital staining, using membrane integrity as a measure of viability. The results clearly demonstrate the importance of exogenous EPS in the desiccation tolerance of both species, while mixed results were found for the freezing trials.

  18. In vivo characterization of the effects of abscisic acid and drying protocols associated with the acquisition of desiccation tolerance in alfalfa (Medicago sativa L.) somatic embryos

    NARCIS (Netherlands)

    Sreedhar, L.; Wolkers, W.F.; Hoekstra, F.A.; Bewley, J.D.

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 ?M abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination.

  19. Effects of desiccation on temperate recalcitrant seeds: differential scanning calorimetry, gas chromatography, electron microscopy, and moisture studies on Quercus nigra and Quercus alba

    Science.gov (United States)

    K.F. Connor; F.T. Bonner; J.A Vozzo

    1996-01-01

    Investigations into the nature of desiccation-sensitive, or recalcitrant, seed behavior have as yet failed to identify exact causes of this phenomenon. Experiments with Quercus nigra L. and Quercus alba L. were conducted to examine physiological and biochemical changes brought about by seed desiccation and to determine if there...

  20. In vivo characterization of the effects of abscisic acid and drying protocols associated with the acquisition of desiccation tolerance in alfalfa (Medicago sativa L.) somatic embryos

    NARCIS (Netherlands)

    Sreedhar, L.; Wolkers, W.F.; Hoekstra, F.A.; Bewley, J.D.

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 ?M abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination.

  1. The desert moss Pterygoneurum lamellatum (Pottiaceae) exhibits an inducible ecological strategy of desiccation tolerance: effects of rate of drying on shoot damage and regeneration

    Science.gov (United States)

    Premise of the study: Bryophytes are regarded as a clade incorporating constitutive desiccation tolerance, especially terrestrial species. Here we test the hypothesis that the opposing ecological strategy of desiccation tolerance, inducibility, is present in a desert moss, and addressed by varying r...

  2. Sexual conflict and environmental change: trade-offs within and between the sexes during the evolution of desiccation resistance

    Indian Academy of Sciences (India)

    Lucia Kwan; Stéphanie Bedhomme; N. G. Prasad; Adam K. Chippindale

    2008-12-01

    Intralocus sexual conflict occurs when males and females experience sex-specific selection on a shared genome. With several notable exceptions, intralocus sexual conflict has been investigated in constant environments to which the study organisms have had an opportunity to adapt. However, a change in the environment can result in differential or even opposing selection pressures on males and females, creating sexual conflict. We used experimental evolution to explore the interaction between intralocus sexual conflict, sexual dimorphism and environmental variation in Drosophila melanogaster. Six populations were selected for adult desiccation resistance (D), with six matched control populations maintained in parallel (C). After 46 generations, the D populations had increased in survival time under arid conditions by 68% and in body weight by 20% compared to the C populations. The increase in size was the result of both extended development and faster growth rate of D juveniles. Adaptation to the stress came at a cost in terms of preadult viability and female fecundity. Because males are innately less tolerant of desiccation stress, very few D males survived desiccation-selection; while potentially a windfall for survivors, these conditions mean that most males’ fitness was determined posthumously. We conjectured that selection for early maturation and mating in males was in conflict with selection for survival and later reproduction in females. Consistent with this prediction, the sexes showed different patterns of age-specific desiccation resistance and resource acquisition, and there was a trend towards increasingly female-biased sexual size dimorphism. However, levels of desiccation resistance were unaffected, with D males and females increasing in parallel. Either there is a strong positive genetic correlation between the sexes that limits independent evolution of desiccation resistance, or fitness pay-offs from the strategy of riding out the stress bout are

  3. Sex-specific divergence for body size and desiccation-related traits in Drosophila hydei from the western Himalayas.

    Science.gov (United States)

    Kalra, Bhawna; Parkash, Ravi

    2014-11-01

    Sex-specific-differences are a widespread source of genetic variation in various Drosophila species. In the present study, we have examined desiccation survival in males and females of Drosophila hydei from colder and drier montane conditions of the western Himalayas (altitudinal populations; 600-2202 m). In contrast with most other studies in drosophilids, D. hydei males exhibited comparatively higher desiccation resistance despite smaller body size compared to females. Accordingly, we tested the physiological basis of such adaptations in both sexes of D. hydei. Body size traits (wing length, wet weight and dry weight) were ~1.2 fold higher in females than males. However, desiccation resistance was 10 to 13 h higher in males than females. These differences matched enhanced storage of trehalose content (~1.2 fold), higher hemolymph content (~1.2 fold) and enhanced cuticular lipid mass (~1.5 fold) in males than females. Water loss before succumbing to death (dehydration tolerance) was much higher in males (~81%) than females (~64%). A greater loss of hemolymph water until death under desiccation stress was associated with higher desiccation resistance in males. Further, there were lacks of differences in the rate of water loss, rate of trehalose utilization and rate of hemolymph depletion between the sexes in D. hydei. Therefore, sex-specific differences in desiccation resistance of D. hydei were independent of body size as well as the exhaustion of metabolite reserves and rather were caused by the higher dehydration tolerance as well as higher acquisition of hemolymph and trehalose contents. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Desiccant dust and the use of CO2 gas as a mobility stimulant for bed bugs: a potential control solution?

    Science.gov (United States)

    Aak, Anders; Roligheten, Espen; Rukke, Bjørn Arne; Birkemoe, Tone

    2017-01-01

    The common bed bug (Cimex lectularius, Hemiptera; Cimicidae) infests homes and service industries, and the number of infestations has greatly increased over the past 20 years. At present, no cost-effective control methods are available, and eradication programs are expensive and laborious. We investigated the control potential of desiccant dust in combination with CO2 as a bed bug activity stimulant. An initial experiment with two desiccant dusts was followed by arena studies with varying doses, available hiding places and the presence or absence of host signals. Finally, we conducted a field experiment with Syloid 244FP with or without CO2 gas. Syloid was superior compared to diatomaceous earth, and effective at the concentration of 1.0 g/m(2) in the field experiment. The number of harborages and partial application of desiccant dust decreased mortality in the laboratory. Bed bug activation by CO2 appeared of minor importance in the arena studies, but was crucial for the eradication in the student dormitories. In fact, all 5 bed bug-infested dormitories with a combined treatment of desiccant dust and CO2 were freed of bed bugs, whereas eradication was not successful in any of the 6 dormitories with only desiccant dust treatment. The different results in the laboratory and field experiment were most likely caused by the longer activation and higher dose of CO2 used in the field experiment than the laboratory experiment. Our study showed that application of desiccant dust in combination with release of CO2 gas to mimic human presence is a promising option for bed bug control.

  5. Role of abscisic acid (ABA) in activating antioxidant tolerance responses to desiccation stress in intertidal seaweed species.

    Science.gov (United States)

    Guajardo, Eduardo; Correa, Juan A; Contreras-Porcia, Loretto

    2016-03-01

    The hormone ABA regulates the oxidative stress state under desiccation in seaweed species; an environmental condition generated during daily tidal changes. Desiccation is one of the most important factors that determine the distribution pattern of intertidal seaweeds. Among most tolerant seaweed is Pyropia orbicularis, which colonizes upper intertidal zones along the Chilean coast. P. orbicularis employs diverse mechanisms of desiccation tolerance (DT) (among others, e.g., antioxidant activation, photoinhibition, and osmo-compatible solute overproduction) such as those used by resurrection plants and bryophytes. In these organisms, the hormone abscisic acid (ABA) plays an important role in regulating responses to water deficit, including gene expression and the activity of antioxidant enzymes. The present study determined the effect of ABA on the activation of antioxidant responses during desiccation in P. orbicularis and in the sensitive species Mazzaella laminarioides and Lessonia spicata. Changes in endogenous free and conjugated ABA, water content during the hydration-desiccation cycle, enzymatic antioxidant activities [ascorbate peroxidase (AP), catalase (CAT) and peroxiredoxine (PRX)], and levels of lipid peroxidation and cell viability were evaluated. The results showed that P. orbicularis had free ABA levels 4-7 times higher than sensitive species, which was overproduced during water deficit. Using two ABA inhibitors (sodium tungstate and ancymidol), ABA was found to regulate the activation of the antioxidant enzymes activities during desiccation. In individuals exposed to exogenous ABA the enzyme activity increased, concomitant with low lipid peroxidation and high cell viability. These results demonstrate the participation of ABA in the regulation of DT in seaweeds, and suggest that regulatory mechanisms with ABA signaling could be of great importance for the adaptation of these organisms to dehydration.

  6. Effect of air desiccation and salt stress factors on in vitro regeneration of rice (Oryza sativa L.)

    Science.gov (United States)

    Siddique, Abu Baker; Ara, Israt; Islam, S M Shahinul; Tuteja, Narendra

    2014-01-01

    Enhancement of callus induction and its regeneration efficiency through in vitro techniques has been optimized for 2 abiotic stresses (salt and air desiccation) using 3 rice genotypes viz. BR10, BRRI dhan32 and BRRI dhan47. The highest frequency of callus induction was obtained for BRRI dhan32 (64.44%) in MS medium supplemented with 2, 4-D (2.5 mgL−1) and Kin (1.0 mgL−1). Different concentrations of NaCl (2.9, 5.9, 8.8 and 11.7 gL−1) were used and its effect was recorded on the basis of viability of calli (VC), relative growth rate (RGR), tolerance index (TI) and relative water content (RWC). It was observed that in all cases BRRI dhan47 showed highest performance on tolerance to VC (45.33%), RGR (1.03%), TI (0.20%) and RWC (10.23%) with 11.7 gL−1 NaCl. Plant regeneration capability was recorded after partial air desiccation pretreatment to calli for 15, 30, 45 and 60 h. In this case BRRI dhan32 gave maximum number of regeneration (76.19%) when 4 weeks old calli were desiccated for 45 h. It was observed that air desiccation was 2-3 folds more effective for enhancing green plantlet regeneration compared to controls. Furthermore, desiccated calli also showed the better capability to survive in NaCl induced abiotic stress; and gave 1.9 fold (88.80%) increased regeneration in 11.7 gL−1 salt level for BRRI dhan47. Analysis of variance (ANOVA) showed that the genotypes, air desiccation and NaCl had significant effect on plant regeneration at P < 0.01. PMID:25482754

  7. Nitrogen limitation and slow drying induce desiccation tolerance in conjugating green algae (Zygnematophyceae, Streptophyta from polar habitats.

    Directory of Open Access Journals (Sweden)

    Martina Pichrtová

    Full Text Available Filamentous Zygnematophyceae are typical components of algal mats in the polar hydro-terrestrial environment. Under field conditions, they form senescent vegetative cells, designated as pre-akinetes, which are tolerant to desiccation and osmotic stress.Pre-akinete formation and desiccation tolerance was investigated experimentally under monitored laboratory conditions in four strains of Arctic and Antarctic isolates with vegetative Zygnema sp. morphology. Phylogenetic analyses of rbcL sequences revealed one Arctic strain as genus Zygnemopsis, phylogenetically distant from the closely related Zygnema strains. Algae were cultivated in liquid or on solidified medium (9 weeks, supplemented with or lacking nitrogen. Nitrogen-free cultures (liquid as well as solidified consisted of well-developed pre-akinetes after this period. Desiccation experiments were performed at three different drying rates (rapid: 10% relative humidity, slow: 86% rh and very slow; viability, effective quantum yield of PS II, visual and ultrastructural changes were monitored. Recovery and viability of pre-akinetes were clearly dependent on the drying rate: slower desiccation led to higher levels of survival. Pre-akinetes survived rapid drying after acclimation by very slow desiccation.The formation of pre-akinetes in polar Zygnema spp. and Zygnemopsis sp. is induced by nitrogen limitation. Pre-akinetes, modified vegetative cells, rather than specialized stages of the life cycle, can be hardened by mild desiccation stress to survive rapid drying. Naturally hardened pre-akinetes play a key role in stress tolerance and dispersal under the extreme conditions of polar regions, where sexual reproduction and production of dormant stages is largely suppressed.

  8. Nitrogen limitation and slow drying induce desiccation tolerance in conjugating green algae (Zygnematophyceae, Streptophyta) from polar habitats.

    Science.gov (United States)

    Pichrtová, Martina; Kulichová, Jana; Holzinger, Andreas

    2014-01-01

    Filamentous Zygnematophyceae are typical components of algal mats in the polar hydro-terrestrial environment. Under field conditions, they form senescent vegetative cells, designated as pre-akinetes, which are tolerant to desiccation and osmotic stress. Pre-akinete formation and desiccation tolerance was investigated experimentally under monitored laboratory conditions in four strains of Arctic and Antarctic isolates with vegetative Zygnema sp. morphology. Phylogenetic analyses of rbcL sequences revealed one Arctic strain as genus Zygnemopsis, phylogenetically distant from the closely related Zygnema strains. Algae were cultivated in liquid or on solidified medium (9 weeks), supplemented with or lacking nitrogen. Nitrogen-free cultures (liquid as well as solidified) consisted of well-developed pre-akinetes after this period. Desiccation experiments were performed at three different drying rates (rapid: 10% relative humidity, slow: 86% rh and very slow); viability, effective quantum yield of PS II, visual and ultrastructural changes were monitored. Recovery and viability of pre-akinetes were clearly dependent on the drying rate: slower desiccation led to higher levels of survival. Pre-akinetes survived rapid drying after acclimation by very slow desiccation. The formation of pre-akinetes in polar Zygnema spp. and Zygnemopsis sp. is induced by nitrogen limitation. Pre-akinetes, modified vegetative cells, rather than specialized stages of the life cycle, can be hardened by mild desiccation stress to survive rapid drying. Naturally hardened pre-akinetes play a key role in stress tolerance and dispersal under the extreme conditions of polar regions, where sexual reproduction and production of dormant stages is largely suppressed.

  9. Localization and Quantification of Callose in the Streptophyte Green Algae Zygnema and Klebsormidium: Correlation with Desiccation Tolerance.

    Science.gov (United States)

    Herburger, Klaus; Holzinger, Andreas

    2015-11-01

    Freshwater green algae started to colonize terrestrial habitats about 460 million years ago, giving rise to the evolution of land plants. Today, several streptophyte green algae occur in aero-terrestrial habitats with unpredictable fluctuations in water availability, serving as ideal models for investigating desiccation tolerance. We tested the hypothesis that callose, a β-d-1,3-glucan, is incorporated specifically in strained areas of the cell wall due to cellular water loss, implicating a contribution to desiccation tolerance. In the early diverging genus Klebsormidium, callose was drastically increased already after 30 min of desiccation stress. Localization studies demonstrated an increase in callose in the undulating cross cell walls during cellular water loss, allowing a regulated shrinkage and expansion after rehydration. This correlates with a high desiccation tolerance demonstrated by a full recovery of the photosynthetic yield visualized at the subcellular level by Imaging-PAM. Furthermore, abundant callose in terminal cell walls might facilitate cell detachment to release dispersal units. In contrast, in the late diverging Zygnema, the callose content did not change upon desiccation for up to 3.5 h and was primarily localized in the corners between individual cells and at terminal cells. While these callose deposits still imply reduction of mechanical damage, the photosynthetic yield did not recover fully in the investigated young cultures of Zygnema upon rehydration. The abundance and specific localization of callose correlates with the higher desiccation tolerance in Klebsormidium when compared with Zygnema. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  10. Cross-tolerance effects due to adult heat hardening, desiccation and starvation acclimation of tropical drosophilid-Zaprionus indianus.

    Science.gov (United States)

    Kalra, Bhawna; Tamang, Aditya Moktan; Parkash, Ravi

    2017-07-01

    Some insect taxa from polar or temperate habitats have shown cross-tolerance for multiple stressors but tropical insect taxa have received less attention. Accordingly, we considered adult flies of a tropical drosophilid-Zaprionus indianus for testing direct as well as cross-tolerance effects of rapid heat hardening (HH), desiccation acclimation (DA) and starvation acclimation (SA) after rearing under warmer and drier season specific simulated conditions. We observed significant direct acclimation effects of HH, DA and SA; and four cases of cross-tolerance effects but no cross-tolerance between desiccation and starvation. Cross-tolerance due to heat hardening on desiccation showed 20% higher effect than its reciprocal effect. There is greater reduction of water loss in heat hardened flies (due to increase in amount of cuticular lipids) as compared with desiccation acclimated flies. However, cross-tolerance effect of SA on heat knockdown was two times higher than its reciprocal. Heat hardened and desiccation acclimated adult flies showed substantial increase in the level of trehalose and proline while body lipids increased due to heat hardening or starvation acclimation. However, maximum increase in energy metabolites was stressor specific i.e. trehalose due to DA; proline due to HH and total body lipids due to SA. Rapid changes in energy metabolites due to heat hardening seem compensatory for possible depletion of trehalose and proline due to desiccation stress; and body lipids due to starvation stress. Thus, observed cross-tolerance effects in Z. indianus represent physiological changes to cope with multiple stressors related to warmer and drier subtropical habitats. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Desiccator Volume: A Vital Yet Ignored Parameter in CaCO3 Crystallization by the Ammonium Carbonate Diffusion Method

    Directory of Open Access Journals (Sweden)

    Joe Harris

    2017-07-01

    Full Text Available Employing the widely used ammonium carbonate diffusion method, we demonstrate that altering an extrinsic parameter—desiccator size—which is rarely detailed in publications, can alter the route of crystallization. Hexagonally packed assemblies of spherical magnesium-calcium carbonate particles or spherulitic aragonitic particles can be selectively prepared from the same initial reaction solution by simply changing the internal volume of the desiccator, thereby changing the rate of carbonate addition and consequently precursor formation. This demonstrates that it is not merely the quantity of an additive which can control particle morphogenesis and phase selectivity, but control of other often ignored parameters are vital to ensure adequate reproducibility.

  12. Transcriptomics of desiccation tolerance in the streptophyte green alga Klebsormidium reveal a land plant-like defense reaction.

    Science.gov (United States)

    Holzinger, Andreas; Kaplan, Franziska; Blaas, Kathrin; Zechmann, Bernd; Komsic-Buchmann, Karin; Becker, Burkhard

    2014-01-01

    Water loss has significant effects on physiological performance and survival rates of algae. However, despite the prominent presence of aeroterrestrial algae in terrestrial habitats, hardly anything is known about the molecular events that allow aeroterrestrial algae to survive harsh environmental conditions. We analyzed the transcriptome and physiology of a strain of the alpine aeroterrestrial alga Klebsormidium crenulatum under control and strong desiccation-stress conditions. For comparison we first established a reference transcriptome. The high-coverage reference transcriptome includes about 24,183 sequences (1.5 million reads, 636 million bases). The reference transcriptome encodes for all major pathways (energy, carbohydrates, lipids, amino acids, sugars), nearly all deduced pathways are complete or missing only a few transcripts. Upon strong desiccation, more than 7000 transcripts showed changes in their expression levels. Most of the highest up-regulated transcripts do not show similarity to known viridiplant proteins, suggesting the existence of some genus- or species-specific responses to desiccation. In addition, we observed the up-regulation of many transcripts involved in desiccation tolerance in plants (e.g. proteins similar to those that are abundant in late embryogenesis (LEA), or proteins involved in early response to desiccation ERD), and enzymes involved in the biosynthesis of the raffinose family of oligosaccharides (RFO) known to act as osmolytes). Major physiological shifts are the up-regulation of transcripts for photosynthesis, energy production, and reactive oxygen species (ROS) metabolism, which is supported by elevated cellular glutathione content as revealed by immunoelectron microscopy as well as an increase in total antiradical power. However, the effective quantum yield of Photosystem II and CO2 fixation decreased sharply under the applied desiccation stress. In contrast, transcripts for cell integrative functions such as cell

  13. Transcriptomics of desiccation tolerance in the streptophyte green alga Klebsormidium reveal a land plant-like defense reaction.

    Directory of Open Access Journals (Sweden)

    Andreas Holzinger

    Full Text Available Water loss has significant effects on physiological performance and survival rates of algae. However, despite the prominent presence of aeroterrestrial algae in terrestrial habitats, hardly anything is known about the molecular events that allow aeroterrestrial algae to survive harsh environmental conditions. We analyzed the transcriptome and physiology of a strain of the alpine aeroterrestrial alga Klebsormidium crenulatum under control and strong desiccation-stress conditions.For comparison we first established a reference transcriptome. The high-coverage reference transcriptome includes about 24,183 sequences (1.5 million reads, 636 million bases. The reference transcriptome encodes for all major pathways (energy, carbohydrates, lipids, amino acids, sugars, nearly all deduced pathways are complete or missing only a few transcripts. Upon strong desiccation, more than 7000 transcripts showed changes in their expression levels. Most of the highest up-regulated transcripts do not show similarity to known viridiplant proteins, suggesting the existence of some genus- or species-specific responses to desiccation. In addition, we observed the up-regulation of many transcripts involved in desiccation tolerance in plants (e.g. proteins similar to those that are abundant in late embryogenesis (LEA, or proteins involved in early response to desiccation ERD, and enzymes involved in the biosynthesis of the raffinose family of oligosaccharides (RFO known to act as osmolytes. Major physiological shifts are the up-regulation of transcripts for photosynthesis, energy production, and reactive oxygen species (ROS metabolism, which is supported by elevated cellular glutathione content as revealed by immunoelectron microscopy as well as an increase in total antiradical power. However, the effective quantum yield of Photosystem II and CO2 fixation decreased sharply under the applied desiccation stress. In contrast, transcripts for cell integrative functions such as

  14. Energy performance of an innovative liquid desiccant dehumidification system with a counter-flow heat and mass exchanger using potassium formate

    DEFF Research Database (Denmark)

    Jradi, Muhyiddine; Riffat, Saffa

    2014-01-01

    with the process air. An environmentally friendly, non-corrosive, nontoxic and chemically stable HCOOK potassium formate liquid desiccant solution was employed in the unit. A set of governing differential equations was established for the dehumidification system operation allowing the development of a numerical......An innovative micro-scale liquid desiccant dehumidification system is numerically investigated. The liquid desiccant dehumidification unit employs a counter-flow low-cost and efficient heat and mass exchange core, improving the thermal performance and eliminating desiccant carryover...... that the dehumidifier effectiveness is directly proportional to the intake air temperature, intake air relative humidity and liquid desiccant flow rate where the effectiveness is inversely proportional to the intake air velocity and the heat exchanger air channel height....

  15. Radiographic image analysis of Anacardium othonianum Rizz (anacardiaceae achenes subjected to desiccation

    Directory of Open Access Journals (Sweden)

    Lílian Abadia da Silva

    2017-04-01

    Full Text Available Studies evaluating the internal morphology and seed quality of native species are essential for successful conservation programs. Our aim was to verify the efficiency of X-ray imagery in evaluating cashew-tree-of-the-cerrado (Anacardium othonianum Rizz. achene viability after desiccation. The achenes were collected at 12% water content (w.b. and dried in silica gel until they reached 10, 8, 6, and 4% (w.b.. The fruit morphology and the quality of the seeds were evaluated by X-ray test together with vigor, electrical conductivity and emergence tests. Achenes with different water contents were exposed to an X-ray machine at 18 kV for 11 s and were thereafter submitted to emergence tests. The images were analyzed, and the achenes were classified based on internal morphology as completely full, malformed, or empty. These results were compared to those from the emergence tests. The statistical design was a complete randomized factorial (5 x 3. Desiccation to 4% (w.b. did not damage or modify the internal structures. X-ray was efficient in evaluating the internal morphology and detecting achene quality, making it possible to remove empty and abnormal fruit and form vigorous seed lots, reducing the cost of storage and bedding plant production for this native species.

  16. Rapid recovery of cyanobacterial pigments in desiccated biological soil crusts following addition of water.

    Directory of Open Access Journals (Sweden)

    Raeid M M Abed

    Full Text Available We examined soil surface colour change to green and hydrotaxis following addition of water to biological soil crusts using pigment extraction, hyperspectral imaging, microsensors and 13C labeling experiments coupled to matrix-assisted laser desorption and ionization time of flight-mass spectrometry (MALD-TOF MS. The topsoil colour turned green in less than 5 minutes following water addition. The concentrations of chlorophyll a (Chl a, scytonemin and echinenon rapidly increased in the top <1 mm layer while in the deeper layer, their concentrations remained low. Hyperspectral imaging showed that, in both wet and dehydrated crusts, cyanobacteria formed a layer at a depth of 0.2-0.4 mm and this layer did not move upward after wetting. 13C labeling experiments and MALDI TOF analysis showed that Chl a was already present in the desiccated crusts and de novo synthesis of this molecule started only after 2 days of wetting due to growth of cyanobacteria. Microsensor measurements showed that photosynthetic activity increased concomitantly with the increase of Chl a, and reached a maximum net rate of 92 µmol m-2 h-1 approximately 2 hours after wetting. We conclude that the colour change of soil crusts to green upon water addition was not due to hydrotaxis but rather to the quick recovery and reassembly of pigments. Cyanobacteria in crusts can maintain their photosynthetic apparatus intact even under prolonged periods of desiccation with the ability to resume their photosynthetic activities within minutes after wetting.

  17. PHYSIOLOGICAL AND SANITARY QUALITY OF DESICCATED AND STORED AZUKI BEAN SEEDS

    Directory of Open Access Journals (Sweden)

    CÁSSIO JARDIM TAVARES

    2016-01-01

    Full Text Available The objective of this research was to evaluate the effects of using different herbicides as desiccants in pre - harvest and the effects of storage on the physiological and sanitary quality of azuki bean seeds ( Vigna angularis Willd. The experiment was arranged in a randomized complete block design in a split plot scheme, with four replications. Four herbicides were tested: paraquat (400 g a.i. ha - 1 , glufosinate ammonium (400 g a.i. ha - 1 , glyphosate (720 g a.i. ha - 1 , flumioxazin (30 g a.i. ha - 1 and a control without herbicide application. In the subplots seed quality was tested in two evaluation periods: at harvest and six months after harvest. Desiccant was applied when the azuki beans were physiologically mature. We assessed the physiological and sanitary quality of the seeds using a vigour and seed health test. The use of glyphosate resulted in a higher incidence of abnormal seedlings and reduced size and weight of the seedlings. With paraquat and flumioxazin the physiological quality was maintained and there was reduced pathogen infestation in the seeds six months after harvest. Storage affected the physiological quality of the azuki bean seeds.

  18. Desiccation tolerance in the tardigrade Richtersius coronifer relies on muscle mediated structural reorganization.

    Science.gov (United States)

    Halberg, Kenneth Agerlin; Jørgensen, Aslak; Møbjerg, Nadja

    2013-01-01

    Life unfolds within a framework of constraining abiotic factors, yet some organisms are adapted to handle large fluctuations in physical and chemical parameters. Tardigrades are microscopic ecdysozoans well known for their ability to endure hostile conditions, such as complete desiccation--a phenomenon called anhydrobiosis. During dehydration, anhydrobiotic animals undergo a series of anatomical changes. Whether this reorganization is an essential regulated event mediated by active controlled processes, or merely a passive result of the dehydration process, has not been clearly determined. Here, we investigate parameters pivotal to the formation of the so-called "tun", a state that in tardigrades and rotifers marks the entrance into anhydrobiosis. Estimation of body volume in the eutardigrade Richtersius coronifer reveals an 87 % reduction in volume from the hydrated active state to the dehydrated tun state, underlining the structural stress associated with entering anhydrobiosis. Survival experiments with pharmacological inhibitors of mitochondrial energy production and muscle contractions show that i) mitochondrial energy production is a prerequisite for surviving desiccation, ii) uncoupling the mitochondria abolishes tun formation, and iii) inhibiting the musculature impairs the ability to form viable tuns. We moreover provide a comparative analysis of the structural changes involved in tun formation, using a combination of cytochemistry, confocal laser scanning microscopy and 3D reconstructions as well as scanning electron microscopy. Our data reveal that the musculature mediates a structural reorganization vital for anhydrobiotic survival, and furthermore that maintaining structural integrity is essential for resumption of life following rehydration.

  19. Desiccation tolerance in the tardigrade Richtersius coronifer relies on muscle mediated structural reorganization.

    Directory of Open Access Journals (Sweden)

    Kenneth Agerlin Halberg

    Full Text Available Life unfolds within a framework of constraining abiotic factors, yet some organisms are adapted to handle large fluctuations in physical and chemical parameters. Tardigrades are microscopic ecdysozoans well known for their ability to endure hostile conditions, such as complete desiccation--a phenomenon called anhydrobiosis. During dehydration, anhydrobiotic animals undergo a series of anatomical changes. Whether this reorganization is an essential regulated event mediated by active controlled processes, or merely a passive result of the dehydration process, has not been clearly determined. Here, we investigate parameters pivotal to the formation of the so-called "tun", a state that in tardigrades and rotifers marks the entrance into anhydrobiosis. Estimation of body volume in the eutardigrade Richtersius coronifer reveals an 87 % reduction in volume from the hydrated active state to the dehydrated tun state, underlining the structural stress associated with entering anhydrobiosis. Survival experiments with pharmacological inhibitors of mitochondrial energy production and muscle contractions show that i mitochondrial energy production is a prerequisite for surviving desiccation, ii uncoupling the mitochondria abolishes tun formation, and iii inhibiting the musculature impairs the ability to form viable tuns. We moreover provide a comparative analysis of the structural changes involved in tun formation, using a combination of cytochemistry, confocal laser scanning microscopy and 3D reconstructions as well as scanning electron microscopy. Our data reveal that the musculature mediates a structural reorganization vital for anhydrobiotic survival, and furthermore that maintaining structural integrity is essential for resumption of life following rehydration.

  20. Glycerolipid analysis during desiccation and recovery of the resurrection plant Xerophyta humilis (Bak) Dur and Schinz.

    Science.gov (United States)

    Tshabuse, Freedom; Farrant, Jill M; Humbert, Lydie; Moura, Deborah; Rainteau, Dominique; Espinasse, Christophe; Taghki, Abdelghani Idrissi; Merlier, Franck; Acket, Sébastien; Rafudeen, Mohamad S; Thomasset, Brigitte; Ruelland, Eric

    2017-09-02

    Xerophyta humilis is a poikilochlorophyllous monocot resurrection plant used as a model to study vegetative desiccation tolerance. Dehydration imposes tension and ultimate loss of integrity of membranes in desiccation sensitive species. We investigated the predominant molecular species of glycerolipids present in root and leaf tissues, using multiple reaction monitoring mass spectrometry, then analysed changes therein during dehydration and subsequent rehydration of whole plants. The presence of fatty acids with long carbon chains and with odd numbers of carbons were detected and confirmed by gas chromatography. Dehydration of both leaves and roots resulted in an increase in species containing polyunsaturated fatty acids and a decrease in disaturated species. Upon rehydration, lipid saturation was reversed, with this being initiated immediately upon watering in roots but only 12 to 24 hr later in leaves. Relative levels of species with short-chained odd-numbered saturated fatty acids decreased during dehydration and increased during rehydration, while the reverse trend was observed for long-chained fatty acids. X. humilis has a unique lipid composition, this report being one of the few to demonstrate the presence of odd-numbered fatty acids in plant phosphoglycerolipids. This article is protected by copyright. All rights reserved.

  1. Mechanisms associated with cellular desiccation tolerance of Artemia encysted embryos from locations around the world.

    Science.gov (United States)

    Hengherr, Steffen; Schill, Ralph O; Clegg, J S

    2011-10-01

    Using differential scanning calorimetry we demonstrated the presence of biological glasses and measured the glass transition temperatures (Tg) in dry encysted gastrula embryos (cysts) of the brine shrimp, Artemia, from eleven different locations, two of which provided cysts from parthenogenetic animals. Values for Tg were highest, by far, in Artemia franciscana cysts from the Mekong Delta, Vietnam (VN), these cysts having been produced from previous sequential inoculations into growth ponds of cysts from the San Francisco Bay, California, USA. Tg values for three groups of A. franciscana cysts were significantly higher than those of other cysts (except those of Artemia persimilis) studied here, as well as all other desiccation-tolerant animal systems studied to date. We also measured three stress proteins (hsc70, artemin and p26) in all these cysts as well as the total alcohol soluble carbohydrates (ASC), about 90% of which is the disaccharide trehalose, a known component of biological glasses. We interpret the results in terms of mechanisms involved with desiccation tolerance and, to some extent, with thermal conditions at the sites of cyst collection.

  2. The influence of saturation on the cracking process in compacted desiccating clays

    Directory of Open Access Journals (Sweden)

    Noack Maria

    2016-01-01

    Full Text Available Tensile failure in unsaturated cohesive soils during desiccation is important for the design of geotechnical applications such as capping systems of landfills and sealing material of dikes. This study presents the results of different initial parameters of compacted clay samples such as gravimetric water content, dry density and degree of saturation. These parameters are varied systematically for each test to find the correlation between those parameters and the tensile failure. The tensile failure for all tests occurred by a comparable constant change of the degree of saturation. The soil specific saturation ratio Sr,s is defined as the quotient of saturation changes ΔSr to initial saturation Sr,0. This parameter related to the total suction shows an equal course for all results. All in all, the course of the soil specific saturation ratio Sr,s is independent of all initial parameters. These results provide a physical and hydraulic-mechanical description for modelling the desiccation process. To demonstrate the initiation and progress of tensile failure, the experimental results are modelled with a Discrete Element Method (DEM approach.

  3. Physiological and biochemical changes during the loss of desiccation tolerance in germinating Adenanthera pavonina L. seeds.

    Science.gov (United States)

    Soares, Giuliana C M; Dias, Denise C F S; Faria, José M R; Borges, Eduardo E L

    2015-01-01

    We investigated the loss of desiccation tolerance (DT) in Adenanthera pavonina seeds during germination. Seeds were subjected to imbibition for 0, 24, 36, 48, 60 and 81 h, then dried to their initial moisture content (13%), rehydrated and evaluated for survival (resumption of growth and development of normal seedlings) and membrane system integrity (electrolyte leakage). Embryonic axes of seeds subjected only to imbibition during the same early time periods were used to investigate the electrophoretic patterns of heat-stable proteins and the relative nuclear DNA content. In A. pavonina seeds, DT remained unchanged until 36 h of imbibition (resulting in germination and 82% normal seedlings), after which it was progressively lost, and seeds with a protruded radicle length of 1 mm did not withstand dehydration. The loss of desiccation tolerance could not be related to either membrane damage caused by drying or the resumption of the cell cycle during germination. However, the decrease in heat-stable protein contents observed throughout germination may be related to the loss of DT in A. pavonina seeds.

  4. The re-establishment of desiccation tolerance in germinated Arabidopsis thaliana seeds and its associated transcriptome.

    Science.gov (United States)

    Maia, Julio; Dekkers, Bas J W; Provart, Nicholas J; Ligterink, Wilco; Hilhorst, Henk W M

    2011-01-01

    The combination of robust physiological models with "omics" studies holds promise for the discovery of genes and pathways linked to how organisms deal with drying. Here we used a transcriptomics approach in combination with an in vivo physiological model of re-establishment of desiccation tolerance (DT) in Arabidopsis thaliana seeds. We show that the incubation of desiccation sensitive (DS) germinated Arabidopsis seeds in a polyethylene glycol (PEG) solution re-induces the mechanisms necessary for expression of DT. Based on a SNP-tile array gene expression profile, our data indicates that the re-establishment of DT, in this system, is related to a programmed reversion from a metabolic active to a quiescent state similar to prior to germination. Our findings show that transcripts of germinated seeds after the PEG-treatment are dominated by those encoding LEA, seed storage and dormancy related proteins. On the other hand, a massive repression of genes belonging to many other classes such as photosynthesis, cell wall modification and energy metabolism occurs in parallel. Furthermore, comparison with a similar system for Medicago truncatula reveals a significant overlap between the two transcriptomes. Such overlap may highlight core mechanisms and key regulators of the trait DT. Taking into account the availability of the many genetic and molecular resources for Arabidopsis, the described system may prove useful for unraveling DT in higher plants.

  5. Key genes involved in desiccation tolerance and dormancy across life forms.

    Science.gov (United States)

    Costa, Maria Cecília D; Farrant, Jill M; Oliver, Melvin J; Ligterink, Wilco; Buitink, Julia; Hilhorst, Henk M W

    2016-10-01

    Desiccation tolerance (DT, the ability of certain organisms to survive severe dehydration) was a key trait in the evolution of life in terrestrial environments. Likely, the development of desiccation-tolerant life forms was accompanied by the acquisition of dormancy or a dormancy-like stage as a second powerful adaptation to cope with variations in the terrestrial environment. These naturally stress tolerant life forms may be a good source of genetic information to generate stress tolerant crops to face a future with predicted higher occurrence of drought. By mining for key genes and mechanisms related to DT and dormancy conserved across different species and life forms, unique candidate key genes may be identified. Here we identify several of these putative key genes, shared among multiple organisms, encoding for proteins involved in protection, growth and energy metabolism. Mutating a selection of these genes in the model plant Arabidopsis thaliana resulted in clear DT-, dormancy- and other seed-associated phenotypes, showing the efficiency and power of our approach and paves the way for the development of drought-stress tolerant crops. Our analysis supports a co-evolution of DT and dormancy by shared mechanisms that favour survival and adaptation to ever-changing environments with strong seasonal fluctuations. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. The re-establishment of desiccation tolerance in germinated Arabidopsis thaliana seeds and its associated transcriptome.

    Directory of Open Access Journals (Sweden)

    Julio Maia

    Full Text Available The combination of robust physiological models with "omics" studies holds promise for the discovery of genes and pathways linked to how organisms deal with drying. Here we used a transcriptomics approach in combination with an in vivo physiological model of re-establishment of desiccation tolerance (DT in Arabidopsis thaliana seeds. We show that the incubation of desiccation sensitive (DS germinated Arabidopsis seeds in a polyethylene glycol (PEG solution re-induces the mechanisms necessary for expression of DT. Based on a SNP-tile array gene expression profile, our data indicates that the re-establishment of DT, in this system, is related to a programmed reversion from a metabolic active to a quiescent state similar to prior to germination. Our findings show that transcripts of germinated seeds after the PEG-treatment are dominated by those encoding LEA, seed storage and dormancy related proteins. On the other hand, a massive repression of genes belonging to many other classes such as photosynthesis, cell wall modification and energy metabolism occurs in parallel. Furthermore, comparison with a similar system for Medicago truncatula reveals a significant overlap between the two transcriptomes. Such overlap may highlight core mechanisms and key regulators of the trait DT. Taking into account the availability of the many genetic and molecular resources for Arabidopsis, the described system may prove useful for unraveling DT in higher plants.

  7. The role of peltate scales in desiccation tolerance of Pleopeltis polypodioides.

    Science.gov (United States)

    John, Susan P; Hasenstein, Karl H

    2017-01-01

    The extreme drought tolerance of the resurrection fern is in part the result of the dorsal scales that assist in water distribution and controlled desiccation. We studied the effect of peltate scales on water uptake and loss of the desiccation-tolerant epiphytic fern Pleopeltis polypodioides using optical and FTIR microscopy and staining with calcofluor, solophenyl flavine7GFE, and Ruthenium Red. We provide information on structure, property, and function of the scales by measuring water uptake and dehydration, contact angles, and metabolic activity. Peltate scales mainly contain cellulose, xylogalactans, and pectin. Water is absorbed from the center of scales, and the overlapping arrangement of scales facilitates surface spreading of water. Intact fronds hydrated fully within 5 h of imbibition of the apical pinna, without scales water uptake stopped after 1 h. Hydration rates via rhizomes followed a longer time course but also improved in the presence of scales. Fronds with and without scales lost half of their water content in 15 or 4 h, respectively. The overall metabolism of rapidly dehydrated fronds was significantly reduced compared with slowly dehydrated fronds. Thus, water management and metabolism of Pleopeltis are dependent on surface properties determined by peltate scales.

  8. Performance Assessment of a Solar-Assisted Desiccant-Based Air Handling Unit Considering Different Scenarios

    Directory of Open Access Journals (Sweden)

    Giovanni Angrisani

    2016-09-01

    Full Text Available In this paper, three alternative layouts (scenarios of an innovative solar-assisted hybrid desiccant-based air handling unit (AHU are investigated through dynamic simulations. Performance is evaluated with respect to a reference system and compared to those of the innovative plant without modifications. For each scenario, different collector types, surfaces and tilt angles are considered. The effect of the solar thermal energy surplus exploitation for other low-temperature uses is also investigated. The first alternative scenario consists of the recovery of the heat rejected by the condenser of the chiller to pre-heat the regeneration air. The second scenario considers the pre-heating of regeneration air with the warmer regeneration air exiting the desiccant wheel (DW. The last scenario provides pre-cooling of the process air before entering the DW. Results reveal that the plants with evacuated solar collectors (SC can ensure primary energy savings (15%–24% and avoid equivalent CO2 emissions (14%–22%, about 10 percentage points more than those with flat-plate collectors, when the solar thermal energy is used only for air conditioning and the collectors have the best tilt angle. If all of the solar thermal energy is considered, the best results with evacuated tube collectors are approximately 73% in terms of primary energy saving, 71% in terms of avoided equivalent CO2 emissions and a payback period of six years.

  9. Performance Analysis of a Solar Dryer Equipped with a Recycling Air System and Desiccant Chamber

    Directory of Open Access Journals (Sweden)

    M.H Aghkhani

    2013-09-01

    Full Text Available Drying is a high energy consuming process. Solar drying is one of the most popular methods for dehydration of agricultural products. In the present study, the performance of a forced convection solar dryer equipped with recycling air system and desiccant chamber was investigated. The solar dryer is comprised of solar collector, drying chamber, silica jell desiccant chamber, air ducts, fan and measuring and controlling system. Drying rate and energy consumption in three levels of air temperature (40, 45 and 50 oC and two modes of drying (with recycling air and no-recycling with open duct system were measured and compared. The results showed that increasing the drying air temperature decreased the drying time and increased the energy consumption in the mode of non-recycling air system. The dryer efficiency and drying rate were better in the mode of recycling air system than open duct system. The highest dryer efficiency was obtained from drying air temperature of 50 oC and the mode of recycling air system. In general, the efficiency of solar collector and the highest efficiency of the dryer were 0.34 and 0.41, respectively.

  10. Post desiccation germination of mature seeds of tea (Camellia sinensis L.) can be enhanced by pro-oxidant treatment, but partial desiccation tolerance does not ensure survival at -20°C.

    Science.gov (United States)

    Chen, Hongying; Pritchard, Hugh W; Seal, Charlotte E; Nadarajan, Jayanthi; Li, Weiqi; Yang, Shixiong; Kranner, Ilse

    2012-03-01

    The maximal potential desiccation tolerance (MPDT) of tea (Camellia sinensis) seeds has been a matter of debate for decades. Here we assessed the ability of tea seeds from three sites in China to germinate after desiccation. Desiccation tolerance was greatest in Kunming, followed by Puer and Lincang, with Kunming seeds tolerating drying to 8% moisture content (MC), or ∼0.5 water activity (a(w)). Such tolerance was observed in Lincang seeds only when hydrogen peroxide (H₂O₂) at 0.5 or 1M was applied to seeds, indicating a stimulatory role for H₂O₂ in post-desiccation germination. Puer seeds exhibited MPDT of 16% MC (∼0.7 a(w)). Therefore, seeds from all three sites were not recalcitrant. The length of the dry season after dispersal and the high ratio of seed coat to seed mass (>0.3) support the observation of non-recalcitrant behaviour. The seeds were not immature, as the lipid signal in embryonic axes mirrored that of the cotyledons (30% oil). Even after high survival [>60% total germination (TG)] on drying to 10-13% MC, no Kunming seeds tolerated 1 month storage at -20 °C coinciding with lipid transitional changes at this temperature. The results indicate that tea seeds from China are neither recalcitrant nor storable at -20 °C. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. Large-scale proteome analysis of abscisic acid and ABSCISIC ACID INSENSITIVE3-dependent proteins related to desiccation tolerance in Physcomitrella patens.

    Science.gov (United States)

    Yotsui, Izumi; Serada, Satoshi; Naka, Tetsuji; Saruhashi, Masashi; Taji, Teruaki; Hayashi, Takahisa; Quatrano, Ralph S; Sakata, Yoichi

    2016-03-18

    Desiccation tolerance is an ancestral feature of land plants and is still retained in non-vascular plants such as bryophytes and some vascular plants. However, except for seeds and spores, this trait is absent in vegetative tissues of vascular plants. Although many studies have focused on understanding the molecular basis underlying desiccation tolerance using transcriptome and proteome approaches, the critical molecular differences between desiccation tolerant plants and non-desiccation plants are still not clear. The moss Physcomitrella patens cannot survive rapid desiccation under laboratory conditions, but if cells of the protonemata are treated by the phytohormone abscisic acid (ABA) prior to desiccation, it can survive 24 h exposure to desiccation and regrow after rehydration. The desiccation tolerance induced by ABA (AiDT) is specific to this hormone, but also depends on a plant transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3). Here we report the comparative proteomic analysis of AiDT between wild type and ABI3 deleted mutant (Δabi3) of P. patens using iTRAQ (Isobaric Tags for Relative and Absolute Quantification). From a total of 1980 unique proteins that we identified, only 16 proteins are significantly altered in Δabi3 compared to wild type after desiccation following ABA treatment. Among this group, three of the four proteins that were severely affected in Δabi3 tissue were Arabidopsis orthologous genes, which were expressed in maturing seeds under the regulation of ABI3. These included a Group 1 late embryogenesis abundant (LEA) protein, a short-chain dehydrogenase, and a desiccation-related protein. Our results suggest that at least three of these proteins expressed in desiccation tolerant cells of both Arabidopsis and the moss are very likely to play important roles in acquisition of desiccation tolerance in land plants. Furthermore, our results suggest that the regulatory machinery of ABA- and ABI3-mediated gene expression for desiccation

  12. Downregulation of dTps1 in Drosophila melanogaster larvae confirms involvement of trehalose in redox regulation following desiccation.

    Science.gov (United States)

    Thorat, Leena; Mani, Krishna-Priya; Thangaraj, Pradeep; Chatterjee, Suvro; Nath, Bimalendu B

    2016-03-01

    As a survival strategy to environmental water deficits, desiccation-tolerant organisms are commonly known for their ability to recruit stress-protective biomolecules such as trehalose. We have previously reported the pivotal role of trehalose in larval desiccation tolerance in Drosophila melanogaster. Trehalose has emerged as a versatile molecule, serving mainly as energy source in insects and also being a stress protectant. While several recent reports have revealed the unconventional role of trehalose in scavenging reactive oxygen species in yeast and plants, this aspect has not received much attention in animals. We examined the status of desiccation-induced generation of reactive oxygen species in D. melanogaster larvae and the possible involvement of trehalose in ameliorating the harmful consequences thereof. Insect trehalose synthesis is governed by the enzyme trehalose 6-phosphate synthase 1 (TPS1). Using the ubiquitous da-GAL4-driven expression of the dTps1-RNAi transgene, we generated dTps1-downregulated Drosophila larvae possessing depleted levels of dTps1 transcripts. This resulted in the inability of the larvae for trehalose synthesis, thereby allowing us to elucidate the significance of trehalose in the regulation of desiccation-responsive redox homeostasis. Furthermore, the results from molecular genetics studies, biochemical assays, electron spin resonance analyses and a simple, non-invasive method of whole larval live imaging suggested that trehalose in collaboration with superoxide dismutase (SOD) is involved in the maintenance of redox state in D. melanogaster.

  13. Energetic efficiency of the use of desiccant in sugarcane; Eficiencia energetica do uso de dessecante em cana-de-acucar

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Gilda B.C.; Ripoli, Tomaz Caetano C.; Romanelli, Thiago L. [Escola Superior de Agricultura Luiz de Queiroz(ESALQ/USP), Piracicaba, SP (Brazil)], E-mail: gildacardoso@usp.br

    2010-07-01

    Economically, sugarcane is one of the most important crop in Brazil, showing a great perspective of expansion in the cultivated area. In the last few years the sugarcane mechanical harvested area has increased, causing a series of inconveniences for the system of harvest of the sugarcane, such as: the increase in the percentage of extraneous matter and losses of sugarcane and/or fractions in the field. Due the high value invested in the system of harvest of the sugarcane, the desiccant is one of the alternatives used to minimize such inconveniences in the pre harvest. In order to quantify the demand of energy of the system, the present work used a base of energy pointers as tool for the planning process and production of sugarcane in two systems, one with application of desiccant (T1) and the other without (T2). The energy flows of entrance (EE) and exit had been established, allowing the identification of the energy rocking (BE), that quantifies the liquid profit of energy for area. The results had shown that the application of the desiccant resulted in a bigger EE in system T1 (86601.44 MJ ha{sup -1} versus 83345.45 MJ ha{sup -1}). The BE of T2 presented superior in 0.14% in relation the T1 (2241318.57 MJ ha{sup -1} against 2238062.57 MJ ha{sup -1}), indicating that the desiccant presents greater energy consumption. (author)

  14. Solar-Powered, Liquid-Desiccant Air Conditioner for Low-Electricity Humidity Control: Report and Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Dean, J.; Kozubal, E.; Herrmann, L.; Miller, J.; Lowenstein, A.; Barker, G.; Slayzak, S.

    2012-11-01

    The primary objective of this project was to demonstrate the capabilities of a new high-performance, liquid-desiccant dedicated outdoor air system (DOAS) to enhance cooling efficiency and comfort in humid climates while substantially reducing electric peak demand at Tyndall Air Force Base (AFB), which is 12 miles east of Panama City, Florida.

  15. Sealed tube comparisons of the compatibility of desiccants with refrigerants and lubricants. Final report, August 1993--January 1995

    Energy Technology Data Exchange (ETDEWEB)

    Field, J.E.

    1995-05-01

    Continuing environmental concerns mandate replacement of CFC`s with alternate refrigeration fluids. Until now, relatively little testing had been reported in the literature for compatibility of desiccants in these new working fluids. Using bench scale test methods generally accepted throughout the industry today, this work provides data necessary to assess the compatibility of virtually all of the currently used desiccant types - both bead and molded core, with thirteen refrigerant/lubricant combinations. The desiccants have been tested by exposure to refrigerant and lubricant in sealed, glass tubes in accordance with ASHRAE/ANSI Standard 97-1989. After aging, the liquid phase was evaluated for acid anion formation, change in color, and presence of halide ions, the gas phase was analyzed for refrigerant decomposition by gas chromatography, and the desiccants were evaluated for changes in crush strength and for retention of acids and halide ions. Metal catalysts, also present in the sealed tubes, were visually examined for corrosion, copper plating, and appearance changes.

  16. Assessment of Energy, Environmental and Economic Performance of a Solar Desiccant Cooling System with Different Collector Types

    Directory of Open Access Journals (Sweden)

    Giovanni Angrisani

    2014-10-01

    Full Text Available Desiccant-based air handling units can achieve reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different collector technologies (air, flat-plate and evacuated collectors. Simulations were then performed to compare the energy, environmental and economic performance of the system with those of a desiccant-based unit where regeneration thermal energy is supplied by a natural gas boiler, and with those of a conventional air-handling unit. The only solution that allows achieving the economic feasibility of the solar desiccant cooling unit consists of 16 m2 of evacuated solar collectors. This is able to obtain, with respect to the reference system, a reduction of primary energy consumption and of the equivalent CO2 emissions of 50.2% and 49.8%, respectively, but with a payback time of 20 years.

  17. Protein and carbohydrate composition of larval food affects tolerance tothermal stress and desiccation in adult Drosophila melanogaster

    DEFF Research Database (Denmark)

    Andersen, Laila H; Kristensen, Torsten N; Loeschcke, Volker

    2010-01-01

    Larval nutrition may affect a range of different life history traits as well as responses to environmental stress in adult insects. Here we test whether raising larvae of fruit flies, Drosophila melanogaster, on two different nutritional regimes affects resistance to cold, heat and desiccation...

  18. Can a genetic correlation with seed mass constrain adaptive evolution of seedling desiccation tolerance in wild barley?

    NARCIS (Netherlands)

    Verhoeven, K.J.F.; Biere, A.; Nevo, E.; Van Damme, J.M.M.

    2004-01-01

    Very young seedlings of wild barley Hordeum spontaneum have the ability to survive extended periods of severe drought. This desiccation tolerance is considered an adaptation to the rain-limited and unpredictable habitats that the species occupies. Genetic variation has been observed for this trait,

  19. Simulation Analysis of the Four Configurations of Solar Desiccant Cooling System Using Evaporative Cooling in Tropical Weather in Malaysia

    Directory of Open Access Journals (Sweden)

    M. M. S. Dezfouli

    2014-01-01

    Full Text Available A high demand for air conditioning systems exists in hot and humid regions because of the warm climate during the year. The high energy consumption of conventional air conditioning system is the reason for our investigation of the solar desiccant cooling system as an energy-efficient cooling system. Four model configurations were considered to determine the best configuration of a solar desiccant cooling system: one-stage ventilation, one-stage recirculation, two-stage ventilation, and two-stage recirculation. These models were stimulated for 8,760 hr of operation under hot and humid weather in Malaysia. Several parameters (i.e., coefficient of performance or COP, room temperature and humidity ratio, and the solar fraction of each system were evaluated by detecting the temperature and humidity ratio of the different points of each configuration by TRNSYS simulation. The latent and sensible loads of the test room were 0.875 kW and 2.625 kW, respectively. By investigating the simulation results of the four systems, the ventilation modes were found to be higher than the recirculation modes in the one- and two-stage solar desiccant cooling systems. The isothermal dehumidification COP of the two-stage ventilation was higher than that of the two-stage recirculation. Hence, the two-stage ventilation mode desiccant cooling system in a hot and humid area has higher efficiency than the other configurations.

  20. Antibiotic and Desiccation Resistance of Cronobacter sakazakii and C. malonaticus Isolates from Powdered Infant Formula and Processing Environments

    Science.gov (United States)

    Fei, Peng; Jiang, Yujun; Feng, Jing; Forsythe, Stephen J.; Li, Ran; Zhou, Yanhong; Man, Chaoxin

    2017-01-01

    This study evaluated the antimicrobial and desiccation resistance of Cronobacter sakazakii and Cronobacter malonaticus isolates from powdered infant formula and processing environments. The antimicrobial susceptibility tests showed that the 70 Cronobacter strains, representing 19 sequence types, were susceptible to the most of the antibiotics except for amoxicillin-clavulanate, ampicillin, and cefazolin. Furthermore, the growth of six C. sakazakii and two C. malonaticus strains from different sequence types (STs) in hyperosmotic media was measured. The growth of the two C. sakazakii strains (CE1 and CE13) from the neonatal pathovars ST4 and ST8, were significantly higher (p < 0.05) than that of other strains. C. malonaticus strain CM35 (ST201) was the slowest grower in all strains, and most could not grow in more than 8% NaCl solution. Also the survival of these strains under desiccation conditions was followed for 1 year. The viable count of Cronobacter spp. under desiccation conditions was reduced on average by 3.02 log cycles during 1 year, with CE13 (ST8) being the most desiccation resistant strain. These results will improve our understanding of the persistence of the two closely related species C. sakazakii and C. malonaticus which are of concern for neonatal and adult health. PMID:28303125

  1. Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.

    2003-01-01

    Membrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast-dried, isolated

  2. An oxidative burst of superoxide in embryonic axes of recalcitrant sweet chestnut seeds as induced by excision and desiccation.

    Science.gov (United States)

    Roach, Thomas; Ivanova, Mariyana; Beckett, Richard P; Minibayeva, Farida V; Green, Ian; Pritchard, Hugh W; Kranner, Ilse

    2008-06-01

    Recalcitrant seeds are intolerant of desiccation and cannot be stored in conventional seed banks. Cryopreservation allows storage of the germplasm of some recalcitrant seeded species, but application to a wide range of plant diversity is still limited. The present work aimed at understanding the stresses that accompany the first steps in cryopreservation protocols, wounding and desiccation, both of which are likely to lead to the formation of reactive oxygen species (ROS). Extracellular ROS production was studied in isolated embryonic axes of sweet chestnut (Castanea sativa). Axis excision was accompanied by a burst of superoxide (O(2)(*-)), demonstrated by a colorimetric assay using epinephrine, electron spin resonance and staining with nitroblue tetrazolium. Superoxide was immediately produced on the cut surface after isolation of the axis from the seed, with an initial 'burst' in the first 5 min. Isolated axes subjected to variable levels of desiccation stress showed a decrease in viability and vigour and increased electrolyte leakage, indicative of impaired membrane integrity. The pattern of O(2)(*-) production showed a typical Gaussian pattern in response to increasing desiccation stress. The results indicate a complex interaction between excision and subsequent drying and are discussed with a view of manipulating ROS production for optimisation of cryopreservation protocols.

  3. Can a genetic correlation with seed mass constrain adaptive evolution of seedling desiccation tolerance in wild barley?

    NARCIS (Netherlands)

    Verhoeven, K.J.F.; Biere, A.; Nevo, E.; Van Damme, J.M.M.

    2004-01-01

    Very young seedlings of wild barley Hordeum spontaneum have the ability to survive extended periods of severe drought. This desiccation tolerance is considered an adaptation to the rain-limited and unpredictable habitats that the species occupies. Genetic variation has been observed for this trait,

  4. Metabolomic profiling in Selaginella lepidophylla at various hydration states provides new insights into the mechanistic basis of desiccation tolerance

    Science.gov (United States)

    Selaginella lepidophylla is one of only a few species of spike mosses (Selaginellaceae) that have evolved desiccation tolerance (DT) or the ability to ‘resurrect’ from an air-dried state. In order to understand the metabolic basis of DT, S. lepidophylla was subjected to a five-stage, rehydration/de...

  5. Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.

    2003-01-01

    Membrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast-dried, isolated

  6. Transcriptomic analysis reveals numerous diverse protein kinases and transcription factors involved in desiccation tolerance in the resurrection plant Myrothamnus flabellifolia

    Science.gov (United States)

    The woody resurrection plant Myrothamnus flabellifolia has remarkable tolerance to desiccation. Pyro-sequencing technology permitted us to analyze the transcriptome of M. flabellifolia during both dehydration and rehydration. We identified a total of 8287 and 8542 differentially transcribed genes du...

  7. Synergistic interaction between the fungus Beauveria bassiana and desiccant dusts applied against poultry red mites (Dermanyssus gallinae)

    DEFF Research Database (Denmark)

    Steenberg, Tove; Kilpinen, Ole Østerlund

    2014-01-01

    , but these fungi often take several days to kill mites. Laboratory experiments were carried out to study the efficacy of 3 types of desiccant dusts, the fungus Beauveria bassiana and combinations of the two control agents against D. gallinae. There was significant synergistic interaction between each...

  8. Sporobolus stapfianus: Insights into desiccation tolerance in the resurrection grasses from linking transcriptomics to metabolomics.

    Science.gov (United States)

    Yobi, Abou; Schlauch, Karen A; Tillett, Richard L; Yim, Won C; Espinoza, Catherine; Wone, Bernard W M; Cushman, John C; Oliver, Melvin J

    2017-03-28

    Understanding the response of resurrection angiosperms to dehydration and rehydration is critical for deciphering the mechanisms of how plants cope with the rigors of water loss from their vegetative tissues. We have focused our studies on the C4 resurrection grass, Sporobolus stapfianus Gandoger, as a member of a group of important forage grasses. We have combined non-targeted metabolomics with transcriptomics, via a NimbleGen array platform, to develop an understanding of how gene expression and metabolite profiles can be linked to generate a more detailed mechanistic appreciation of the cellular response to both desiccation and rehydration. The rehydration transcriptome and metabolome are primarily geared towards the rapid return of photosynthesis, energy metabolism, protein turnover, and protein synthesis during the rehydration phase. However, there are some metabolites associated with ROS protection that remain elevated during rehydration, most notably the tocopherols. The analysis of the dehydration transcriptome reveals a strong concordance between transcript abundance and the associated metabolite abundance reported earlier, but only in responses that are directly related to cellular protection during dehydration: carbohydrate metabolism and redox homeostasis. The transcriptome response also provides strong support for the involvement of cellular protection processes as exemplified by the increases in the abundance of transcripts encoding late embryogenesis abundant (LEA) proteins, anti-oxidant enzymes, early light-induced proteins (ELIP) proteins, and cell-wall modification enzymes. There is little concordance between transcript and metabolite abundance for processes such as amino acid metabolism that do not appear to contribute directly to cellular protection, but are nonetheless important for the desiccation tolerant phenotype of S. stapfianus. The transcriptomes of both dehydration and rehydration offer insight into the complexity of the regulation of

  9. Evidence for the absence of enzymatic reactions in the glassy state. A case study of xanthophyll cycle pigments in the desiccation-tolerant moss Syntrichia ruralis.

    Science.gov (United States)

    Fernández-Marín, Beatriz; Kranner, Ilse; San Sebastián, María; Artetxe, Unai; Laza, José Manuel; Vilas, José Luis; Pritchard, Hugh W; Nadajaran, Jayanthi; Míguez, Fátima; Becerril, José María; García-Plazaola, José Ignacio

    2013-07-01

    Desiccation-tolerant plants are able to withstand dehydration and resume normal metabolic functions upon rehydration. These plants can be dehydrated until their cytoplasm enters a 'glassy state' in which molecular mobility is severely reduced. In desiccation-tolerant seeds, longevity can be enhanced by drying and lowering storage temperature. In these conditions, they still deteriorate slowly, but it is not known if deteriorative processes include enzyme activity. The storage stability of photosynthetic organisms is less studied, and no reports are available on the glassy state in photosynthetic tissues. Here, the desiccation-tolerant moss Syntrichia ruralis was dehydrated at either 75% or <5% relative humidity, resulting in slow (SD) or rapid desiccation (RD), respectively, and different residual water content of the desiccated tissues. The molecular mobility within dry mosses was assessed through dynamic mechanical thermal analysis, showing that at room temperature only rapidly desiccated samples entered the glassy state, whereas slowly desiccated samples were in a 'rubbery' state. Violaxanthin cycle activity, accumulation of plastoglobules, and reorganization of thylakoids were observed upon SD, but not upon RD. Violaxanthin cycle activity critically depends on the activity of violaxanthin de-epoxidase (VDE). Hence, it is proposed that enzymatic activity occurred in the rubbery state (after SD), and that in the glassy state (after RD) no VDE activity was possible. Furthermore, evidence is provided that zeaxanthin has some role in recovery apparently independent of its role in non-photochemical quenching of chlorophyll fluorescence.

  10. Evidence for the absence of enzymatic reactions in the glassy state. A case study of xanthophyll cycle pigments in the desiccation-tolerant moss Syntrichia ruralis

    Science.gov (United States)

    Fernández-Marín, Beatriz; Kranner, Ilse; Sebastián, María San; Artetxe, Unai; Laza, José Manuel; Vilas, José Luis; Pritchard, Hugh W.; Nadajaran, Jayanthi; Míguez, Fátima; Becerril, José María; García-Plazaola, José Ignacio

    2013-01-01

    Desiccation-tolerant plants are able to withstand dehydration and resume normal metabolic functions upon rehydration. These plants can be dehydrated until their cytoplasm enters a ‘glassy state’ in which molecular mobility is severely reduced. In desiccation-tolerant seeds, longevity can be enhanced by drying and lowering storage temperature. In these conditions, they still deteriorate slowly, but it is not known if deteriorative processes include enzyme activity. The storage stability of photosynthetic organisms is less studied, and no reports are available on the glassy state in photosynthetic tissues. Here, the desiccation-tolerant moss Syntrichia ruralis was dehydrated at either 75% or <5% relative humidity, resulting in slow (SD) or rapid desiccation (RD), respectively, and different residual water content of the desiccated tissues. The molecular mobility within dry mosses was assessed through dynamic mechanical thermal analysis, showing that at room temperature only rapidly desiccated samples entered the glassy state, whereas slowly desiccated samples were in a ‘rubbery’ state. Violaxanthin cycle activity, accumulation of plastoglobules, and reorganization of thylakoids were observed upon SD, but not upon RD. Violaxanthin cycle activity critically depends on the activity of violaxanthin de-epoxidase (VDE). Hence, it is proposed that enzymatic activity occurred in the rubbery state (after SD), and that in the glassy state (after RD) no VDE activity was possible. Furthermore, evidence is provided that zeaxanthin has some role in recovery apparently independent of its role in non-photochemical quenching of chlorophyll fluorescence. PMID:23761488

  11. Deep Vadose Zone Treatability Test for the Hanford Central Plateau: Interim Post-Desiccation Monitoring Results, Fiscal Year 2014

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Strickland, Christopher E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Christian D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clayton, Ray E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chronister, Glen B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-09-01

    Over decades of operation, the U.S. Department of Energy (DOE) and its predecessors have released nearly 2 trillion L (450 billion gal.) of liquid into the vadose zone at the Hanford Site. Much of this discharge of liquid waste into the vadose zone occurred in the Central Plateau, a 200 km2 (75 mi2) area that includes approximately 800 waste sites. Some of the inorganic and radionuclide contaminants in the deep vadose zone at the Hanford Site are at depths below the limit of direct exposure pathways, but may need to be remediated to protect groundwater. The Tri-Party Agencies (DOE, U.S. Environmental Protection Agency, and Washington State Department of Ecology) established Milestone M 015 50, which directed DOE to submit a treatability test plan for remediation of technetium-99 (Tc-99) and uranium in the deep vadose zone. These contaminants are mobile in the subsurface environment and have been detected at high concentrations deep in the vadose zone, and at some locations have reached groundwater. Testing technologies for remediating Tc-99 and uranium will also provide information relevant for remediating other contaminants in the vadose zone. A field test of desiccation is being conducted as an element of the DOE test plan published in March 2008 to meet Milestone M 015 50. The active desiccation portion of the test has been completed. Monitoring data have been collected at the field test site during the post-desiccation period and are reported herein. This is an interim data summary report that includes about 3 years of post-desiccation monitoring data. The DOE field test plan proscribes a total of 5 years of post-desiccation monitoring.

  12. A New Physiological Role for the DNA Molecule as a Protector against Drying Stress in Desiccation-Tolerant Microorganisms

    Science.gov (United States)

    García-Fontana, Cristina; Narváez-Reinaldo, Juan J.; Castillo, Francisco; González-López, Jesús; Luque, Irene; Manzanera, Maximino

    2016-01-01

    The DNA molecule is associated with the role of encoding information required to produce RNA which is translated into proteins needed by the cell. This encoding involves information transmission to offspring or to other organisms by horizontal transfer. However, despite the abundance of this molecule in both the cell and the environment, its physiological role seems to be restricted mainly to that of a coding and inheritance molecule. In this paper, we report a new physiological role for the DNA molecule as involved in protection against desiccation, in addition to its well-established main information transfer and other recently reported functions such as bio-film formation in eDNA form. Desiccation-tolerant microorganisms such as Microbacterium sp. 3J1 significantly upregulate genes involved in DNA synthesis to produce DNA as part of their defensive mechanisms to protect protein structures and functions from drying according to RNA-seq analysis. We have observed the intracellular overproduction of DNA in two desiccation-tolerant microorganisms, Microbacterium sp. 3J1 and Arthrobacter siccitolerans 4J27, in response to desiccation signals. In addition, this conclusion can be made from our observations that synthetic DNA protects two proteins from drying and when part of a xeroprotectant preparation, DNA from various organisms including desiccation-sensitive species, does the same. Removal of DNA by nuclease treatment results in absence of this additive protective effect. We validated this role in biochemical and biophysical assays in proteins and occurs in trans even with short, single chains of synthetically produced DNA. PMID:28066383

  13. Great Salt Lake halophilic microorganisms as models for astrobiology: evidence for desiccation tolerance and ultraviolet irradiation resistance

    Science.gov (United States)

    Baxter, Bonnie K.; Eddington, Breanne; Riddle, Misty R.; Webster, Tabitha N.; Avery, Brian J.

    2007-09-01

    Great Salt Lake (GSL) is home to halophiles, salt-tolerant Bacteria and Archaea, which live at 2-5M NaCl. In addition to salt tolerance, GSL halophiles exhibit resistance to both ultraviolet (UV) irradiation and desiccation. First, to understand desiccation resistance, we sought to determine the diversity of GSL halophiles capable of surviving desiccation in either recently formed GSL halite crystals or GSL Artemia (brine shrimp) cysts. From these desiccated environments, surviving microorganisms were cultured and isolated, and genomic DNA was extracted from the individual species for identification by 16S rRNA gene homology. From the surface-sterilized cysts we also extracted DNA of the whole microbial population for non-cultivation techniques. We amplified the archaeal or bacterial 16S rRNA gene from all genomic DNA, cloned the cyst population amplicons, and sequenced. These sequences were compared to gene databases for determination of closest matched species. Interestingly, the isolates from the crystal dissolution are distinct from those previously isolated from GSL brine. The cyst population results reveal species not found in crystals or brine, and may indicate microorganisms that live as endosymbionts of this hypersaline arthropod. Second, we explored UV resistance in a GSL haloarchaea species, "H. salsolis." This strain resists UV irradiation an order of magnitude better than control species, all of which have intact repair systems. To test the hypothesis that halophiles have a photoprotection system, which prevents DNA damage from occurring, we designed an immunoassay to detect thymine dimers following UV irradiation. "H. salsolis" showed remarkable resistance to dimer formation. Evidence for both UV and desiccation resistance in these salt-tolerant GSL halophiles makes them well-suited as models for Astrobiological studies in pursuit of questions about life beyond earth.

  14. Global Transcriptome Analysis Reveals Acclimation-Primed Processes Involved in the Acquisition of Desiccation Tolerance in Boea hygrometrica.

    Science.gov (United States)

    Zhu, Yan; Wang, Bo; Phillips, Jonathan; Zhang, Zhen-Nan; Du, Hong; Xu, Tao; Huang, Lian-Cheng; Zhang, Xiao-Fei; Xu, Guang-Hui; Li, Wen-Long; Wang, Zhi; Wang, Ling; Liu, Yong-Xiu; Deng, Xin

    2015-07-01

    Boea hygrometrica resurrection plants require a period of acclimation by slow soil-drying in order to survive a subsequent period of rapid desiccation. The molecular basis of this observation was investigated by comparing gene expression profiles under different degrees of water deprivation. Transcripts were clustered according to the expression profiles in plants that were air-dried (rapid desiccation), soil-dried (gradual desiccation), rehydrated (acclimated) and air-dried after acclimation. Although phenotypically indistinguishable, it was shown by principal component analysis that the gene expression profiles in rehydrated, acclimated plants resemble those of desiccated plants more closely than those of hydrated acclimated plants. Enrichment analysis based on gene ontology was performed to deconvolute the processes that accompanied desiccation tolerance. Transcripts associated with autophagy and α-tocopherol accumulation were found to be activated in both air-dried, acclimated plants and soil-dried non-acclimated plants. Furthermore, transcripts associated with biosynthesis of ascorbic acid, cell wall catabolism, chaperone-assisted protein folding, respiration and macromolecule catabolism were activated and maintained during soil-drying and rehydration. Based on these findings, we hypothesize that activation of these processes leads to the establishment of an optimal physiological and cellular state that enables tolerance during rapid air-drying. Our study provides a novel insight into the transcriptional regulation of critical priming responses to enable survival following rapid dehydration in B. hygrometrica. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. Programming desiccation-tolerance: from plants to seeds to resurrection plants.

    Science.gov (United States)

    Farrant, Jill M; Moore, John P

    2011-06-01

    Desiccation-tolerance (DT) evolved as the key solution to survival on land by the early algal ancestors of terrestrial plants. This 'first' DT involved utilizing rapidly mobilisable repair mechanisms and is still found today in mosses, such as Tortula ruralis, and ferns, such as Mohria caffrorum. The first seed plants lost vegetative DT while investing their seeds with tolerance mechanisms improving their survival in unfavourable environments. The mechanisms of DT in seeds are strongly connected to their developmentally regulated maturation programs. We propose that angiosperm resurrection plants acquired tolerance by re-activating their innate DT mechanisms in their vegetative tissues. Here we review the current hypotheses regarding the genetic evidence for the evolution of DT in resurrection plants. We also present strong evidence showing the activation of seed specific genetic elements in the vegetative tissues of resurrection plants. Copyright © 2011. Published by Elsevier Ltd.

  16. Halophilic Archaea: Life with Desiccation, Radiation and Oligotrophy over Geological Times

    Directory of Open Access Journals (Sweden)

    Helga Stan-Lotter

    2015-07-01

    Full Text Available Halophilic archaebacteria (Haloarchaea can survive extreme desiccation, starvation and radiation, sometimes apparently for millions of years. Several of the strategies that are involved appear specific for Haloarchaea (for example, the formation of halomucin, survival in fluid inclusions of halite, and some are known from other prokaryotes (dwarfing of cells, reduction of ATP. Several newly-discovered haloarchaeal strategies that were inferred to possibly promote long-term survival—halomucin, polyploidy, usage of DNA as a phosphate storage polymer, production of spherical dormant stages—remain to be characterized in detail. More information on potential strategies is desirable, since evidence for the presence of halite on Mars and on several moons in the solar system increased interest in halophiles with respect to the search for extraterrestrial life. This review deals in particular with novel findings and hypotheses on haloarchaeal long-term survival.

  17. Dehydration Kinetics of Embryonic Axes from Desiccation-sensitive Seeds:An Assessment of Descriptive Models

    Institute of Scientific and Technical Information of China (English)

    Tobias M.Ntuli; Norman W.Pammenter

    2009-01-01

    The response of desiccation-sensitive plant tissues to dehydration is significantly affected by dehydration conditions,particularly the rate of drying. Consequently it is important to be able to quantify drying rate. The aim of the study was to assess two models that have been proposed to describe drying kinetics, and thus to provide a quantification of non-linear drying rates, of embryonic axes excised from recalcitrant seeds. These models are an exponential drying time course, and a modified inverse relationship, respectively. For the six species investigated here the inverse function was generally found to fit drying data better than the exponential function under both rapid and slow drying conditions,and so is recommended. The rate of drying, under the conditions used here, was determined by axis size and possibly the nature of the axis outer coverings, rather than the water activity difference between the tissue and surrounding air.

  18. Cryopreservation of Quercus suber and Quercus ilex embryonic axes: in vitro culture, desiccation and cooling factors.

    Science.gov (United States)

    Gonzalez-Benito, M Elena; Prieto, Roberto-Moreno; Herradon, Esther; Martin, Carmen

    2002-01-01

    This study examines different factors included in the cryopreservation protocols for Quercus ilex and Q. suber embryonic axes. In vitro incubation temperature played an important role in the appropriate development of Q. ilex axes, as 15 degrees C was superior to 25 degrees C. Q. suber axes proved to be more sensitive to desiccation and cooling. Poor survival (35%) was observed when axes were included into cryovials and then in liquid nitrogen, and none when immersed in sub-cooled liquid nitrogen (-210 degrees C). Q. ilex axes showed poorly organised development in vitro (c. 50% of non-cooled axes showed shoot development). However, c. 80% survival was observed after cryopreservation (either in liquid nitrogen or sub-cooled liquid nitrogen at 0.34 g water / g dry weight), of which c. 15% showed shoot development.

  19. PHYSIOLOGICAL CLASSIFICATION OF FOREST SEEDS REGARDING THE DESICCATION TOLERANCE AND STORAGE BEHAVIOUR

    Directory of Open Access Journals (Sweden)

    Rafaella Carvalho Mayrinck

    2016-03-01

    Full Text Available This work aims to classify forest seeds native to the Alto Rio Grande region regarding the desiccation tolerance and storage behaviour. Germination and water content tests were performed in seeds of different species. The tests were conducted immediately after seed processing, at 12% and 5% of water content, and at 5% after 3 months of storage in -18°C. Based on the results obtained, seeds were classified into recalcitrant, intermediate and orthodox class. Seeds of Brosimum gaudichaudii, Erythroxylum deciduum, Eugenia pleurantha, Myrcia venulosa, Nectandra megapotamica were classified as recalcitrant (22.7% of all species. Seeds of Aegiphila sellowiana, Aspidosperma parvifolium, Blepharocalyx salicifolius, Casearia lasiophylla, Cassia occidentalis, Dalbergia miscolobium, Diospyros brasiliensis, Diospyros hispida, Ilex brevicuspis, Ilex cerasifolia, Myrocarpus fastigiatus, Senna aversiflora, Senna splendida e Blepharocalyx salicifolius were classified as intermediate (59.1% of all species. Seeds of Miconia albicans, Platycyamus regnellii, Styrax camporum and Piptadenia gonoacantha were classified as orthodox (18.2% of all species.

  20. The Aggregation of Brucella abortus Occurs Under Microaerobic Conditions and Promotes Desiccation Tolerance and Biofilm Formation.

    Science.gov (United States)

    Almirón, Marta A; Roset, Mara S; Sanjuan, Norberto

    2013-01-01

    Brucella abortus causes brucellosis mainly in cattle. The infection is transmitted to humans by ingestion of animal products or direct contact with infected material. While the intracellular lifestyle of Brucella is well characterized, its extracellular survival is poorly understood. In nature, bacterial persistence is associated with biofilms, where aggregated cells are protected from adversity. The inability of Brucella abortus to aggregate under aerobiosis and that fact that the replicative niche of Brucella is characterized by microaerobic conditions prompted us to investigate the capacity of this pathogen to aggregate and grow in biofilms under microaerobiotic conditions. The results show that B. abortus aggregates and produces biofilms. The aggregates tolerate desiccation better than planktonic cells do, adhere and displace even in the absence of the lipopolysaccharide-O antigen, flagella, the transcriptional regulator VjbR, or the enzymes that synthesize, transport, and modify cyclic β (1,2) glucan.

  1. Investigation of Desiccants and CO2 Sorbents for Exploration Systems 2016-2017

    Science.gov (United States)

    Knox, James C.; Watson, David W.; Giesy, Timothy J.; Cmarik, Gregory E.; Miller, Lee A.

    2017-01-01

    NASA has embarked on the mission to enable humans to explore deep space, including the goal of sending humans to Mars. This journey will require significant developments in a wide range of technical areas as resupply and early return are not possible. Additionally, mass, power, and volume must be minimized for all phases to maximize propulsion availability. Among the critical areas identified for development are life support systems, which will require increases in reliability as well as reduce resource usage. Two primary points for reliability are the mechanical stability of sorbent pellets and recovery of CO2 sorbent productivity after off-nominal events. In this paper, we discuss the present efforts towards screening and characterizing commercially-available sorbents for extended operation in desiccant and CO2 removal beds. With minimized dusting as the primary criteria, a commercial 13X zeolite was selected and tested for performance and risk.

  2. Dehydration rate determines the degree of membrane damage and desiccation tolerance in bryophytes.

    Science.gov (United States)

    Cruz de Carvalho, Ricardo; Catalá, Myriam; Branquinho, Cristina; Marques da Silva, Jorge; Barreno, Eva

    2017-03-01

    Desiccation tolerant (DT) organisms are able to withstand an extended loss of body water and rapidly resume metabolism upon rehydration. This ability, however, is strongly dependent on a slow dehydration rate. Fast dehydration affects membrane integrity leading to intracellular solute leakage upon rehydration and thereby impairs metabolism recovery. We test the hypothesis that the increased cell membrane damage and membrane permeability observed under fast dehydration, compared with slow dehydration, is related to an increase in lipid peroxidation. Our results reject this hypothesis because following rehydration lipid peroxidation remains unaltered, a fact that could be due to the high increase of NO upon rehydration. However, in fast-dried samples we found a strong signal of red autofluorescence upon rehydration, which correlates with an increase in ROS production and with membrane leakage, particularly the case of phenolics. This could be used as a bioindicator of oxidative stress and membrane damage.

  3. High radiation and desiccation tolerance of nitrogen-fixing cultures of the cyanobacterium Anabaena sp. strain PCC 7120 emanates from genome/proteome repair capabilities.

    Science.gov (United States)

    Singh, Harinder; Anurag, Kirti; Apte, Shree Kumar

    2013-10-12

    The filamentous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120 was found to tolerate very high doses of (60)Co-gamma radiation or prolonged desiccation. Post-stress, cells remained intact and revived all the vital functions. A remarkable capacity to repair highly disintegrated genome and recycle the damaged proteome appeared to underlie such high radioresistance and desiccation tolerance. The close similarity observed between the cellular response to irradiation or desiccation stress lends strong support to the notion that tolerance to these stresses may involve similar mechanisms.

  4. Developmental changes in the germinability, desiccation tolerance, hardseededness, and longevity of individual seeds of Trifolium ambiguum

    Science.gov (United States)

    Hay, F. R.; Smith, R. D.; Ellis, R. H.; Butler, L. H.

    2010-01-01

    Background and Aims Using two parental clones of outcrossing Trifolium ambiguum as a potential model system, we examined how during seed development the maternal parent, number of seeds per pod, seed position within the pod, and pod position within the inflorescence influenced individual seed fresh weight, dry weight, water content, germinability, desiccation tolerance, hardseededness, and subsequent longevity of individual seeds. Methods Near simultaneous, manual reciprocal crosses were carried out between clonal lines for two experiments. Infructescences were harvested at intervals during seed development. Each individual seed was weighed and then used to determine dry weight or one of the physiological behaviour traits. Key Results Whilst population mass maturity was reached at 33–36 days after pollination (DAP), seed-to-seed variation in maximum seed dry weight, when it was achieved, and when maturation drying commenced, was considerable. Individual seeds acquired germinability between 14 and 44 DAP, desiccation tolerance between 30 and 40 DAP, and the capability to become hardseeded between 30 and 47 DAP. The time for viability to fall to 50 % (p50) at 60 % relative humidity and 45 °C increased between 36 and 56 DAP, when the seed coats of most individuals had become dark orange, but declined thereafter. Individual seed f. wt at harvest did not correlate with air-dry storage survival period. Analysing survival data for cohorts of seeds reduced the standard deviation of the normal distribution of seed deaths in time, but no sub-population showed complete uniformity of survival period. Conclusions Variation in individual seed behaviours within a developing population is inherent and inevitable. In this outbreeder, there is significant variation in seed longevity which appears dependent on embryo genotype with little effect of maternal genotype or architectural factors. PMID:20228084

  5. Preparation of desiccation-resistant aquatic-living Nostoc flagelliforme (Cyanophyceae) for potential ecological application.

    Science.gov (United States)

    Gao, Xiang; Yang, Yi-Wen; Cui, Li-Juan; Zhou, De-Bao; Qiu, Bao-Sheng

    2015-11-01

    Nostoc flagelliforme is a terrestrial edible cyanobacterium that grows in arid and semi-arid steppes. The continued over-exploitation in the last century has led to a sharp decline of this resource and a severe deterioration of the steppe ecology. Liquid-cultured N. flagelliforme serves as promising algal 'seeds' for resource restoration. In this study, macroscopic (or visible) aquatic-living colonies (MaACs) of N. flagelliforme were developed under weak light and high nitrogen conditions. In a 24 day shake-flask culture, MaACs were propagated by about 4.5-fold in biomass without loss of their macro-morphology; at the same time, the addition of weak UV-B treatment resulted in slightly bigger MaACs. Polyvinylpyrrolidone (PVP) k30, a water-soluble polymer, was used to generate the coating around MaACs, and after full desiccation, the coated MaACs could recover their photosynthetic physiological activity when rehydrated, with 4% PVP k30 for coating being most effective. In contrast, PVP k30-coated microscopic aquatic-living colonies of N. flagelliforme and non-coated MaACs showed no resistance to full desiccation. The macroscopic morphology or structure of MaACs should be crucial for the formation of protection by PVP k30 coating. PVP k30-coated MaACs were more approaching to actual application for resource restoration. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  6. Liposomes with diverse compositions are protected during desiccation by LEA proteins from Artemia franciscana and trehalose.

    Science.gov (United States)

    Moore, Daniel S; Hansen, Richard; Hand, Steven C

    2016-01-01

    Intracellular accumulation of Late Embryogenesis Abundant (LEA) proteins and the disaccharide trehalose is associated with cellular desiccation tolerance in a number of animal species. Two LEA proteins from anhydrobiotic embryos of the brine shrimp Artemia franciscana were tested for the ability to protect liposomes of various compositions against desiccation-induced damage in the presence and absence of trehalose. Damage was assessed by carboxyfluorescein leakage after drying and rehydration. Further, using a cytoplasmic-localized (AfrLEA2) and a mitochondrial-targeted (AfrLEA3m) LEA protein allowed us to evaluate whether each may preferentially stabilize membranes of a particular lipid composition based on the protein's subcellular location. Both LEA proteins were able to offset damage during drying of liposomes that mimicked the lipid compositions of the inner mitochondrial membrane (with cardiolipin), outer mitochondrial membrane, and the inner leaflet of the plasma membrane. Thus liposome stabilization by AfrLEA3m or AfrLEA2 was not dependent on lipid composition, provided physiological amounts of bilayer and non-bilayer-forming lipids were present (liposomes with a non-biological composition of 100% phosphatidylcholine were not protected by either protein). Additive protection by LEA proteins plus trehalose was dependent on the lipid composition of the target membrane. Minimal additional damage occurred to liposomes stored at room temperature in the dried state for one week compared to liposomes rehydrated after 24h. Consistent with the ability to stabilize lipid bilayers, molecular modeling of the secondary structures for AfrLEA2 and AfrLEA3m revealed bands of charged amino acids similar to other amphipathic proteins that interact directly with membranes.

  7. Transition from natively unfolded to folded state induced by desiccation in an anhydrobiotic nematode protein.

    Science.gov (United States)

    Goyal, Kshamata; Tisi, Laurence; Basran, Amrik; Browne, John; Burnell, Ann; Zurdo, Jesus; Tunnacliffe, Alan

    2003-04-11

    Late embryogenesis abundant (LEA) proteins are associated with desiccation tolerance in resurrection plants and in plant seeds, and the recent discovery of a dehydration-induced Group 3 LEA-like gene in the nematode Aphelenchus avenae suggests a similar association in anhydrobiotic animals. Despite their importance, little is known about the structure of Group 3 LEA proteins, although computer modeling and secondary structure algorithms predict a largely alpha-helical monomer that forms coiled coil oligomers. We have therefore investigated the structure of the nematode protein, AavLEA1, in the first such analysis of a well characterized Group 3 LEA-like protein. Immunoblotting and subunit cross-linking experiments demonstrate limited oligomerization of AavLEA1, but analytical ultracentrifugation and gel filtration show that the vast majority of the protein is monomeric. Moreover, CD, fluorescence emission, and Fourier transform-infrared spectroscopy indicate an unstructured conformation for the nematode protein. Therefore, in solution, no evidence was found to support structure predictions; instead, AavLEA1 seems to be natively unfolded with a high degree of hydration and low compactness. Such proteins can, however, be induced to fold into more rigid structures by partner molecules or by altered physiological conditions. Because AavLEA1 is associated with desiccation stress, its Fourier transform-infrared spectrum in the dehydrated state was examined. A dramatic but reversible increase in alpha-helix and, possibly, coiled coil formation was observed on drying, indicating that computer predictions of secondary structure may be correct for the solid state. This unusual finding offers the possibility that structural shifts in Group 3 LEA proteins occur on dehydration, perhaps consistent with their role in anhydrobiosis.

  8. Impact of protective agents and drying methods on desiccation tolerance of Salix nigra L. seeds.

    Science.gov (United States)

    Santagapita, Patricio R; Ott Schneider, Helena; Agudelo-Laverde, Lina M; Buera, M Pilar

    2014-09-01

    Willow seeds are classified as orthodox, but they show some recalcitrant characteristics, as they lose viability in a few weeks at room temperature. The aim of this work was to improve the desiccation tolerance of willow seeds (Salix nigra L.), as a model of sensitive materials to dehydration, through imbibition in solutions and later vacuum (VD) or freeze-drying (FD). Imbibition was conducted with 45% w/v trehalose or polyethylene glycol 400 -PEG- or water prior to dehydration treatments. Water- and especially trehalose-imbibed seeds subjected to VD showed better germination capability with respect to the freeze-dried ones. Water crystallization was mainly responsible for the great loss of capability germination observed in water- or trehalose-imbibed seeds subjected to FD. PEG behavior was better when seeds were FD instead of VD. DSC thermograms of seeds allowed to identify two thermal transitions corresponding to lipids melting and to proteins denaturation. This last transition reveals information about proteins state/functionality. Dehydration of control and PEG- or water-imbibed seeds affected proteins functionality leading to lower germinability. In the case of trehalose-imbibed seeds subjected to VD, proteins maintained their native state along dehydration, and the seeds showed a great germination capacity for all the water content range. Germinated seeds showed higher luminosity (L*), greenness (a*) and yellowness (b*) values than not-germinated seeds independently of the employed agent. Present work reveals that the presence of adequate protective agents as well the dehydration method were the main critical factors involved in willow seed desiccation tolerance. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  9. Developmental changes in the germinability, desiccation tolerance, hardseededness, and longevity of individual seeds of Trifolium ambiguum.

    Science.gov (United States)

    Hay, F R; Smith, R D; Ellis, R H; Butler, L H

    2010-06-01

    Using two parental clones of outcrossing Trifolium ambiguum as a potential model system, we examined how during seed development the maternal parent, number of seeds per pod, seed position within the pod, and pod position within the inflorescence influenced individual seed fresh weight, dry weight, water content, germinability, desiccation tolerance, hardseededness, and subsequent longevity of individual seeds. Near simultaneous, manual reciprocal crosses were carried out between clonal lines for two experiments. Infructescences were harvested at intervals during seed development. Each individual seed was weighed and then used to determine dry weight or one of the physiological behaviour traits. Whilst population mass maturity was reached at 33-36 days after pollination (DAP), seed-to-seed variation in maximum seed dry weight, when it was achieved, and when maturation drying commenced, was considerable. Individual seeds acquired germinability between 14 and 44 DAP, desiccation tolerance between 30 and 40 DAP, and the capability to become hardseeded between 30 and 47 DAP. The time for viability to fall to 50 % (p(50)) at 60 % relative humidity and 45 degrees C increased between 36 and 56 DAP, when the seed coats of most individuals had become dark orange, but declined thereafter. Individual seed f. wt at harvest did not correlate with air-dry storage survival period. Analysing survival data for cohorts of seeds reduced the standard deviation of the normal distribution of seed deaths in time, but no sub-population showed complete uniformity of survival period. Variation in individual seed behaviours within a developing population is inherent and inevitable. In this outbreeder, there is significant variation in seed longevity which appears dependent on embryo genotype with little effect of maternal genotype or architectural factors.

  10. The C. elegans dauer larva as a paradigm to study metabolic suppression and desiccation tolerance.

    Science.gov (United States)

    Erkut, Cihan; Kurzchalia, Teymuras V

    2015-08-01

    The hypometabolic, stress-resistant dauer larva of Caenorhabditis elegans serves as an excellent model to study the molecular mechanisms of desiccation tolerance, such as maintenance of membrane organization, protein folding, xenobiotic and ROS detoxification in the dry state. Many organisms from diverse taxa of life have the remarkable ability to survive extreme desiccation in the nature by entering an ametabolic state known as anhydrobiosis (life without water). The hallmark of the anhydrobiotic state is the achievement and maintenance of an exceedingly low metabolic rate, as well as preservation of the structural integrity of the cell. Although described more than three centuries ago, the biochemical and biophysical mechanisms underlying this phenomenon are still not fully comprehended. This is mainly due to the fact that anhydrobiosis in animals was studied using non-model organisms, which are very difficult, if not impossible, to manipulate at the molecular level. Recently, we introduced the roundworm (nematode) Caenorhabditis elegans as a model for anhydrobiosis. Taking advantage of powerful genetic, biochemical and biophysical tools, we investigated several aspects of anhydrobiosis in a particular developmental stage (the dauer larva) of this organism. First, our studies allowed confirming the previously suggested role of the disaccharide trehalose in the preservation of lipid membranes. Moreover, in addition to known pathways such as reactive oxygen species defense, heat-shock and intrinsically disordered protein expression, evidence for some novel strategies of anhydrobiosis has been obtained. These are increased glyoxalase activity, polyamine and polyunsaturated fatty acid biosynthesis. All these pathways may constitute a generic toolbox of anhydrobiosis, which is possibly conserved between animals and plants.

  11. Expression profiling and cross-species RNA interference (RNAi) of desiccation-induced transcripts in the anhydrobiotic nematode Aphelenchus avenae

    Science.gov (United States)

    2010-01-01

    Background Some organisms can survive extreme desiccation by entering a state of suspended animation known as anhydrobiosis. The free-living mycophagous nematode Aphelenchus avenae can be induced to enter anhydrobiosis by pre-exposure to moderate reductions in relative humidity (RH) prior to extreme desiccation. This preconditioning phase is thought to allow modification of the transcriptome by activation of genes required for desiccation tolerance. Results To identify such genes, a panel of expressed sequence tags (ESTs) enriched for sequences upregulated in A. avenae during preconditioning was created. A subset of 30 genes with significant matches in databases, together with a number of apparently novel sequences, were chosen for further study. Several of the recognisable genes are associated with water stress, encoding, for example, two new hydrophilic proteins related to the late embryogenesis abundant (LEA) protein family. Expression studies confirmed EST panel members to be upregulated by evaporative water loss, and the majority of genes was also induced by osmotic stress and cold, but rather fewer by heat. We attempted to use RNA interference (RNAi) to demonstrate the importance of this gene set for anhydrobiosis, but found A. avenae to be recalcitrant with the techniques used. Instead, therefore, we developed a cross-species RNAi procedure using A. avenae sequences in another anhydrobiotic nematode, Panagrolaimus superbus, which is amenable to gene silencing. Of 20 A. avenae ESTs screened, a significant reduction in survival of desiccation in treated P. superbus populations was observed with two sequences, one of which was novel, while the other encoded a glutathione peroxidase. To confirm a role for glutathione peroxidases in anhydrobiosis, RNAi with cognate sequences from P. superbus was performed and was also shown to reduce desiccation tolerance in this species. Conclusions This study has identified and characterised the expression profiles of members

  12. Expression profiling and cross-species RNA interference (RNAi of desiccation-induced transcripts in the anhydrobiotic nematode Aphelenchus avenae

    Directory of Open Access Journals (Sweden)

    Culleton Bridget A

    2010-01-01

    Full Text Available Abstract Background Some organisms can survive extreme desiccation by entering a state of suspended animation known as anhydrobiosis. The free-living mycophagous nematode Aphelenchus avenae can be induced to enter anhydrobiosis by pre-exposure to moderate reductions in relative humidity (RH prior to extreme desiccation. This preconditioning phase is thought to allow modification of the transcriptome by activation of genes required for desiccation tolerance. Results To identify such genes, a panel of expressed sequence tags (ESTs enriched for sequences upregulated in A. avenae during preconditioning was created. A subset of 30 genes with significant matches in databases, together with a number of apparently novel sequences, were chosen for further study. Several of the recognisable genes are associated with water stress, encoding, for example, two new hydrophilic proteins related to the late embryogenesis abundant (LEA protein family. Expression studies confirmed EST panel members to be upregulated by evaporative water loss, and the majority of genes was also induced by osmotic stress and cold, but rather fewer by heat. We attempted to use RNA interference (RNAi to demonstrate the importance of this gene set for anhydrobiosis, but found A. avenae to be recalcitrant with the techniques used. Instead, therefore, we developed a cross-species RNAi procedure using A. avenae sequences in another anhydrobiotic nematode, Panagrolaimus superbus, which is amenable to gene silencing. Of 20 A. avenae ESTs screened, a significant reduction in survival of desiccation in treated P. superbus populations was observed with two sequences, one of which was novel, while the other encoded a glutathione peroxidase. To confirm a role for glutathione peroxidases in anhydrobiosis, RNAi with cognate sequences from P. superbus was performed and was also shown to reduce desiccation tolerance in this species. Conclusions This study has identified and characterised the

  13. Composite desiccant material "CaCl2/Vermiculite/Saw wood": a new material for fresh water production from atmospheric air

    Science.gov (United States)

    Kumar, Manoj; Yadav, Avadhesh

    2016-04-01

    In this study a novel composite desiccant material "CaCl2/Vermiculite/Saw wood" have been synthesized and tested for the water generation from atmospheric air. The vermiculite- saw wood used as a host matrix and CaCl2 as a hygroscopic salt. A solar glass desiccant box type system with a collector area of 0.36 m2 has been used. Design parameters for water generation are height of glass from the desiccant material bed as 0.22 m, inclination in angle as 30º, the effective thickness of glass as 3 mm and number of glazing as single. It has been found that the concentration of calcium chloride is the most influencing factor for fresh water generation from atmospheric air. The maximum amount of water produced by using novel composite desiccant material is 195 ml/kg/day.

  14. The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans

    OpenAIRE

    Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

    2016-01-01

    Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreove...

  15. Change in desiccation tolerance of maize embryos during development and germination at different water potential PEG-6000 in relation to oxidative process.

    Science.gov (United States)

    Huang, Hui; Song, Songquan

    2013-07-01

    Desiccation tolerance is one of the most important traits determining seed survival during storage and under stress conditions. However, the mechanism of seed desiccation tolerance is still unclear in detail. In the present study, we used a combined model system, desiccation-tolerant and -sensitive maize embryos with identical genetic background, to investigate the changes in desiccation tolerance, malonyldialdehyde (MDA) level, hydrogen peroxide (H₂O₂) content and antioxidant enzyme activity during seed development and germination in 0, -0.6 and -1.2 MPa polyethylene glycol (PEG)-6000 solutions. Our results indicated that maize embryos gradually acquired and lost desiccation tolerance during development and germination, respectively. The acquirement and loss of desiccation tolerance of embryos during development and germination were related to the ability of antioxidant enzymes including superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6), glutathione reductase (GR, EC 1.6.4.2) and dehydroascorbate reductase (DHAR, EC 1.8.5.1) to scavenge reactive oxygen species (ROS) and to control MDA content. Compared with treatment in water, PEG-6000 treatment could markedly delay the loss of desiccation tolerance of germinating embryos by delaying water uptake and time course of germination, increasing GR activity and decreasing MDA content. Our data showed the combination of antioxidant enzyme activity and MDA content is a good parameter for assessing the desiccation tolerance of maize embryos. In addition, H₂O₂ accumulated in mature embryos and PEG-treated embryos after drying, which was at least partially related to a longer embryo/seedling length in rehydration and the physiological mechanisms of priming. Copyright © 2013. Published by Elsevier Masson SAS.

  16. Relative importance of seed drying rate, desiccation tolerance, and cryotolerance for the conservation of Ardisia elliptica, A. brunnescens and A. virens.

    Science.gov (United States)

    Yao, X; Goodale, U M; Li, Z L; Huang, Y; Wang, X F; Cheng, F Y; Tan, Y H; Xiao, C F; Lan, Q Y

    2014-01-01

    The pan-tropical genus Ardisia has more than 400 species and is of high horticultural and medicinal value. Due to overexploitation it is important to conserve the germplasm of this genus. To investigate the feasibility and methods of cryopreservation for long-term seed storage of three Ardisia species: A. elliptica Thunb., A. brunnescens Walker, and A. virens Kurz. We tested whether rapid desiccation can increase desiccation tolerance and cryotolerance, and whether the thawing rate can affect cryopreservation success. Seeds were subjected to three desiccation treatments: 1) activated silica gel at 25 +/- 2 degree C, and 4% relative humidity (RH); 2) saturated NaCl solution in closed jars in 25 +/- 2 degree C and 75% RH; and 3) air-drying at room conditions at 27 +/- 2 degree C and RH 60% for different desiccation durations (12h, 24h, 48h, 96h, and 196h). Seeds were then assessed for desiccation tolerance and cryotolerance after rapid thawing (direct immersion in 36 degree C water bath for 2 min) or slow thawing (at 27°C for 1 h). For all three species, desiccation method and duration significantly affected cryotolerance (P seeds (P seed did not survive cryopreservation. Cryopreservation protocols of Ardisia species may be species-specific and should be established for each species in the genus so that cryopreservation can be used as a successful conservation strategy.

  17. Trade-off of energy metabolites as well as body color phenotypes for starvation and desiccation resistance in montane populations of Drosophila melanogaster.

    Science.gov (United States)

    Parkash, Ravi; Aggarwal, Dau Dayal

    2012-02-01

    Storage of energy metabolites has been investigated in different sets of laboratory selected desiccation or starvation resistant lines but few studies have examined such changes in wild-caught populations of Drosophila melanogaster. In contrast to parallel selection of desiccation and starvation tolerance under laboratory selection experiments, opposite clines were observed in wild populations of D. melanogaster. If resistance to desiccation and starvation occurs in opposite directions under field conditions, we may expect a trade-off for energy metabolites but such correlated changes are largely unknown. We tested whether there is a trade-off for storage as well as actual utilization of carbohydrates (trehalose and glycogen), lipids and proteins in D. melanogaster populations collected from different altitudes (512-2500 m). For desiccation resistance, darker flies (>50% body melanization) store more body water content and endure greater loss of water (higher dehydration tolerance) as compared to lighter flies (energy metabolites may contribute to greater stress resistance. Further, for increased desiccation resistance of darker flies, about two-third of total energy budget is provided by carbohydrates. By contrast, lighter flies derive about 66% of total energy content from lipids which sustain higher starvation tolerance. Our results support evolutionary trade-off for storage as well as utilization of energy metabolites for desiccation versus starvation resistance in D. melanogaster.

  18. Contrasting strategies used by lichen microalgae to cope with desiccation-rehydration stress revealed by metabolite profiling and cell wall analysis.

    Science.gov (United States)

    Centeno, Danilo C; Hell, Aline F; Braga, Marcia R; Del Campo, Eva M; Casano, Leonardo M

    2016-05-01

    Most lichens in general, and their phycobionts in particular, are desiccation tolerant, but their mechanisms of desiccation tolerance (DT) remain obscure. The physiological responses and cell wall features of two putatively contrasting lichen-forming microalgae, Trebouxia sp. TR9 (TR9), isolated from Ramalina farinacea (adapted to frequent desiccation-rehydration cycles), and Coccomyxa solorina-saccatae (Csol), obtained from Solorina saccata (growing in usually humid limestone crevices, subjected to seasonal dry periods) was characterized. Microalgal cultures were desiccated under 25%-30% RH and then rehydrated. Under these conditions, RWC and ψw decreased faster and simultaneously during dehydration in Csol, whereas TR9 maintained its ψw until 70% RWC. The metabolic profile indicated that polyols played a key role in DT of both microalgae. However, TR9 constitutively accumulated higher amounts of polyols, whereas Csol induced the polyol synthesis under desiccation-rehydration. Csol also accumulated ascorbic acid, while TR9 synthesized protective raffinose-family oligosaccharides (RFOs) and increased its content of phenolics. Additionally, TR9 exhibited thicker and qualitatively different cell wall and extracellular polymeric layer compared with Csol, indicating higher water retention capability. The findings were consistent with the notion that lichen microalgae would have evolved distinct strategies to cope with desiccation-rehydration stress in correspondence with the water regime of their respective habitats. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Repellent activity of desiccant dusts and conidia of the entomopathogenic fungus Beauveria bassiana when tested against poultry red mites (Dermanyssus gallinae) in laboratory experiments.

    Science.gov (United States)

    Kilpinen, Ole; Steenberg, Tove

    2016-11-01

    Desiccant dusts and entomopathogenic fungi have previously been found to hold potential against the poultry red mite, which is an important pest in egg production and notoriously difficult to control. Both control agents may cause repellence in other arthropods and potentially also influence control levels adversely when used against the poultry red mite. Five desiccant dust products with good efficacy against the poultry red mite Dermanyssus gallinae caused avoidance behavior in mites when tested in bioassays. The repellent activity was correlated with efficacy, which was found to depend on both dose and relative humidity (RH). However, one desiccant dust was significantly less repellent compared to other dusts with similar levels of efficacy. Further, dry conidia of the fungus Beauveria bassiana were also shown to be repellent to poultry red mites, both when applied on its own and when admixed with a low dose of the desiccant dust Diamol. The pick-up of desiccant dust particles and fungus conidia from treated surfaces by mites did not differ depending on RH, whereas the overall efficacy of the two control agents were significantly higher at 75 than at 85 % RH. In addition, the combined effect of the two substances was synergistic when tested in a bioassay where mites could choose whether to cross a treated surface. This is the first time a member of Acari has been shown to be repelled by desiccant dusts and by conidia of an entomopathogenic fungus.

  20. Dentin sensitivity, odontoblasts and nerves under desiccated or infected experimental cavities. A clinical, light microscopic and ultrastructural investigation.

    Science.gov (United States)

    Lilja, J; Nordenvall, K J; Bränström, M

    1982-01-01

    Cavities were prepared in 35 pairs of young human premolars. One tooth in each pair served as a control. In one Series the test cavity was desiccated with compressed air for one minute. LM and TEM examination of the dentin and the adjacent pulp revealed an extensive aspiration of odontoblasts. Nerve fibers had moved 0.1 to 0.2 mm outward in the tubules. It is suggested that a streching or disruption of the nerve had occurred during desiccation. In a second Series, the test cavity was infected for 1 to 2 weeks. No nerve fibers were seen in the dentinal tubules under the cavities, only cellular remnants and some microorganisms. Despite the absence of nerves the dentin in the bottom of the infected cavities was highly sensitive to stimulation. It was concluded that the nociceptive nerves present in the adjacent inflamed pulp may be terminals, mechanosensitive in nature and that they activated by rapid outward movements of the tubules fluid.

  1. Methods Reduce Cost, Enhance Quality of Nanotubes

    Science.gov (United States)

    2009-01-01

    For all the challenges posed by the microgravity conditions of space, weight is actually one of the more significant problems NASA faces in the development of the next generation of U.S. space vehicles. For the Agency s Constellation Program, engineers at NASA centers are designing and testing new vessels as safe, practical, and cost-effective means of space travel following the eventual retirement of the space shuttle. Program components like the Orion Crew Exploration Vehicle, intended to carry astronauts to the International Space Station and the Moon, must be designed to specific weight requirements to manage fuel consumption and match launch rocket capabilities; Orion s gross liftoff weight target is about 63,789 pounds. Future space vehicles will require even greater attention to lightweight construction to help conserve fuel for long-range missions to Mars and beyond. In order to reduce spacecraft weight without sacrificing structural integrity, NASA is pursuing the development of materials that promise to revolutionize not only spacecraft construction, but also a host of potential applications on Earth. Single-walled carbon nanotubes are one material of particular interest. These tubular, single-layer carbon molecules - 100,000 of them braided together would be no thicker than a human hair - display a range of remarkable characteristics. Possessing greater tensile strength than steel at a fraction of the weight, the nanotubes are efficient heat conductors with metallic or semiconductor electrical properties depending on their diameter and chirality (the pattern of each nanotube s hexagonal lattice structure). All of these properties make the nanotubes an appealing material for spacecraft construction, with the potential for nanotube composites to reduce spacecraft weight by 50 percent or more. The nanotubes may also feature in a number of other space exploration applications, including life support, energy storage, and sensor technologies. NASA s various efforts with carbon nanotubes have made it a global leader in this field. Among the many examples are Johnson Space Center s Carbon Nanotube Project, which focuses on bulk nanotube production, purification, and application, and Goddard Space Flight Center s improved arc discharge method of nanotube production, developed under the direction of Jeannette Benavides (featured in Spinoff 2007 and 2008). While the Agency continues its own research, it partners with private companies to advance this unique technology for use on Earth as well as among the stars.

  2. New pharmaceuticals reduce cost of illness.

    Science.gov (United States)

    Hansen, R W

    1986-06-01

    The cost of illness includes not only the funds required to treat illness, but also the effect on the patient's quality of life. Recent concern about rising health costs have focused on the direct expenditures without noting that the cost of illness in terms of mortality and morbidity has declined significantly. Pharmaceuticals have played a major role in reducing the total cost of illness. Several studies of the cost-effectiveness of past introductions of vaccines and pharmaceuticals reveal large cost savings. Although the focus of most studies has been on major advances, the continuing process of less dramatic therapeutic improvements has significantly trimmed the cost of illness. Cost-benefit studies of new drugs or changes in drug use, while more difficult to perform, make it possible to influence the selection of therapy. Since pharmaceuticals represent less than 10% of total treatment costs, reduction in the cost of pharmaceutical products can only have a minor impact on the total cost of illness. Pharmaceuticals can reduce the cost of illness by providing alternative therapies that reduce direct treatment cost or improve the public health.

  3. ProP is required for the survival of desiccated Salmonella enterica serovar typhimurium cells on a stainless steel surface.

    Science.gov (United States)

    Finn, Sarah; Händler, Kristian; Condell, Orla; Colgan, Aoife; Cooney, Shane; McClure, Peter; Amézquita, Aléjandro; Hinton, Jay C D; Fanning, Séamus

    2013-07-01

    Consumers trust commercial food production to be safe, and it is important to strive to improve food safety at every level. Several outbreaks of food-borne disease have been caused by Salmonella strains associated with dried food. Currently we do not know the mechanisms used by Salmonella enterica serovar Typhimurium to survive in desiccated environments. The aim of this study was to discover the responses of S. Typhimurium ST4/74 at the transcriptional level to desiccation on a stainless steel surface and to subsequent rehydration. Bacterial cells were dried onto the same steel surfaces used during the production of dry foods, and RNA was recovered for transcriptomic analysis. Subsequently, dried cells were rehydrated and were again used for transcriptomic analysis. A total of 266 genes were differentially expressed under desiccation stress compared with a static broth culture. The osmoprotectant transporters proP, proU, and osmU (STM1491 to STM1494) were highly upregulated by drying. Deletion of any one of these transport systems resulted in a reduction in the long-term viability of S. Typhimurium on a stainless steel food contact surface. The proP gene was critical for survival; proP deletion mutants could not survive desiccation for long periods and were undetectable after 4 weeks. Following rehydration, 138 genes were differentially expressed, with upregulation observed for genes such as proP, proU, and the phosphate transport genes (pstACS). In time, this knowledge should prove valuable for understanding the underlying mechanisms involved in pathogen survival and should lead to improved methods for control to ensure the safety of intermediate- and low-moisture foods.

  4. Identification and characterization of a NaCl-responsive genetic locus involved in survival during desiccation in Sinorhizobium meliloti.

    Science.gov (United States)

    Vriezen, Jan A C; de Bruijn, Frans J; Nüsslein, Klaus

    2013-09-01

    The Rhizobiaceae are a bacterial family of enormous agricultural importance due to the ability of its members to fix atmospheric nitrogen in an intimate relationship with plants. Their survival as naturally occurring soil bacteria in agricultural soils as well as popular seed inocula is affected directly by drought and salinity. Survival after desiccation in the presence of NaCl is enabled by underlying genetic mechanisms in the model organism Sinorhizobium meliloti 1021. Since salt stress parallels a loss in water activity, the identification of NaCl-responsive loci may identify loci involved in survival during desiccation. This approach enabled identification of the loci asnO and ngg by their reduced ability to grow on increased NaCl concentrations, likely due to their inability to produce the osmoprotectant N-acetylglutaminylglutamine (NAGGN). In addition, the mutant harboring ngg::Tn5luxAB was affected in its ability to survive desiccation and responded to osmotic stress. The desiccation sensitivity may have been due to secondary functions of Ngg (N-acetylglutaminylglutamine synthetase)-like cell wall metabolism as suggested by the presence of a d-alanine-d-alanine ligase (dAla-dAla) domain and by sensitivity of the mutant to β-lactam antibiotics. asnO::Tn5luxAB is expressed during the stationary phase under normal growth conditions. Amino acid sequence similarity to enzymes producing β-lactam inhibitors and increased resistance to β-lactam antibiotics may indicate that asnO is involved in the production of a β-lactam inhibitor.

  5. Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades.

    Directory of Open Access Journals (Sweden)

    Veronika Ostermaier

    Full Text Available Historic samples of phytoplankton can provide information on the abundance of the toxigenic genotypes of cyanobacteria in dependence on increased or decreased eutrophication. The analysis of a time-series from preserved phytoplankton samples by quantitative PCR (qPCR extends observation periods considerably. The analysis of DNA from heat-desiccated samples by qPCR can be aggravated by point substitutions or the fragmentation of DNA introduced by the high temperature. In this study, we analyzed whether the heat desiccation of the cellular material of the cyanobacterium Planktothrix sp. introduced potential errors to the template DNA that is used for qPCR within (i 16S rDNA and phycocyanin genes and (ii the mcyA gene indicative of the incorporation of either dehydrobutyrine (Dhb or N-methyl-dehydroalanine (Mdha in position 7, and (ii the mcyB gene, which is indicative of homotyrosine (Hty in position 2 of the microcystin (MC molecule. Due to high temperature desiccation, the deterioration of the DNA template quality was rather due to fragmentation than due to nucleotide substitutions. By using the heat-desiccated samples of Lake Zürich, Switzerland the abundance of the Dhb, Mdha and Hty genotypes was determined during three decades (1977-2008. Despite major changes in the trophic state of the lake resulting in a major increase of the total Planktothrix population density, the proportion of these genotypes encoding the synthesis of different MC congeners showed high stability. Nevertheless, a decline of the most abundant mcyA genotype indicative of the synthesis of Dhb in position 7 of the MC molecule was observed. This decline could be related to the gradual incline in the proportion of a mutant genotype carrying a 1.8kbp deletion of this gene region. The increase of this mcyA (Dhb gene deletion mutant has been minor so far, however, and likely did not affect the overall toxicity of the population.

  6. Complete inactivation of photosynthetic activity during desiccation and rapid recovery by rehydration in the aerial microalga Trentepohlia jolithus.

    Science.gov (United States)

    Zhang, L; Li, Y; Liu, J

    2016-11-01

    Aerial microalgae are more exposed to harsh and rapidly changing environmental conditions, including desiccation and radiation. Under high light, aerial algae in the desiccated state would be highly subject to photodamage. Therefore, aerial algae need effective protective mechanisms to dissipate excess excitation energy. In this study, the changes in photosynthetic behaviors during desiccation and after rehydration in Trentepohlia jolithus were confirmed using chlorophyll a fluorescence (OJIP) transient, allowing determination of the photoprotection mechanisms of this aerial alga. The filaments of T. jolithus cells at 25% relative air humidity (RH) are significantly shrunken compared with those at 100% and 87% RH, decreasing the surface area for light absorption. At 25% RH, the shape and intensity of the OJIP transient disappeared, but recovered rapidly to the level at 100% RH after 5 s of rehydration. Compared with 100% RH, the maximum quantum yield of PSII (φPo ), phenomenological energy fluxes for absorption (ABS/CSm) and active PSII reaction centers (RCs) at 25% RH decreased significantly, the specific energy fluxes for absorption (ABS/RC) increased significantly, but the specific energy fluxes for trapping (TRo/RC) at 25% RH did not change. These parameters at 25% RH recovered rapidly to the level at 100% RH after 5 s of rehydration. These results suggest that the efficiency of PSII light absorption and activities of PSII RCs were reversibly down-regulated in desiccated T. jolithus, which may be a special adaptive mechanism for the survivability of aerial microalgae in habitats with rapidly changing water availability.

  7. Temporal separation between CO2 assimilation and growth? Experimental and theoretical evidence from the desiccation-tolerant moss Syntrichia ruralis.

    Science.gov (United States)

    Royles, Jessica; Ogée, Jérôme; Wingate, Lisa; Hodgson, Dominic A; Convey, Peter; Griffiths, Howard

    2013-03-01

    The extent of an external water layer around moss tissue influences CO(2) assimilation. Experiments on the desiccation-tolerant moss Syntrichia ruralis assessed the real-time dependence of the carbon and oxygen isotopic compositions of CO(2) and H(2)O in terms of moss water status and integrated isotope signals in cellulose. As external (capillary) water, and then mesophyll water, evaporated from moss tissue, assimilation rate, relative water content and the stable isotope composition of tissue water (δ(18)O(TW)), and the CO(2) and H(2)O fluxes, were analysed. After drying, carbon (δ(13)C(C)) and oxygen (δ(18)O(C)) cellulose compositions were determined. During desiccation, assimilation and (13)CO(2) discrimination increased to a maximum and then declined; δ(18)O(TW) increased progressively by 8‰, indicative of evaporative isotopic enrichment. Experimental and meteorological data were combined to predict tissue hydration dynamics over one growing season. Nonsteady-state model predictions of δ(18)O(TW) were consistent with instantaneous measurements. δ(13)C(C) values suggest that net assimilation occurs at 25% of maximum relative water content, while δ(18)O(C) data suggests that cellulose is synthesized during much higher relative water content conditions. This implies that carbon assimilation and cellulose synthesis (growth) may be temporally separated, with carbon reserves possibly contributing to desiccation tolerance and resumption of metabolism upon rehydration.

  8. Trehalose-Based Eye Drops Preserve Viability and Functionality of Cultured Human Corneal Epithelial Cells during Desiccation

    Directory of Open Access Journals (Sweden)

    Aneta Hill-Bator

    2014-01-01

    Full Text Available This paper presents the evaluation of cytoprotective ability of trehalose-based eye drops in comparison with commercially available preparations during the experimental desiccation of cultured human corneal epithelial cells. Cultured human corneal epithelial cells (hCEC underwent incubation with 7 different, commercially available medicaments used commonly in dry eye syndrome treatment, followed by desiccation trial performed on air under the flow hood for 5, 15, 30, and 45 minutes. Cell viability was quantified by live/dead fluorescent assay, while the presence of apoptotic cells was estimated by immunofluorescent staining for active caspase 3 protein. The preservation of membrane functions was evaluated using neutral red staining, while the preservation of proper morphology and phenotype was determined by fluorescent staining for actin filaments, nuclei, and p63 protein. The trehalose-based eye drops showed the highest efficiency in prevention of cell death from desiccation; moreover, this preparation preserved the normal cellular morphology, functions of cell membrane, and proliferative activity more effectively than other tested medicaments.

  9. PERFORMANCE OF A SOLID DESICCANT BASED EVAPORATIVE COOLING SYSTEM IN WARM AND HUMID CLIMATIC ZONE OF INDIA

    Directory of Open Access Journals (Sweden)

    HEMANT PARMAR

    2010-10-01

    Full Text Available Vapour compression based air conditioners are being used for comfort cooling in residences, offices and commercial buildings in many countries throughout the world. Several issues arise seriously challenge the conventional technology which include harmful impact of CFCs and HCFCs on environment, energy and cost problems etc. However use of low energy and eco friendly techniques may be helpful to overcome these problems up to some extent. The evaporative cooling may be considered as one of such eco friendly methods of achieving comfortable conditions in buildings during summer. These systems have great potential to provide thermal comfort in places where ambient air humidity is low. Such systems alone are not efficient for humidclimatic conditions. However such systems can be used if combined with desiccant based dehumidifier. India with its widely different climates has been divided into six climatic zones viz. Hot and Dry, Moderate, Warm and Humid, Composite, Cold and Cloudy and Cold and Sunny. This paper examines the potential of a simple desiccant evaporative cooling cycle in five selected cities in Warm and Humid climatic zone of India. The coefficient of performance (COP has been computed for each location and compared. It has been found that COP for different cities varies in the range of 0.14 to 0.21. Mumbai (coastal city has been identified as the city where desiccant evaporative cooling system can be operated with higher COP compared to that of other cities in the same climatic zone.

  10. Experimental Validation of the Simulation Model of a DOAS Equipped with a Desiccant Wheel and a Vapor Compression Refrigeration System

    Directory of Open Access Journals (Sweden)

    Pedro J. Martínez

    2017-09-01

    Full Text Available A dedicated outdoor air system (DOAS can be designed to supply 100% of the outside air and meet the latent load of the room with dry air. The objectives of this study were to develop a model of a DOAS equipped with a desiccant wheel and a vapor-compression refrigeration system, build a prototype, validate the model with experimental data, and gain knowledge about the system operation. The test facility was designed with the desiccant wheel downstream of the cooling coil to take advantage of the operating principles of cooling coils and desiccants. A model of the DOAS was developed in the TRNSYS environment. The root mean standard error (RMSE was used for model validation by comparing the measured air and refrigerant properties with the corresponding calculated values. The results obtained with the developed model showed that the DOAS was able to maintain an indoor humidity ratio depending on outdoor conditions. Laboratory tests were also used to investigate the effect of changes in the regeneration air temperature and the process airflow rate on the process air humidity ratio at the outlet of the wheel. The results are consistent with the technical literature.

  11. Evaluation of formaldehyde emission from particleboard using the large chamber and desiccator method at various loading ratios

    Institute of Scientific and Technical Information of China (English)

    QUE Ze-li; WANG Fei-bin; MA Ling-fei; Furuno Takeshi

    2013-01-01

    We studied formaldehyde emission from uncoated particleboard with 16-mm thickness using the large chamber and the desiccator method.A chamber of 28.4 m3 was installed to simulate a mobile home.The formaldehyde off-gassing properties of particleboard were evaluated using the chamber.The relationship between the concentration obtained by the chamber and the values by the desiccator test was discussed in this study under different conditions of conditioning day,air exchange,and loading ratio.These two methods were compared and discussed regarding the formaldehyde emission level.Three loading ratios,0.429 m2/m3,0.264 m2/m3,and 0.132 m2/m3,were chosen to represent different applications of particleboard products.There was strong correlation between emissions and air exchange rates at equal product-loading ratios in the large chamber,the related coefficient R2 exceeded 0.90.There was also an indication of a generic correlation between the large chamber and the two-hour desiccator test with a single product designated loading ratio,air exchange rate,and climatic conditions.

  12. Evidence of Tolerance to Silica-Based Desiccant Dusts in a Pyrethroid-Resistant Strain of Cimex lectularius (Hemiptera: Cimicidae).

    Science.gov (United States)

    Lilly, David G; Webb, Cameron E; Doggett, Stephen L

    2016-12-09

    Insecticide resistance in bed bugs (Cimex lectularius and Cimex hemipterus) has become widespread, which has necessitated the development of new IPM (Integrated Pest Management) strategies and products for the eradication of infestations. Two promising options are the diatomaceous earth and silica gel-based desiccant dusts, both of which induce dehydration and eventual death upon bed bugs exposed to these products. However, the impact of underlying mechanisms that confer resistance to insecticides, such as cuticle thickening, on the performance of these dusts has yet to be determined. In the present study, two desiccant dusts, CimeXa Insecticide Dust (silica gel) and Bed Bug Killer Powder (diatomaceous earth) were evaluated against two strains of C. lectularius; one highly pyrethroid-resistant and one insecticide-susceptible. Label-rate doses of both products produced 100% mortality in both strains, albeit over dissimilar time-frames (3-4 days with CimeXa vs. 14 days with Bed Bug Killer). Sub-label rate exposure to CimeXa indicated that the pyrethroid-resistant strain possessed a degree of tolerance to this product, surviving 50% longer than the susceptible strain. This is the first study to suggest that mechanisms conferring resistance to pyrethroids, such as cuticular thickening, may have potential secondary impacts on non-synthetic insecticides, including desiccant dusts, which target the bed bug's cuticle.

  13. Evidence of Tolerance to Silica-Based Desiccant Dusts in a Pyrethroid-Resistant Strain of Cimex lectularius (Hemiptera: Cimicidae

    Directory of Open Access Journals (Sweden)

    David G. Lilly

    2016-12-01

    Full Text Available Insecticide resistance in bed bugs (Cimex lectularius and Cimex hemipterus has become widespread, which has necessitated the development of new IPM (Integrated Pest Management strategies and products for the eradication of infestations. Two promising options are the diatomaceous earth and silica gel-based desiccant dusts, both of which induce dehydration and eventual death upon bed bugs exposed to these products. However, the impact of underlying mechanisms that confer resistance to insecticides, such as cuticle thickening, on the performance of these dusts has yet to be determined. In the present study, two desiccant dusts, CimeXa Insecticide Dust (silica gel and Bed Bug Killer Powder (diatomaceous earth were evaluated against two strains of C. lectularius; one highly pyrethroid-resistant and one insecticide-susceptible. Label-rate doses of both products produced 100% mortality in both strains, albeit over dissimilar time-frames (3–4 days with CimeXa vs. 14 days with Bed Bug Killer. Sub-label rate exposure to CimeXa indicated that the pyrethroid-resistant strain possessed a degree of tolerance to this product, surviving 50% longer than the susceptible strain. This is the first study to suggest that mechanisms conferring resistance to pyrethroids, such as cuticular thickening, may have potential secondary impacts on non-synthetic insecticides, including desiccant dusts, which target the bed bug’s cuticle.

  14. Desiccation as a mitigation tool to manage biofouling risks: trials on temperate taxa to elucidate factors influencing mortality rates.

    Science.gov (United States)

    Hopkins, Grant A; Prince, Madeleine; Cahill, Patrick L; Fletcher, Lauren M; Atalah, Javier

    2016-01-01

    The desiccation tolerance of biofouling taxa (adults and early life-stages) was determined under both controlled and 'realistic' field conditions. Adults of the ascidian Ciona spp. died within 24 h. Mortality in the adult blue mussel Mytilus galloprovincialis occurred within 11 d under controlled conditions, compared with 7 d when held outside. The Pacific oyster Crassostrea gigas was the most desiccation-tolerant taxon tested (up to 34 d under controlled conditions). Biofouling orientated to direct sunlight showed faster mortality rates for all the taxa tested. Mortality in Mytilus juveniles took up to 24 h, compared with 8 h for Ciona, with greater survival at the higher temperature (18.5°C) and humidity (~95% RH) treatment combination. This study demonstrated that desiccation can be an effective mitigation method for a broad range of fouling taxa, especially their early life-stages. Further work is necessary to assess risks from other high-risk species such as algae and cyst forming species.

  15. Group 1 LEA proteins contribute to the desiccation and freeze tolerance of Artemia franciscana embryos during diapause.

    Science.gov (United States)

    Toxopeus, Jantina; Warner, Alden H; MacRae, Thomas H

    2014-11-01

    Water loss either by desiccation or freezing causes multiple forms of cellular damage. The encysted embryos (cysts) of the crustacean Artemia franciscana have several molecular mechanisms to enable anhydrobiosis-life without water-during diapause. To better understand how cysts survive reduced hydration, group 1 late embryogenesis abundant (LEA) proteins, hydrophilic unstructured proteins that accumulate in the stress-tolerant cysts of A. franciscana, were knocked down using RNA interference (RNAi). Embryos lacking group 1 LEA proteins showed significantly lower survival than control embryos after desiccation and freezing, or freezing alone, demonstrating a role for group 1 LEA proteins in A. franciscana tolerance of low water conditions. In contrast, regardless of group 1 LEA protein presence, cysts responded similarly to hydrogen peroxide (H2O2) exposure, indicating little to no function for these proteins in diapause termination. This is the first in vivo study of group 1 LEA proteins in an animal and it contributes to the fundamental understanding of these proteins. Knowing how LEA proteins protect A. franciscana cysts from desiccation and freezing may have applied significance in aquaculture, where Artemia is an important feed source, and in the cryopreservation of cells for therapeutic applications.

  16. Abscisic acid-induced rearrangement of intracellular structures associated with freezing and desiccation stress tolerance in the liverwort Marchantia polymorpha.

    Science.gov (United States)

    Akter, Khaleda; Kato, Masahiro; Sato, Yuki; Kaneko, Yasuko; Takezawa, Daisuke

    2014-09-15

    The plant growth regulator abscisic acid (ABA) is known to be involved in triggering responses to various environmental stresses such as freezing and desiccation in angiosperms, but little is known about its role in basal land plants, especially in liverworts, representing the earliest land plant lineage. We show here that survival rate after freezing and desiccation of Marchantia polymorpha gemmalings was increased by pretreatment with ABA in the presence of increasing concentrations of sucrose. ABA treatment increased accumulation of soluble sugars in gemmalings, and sugar accumulation was further increased by addition of sucrose to the culture medium. ABA treatment of gemmalings also induced accumulation of transcripts for proteins with similarity to late embryogenesis abundant (LEA) proteins, which accumulate in association with acquisition of desiccation tolerance in maturing seeds. Observation by light and electron microscopy indicated that the ABA treatment caused fragmentation of vacuoles with increased cytosolic volume, which was more prominent in the presence of a high concentration of external sucrose. ABA treatment also increased the density of chloroplast distribution and remarkably enlarged their volume. These results demonstrate that ABA induces drastic physiological changes in liverwort cells for stress tolerance, accompanied by accumulation of protectants against dehydration and rearrangement and morphological alterations of cellular organelles. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Selective breeding for desiccation tolerance in liquid culture provides genetically stable inbred lines of the entomopathogenic nematode Heterorhabditis bacteriophora.

    Science.gov (United States)

    Anbesse, Samuel; Sumaya, Nanette Hope; Dörfler, Anna Verena; Strauch, Olaf; Ehlers, Ralf-Udo

    2013-01-01

    The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora is used in biological plant protection to control pest insects. In the past, several attempts targeted at an enhancement of the desiccation tolerance of EPN by genetic selection in order to improve their storage stability. The subsequent loss of improved beneficial traits after release of selection pressure has often been reported. In order to stabilize progress of selective breeding, selection during liquid culturing was tested against propagation in host insects. After release of the selection pressure, the tolerance was monitored over additional reproductive cycles in vivo and in vitro to compare the stability of the trait. Furthermore, it was tested whether the virulence of the selected strains would be impaired. Exposure to desiccation stress prior to propagation, in vivo or in vitro, both resulted in increasing desiccation tolerance. When selection pressure was released, the gained tolerance was lost again during in vivo production, whereas the tolerance was maintained at a high level when EPNs were cultured in liquid culture. In Heterorhabditis sp., liquid culture conditions produce highly homozygous, genetically stable inbred lines. The investigation provides easily applicable methods to improve and stabilize beneficial traits of heterorhabditid EPNs through selective breeding in liquid culture. Compared to nematodes from in vivo propagation, production in liquid media yielded EPN of higher virulence.

  18. Cross-tolerance and cross-talk in the cold: relating low temperatures to desiccation and immune stress in insects.

    Science.gov (United States)

    Sinclair, Brent J; Ferguson, Laura V; Salehipour-shirazi, Golnaz; MacMillan, Heath A

    2013-10-01

    Multiple stressors, both abiotic and biotic, often are experienced simultaneously by organisms in nature. Responses to these stressors may share signaling pathways ("cross-talk") or protective mechanisms ("cross-tolerance"). Temperate and polar insects that must survive the winter experience low temperatures accompanied by additional abiotic stressors, such as low availability of water. Cold and desiccation have many similar effects at a cellular level, and we present evidence that the cellular mechanisms that protect against cold stress also protect against desiccation, and that the responses to cold and dehydration likely evolved as cross-tolerance. By contrast, there are several lines of evidence suggesting that low temperature stress elicits an upregulation of immune responses in insects (and vice versa). Because there is little mechanistic overlap between cold stress and immune stress at the cellular level, we suggest that this is cross-talk. Both cross-talk and cross-tolerance may be adaptive and likely evolved in response to synchronous stressors; however, we suggest that cross-talk and cross-tolerance may lead to different responses to changes in the timing and severity of multiple stress interactions in a changing world. We present a framework describing the potentially different responses of cross-tolerance and cross-talk to a changing environment and describe the nature of these impacts using interaction of cold-desiccation and cold-immunity in overwintering insects as an example.

  19. Improved somatic embryogenesis in wheat by partial simulation of the in-ovulo oxygen, growth-regulator and desiccation environments.

    Science.gov (United States)

    Carman, J G

    1988-09-01

    The effects of O2, growth-regulators and desiccation on callus growth and somatic embryo (embryoid) development were investigated in cultures of immature embryos of two lines of Triticum aestivum L. Callus and embryoid formation were induced on media that contained N(6)-furfurylamin-opurine (kinetin) and either 2,4-dichlorophenoxyacetic acid or 3,6-dichloro-o-anisic acid, either with or without abscisic acid (ABA). Cultures containing differentiated embryoids were then exposed to high concentrations of both ABA and indole-3-acetic acid, after which samples were desiccated to approx. 10% tissue moisture. Incubating cultures in 3.2 mmol·l(-1) O2 (approx. 9%, low-O2) increased embryoid formation sixfold in one wheat line and nearly threefold in another. In the former line low-O2 caused the formation of mostly embryogenic callus. Low-O2 also decreased precocious germination of immature embryos, decreased callus growth, and improved development and viability of the resultant embryoids. Including 1.9 μmol·l(-1) ABA in the callus-induction medium reduced germination of immature embryos and reduced the incidence of embryoids with visible abnormalities. Despite the improved morphology, significantly fewer of the embryoids produced on ABA-containing medium germinated. Desiccation significantly enhanced germination of these embryoids as well as those produced on ABA-free medium.

  20. Silica desiccant packets for storage and transport of Streptococcus pneumoniae and other clinically relevant species.

    Directory of Open Access Journals (Sweden)

    Casey L Pell

    Full Text Available Bacterial isolates are often transported between laboratories for research and diagnostic purposes. Silica desiccant packets (SDPs, which are inexpensive and do not require freezing, were evaluated for storage and recovery of bacterial isolates. Conditions such as inoculum size, swab type and temperature of storage were investigated using ten Streptococcus pneumoniae isolates. The optimized protocol was then tested using 49 additional S. pneumoniae isolates representing 40 serogroups. Overall, S. pneumoniae growth was considered satisfactory (>100 colony forming units for 98/109 (89.9% and 20/20 (100% swabs after 14 days at room temperature or 28 days at 4° C, respectively. Storage in SDPs did not impact on the ability of S. pneumoniae isolates to be subsequently serotyped. When the survival of nine other clinically relevant bacterial species was tested, seven were viable after 28 days at room temperature, the exceptions being Neisseria gonorrhoeae and Haemophilus influenzae. SDPs are suitable for transport and short-term storage of bacterial species including S. pneumoniae.

  1. Pigment composition and location in honey locust (Gleditsia triacanthos) seeds before and after desiccation.

    Science.gov (United States)

    Schoefs, Benoit

    2002-03-01

    Gleditsia triacanthos L. pods were harvested at San Lorenzo del Escorial, Madrid, Spain, before and after seed desiccation. Maturing green pods, harvested from trees, contained soft light-green seeds, whereas fully mature brown pods, collected on the ground, contained hard dark-green seeds. Based on visual inspection of seeds, it was determined that the green color is located in the cotyledons and embryo of soft seeds but mainly in the seed coat of hard seeds. High performance liquid chromatographic analysis indicated that both hard and soft seeds contained the same set of photosynthetic pigments as fully developed leaves, but in different proportions. The hard and soft seeds mainly differed in their chlorophyll a to chlorophyll b ratio and in the composition of the xanthophyll cycle pool of pigments. Fluorescence at -196 degrees C revealed that the molecular organization of the pigment molecules in the seed coat of hard seeds differed from that in intact cotyledons of soft seeds and intact green leaves. The -196 degrees C fluorescence spectra also revealed the presence of a small heterogenous pool of non-photoactive protochlorophyll(ide)s, similar to those found in dark-grown tissues of gymnosperms and angiosperms.

  2. Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara

    Science.gov (United States)

    Eggermont, Hilde; Verschuren, Dirk; Fagot, Maureen; Rumes, Bob; Van Bocxlaer, Bert; Kröpelin, Stefan

    2008-12-01

    The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid production peaked during the fresh-to-saline transition period, then stabilized at about half that of the earlier freshwater ecosystem. Quantitative salinity inferences based on fossil chironomid assemblages indicate that the fresh-to-saline transition occurred fairly abruptly between ˜4100 and 3400 cal yr BP, but that the ecosystem was buffered against shorter-term climate fluctuations due to continuous inflow of fossil groundwater. The mixture of tropical-African and southern Palaearctic chironomid faunas in the Lake Yoa fossil record required us to address several methodological issues concerning chironomid-based salinity reconstruction, and the applicability of a calibration dataset based on tropical East and West African lakes to this Sahara desert locality. The most coherent reconstruction was obtained with an inference model that applies a weighted best-modern-analogue (WMAT) transfer function to the African calibration dataset expanded with six Sahara lakes.

  3. Liquid desiccant dehumidification and regeneration process to meet cooling and freshwater needs of desert greenhouses

    KAUST Repository

    Lefers, Ryan

    2016-04-19

    Agriculture accounts for ~70% of freshwater usage worldwide. Seawater desalination alone cannot meet the growing needs for irrigation and food production, particularly in hot, desert environments. Greenhouse cultivation of high-value crops uses just a fraction of freshwater per unit of food produced when compared with open field cultivation. However, desert greenhouse producers face three main challenges: freshwater supply, plant nutrient supply, and cooling of the greenhouse. The common practice of evaporative cooling for greenhouses consumes large amounts of fresh water. In Saudi Arabia, the most common greenhouse cooling schemes are fresh water-based evaporative cooling, often using fossil groundwater or energy-intensive desalinated water, and traditional refrigeration-based direct expansion cooling, largely powered by the burning of fossil fuels. The coastal deserts have ambient conditions that are seasonally too humid to support adequate evaporative cooling, necessitating additional energy consumption in the dehumidification process of refrigeration-based cooling. This project evaluates the use of a combined-system liquid desiccant dehumidifier and membrane distillation unit that can meet the dual needs of cooling and freshwater supply for a greenhouse in a hot and humid environment. © 2016 Balaban Desalination Publications. All rights reserved.

  4. Desiccation of sediments affects assimilate transport within aquatic plants and carbon transfer to microorganisms.

    Science.gov (United States)

    von Rein, I; Kayler, Z E; Premke, K; Gessler, A

    2016-11-01

    With the projected increase in drought duration and intensity in future, small water bodies, and especially the terrestrial-aquatic interfaces, will be subjected to longer dry periods with desiccation of the sediment. Drought effects on the plant-sediment microorganism carbon continuum may disrupt the tight linkage between plants and microbes which governs sediment carbon and nutrient cycling, thus having a potential negative impact on carbon sequestration of small freshwater ecosystems. However, research on drought effects on the plant-sediment carbon transfer in aquatic ecosystems is scarce. We therefore exposed two emergent aquatic macrophytes, Phragmites australis and Typha latifolia, to a month-long summer drought in a mesocosm experiment. We followed the fate of carbon from leaves to sediment microbial communities with (13) CO2 pulse labelling and microbial phospholipid-derived fatty acid (PLFA) analysis. We found that drought reduced the total amount of carbon allocated to stem tissues but did not delay the transport. We also observed an increase in accumulation of (13) C-labelled sugars in roots and found a reduced incorporation of (13) C into the PLFAs of sediment microorganisms. Drought induced a switch in plant carbon allocation priorities, where stems received less new assimilates leading to reduced starch reserves whilst roots were prioritised with new assimilates, suggesting their use for osmoregulation. There were indications that the reduced carbon transfer from roots to microorganisms was due to the reduction of microbial activity via direct drought effects rather than to a decrease in root exudation or exudate availability.

  5. High energy efficiency desiccant assisted automobile air-conditioner and its temperature and humidity control system

    Energy Technology Data Exchange (ETDEWEB)

    Nagaya, K. [Department of Mechanical Engineering, Gunma University Kiryu, Gunma 376-8515 (Japan)]. E-mail: nagaya@me.gunma-u.ac.jp; Senbongi, T. [Department of Mechanical Engineering, Gunma University Kiryu, Gunma 376-8515 (Japan); Li, Y. [Department of Mechanical Engineering, Gunma University Kiryu, Gunma 376-8515 (Japan); Zheng, J. [Department of Mechanical Engineering, Gunma University Kiryu, Gunma 376-8515 (Japan); Murakami, I. [Department of Mechanical Engineering, Gunma University Kiryu, Gunma 376-8515 (Japan)

    2006-10-15

    The energy efficiency is of importance in air conditioning systems for automobiles. The present article provides a new type air conditioning system for automobiles in which energy loss is small in comparison with the previous system. In the system, a desiccant is installed in the air conditioning system for controlling both temperature and humidity. The control is performed by an electromagnetic control valve, which controls an inclination of the rotating plate of a compressor. It is difficult to control both temperature and humidity precisely, because there are some delays in the control due to the time of heat exchange and that of coolant flow from the actuator (electromagnetic valve) to the evaporator. In order to have precise control, this article also presents a method of control with consideration of control delays. The energy of our system is compared with that in the previous conventional system in the same condition. It is shown that our controlled results and energy efficiency are better than those in the previous system.

  6. A new photobioreactor concept enabling the production of desiccation induced biotechnological products using terrestrial cyanobacteria.

    Science.gov (United States)

    Kuhne, S; Strieth, D; Lakatos, M; Muffler, K; Ulber, R

    2014-12-20

    Cyanobacteria offer great potential for the production of biotechnological products for pharmaceutical applications. However, these organisms can only be cultivated efficiently using photobioreactors (PBR). Under submerged conditions though, terrestrial cyanobacteria mostly grow in a suboptimal way, which makes this cultivation-technique uneconomic and thus terrestrial cyanobacteria unattractive. Therefore, a novel emersed photobioreactor (ePBR) has been developed, which can provide the natural conditions for these organisms. Proof of concept as well as first efficiency tests are conducted using the terrestrial cyanobacteria Trichocoleus sociatus as a model organism. The initial maximum growth rate of T. sociatus (0.014±0.001h(-1)) in submerged systems could be increased by 35%. Furthermore, it is now possible to control desiccation-correlated product formation and related metabolic processes. This is shown for the production of extracellular polymeric substances (EPS). In this case the yield of 0.068±0.006g of EPS/g DW could be increased by more than seven times.

  7. Differential proteomics of dehydration and rehydration in bryophytes: evidence towards a common desiccation tolerance mechanism.

    Science.gov (United States)

    Cruz DE Carvalho, Ricardo; Bernardes DA Silva, Anabela; Soares, Renata; Almeida, André M; Coelho, Ana Varela; Marques DA Silva, Jorge; Branquinho, Cristina

    2014-07-01

    All bryophytes evolved desiccation tolerance (DT) mechanisms during the invasion of terrestrial habitats by early land plants. Are these DT mechanisms still present in bryophytes that colonize aquatic habitats? The aquatic bryophyte Fontinalis antipyretica Hedw. was subjected to two drying regimes and alterations in protein profiles and sucrose accumulation during dehydration and rehydration were investigated. Results show that during fast dehydration, there is very little variation in protein profiles, and upon rehydration proteins are leaked. On the other hand, slow dehydration induces changes in both dehydration and rehydration protein profiles, being similar to the protein profiles displayed by the terrestrial bryophytes Physcomitrella patens (Hedw.) Bruch and Schimp. and, to what is comparable with Syntrichia ruralis (Hedw.) F. Weber and D. Mohr. During dehydration there was a reduction in proteins associated with photosynthesis and the cytoskeleton, and an associated accumulation of proteins involved in sugar metabolism and plant defence mechanisms. Upon rehydration, protein accumulation patterns return to control values for both photosynthesis and cytoskeleton whereas proteins associated with sugar metabolism and defence proteins remain high. The current results suggest that bryophytes from different ecological adaptations may share common DT mechanisms.

  8. Identification of desiccation tolerance transcripts potentially involved in rape (Brassica napus L.) seeds development and germination.

    Science.gov (United States)

    Lang, Sirui; Liu, Xiaoxia; Ma, Gang; Lan, QinYing; Wang, Xiaofeng

    2014-10-01

    To investigate regulatory processes and protective mechanisms leading to desiccation tolerance (DT) in seeds, cDNA amplified fragment length polymorphism (cDNA-AFLP) in conjunction with 128 primer combinations was used to detect differential gene expression in rape seeds in response to DT during seed development and germination. We obtained approximately 8000 transcript-derived fragments (TDFs), of which 394 TDFs with differential expression patterns ("sustained expression", "up-regulated", "couple with seed DT", and "down-regulated") were excised from gels and re-amplified by polymerase chain reaction (PCR). After sequencing and comparison with the National Center for Biotechnology Information database, 176 TDFs presented significant similarity with known genes that could be classified into the following categories: metabolism and energy, stress resistance and defense, storage, signal transduction, and other functional categories. Using semiquantitative reverse-transcription PCR and real-time PCR approaches, the significance of the differences was further confirmed in fresh seeds and dehydrated seeds. The genes that encode superoxide dismutase, peroxiredoxin, caleosin, oleosin S3, steroleosin, late embryogenesis abundant protein, glutathione reductase, β-glucosidase, S23 transcriptional repressor, and some heat-shock proteins could be associated with DT. The results of this study will aid in the identification of candidate genes for future experiments that seek to understand seed DT.

  9. A study of the effect of sorbitol on osmotic tolerance during partial desiccation of bovine sperm.

    Science.gov (United States)

    Sitaula, Ranjan; Fowler, Alex; Toner, Mehmet; Bhowmick, Sankha

    2010-06-01

    The goal of the study was to improve the partial desiccation survival of bovine sperm by decreasing the dehydration induced osmotic injury. The protective role of sorbitol, a polyol, was investigated by (i) studying the osmotic behavior of sperm in hypertonic Tyrode's buffer in the presence of sorbitol and trehalose, (ii) studying the effect of sorbitol and trehalose on sperm motility following partial dehydration. The osmotic behavior studies included the assessment of motility and volumetric responses in the presence of the additives. For the drying experiments, motility was assayed after drying the samples to different end water content followed by immediate rehydration. Compared to the effect of "intracellular+extracellular" trehalose alone, results showed a much improved motility in the presence of sorbitol and trehalose. While the drying results suggest an enhanced osmotolerance in the presence of sorbitol, the study of motility under hypertonic conditions combined with the sperm volume excursion experiments suggest that sorbitol imparts the enhancement by permeating into the cell cytoplasm. Copyright 2010 Elsevier Inc. All rights reserved.

  10. Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium Chroococcidiopsis

    Science.gov (United States)

    Billi, D.; Friedmann, E. I.; Hofer, K. G.; Caiola, M. G.; Ocampo-Friedmann, R.

    2000-01-01

    The effect of X-ray irradiation on cell survival, induction, and repair of DNA damage was studied by using 10 Chroococcidiopsis strains isolated from desert and hypersaline environments. After exposure to 2.5 kGy, the percentages of survival for the strains ranged from 80 to 35%. In the four most resistant strains, the levels of survival were reduced by 1 or 2 orders of magnitude after irradiation with 5 kGy; viable cells were recovered after exposure to 15 kGy but not after exposure to 20 kGy. The severe DNA damage evident after exposure to 2.5 kGy was repaired within 3 h, and the severe DNA damage evident after exposure to 5 kGy was repaired within 24 h. The increase in trichloroacetic acid-precipitable radioactivity in the culture supernatant after irradiation with 2.5 kGy might have been due to cell lysis and/or an excision process involved in DNA repair. The radiation resistance of Chroococcidiopsis strains may reflect the ability of these cyanobacteria to survive prolonged desiccation through efficient repair of the DNA damage that accumulates during dehydration.

  11. Detection of Toxoplasma gondii DNA by polymerase chain reaction in experimentally desiccated tissues

    Directory of Open Access Journals (Sweden)

    Márcia Andreia Barge Loução Terra

    2004-03-01

    Full Text Available Despite toxoplasmosis being a common infection among human and other warm-blooded animals worldwide, there are no findings about Toxoplasma gondii evolutionary forms in ancient populations. The molecular techniques used for amplification of genetic material have allowed recovery of ancient DNA (aDNA from parasites contained in mummified tissues. The application of polymerase chain r