Oxidative Damage in Pea Plants Exposed to Water Deficit or Paraquat1

The application of a moderate water deficit (water potential of −1.3 MPa) to pea (Pisum sativum L. cv Lincoln) leaves led to a 75% inhibition of photosynthesis and to increases in zeaxanthin, malondialdehyde, oxidized proteins, and mitochondrial, cytosolic, and chloroplastic superoxide dismutase activities. Severe water deficit (−1.9 MPa) almost completely inhibited photosynthesis, decreased chlorophylls, β-carotene, neoxanthin, and lutein, and caused further conversion of violaxanthin to zeaxanthin, suggesting damage to the photosynthetic apparatus. There were consistent decreases in antioxidants and pyridine nucleotides, and accumulation of catalytic Fe, malondialdehyde, and oxidized proteins. Paraquat (PQ) treatment led to similar major decreases in photosynthesis, water content, proteins, and most antioxidants, and induced the accumulation of zeaxanthin and damaged proteins. PQ decreased markedly ascorbate, NADPH, ascorbate peroxidase, and chloroplastic Fe-superoxide dismutase activity, and caused major increases in oxidized glutathione, NAD+, NADH, and catalytic Fe. It is concluded that, in cv Lincoln, the increase in catalytic Fe and the lowering of antioxidant protection may be involved in the oxidative damage caused by severe water deficit and PQ, but not necessarily in the incipient stress induced by moderate water deficit. Results also indicate that the tolerance to water deficit in terms of oxidative damage largely depends on the legume cultivar.

Absence of opioid stress-induced analgesia in mice lacking beta-endorphin by site-directed mutagenesis.

A physiological role for beta-endorphin in endogenous pain inhibition was investigated by targeted mutagenesis of the proopiomelanocortin gene in mouse embryonic stem cells. The tyrosine codon at position 179 of the proopiomelanocortin gene was converted to a premature translational stop codon. The resulting transgenic mice display no overt developmental or behavioral alterations and have a normally functioning hypothalamic-pituitary-adrenal axis. Homozygous transgenic mice with a selective deficiency of beta-endorphin exhibit normal analgesia in response to morphine, indicating the presence of functional mu-opiate receptors. However, these mice lack the opioid (naloxone reversible) analgesia induced by mild swim stress. Mutant mice also display significantly greater nonopioid analgesia in response to cold water swim stress compared with controls and display paradoxical naloxone-induced analgesia. These changes may reflect compensatory upregulation of alternative pain inhibitory mechanisms.

Surface wind-stress threshold for glacial Atlantic overturning

Using a coupled model of intermediate complexity the sensitivity of the last glacial maximum (LGM) Atlantic meridional overturning circulation (AMOC) to the strength of surface wind-stress is investigated. A threshold is found below which North Atlantic deep water formation (DWF) takes place south of Greenland and the AMOC is relatively weak. Above this threshold, DWF occurs north of the Greenland-Scotland ridge, leading to a vigorous AMOC. This nonlinear behavior is explained through enhanced salt transport by the wind-driven gyre circulation and the overturning itself. Both pattern and magnitude of the Nordic Sea's temperature difference between strong and weak AMOC states are consistent with those reconstructed for abrupt climate changes of the last glacial period. Our results thus point to a potentially relevant role of surface winds in these phenomena.

Trees as Tools in Environmental Improvement; An Analysis of the Contribution of Vegetation to Energy and Water Conservation in the Front Range of Colorado

The Denver metropolitan area is facing rapid population growth that increases the stress on already limited resources. Research and advanced computer modeling show that trees, especially those in urban areas, have significant environmental benefits. These benefits include air quality improvements, energy savings, greenhouse gas reduction, and possible water conservation. This Capstone Project applies statistical methods to analyze a small data set of residential homes and their energy and water consumption, as a function of their individual landscape. Results indicate that tree shade can influence water conservation, and that irrigation methods can be an influential factor as well. The Capstone is a preliminary analysis for future study to be performed by the Institute for Environmental Solutions in 2007.

Fuzzy control of a water pump for an agricultural plant growth system

At the present time there is a high pressure toward the improvement of all the production processes. Those improvements can be sensed in several directions in particular those that involve energy efficiency. The definition of tight energy efficiency improvement policies is transversal to several operational areas ranging from industry to public services. As can be expected, agricultural processes are not immune to this tendency. This statement takes more severe contours when dealing with indoor productions where it is required to artificially control the climate inside the building or a partial growing zone. Regarding the latter, this paper presents an innovative system that improves energy efficiency of a trees growing platform. This new system requires the control of both a water pump and a gas heating system based on information provided by an array of sensors. In order to do this, a multi-input, multi-output regulator was implemented by means of a Fuzzy logic control strategy. Presented results show that it is possible to simultaneously keep track of the desired growing temperature set-point while maintaining actuators stress within an acceptable range.

Assessment of Socio-Economic and Climate Change Effects on Water Resources and Agriculture in Southern and Eastern Mediterranean countries. MEDPRO Technical Paper No. 28/March 2013

This study aims at assessing the socio-economic and environmental effects of different societal and human development scenarios and climate change in the water-scarce southern and eastern Mediterranean. The study develops a two-stage modelling methodology that includes an econometric analysis for the southern and eastern Mediterranean region as a whole and a detailed, integrated socioecological assessment focusing on Jordan, Syria and Morocco. The results show that water resources will be under increasing stress in future years. In spite of country differences, a future path of sustainable development is possible in the region. Water withdrawals could decrease, preserving renewable water resources and reversing the negative effects on agricultural production and rural society. This, however, requires a combination across the region of technical, managerial, economic, social and institutional changes that together foster a substantive structural change. A balanced implementation of water supply-enhancing and demand-management measures along with improved governance are key to attaining a cost-effective sustainable future in which economic growth, a population increase and trade expansion are compatible with the conservation of water resources.

Masking odour when regrouping rabbit does: Effect on aggression, stress and lesions.

Regrouping female rabbits (Oryctolagus cuniculus) in group housing systems is a common management practice in Swiss rabbit breeding which may, however, induce agonistic interactions resulting in social stress and severe lesions. On farms using artificial insemination, does are usually kept singly for 12 days after parturition to avoid pseudopregnancy and fighting for nests. The integration of new group members usually occurs after this isolation phase. This study was conducted with 128 gravid does of the Hycole hybrid, housed in pens covering a floor area of 5.7 m2 that was bedded with straw and furnished with elevated areas, hiding places and eight compartments with nest boxes. In the experiment, the fur of 16 groups of 8 does each was sprayed with either alcohol or vinegar to mask the pre-existing group odours, or with water (control groups) shortly before regrouping. Lesion scores, stress parameters (body temperature and blood glucose level) and behaviour were assessed before and after the isolation phase. Effects of treatment and time on all collected parameters were analysed using mixed models. On the second day after regrouping 43% of the does showed new lesions. In the first five days after regrouping, new lesions occurred in 60% of the does; 32% had severe lesions. After regrouping, more agonistic interactions were observed and body temperature and blood glucose levels were higher than before regrouping (P<0.001 each). Body temperature increased less in groups treated with vinegar compared to the other two treatments on the first day after regrouping (P=0.017). In all other parameters no influence of the treatment with alcohol or vinegar was found. These findings suggest that masking the group odours with alcohol or vinegar had little effect on lesions, stress and agonistic interactions. Therefore, alternative management procedures need to be developed to reduce lesions and stress caused by aggressive behaviour.

Coral communities exposed to differential large amplitude internal waves cooling and a severe heat stress in 2010 in the Andaman Sea

Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SST) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proven a good predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale, which are only poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. In spite of a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large amplitude internal waves (LAIW) alleviated heating and mitigated coral bleaching and mortality in shallow LAIW-exposed waters. In LAIW-sheltered waters, by contrast, bleaching susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW, which are ubiquitous in tropical stratified waters, benefit coral reefs during thermal stress and provide local refugia for bleaching susceptible corals. The swash zones of LAIW may thus be important, so far overlooked, conservation areas for the maintainance of coral diversity in a warming climate. The consideration of LAIW can significantly improve coral bleaching predictions and can provide a valuable tool for coral reef conservation and management.

The effects of Produced Formation Water (PFW) on coral and isolated symbiotic dinoflagellates of coral

There is concern of the effects of Produced Formation Water (PFW, an effluent of the offshore oil and gas industry) on temperate/tropical marine organisms of the North West Shelf (NWS) of Australia. Little is known of the effects of PFW on tropical marine organisms, especially keystone species. Exposing the coral Plesiastrea versipora to a range (3-50% v/v) of PFW from Harriet A oil platform resulted in a reduction in photochemical efficiency of the symbiotic dinoflagellate algae in hospite ( in the coral tissues), assessed as a decrease in the ratio of variable fluorescence (F-v) to maximal fluorescence (F-m) measured using chlorophyll fluorescence techniques. Significant differences were noted at PFW concentrations >12.5% ( v/v). In corals where F-v/F-m was significantly lowered by PFW exposure, significant discolouration of the tissues occurred in a subsequent 4-day observation period. The discolouration ( coral bleaching) was caused by a loss of the symbiotic dinoflagellates from the tissues, a known sublethal stress response of corals. PFW caused a significant decrease in F-v/F-m in symbiotic dinoflagellates freshly isolated from the coral Heliofungia actiniformis at 6.25% PFW, slightly lower than the studies in hospite. Corals exposed to lower PFW concentrations (range 0.1%-10% PFW v/v) for longer periods (8 days) showed no decrease in F-v/F-m, discolouration, loss of symbiotic dinoflagellates or changes in gross photosynthesis or respiration ( measured using O-2 exchange techniques). The study demonstrates minor toxicity of PFW from Harriet A oil platform to corals and their symbiotic algae.

Cot-nursing using a heated, water-filled mattress and incubator care: a randomized clinical trial

Aims: To evaluate the thermal responses and weight gain in preterm infants nursed in a cot on a heated, water-filled mattress (HWM) compared with infants receiving care in an air-heated incubator and to compare mothers' stress, anxiety levels and perceptions of their infants in the two groups. Methods: Stable preterm infants weighing 1300 to 1500 g were enrolled, being randomly allocated to either the study group (n = 41) receiving care in a cot on an HWM, or the control group ( n = 33) receiving incubator care. The mean daily body temperature and episodes of cold stress and hyperthermia were recorded. Weight gain (g kg(-1) body weight d(-1)) was also calculated. The mothers completed questionnaires on their perceptions of their infants, and their anxiety and stress levels before randomization, and 2 - 3 wk later during the trial. Results: The mean body temperature was similar for the first week of the trial ( study group 36.9degreesC vs controls 36.9degreesC). There were no significant differences in the incidence of cold stress, while more hyperthermic episodes were seen in the study group ( p = 0.03). There were no significant differences in weight gain during the first ( study group 21.4 g vs controls 19.6 g) or second weeks of the trial ( study group 20.5 g vs controls 19.2 g). Neonatal morbidity did not differ between the groups. There were no differences in mothers' perceptions of their babies, or feelings of stress or anxiety. Conclusion: There were no differences between infants cot-nursed on an HWM and those receiving incubator care, with the exception of episodes of high temperature. The results suggest that the HWM may be used safely for low-weight preterm infants.

Seasonal patterns of growth, dehydrins and water-soluble carbohydrates in genotypes of Dactylis glomerata varying in summer dormancy

Background and Aims Summer dormancy in perennial grasses has been studied inadequately, despite its potential to enhance plant survival and persistence in Mediterranean areas. The aim of the present work was to characterize summer dormancy and dehydration tolerance in two cultivars of Dactylis glomerata (dormant 'Kasbah', non-dormant 'Oasis') and their hybrid using physiological indicators associated with these traits. Methods Dehydration tolerance was assessed in a glasshouse experiment, while seasonal metabolic changes which produce putative protectants for drought, such as carbohydrates and dehydrins that might be associated with summer dormancy, were analysed in the field. Key Results The genotypes differed in their ability to survive increasing soil water deficit: lethal soil water potential (ψ(s)) was -3(.)4 MPa for 'Kasbah' (although non-dormant), -1(.)3 MPa for 'Oasis', and -1(.)6 MPa for their hybrid. In contrast, lethal water content of apices was similar for all genotypes (approx. 0(.)45 g H2O g d. wt(-1)), and hence the greater survival of 'Kasbah' can be ascribed to better drought avoidance rather than dehydration tolerance. In autumn-sown plants, 'Kasbah' had greatest dormancy, the hybrid was intermediate and 'Oasis' had none. The more dormant the genotype, the lower the metabolic activity during summer, and the earlier the activity declined in spring. Decreased monosaccharide content was an early indicator of dormancy induction. Accumulation of dehydrins did not correlate with stress tolerance, but dehydrin content was a function of the water status of the tissues, irrespective of the soil moisture. A protein of approx. 55 kDa occurred in leaf bases of the most dormant cultivar even in winter. Conclusions Drought avoidance and summer dormancy are correlated but can be independently expressed. These traits are heritable, allowing selection in breeding programmes.

Water quality in the Great Barrier Reef region: responses of mangrove, seagrass and macroalgal communities

Marine plants colonise several interconnected ecosystems in the Great Barrier Reef region including tidal wetlands, seagrass meadows and coral reefs. Water quality in some coastal areas is declining from human activities. Losses of mangrove and other tidal wetland communities are mostly the result of reclamation for coastal development of estuaries, e.g. for residential use, port infrastructure or marina development, and result in river bank destabilisation, deterioration of water clarity and loss of key coastal marine habitat. Coastal seagrass meadows are characterized by small ephemeral species. They are disturbed by increased turbidity after extreme flood events, but generally recover. There is no evidence of an overall seagrass decline or expansion. High nutrient and substrate availability and low grazing pressure on nearshore reefs have lead to changed benthic communities with high macroalgal abundance. Conservation and management of GBR macrophytes and their ecosystems is hampered by scarce ecological knowledge across macrophyte community types. (c) 2004 Elsevier Ltd. All rights reserved.

Response of holosymbiont pigments from the scleractinian coral Montipora monasteriata to short-term heat stress

Heating the scleractinian coral, Montipora monasteriata (Forskal 1775) to 32 degrees C under < 650 mu mol quanta m(-2) s(-1) led to bleaching in the form of a reduction in Peridinin, xanthophyll pool, chlorophyll c(2) and chlorophyll a, but areal dinoflagellates densities did not decline. Associated with this bleaching, chlorophyll (Chl) allomerization and dinoflagellate xanthophyll cycling increased. Chl allomerization is believed to result from the interaction of Chl with singlet oxygen (O-1(2)) or other reactive oxygen species. Thermally induced increases in Chl allomerization are consistent with other studies that have demonstrated that thermal stress generates reactive oxygen species in symbiotic dinoflagellates. Xanthophyll cycling requires the establishment of a pH gradient across the thylakoid membrane. Our results indicate that, during the early stages of thermal stress, thylakoid membranes are intact. Different morphs of M. monasteriata responded differently to the heat stress applied: heavily pigmented coral hosts taken from a high-light environment showed significant reductions in green fluorescent protein (GFP)-like homologues, whereas nonhost pigmented high-light morphs experienced a significant reduction in water-soluble protein content. Paradoxically, the more shade acclimated cave morph were, based on Chl fluorescence data, less thermally stressed than either of the high-light morphs. These results Support the importance of coral pigments for the regulation of the light environment within the host tissue.

Mechanical properties of interfacial films formed by lysozyme self-assembly at the air-water interface

We present the first characterization of the mechanical properties of lysozyme films formed by self-assembly at the air-water interface using the Cambridge interfacial tensiometer (CIT), an apparatus capable of subjecting protein films to a much higher level of extensional strain than traditional dilatational techniques. CIT analysis, which is insensitive to surface pressure, provides a direct measure of the extensional stress-strain behavior of an interfacial film without the need to assume a mechanical model (e.g., viscoelastic), and without requiring difficult-to-test assumptions regarding low-strain material linearity. This testing method has revealed that the bulk solution pH from which assembly of an interfacial lysozyme film occurs influences the mechanical properties of the film more significantly than is suggested by the observed differences in elastic moduli or surface pressure. We have also identified a previously undescribed pH dependency in the effect of solution ionic strength on the mechanical strength of the lysozyme films formed at the air-water interface. Increasing solution ionic strength was found to increase lysozyme film strength when assembly occurred at pH 7, but it caused a decrease in film strength at pH 11, close to the pI of lysozyme. This result is discussed in terms of the significant contribution made to protein film strength by both electrostatic interactions and the hydrophobic effect. Washout experiments to remove protein from the bulk phase have shown that a small percentage of the interfacially adsorbed lysozyme molecules are reversibly adsorbed. Finally, the washout tests have probed the role played by additional adsorption to the fresh interface formed by the application of a large strain to the lysozyme film and have suggested the movement of reversibly bound lysozyme molecules from a subinterfacial layer to the interface.

The effect of salinity on plant available water

Salinity acts to inhibit plant access to soil water by increasing the osmotic strength of the soil solution. As the soil dries, the soil solution becomes increasingly concentrated, further limiting plant access to soil water. An experiment was conducted to examine the effect of salt on plant available water in a heavy clay soil, using a relatively salt tolerant species, wheat ‘Kennedy’, and a more salt sensitive species, chickpea ‘Jimbour’. Sodium chloride was applied to Red Ferrosol at 10 rates from 0 to 3 g/kg. Plants were initially maintained at field capacity. After 3 weeks, plants had become established and watering was ceased. The plants then grew using the water stored in the soil. Once permanent wilting point was reached plants were harvested, and soil water content was measured. The results showed that without salt stress, wheat and chickpea extracted approximately the same amount of water. However, as the salt concentration increased, the ability of chickpea to extract water was severely impaired, while wheat’s ability to extract water was not affected over the range of concentrations examined. Growth of both wheat and chickpea was reduced even from low salt concentrations. Possible explanations for this are that the effect on growth is due to Cl- toxicity and that this occurs at lower concentrations than the osmotic effect of salinity, or that the metabolic demands of maintaining plant water balance and extracting soil water under saline conditions result in reduced growth.