Binder-free all-carbon composite supercapacitors

Carbon-based electrode materials have widely been used in supercapacitors. Unfortunately, the fabrication of the supercapacitors includes a polymeric binding material that leads to an undesirable addition of weight along with an increased charge transfer resistance. Herein, binder-free and lightweight electrodes were fabricated using powder processing of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) resulting in a hybrid all-carbon composite material. The structural, morphological, and electrochemical properties of the composite electrodes were studied at different concentrations of GNPs. The specific capacitance (Cs) of the CNFs/GNPs composite was improved by increasing the concentration of GNPs. A maximum Cs of around 120 F g-1was achieved at 90 wt% GNPs which is around 5-fold higher in value than the pristine CNFs in 1 M potassium hydroxides (KOH), which then further increased to 189 F g-1in 6 M KOH electrolyte. The energy density of around 20 Wh kg-1with the corresponding power density of 340 W kg-1was achieved in the supercapacitor containing 90 wt% GNPs. The enhanced electrochemical performance of the composite is related to the presence of a synergistic effect and the CNFs establishing conductive/percolating networks. Such binder-free all-carbon electrodes can be a potential candidate for next-generation energy applications.

Desalination brine effects beyond excess salinity: Unravelling specific stress signaling and tolerance responses in the seagrass Posidonia oceanica

Desalination has been proposed as a global strategy for tackling freshwater shortage in the climate change era. However, there is a concern regarding the environmental effects of high salinity brines discharged from desalination plants on benthic communities. In this context, seagrasses such as the Mediterranean endemic and ecologically important Posidonia oceanica have shown high vulnerability to elevated salinities. Most ecotoxicological studies regarding desalination effects are based on salinity increments using artificial sea salts, although it has been postulated that certain additives within the industrial process of desalination may exacerbate a negative impact beyond just the increased salinities of the brine. To assess the potential effect of whole effluent brines on P. oceanica, mesocosm experiments were conducted within 10 days, simulating salinity increment with either artificial sea salts or brines from a desalination plant (at 43 psμ, 6 psμ over the natural 37 psμ). Morphometrical (growth and necrosis), photochemical (PSII chlorophyll a fluorometry), metabolic, such as hydrogen peroxide (H2O2), thiobarbituric reactive substances (TBARS) and ascorbate/dehydroascorbate (ASC/DHA), and molecular (expression of key tolerance genes) responses were analyzed in each different treatment. Although with a still positive leaf growth, associated parameters decreased similarly for both artificial sea salt and brine treatments. Photochemical parameters did not show general patterns, although only P. oceanica under brines demonstrated greater energy release through heat (NPQ). Lipid peroxidation and upregulation of genes related to oxidative stress (GR, MnSOD, and FeSOD) or ion exclusion (SOS3 and AKT2/3) were similarly incremented on both hypersalinity treatments. Conversely, the ASC/DHA ratio was significantly lower, and the expression of SOS1, CAT, and STRK1 was increased under brine influence. This study revealed that although metabolic and photochemical differences occurred under both hypersalinity treatments, growth (the last sign of physiological detriment) was similarly compromised, suggesting that the potential effects of desalination are mainly caused by brine-associated salinities and are not particularly related to other industrial additives.

Quantifying the role of photoacclimation and self-facilitation for seagrass resilience to light deprivation

Introduction

Light gradients are ubiquitous in marine systems as light reduces exponentially with depth. Seagrasses have a set of mechanisms that help them to cope with light stress gradients. Physiological photoacclimation and clonal integration help to maximize light capture and minimize carbon losses. These mechanisms can shape plants minimum light requirements (MLR), which establish critical thresholds for seagrass survival and help us predict ecosystem responses to the alarming reduction in light availability.

Methods

Using the seagrass Cymodocea nodosa as a case study, we compare the MLR under different carbon model scenarios, which include photoacclimation and/or self-facilitation (based on clonal integration) and that where parameterized with values from field experiments.

Results

Physiological photoacclimation conferred plants with increased tolerance to reducing light, approximately halving their MLR from 5-6% surface irradiance (SI) to ≈ 3% SI. In oligotrophic waters, this change in MLR could translate to an increase of several meters in their depth colonization limit. In addition, we show that reduced mortality rates derived from self-facilitation mechanisms (promoted by high biomass) induce bistability of seagrass meadows along the light stress gradient, leading to abrupt shifts and hysteretic behaviors at their deep limit.

Discussion

The results from our models point to (i) the critical role of physiological photoacclimation in conferring greater resistance and ability to recover (i.e., resilience), to seagrasses facing light deprivation and (ii) the importance of self-facilitating reinforcing mechanisms in driving the resilience and recovery of seagrass systems exposed to severe light reduction events.

Phytoplankton dynamics in the Mar Menor, a Mediterranean coastal lagoon strongly impacted by eutrophication

The Mar Menor hypersaline coastal lagoon has suffered serious degradation in the last three decades attributable to nutrient pollution. In 2015, the lagoon experienced an intensive bloom of cyanobacteria that triggered a drastic change of its ecosystem. Our analyses indicate that phytoplankton in 2016-2021 did not present a seasonal variability pattern; the community was mainly dominated by diatoms and punctually reached abundance peaks above 10⁷ cell L^-1 along with chlorophyll a concentrations exceeding 20 μg L^-1. The predominant diatom genera during these blooms were different as well as the nutrient conditions under which they were produced. These high diatom abundances are unprecedented in the lagoon; in fact, our data indicate that the taxonomic composition, time variation patterns and cell abundance of phytoplankton in 2016-2021 differ notably in comparison to the data published before 2015. Consequently, our results support the finding that the trophic status of the lagoon has changed profoundly.

Advances in understanding multilevel responses of seagrasses to hypersalinity

Human- and nature-induced hypersaline conditions in coastal systems can lead to profound alterations of the structure and vitality of seagrass meadows and their socio-ecological benefits. In the last two decades, recent research efforts (>50 publications) have contributed significantly to unravel the physiological basis underlying the seagrass-hypersalinity interactions, although most (∼70%) are limited to few species (e.g. Posidonia oceanica, Zostera marina, Thalassia testudinum, Cymodocea nodosa). Variables related to photosynthesis and carbon metabolism are among the most prevalent in the literature, although other key metabolic processes such as plant water relations and responses at molecular (i.e. gene expression) and ultrastructure level are attracting attention. This review emphasises all these latest insights, offering an integrative perspective on the interplay among biological responses across different functional levels (from molecular to clonal structure), and their interaction with biotic/abiotic factors including those related to climate change. Other issues such as the role of salinity in driving the evolutionary trajectory of seagrasses, their acclimation mechanisms to withstand salinity increases or even the adaptive properties of populations that have historically lived under hypersaline conditions are also included. The pivotal role of the costs and limits of phenotypic plasticity in the successful acclimation of marine plants to hypersalinity is also discussed. Finally, some lines of research are proposed to fill the remaining knowledge gaps.

Application of an Enzymatic Hydrolysed L-α-Amino Acid Based Biostimulant to Improve Sunflower Tolerance to Imazamox

Herbicides, commonly used in agriculture to control weeds, often cause negative effects on crops. Safeners are applied to reduce the damage to crops without affecting the effectiveness of herbicides against weeds. Plant biostimulants have the potential to increase tolerance to a series of abiotic stresses, but very limited information exists about their effects on herbicide-stressed plants. This study aims to verify whether the application of a potential safener such as Terra-Sorb^®, an L-α-amino acid-based biostimulant, reduces the phytotoxicity of an Imazamox-based herbicide and to elucidate which tolerance mechanisms are induced. Sunflower plants were treated with Pulsar^® 40 (4% Imazamox) both alone and in combination with Terra-Sorb^®. Plants treated with the herbicide in combination with Terra-Sorb^® showed higher growth, increased acetolactate synthase (ALS) activity, and amino acid concentration with respect to the plants treated with Imazamox alone. Moreover, the biostimulant protected photosynthetic activity and reduced oxidative stress. This protective effect could be due to the glutathione S-transferase (GST) induction and antioxidant systems dependent on glutathione (GSH). However, no effect of the biostimulant application was observed regarding phenolic compound phenylalanine ammonium-lyase (PAL) activity. Therefore, this study opens the perspective of using Terra-Sorb^® in protecting sunflower plants against an imazamox-based herbicide effect.

Factors structuring microbial communities in highly impacted coastal marine sediments (Mar Menor lagoon, SE Spain)

Coastal marine lagoons are environments highly vulnerable to anthropogenic pressures such as agriculture nutrient loading or runoff from metalliferous mining. Sediment microorganisms, which are key components in the biogeochemical cycles, can help attenuate these impacts by accumulating nutrients and pollutants. The Mar Menor, located in the southeast of Spain, is an example of a coastal lagoon strongly altered by anthropic pressures, but the microbial community inhabiting its sediments remains unknown. Here, we describe the sediment prokaryotic communities along a wide range of environmental conditions in the lagoon, revealing that microbial communities were highly heterogeneous among stations, although a core microbiome was detected. The microbiota was dominated by Delta- and Gammaproteobacteria and members of the Bacteroidia class. Additionally, several uncultured groups such as Asgardarchaeota were detected in relatively high proportions. Sediment texture, the presence of Caulerpa or Cymodocea, depth, and geographic location were among the most important factors structuring microbial assemblages. Furthermore, microbial communities in the stations with the highest concentrations of potentially toxic elements (Fe, Pb, As, Zn, and Cd) were less stable than those in the non-contaminated stations. This finding suggests that bacteria colonizing heavily contaminated stations are specialists sensitive to change.

Improvement of the physiological response of barley plants to both Zinc deficiency and toxicity by the application of calcium silicate

An adequate availability of Zinc (Zn) is crucial for plant growth and development given the essentiality of this element. Thus, both Zn deficiency and Zn toxicity can limit crop yields. In plants, the responses to Zn imbalances involve important physiological aspects such as reactive oxygen species (ROS) accumulation, phytohormone balance, tricarboxylic acid cycle (TCA) metabolism, and organic acids (OAs) accumulation. However, a way to improve tolerance to stresses such as those produced by nutritional imbalances is the application of beneficial elements such as silicon (Si). In this study, we grew barley plants in hydroponics under Zn deficiency and toxicity conditions, applying Si in the form of CaSiO₃ in order to assess its effectiveness against Zn imbalances. Parameters related to plant growth, oxidative stress, TCA enzyme activities, phytohormones and OAs accumulation were analyzed. Both Zn deficiency and toxicity reduced leaf biomass, increased ROS accumulation, and affected phytohormone and OAs concentrations and TCA enzyme activities. CaSiO₃ treatment was effective in counteracting these effects enhancing Zn accumulation under Zn deficient conditions and limiting its accumulation under toxic conditions. In addition, this treatment decreased ROS levels, and improved ascorbate/glutathione and phytohormonal responses, citrate synthase activity, and malate/oxalate ratio. Therefore, this study enhanced the notion of the efficacy of CaSiO₃ in improving tolerance to Zn imbalances.

Photo-acclimatory thresholds anticipate sudden shifts in seagrass ecosystem state under reduced light conditions

Seagrass ecosystems usually respond in a nonlinear fashion to increasing pressures and environmental changes. Feedback mechanisms operating at the ecosystem level and involving multiple interactions among the seagrass meadow, its associated community and the physical environment are known to play a major role in such nonlinear responses. Phenotypic plasticity may also be important for buffering these ecological thresholds (i.e., regime shifts) as many physiological processes show nonlinear responses to gradual environmental changes, conferring the appearance of resistance before the effects at the organism and population levels are visible. However, the potential involvement of plant plasticity in driving catastrophic shifts in seagrass ecosystems has not yet been assessed. In this study, we conducted a manipulative 6-month light-gradient experiment in the field to capture nonlinearities of the physiological and population responses of the seagrass Cymodocea nodosa to gradual light reduction. The aim was to explore if and how the photo-acclimatory responses of shaded plants are translated to the population level and, hence, to the ecosystem level. Results showed that the seagrass population was rather stable under increasing shading levels through the activation of multilevel photo-acclimative responses, which are initiated with light reduction and modulated in proportion to shading intensity. The activation of photo-physiological and metabolic compensatory responses allowed shaded plants to sustain nearly constant plant productivity (metabolic carbon balance) along a range of shading levels before losing linearity and starting to decline. The species then activated plant- and meadow-scale photo-acclimative responses and drew on its energy reserves (rhizome carbohydrates) to confer additional population resilience. However, when the integration of all these buffering mechanisms failed to counterbalance the effects of extreme light limitation, the population collapsed, giving place to a phase shift from vegetated to bare sediments with catastrophic ecosystem outcomes. Our findings evidence that ecological thresholds in seagrass ecosystems under light limitation can be explained by the role of species' compensatory responses in modulating population-level responses. The thresholds of these plastic responses anticipate the sudden loss of seagrass meadows with the potential to be used as early warning indicators signalling the imminent collapse of the ecosystem, which is of great value for the real-world management of seagrass ecosystems.

Thermo-priming increases heat-stress tolerance in seedlings of the Mediterranean seagrass P. oceanica

Seawater warming and increased incidence of marine heatwaves (MHW) are threatening the integrity of coastal marine habitats including seagrasses, which are particularly vulnerable to climate changes. Novel stress tolerance-enhancing strategies, including thermo-priming, have been extensively applied in terrestrial plants for enhancing resilience capacity under the re-occurrence of a stress event. We applied, for the first time in seedlings of the Mediterranean seagrass Posidonia oceanica, a thermo-priming treatment through the exposure to a simulated warming event. We analyzed the photo-physiological and growth performance of primed and non-primed seedlings, and the gene expression responses of selected genes (i.e. stress-, photosynthesis- and epigenetic-related genes). Results revealed that during the re-occurring stress event, primed seedlings performed better than unprimed showing unaltered photo-physiology supported by high expression levels of genes related to stress response, photosynthesis, and epigenetic modifications. These findings offer new opportunities to improve conservation and restoration efforts in a future scenario of environmental changes.

The role of competition and herbivory in biotic resistance against invaders: a synergistic effect

Invasive species pose a major threat to global diversity, and once they are well established their eradication typically becomes unfeasible. However, certain natural mechanisms can increase the resistance of native communities to invaders and can be used to guide effective management policies. Both competition and herbivory have been identified as potential biotic resistance mechanisms that can limit plant invasiveness, but it is still under debate to what extent they might be effective against well-established invaders. Surprisingly, whereas biotic mechanisms are known to interact strongly, most studies to date have examined single biotic mechanisms separately, which likely influences our understanding of the strength and effectiveness of biotic resistance against invaders. Here we use long-term field data, benthic assemblage sampling, and exclusion experiments to assess the effect of native assemblage complexity and herbivory on the invasion dynamics of a successful invasive species, the alga Caulerpa cylindracea. A higher complexity of the native algal assemblage limited C. cylindracea invasion, probably through competition by canopy-forming and erect algae. Additionally, high herbivory pressure by the fish Sarpa salpa reduced C. cylindracea abundance by more than four times. However, long-term data of the invasion reflects that biotic resistance strength can vary across the invasion process and it is only where high assemblage complexity is concomitant with high herbivory pressure, that the most significant limitation is observed (synergistic effect). Overall, the findings reported in this study highlight that neglecting the interactions between biotic mechanisms during invasive processes and restricting the studied time scales may lead to underestimations of the true capacity of native assemblages to develop resistance to invaders.

Warming intensifies the interaction between the temperate seagrass Posidonia oceanica and its dominant fish herbivore Sarpa salpa

Apart from directly influencing individual life histories of species, climate change is altering key biotic interactions as well, causing community processes to unravel. With rising temperatures, disruptions to producer-consumer relationships can have major knock-on effects, particularly when the producer is a habitat-forming species. We studied how sea surface temperature (SST) modifies multiple pathways influencing the interaction between the foundational seagrass species, Posidonia oceanica, and its main consumer, the fish Sarpa salpa in the Mediterranean Sea. We used a combination of a field-based temperature gradient approaches and experimental manipulations to assess the effect of temperature on seagrass performance (growth) and fish early life history (larval development) as well as on the interaction itself (seagrass palatability and fish foraging activity). Within the range of temperatures assessed, S. salpa larvae grew slightly faster at warmer conditions but maintained their settlement size, resulting in a relatively small reduction in pelagic larval duration (PLD) and potentially reducing dispersion. Under warmer conditions (>24 °C), P. oceanica reduced its growth rate considerably and seemed to display fewer deterring mechanisms as indicated by a disproportionate consumption in choice experiments. However, our field-based observations along the temperature gradient showed no change in fish foraging time, or in other aspects of feeding behaviour. As oceans warm, our results indicate that, while S. salpa may show little change in early life history, its preference towards P. oceanica might increase, which, together with reduced seagrass growth, could considerably intensify the strength of herbivory. It is unclear if P. oceanica meadows can sustain such an intensification, but it will clearly add to the raft of pressures this threatened ecosystem already faces from global and local environmental change.

Positive effects of high salinity can buffer the negative effects of experimental warming on functional traits of the seagrass Halophila ovalis

Coastal ecosystems, and especially estuaries, are subject to environmental fluctuations that can be amplified by anthropogenic changes. Under a future scenario of global warming, temperature and salinity are likely to be altered and the persistence of macrophyte-dominated ecosystems can be compromised, particularly native or local seagrass communities. This study examined the response of the local seagrass Halophila ovalis to the joint effect of a short-term salinity increase and a transient temperature stress, through two mesocosm experiments. Warming caused a decline in F_v/F_m, TNC content in leaves and plant growth, and increased dark respiration, revealing clear detrimental symptoms of heat stress on plant metabolism and performance. Salinity increase in isolation favoured ramet survival. However, in combination with warming, salinity had a positive effect on Gross P_max. This suggests that increased salinities might dampen the negative effects of high temperatures, buffering, to some extent, the impact of global warming in temperate estuaries.

The dominant seagrass herbivore Sarpa salpa shifts its shoaling and feeding strategies as they grow

The relative benefits of group foraging change as animals grow. Metabolic requirements, competitive abilities and predation risk are often allometric and influenced by group size. How individuals optimise costs and benefits as they grow can strongly influence consumption patterns. The shoaling fish Sarpa salpa is the principal herbivore of temperate Posidonia oceanica seagrass meadows. We used in-situ observations to describe how ontogeny influenced S. salpa individual feeding behaviour, shoaling behaviour and group foraging strategies, and its potential consequences to seagrass meadows. Shoaling was strongly influenced by body length: shoals were highly length-assorted and there was a clear positive relationship between body length and shoal size. Foraging strategies changed dramatically with shoal size. Small shoals foraged simultaneously and scattered over large areas. In contrast, larger shoals (made of larger individuals) employed a potentially cooperative strategy where individuals fed rotationally and focused in smaller areas for longer times (spot feeding). Thus, as individuals grew, they increased their potential impact as well, not merely because they consumed more, but because they formed larger shoals capable of considerably concentrating their grazing within the landscape. Our results indicate that ontogenetic shifts in group foraging strategies can have large ecosystem-wide consequences when the species is an important ecosystem modifier.

The negative effects of short-term extreme thermal events on the seagrass Posidonia oceanica are exacerbated by ammonium additions

Global warming is increasingly affecting our biosphere. However, in addition to global warming, a panoply of local stressors caused by human activities is having a profound impact on our environment. The risk that these local stressors could modify the response of organisms to global warming has attracted interest and fostered research on their combined effect, especially with a view to identifying potential synergies. In coastal areas, where human activities are heavily concentrated, this scenario is particularly worrying, especially for foundation species such as seagrasses. In this study we explore these potential interactions in the seagrass Posidonia oceanica. This species is endemic to the Mediterranean Sea. It is well known that the Mediterranean is already experiencing the effects of global warming, especially in the form of heat waves, whose frequency and intensity are expected to increase in the coming decades. Moreover, this species is especially sensitive to stress and plays a key role as a foundation species. The aim of this work is thus to evaluate plant responses (in terms of photosynthetic efficiency and growth) to the combined effects of short-term temperature increases and ammonium additions.To achieve this, we conducted a mesocosm experiment in which plants were exposed to three thermal treatments (20°C, 30°C and 35°C) and three ammonium concentrations (ambient, 30 μM and 120 μM) in a full factorial experiment. We assessed plant performance by measuring chlorophyll fluorescence variables (maximum quantum yield (Fv/Fm), effective quantum yield of photosystem II (ΔF/Fm'), maximum electron transport rate (ETRmax) and non-photochemical quenching (NPQ)), shoot growth rate and leaf necrosis incidence. At ambient ammonium concentrations, P. oceanica tolerates short-term temperature increases up to 30°C. However, at 35°C, the plant loses functionality as indicated by a decrease in photosynthetic performance, an inhibition of plant growth and an increase of the necrosis incidence in leaves. On the other hand, ammonium additions at control temperatures showed only a minor effect on seagrass performance. However, the combined effects of warming and ammonium were much worse than those of each stressor in isolation, given that photosynthetic parameters and, above all, leaf growth were affected. This serves as a warning that the impact of global warming could be even worse than expected (based on temperature-only approaches) in environments that are already subject to eutrophication, especially in persistent seagrass species living in oligotrophic environments.

Recent trend reversal for declining European seagrass meadows

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast-growing species recovered in some locations, making the net rate of change in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide.

Seagrass meadows are important but one of the most threatened ecosystems globally. Here the authors analyse data about extent and density of seagrasses in Europe from 1869 to 2016, and find evidence of recent trend reversal for declining European seagrass meadows.

Heat-stress induced flowering can be a potential adaptive response to ocean warming for the iconic seagrass Posidonia oceanica

The Mediterranean Sea is particularly vulnerable to warming and the abrupt declines experienced by the endemic Posidonia oceanica populations after recent heatwaves have forecasted severe consequences for the ecological functions and socio-economical services this habitat forming species provides. Nevertheless, this highly clonal and long-lived species could be more resilient to warming than commonly thought since heat-sensitive plants massively bloomed after a simulated heatwave, which provides the species with an opportunity to adapt to climate change. Taking advantage of this unexpected plant response, we investigated for the first time the molecular and physiological mechanisms involved in seagrass flowering through the transcriptomic analysis of bloomed plants. We also aimed to identify if flowering is a stress-induced response as suggested from the fact that heat-sensitive but not heat-tolerant plants flowered. The transcriptomic profiles of flowered plants showed a strong metabolic activation of sugars and hormones and indications of an active transport of these solutes within the plant, most likely to induce flower initiation in the apical meristem. Preflowered plants also activated numerous epigenetic-related genes commonly used by plants to regulate the expression of key floral genes and stress-tolerance genes, which could be interpreted as a mechanism to survive and optimize reproductive success under stress conditions. Furthermore, these plants provided numerous molecular clues suggesting that the factor responsible for the massive flowering of plants from cold environments (heat-sensitive) can be considered as a stress. Heat-stress induced flowering may thus be regarded as an ultimate response to survive extreme warming events with potential adaptive consequences for the species. Fitness implications of this unexpected stress-response and the potential consequences on the phenotypic plasticity (acclimation) and evolutionary (adaptation) opportunity of the species to ocean warming are finally discussed.

Interactive effects of global warming and eutrophication on a fast-growing Mediterranean seagrass

Coastal ecosystems, such as seagrasses, are subjected to local (e.g. eutrophication) and global (e.g. warming) stressors. While the separate effects of warming and eutrophication on seagrasses are relatively well known, their joint effects remain largely unstudied. In order to fill this gap, and using Cymodocea nodosa as a model species, we assessed the joint effects of warming (three temperatures, 20 °C, 30 °C and 35 °C) with two potential outcomes of eutrophication: (i) increase in nutrients concentration in the water column (30 and 300 μM), and (ii) organic enrichment in the sediment). Our results confirm that temperature in isolation clearly affects plant performance; while plants exposed to 30 °C performed better than control plants, plants exposed to 35 °C showed clear symptoms of deterioration (e.g. decline of photosynthetic capacity, increase of incidence of necrotic tissue). Plants were unaffected by high ammonium concentrations; however, organic enrichment of sediment had deleterious effects on plant function (photosynthesis, growth, demographic balance). Interestingly, these negative effects were exacerbated by increased temperature. Our findings indicate that in addition to the possibility of the persistence of C. nodosa being directly jeopardized by temperature increase, the joint effects of warming and eutrophication may further curtail its survival. This should be taken into consideration in both predictions of climate change consequences and in local planning.

Influence of the proline metabolism and glycine betaine on tolerance to salt stress in tomato (Solanum lycopersicum L.) commercial genotypes

Tomato is the crop with the greatest economic importance in the world and salinity stress causes a reduction in the quantity and quality of crop production. The objective of this work is to verify if the accumulation of proline and glycine betaine (GB) and their metabolisms improve tolerance to salt stress. Two commercial genotypes of Solanum Lycopersicum L., Grand Brix and Marmande RAF were used for this work. The analyzed parameters were growth parameters, proline concentration and its metabolism, GB and its above betaine aldehyde dehydrogenase (BADH) synthesis and some related amino acids. Saline stress reduced biomass and relative growth rate (RGR) in both genotypes, this effect being greater in Marmande RAF. These results, together with the proline accumulation indicate that Grand Brix is more tolerant to saline stress. The proline increase in Grand Brix came by the ornithine pathway, leaving the glutamate pathway repressed. On the other hand, it was found in both genotypes a BADH and GB decreases as a salinity tolerance mechanism. We propose that, unlike proline, GB synthesis can produce H₂O₂ thereby, GB not act as compatible solute and salt tolerance does not improve.

Investigating cellular stress response to heat stress in the seagrass Posidonia oceanica in a global change scenario

Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a mesocosm experiment, we aimed at disentangling the molecular response of P. oceanica under increasing temperature (20 °C-32 °C). The experiment was carried out in spring, when heat waves can potentially occur and plants are putatively more sensitive to heat stress, since they are deprived in carbohydrates reserves after the cold winter months. We aimed to identify the activation of different phases of the cellular stress response (CSR) reaction and the responsive genes activated or repressed in heated plants. A molecular traffic light was proposed as a response model including green (protein folding and membrane protection), yellow (ubiquitination and proteolysis) and red (DNA repair and apoptosis) categories. Additionally, we estimated phenological trait variations to complement the information obtained from the molecular proxies of stress. Despite reduced leaf growth rate, heated plants did not exhibit signs of irreversible damage, probably underlying species pre-adaptation to warm and fluctuating regimes. Gene expression analyses revealed that molecular chaperoning, DNA repair and apoptosis inhibition processes related genes were the ones that mostly responded to high thermal stress and will be target of further investigation and in situ proofing for assessing their use as indicators of P. oceanica performance under sub-lethal heat stress.

Carbon economy of Mediterranean seagrasses in response to thermal stress

Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebrates. To test this hypothesis, the carbon balance of Posidonia oceanica and Cymodocea nodosa plants from contrasting thermal environments was investigated during a simulated heatwave, by analyzing their photosynthetic performance, carbon balance (ratio photosynthesis:respiration), carbohydrates content, growth and mortality. Both species were able to overcome and recover from the thermal stress produced by the six-week exposure to temperatures 4 °C above mean summer levels, albeit plants from cold waters were more sensitive to warming than plants from warm waters as reflected by their inability to maintain their P:R ratio unaltered. The strategies through which plants tend to preserve their energetic status varied depending on the biology of the species and the thermal origin of plants. These included respiratory homeostasis (P. oceanica warm-plants), carbon diversion from growth to respiration (C. nodosa cold-plants) or storage (P. oceanica warm-plants) and changes in biomass allocation (C. nodosa warm-plants). Findings suggest an important geographic heterogeneity in the overall response of Mediterranean seagrasses to warming with potential negative impacts on the functions and services offered by seagrass meadows including among others their capacity for carbon sequestration and carbon export to adjacent ecosystems.

Experimental evidence of warming-induced flowering in the Mediterranean seagrass Posidonia oceanica

Sexual reproduction in predominantly clonal marine plants increases recombination favoring adaptation and enhancing species resilience to environmental change. Recent studies of the seagrass Posidonia oceanica suggest that flowering intensity and frequency are correlated with warming events associated with global climate change, but these studies have been observational without direct experimental support. We used controlled experiments to test if warming can effectively trigger flowering in P. oceanica. A six-week heat wave was simulated under laboratory mesocosm conditions. Heating negatively impacted leaf growth rates, but by the end of the experiment most of the heated plants flowered, while controls plants did not. Heated and control plants were not genetically distinct and flowering intensity was significantly correlated with allelic richness and heterozygosity. This is an unprecedented finding, showing that the response of seagrasses to warming will be more plastic, more complex and potentially more resilient than previously imagined.

Effects of an experimental heat wave on fatty acid composition in two Mediterranean seagrass species

Global warming is emerging as one of the most critical threats to terrestrial and marine species worldwide. This study assessed the effects of simulated warming events in culture on two seagrass species, Posidonia oceanica and Cymodocea nodosa, which play a key role in coastal ecosystems of the Mediterranean Sea. Changes in fatty acids as key metabolic indicators were assessed in specimens from two geographical populations of each species adapted to different in situ temperature regimes. Total fatty acid (TFA) content and composition were compared in C. nodosa and P. oceanica from natural populations and following exposure to heat stress in culture. After heat exposure, individuals of C. nodosa and P. oceanica adapted to colder temperatures in situ accumulated significantly more TFA than controls. For both species, the proportion of polyunsaturated fatty acids (PUFA) decreased, and the percentage of saturated fatty acids (SFA) increased significantly after the heat treatment. These results highlight that populations of both species living at warmest temperatures in situ were more thermo-tolerant and exhibited a greater capacity to cope with heat stress by readjusting their lipid composition faster. Finally, exposure of seagrasses to warmer conditions may induce a decrease in PUFA/SFA ratio which could negatively affect their nutritional value and generate important consequences in the healthy state of next trophic levels.

Antioxidant response to heat stress in seagrasses. A gene expression study

Seawater warming associated to the ongoing climate change threatens functioning and survival of keystone coastal benthic species such as seagrasses. Under elevated temperatures, the production of reactive oxygen species (ROS) is increased and plants must activate their antioxidant defense mechanisms to protect themselves from oxidative damage. Here we explore from a molecular perspective the ability of Mediterranean seagrasses to activate heat stress response mechanisms, with particular focus on antioxidants. The level of expression of targeted genes was analyzed in shallow and deep plants of the species Posidonia oceanica and in shallow plants of Cymodocea nodosa along an acute heat exposure of several days and after recovery. The overall gene expression response of P. oceanica was more intense and complete than in C. nodosa and reflected a higher oxidative stress level during the experimental heat exposure. The strong activation of genes with chaperone activity (heat shock proteins and a luminal binding protein) just in P. oceanica plants, suggested the higher sensitivity of the species to increased temperatures. In spite of the interspecific differences, genes from the superoxide dismutase (SOD) family seem to play a pivotal role in the thermal stress response of Mediterranean seagrasses as previously reported for other marine plant species. Shallow and deep P. oceanica ecotypes showed a different timing of response to heat. Shallow plants early responded to heat and after a few days relaxed their response which suggests a successful early metabolic adjustment. The response of deep plants was delayed and their recovery incomplete evidencing a lower resilience to heat in respect to shallow ecotypes. Moreover, shallow ecotypes showed some degree of pre-adaptation to heat as most analyzed genes showed higher constitutive expression levels than in deep ecotypes. The recurrent exposure of shallow plants to elevated summer temperatures has likely endowed them with a higher basal level of antioxidant defense and a faster responsiveness to warming than deep plants. Our findings match with previous physiological studies and supported the idea that warming will differently impact Mediterranean seagrass meadows depending on the species as well as on the depth (i.e. thermal regimen) at which the meadow grows. The increase in the incidence of summer heat waves could therefore produce a significant change in the distribution and composition of Mediterranean seagrass meadows with considerable consequences for the functioning of the whole ecosystem and for the socio-economic services that these ecosystems offer to the riverine populations.

Study of phytohormone profile and oxidative metabolism as key process to identification of salinity response in tomato commercial genotypes

Climatic change, intensive agriculture, and worsening water quality induce abiotic stress conditions for plants. Among these factors, salinity stress is a limit factor for plant growth. Therefore, the purpose of this study was to analyze the phytohormones role and oxidative metabolism in response to salt stress of two genotypes of tomato cv. Grand Brix and cv. Marmande RAF, the crops were carried out in a growth chamber. Salinity stress reduces biomass and relative growth rate (RGR) in both genotypes, this effect being greater in cv. Marmande RAF. These results, together with main stress indicator response, the O₂^.-, indicate that cv. Marmande RAF is more sensitive to Saline stress. Grand Brix showed less oxidative stress, because it presented greater detoxification of the O₂^-, due to SOD enzyme activity induction and greater antioxidant capacity. Furthermore, Grand Brix has a better hormonal profile adapted to salt stress resistance, the accumulation of IAA, GA4 and CKs and their beneficial role against oxidative stress could make the difference between resistance and sensitivity to salt stress. On the other hand, a lower ACC concentration, ethylene precursor, combined with a greater O₂^.- detoxification in the cv. Grand Brix could play a fundamental role in tolerance to saline stress. Besides, an increase in ABA levels promotes better stomatal closure, better photosynthesis control and a lower rate of water loss. This data could be essential to select plants with greater resistance to saline stress.

Zinc biofortification improves phytochemicals and amino-acidic profile in Brassica oleracea cv. Bronco

Zn deficiency is currently listed as a major risk factor for human health. Recently, a complimentary solution to mineral malnutrition termed 'biofortification' has been proposed. The aim of this study was to investigate the possible effects of a Zn-biofortification program on Zn levels, amino acidic profile and the phytochemicals content in an edible leafy vegetable, such as Brassica oleracea cv. Bronco. Our results indicate that supplementation of 80-100μM Zn is optimal for maintaining the normal growth of plants and to promote the major Zn concentration in the edible part of B. oleracea. Any further increase of Zn supply induced an accumulation of total amino acids, and increased the enzymatic activities involved in sulfur assimilation and synthesis of phenols, finally resulting in a foliar accumulation of glucosinolates and phenolic compounds. Thus, it could be proposed that the growth of B. oleracea under 80-100μM Zn may increase the intake of this micronutrient and other beneficial compunds for the human health.

Zn-biofortification enhanced nitrogen metabolism and photorespiration process in green leafy vegetable Lactuca sativa L

BACKGROUND

Excessive rates of nitrogen (N) fertilizers may result in elevated concentrations of nitrate (NO3- ) in plants. Considering that many programs of biofortification with trace elements are being performed, it has become important to study how the application of these elements affects plant physiology and, particularly, N utilization in leaf crops. The main objective of the present study was to determine whether the NO3- accumulation and the nitrogen use efficiency was affected by the application of different doses of Zn in Lactuca sativa plants.

RESULTS

Zn doses in the range 80-100 µmol L-1 produced an increase in Zn concentration provoking a decrease of NO3- concentration and increase of the nitrate reductase, glutamine synthetase and aspartate aminotransferase activities, as well as the photorespiration processes. As result, we observed an increase in reduced N, total N concentration and N utilization efficiency. Consequently, at a dose of 80 µmol L-1 of Zn, the amino acid concentration increased significantly.

CONCLUSION

Adequate Zn fertilization is an important critical player in lettuce, especially at a dose of 80 µmol L-1 of Zn, because it could result in an increase in the Zn concentration, a reduction of NO3- levels and an increase the concentration of essential amino acids, with all of them having beneficial properties for the human diet. © 2016 Society of Chemical Industry.

Bi-species imposex monitoring in Galicia (NW Spain) shows contrasting achievement of the OSPAR Ecological Quality Objective for TBT

Imposex is decreasing worldwide after the total ban on tributyltin (TBT) from antifouling paints. In order to assess improvement in the NE Atlantic, the OSPAR Convention designed an Ecological Quality Objective (EcoQO) based on the VDSI (vas deferens sequence index, an agreed measure of imposex) in the rock snail Nucella lapillus; wherever this is not available, the mud snail Nassarius reticulatus was proposed as a proxy. We determined VDSI in Galician populations of rock (n≥34) and mud (n≥18) snails at regular intervals from pre-ban times until 2009 and 2011, respectively. While imposex in the former started decreasing in 2006 and by 2009 the EcoQO had been met in the area, VDSI in the latter was not significantly reduced until 2011 and values contradict such an achievement. This suggests that the OSPAR imposex bi-species scheme may not be of direct application in the current post-ban scenario.

Long-term acclimation to reciprocal light conditions suggests depth-related selection in the marine foundation species Posidonia oceanica

Phenotypic differences among populations of the same species reflect selective responses to ecological gradients produced by variations in abiotic and biotic factors. Moreover, they can also originate from genetic differences among populations, due to a reduced gene flow. In this study, we examined the extent of differences in photo‐acclimative traits of Posidonia oceanica (L.) Delile clones collected above and below the summer thermocline (i.e., −5 and −25 m) in a continuous population extending along the water depth gradient. During a reciprocal light exposure and subsequent recovery in mesocosms, we assessed degree of phenotypic plasticity and local adaptation of plants collected at different depths, by measuring changes in several traits, such as gene expression of target genes, photo‐physiological features, and other fitness‐related traits (i.e., plant morphology, growth, and mortality rates). Samples were also genotyped, using microsatellite markers, in order to evaluate the genetic divergence among plants of the two depths. Measures collected during the study have shown a various degree of phenotypic changes among traits and experimental groups, the amount of phenotypic changes observed was also dependent on the type of light environments considered. Overall plants collected at different depths seem to be able to acclimate to reciprocal light conditions in the experimental time frame, through morphological changes and phenotypic buffering, supported by the plastic regulation of a reduced number of genes. Multivariate analyses indicated that plants cluster better on the base of their depth origin rather than the experimental light conditions applied. The two groups were genetically distinct, but the patterns of phenotypic divergence observed during the experiment support the hypothesis that ecological selection can play a role in the adaptive divergence of P. oceanica clones along the depth gradient.

Hydrochemical and isotopes studies in a hypersaline wetland to define the hydrogeological conceptual model: Fuente de Piedra Lake (Malaga, Spain)

The Fuente de Piedra lake is a hypersaline wetland of great extension (13.5km²) and rich in aquatic birds and other species. It became therefore the third Spanish wetland to be included in the Ramsar convention and has been a "nature reserve" since 1984. The lake has an endorheic basin (150km²) with variable-density flows dominated by complex hydrogeological conditions. The traditional conceptualization of endorheic basins in semiarid climates considered that the brine in this hydric system was exclusively of evaporative origin and was placed only in the lake and its surrounding discharge area in the basin. Previous geophysical and hydrochemical studies identified different types of waters and brines. In this work, natural tracers (Cl^-, Br^-, Na⁺, Mg²⁺) and environmental isotopes (¹⁸O, ²H, ¹⁴C, ¹³C and ³H) were employed to a) discriminate different types of brines according to their degree of evaporation and genesis, and b) to estimate residence times of brine waters and identify recharge areas of the different flow subsystems. A conceptual model of the hydrogeological system of the lake basin and its links to a regional karst system is proposed.

Molecular Mechanisms behind the Physiological Resistance to Intense Transient Warming in an Iconic Marine Plant

The endemic Mediterranean seagrass Posidonia oceanica is highly threatened by the increased frequency and intensity of heatwaves. Meadows of the species offer a unique opportunity to unravel mechanisms marine plants activate to cope transient warming, since their wide depth distribution impose divergent heat-tolerance. Understanding these mechanisms is imperative for their conservation. Shallow and deep genotypes within the same population were exposed to a simulated heatwave in mesocosms, to analyze their transcriptomic and photo-physiological responses during and after the exposure. Shallow plants, living in a more unstable thermal environment, optimized phenotype variation in response to warming. These plants showed a pre-adaptation of genes in anticipation of stress. Shallow plants also showed a stronger activation of heat-responsive genes and the exclusive activation of genes involved in epigenetic mechanisms and in molecular mechanisms that are behind their higher photosynthetic stability and respiratory acclimation. Deep plants experienced higher heat-induced damage and activated metabolic processes for obtaining extra energy from sugars and amino acids, likely to support the higher protein turnover induced by heat. In this study we identify transcriptomic mechanisms that may facilitate persistence of seagrasses to anomalous warming events and we discovered that P. oceanica plants from above and below the mean depth of the summer thermocline have differential resilience to heat.

Silicon-mediated Improvement in Plant Salinity Tolerance: The Role of Aquaporins

Silicon (Si) is an abundant and differentially distributed element in soils that is believed to have important biological functions. However, the benefits of Si and its essentiality in plants are controversial due to differences among species in their ability to take up this element. Despite this, there is a consensus that the application of Si improves the water status of plants under abiotic stress conditions. Hence, plants treated with Si are able to maintain a high stomatal conductance and transpiration rate under salt stress, suggesting that a reduction in Na⁺ uptake occurs due to deposition of Si in the root. In addition, root hydraulic conductivity increases when Si is applied. As a result, a Si-mediated upregulation of aquaporin (PIP) gene expression is observed in relation to increased root hydraulic conductivity and water uptake. Aquaporins of the subclass nodulin 26-like intrinsic proteins are further involved in allowing Si entry into the cell. Therefore, on the basis of available published results and recent developments, we propose a model to explain how Si absorption alleviates stress in plants grown under saline conditions through the conjugated action of different aquaporins.

Phytohormone profile in Lactuca sativa and Brassica oleracea plants grown under Zn deficiency

Phytohormones, structurally diverse compounds, are involved in multiple processes within plants, such as controlling plant growth and stress response. Zn is an essential micronutrient for plants and its deficiency causes large economic losses in crops. Therefore, the purpose of this study was to analyse the role of phytohormones in the Zn-deficiency response of two economically important species, i.e. Lactuca sativa and Brassica oleracea. For this, these two species were grown hydroponically with different Zn-application rates: 10 μM Zn as control and 0.1 μM Zn as deficiency treatment and phytohormone concentration was determined by U-HPLC-MS. Zn deficiency resulted in a substantial loss of biomass in L. sativa plants that was correlated with a decline in growth-promoting hormones such as indole-3-acetic acid (IAA), cytokinins (CKs), and gibberellins (GAs). However these hormones increased or stabilized their concentrations in B. oleracea and could help to maintain the biomass in this species. A lower concentration of stress-signaling hormones such as ethylene precursor aminocyclopropane-1-carboxylic acid (ACC), abscisic acid (ABA), salicylic acid (SA) and jasmonic acid (JA) and also CKs might be involved in Zn uptake in L. sativa while a rise in GA4, isopentenyl adenine (iP), and ACC and a fall in JA and SA might contribute to a better Zn-utilization efficiency (ZnUtE), as observed in B. oleracea plants.

Comparative study of Zn deficiency in L. sativa and B. oleracea plants: NH4(+) assimilation and nitrogen derived protective compounds

Zinc (Zn) deficiency is a major problem in agricultural crops of many world regions. N metabolism plays an essential role in plants and changes in their availability and their metabolism could seriously affect crop productivity. The main objective of the present work was to perform a comparative analysis of different strategies against Zn deficiency between two plant species of great agronomic interest such as Lactuca sativa cv. Phillipus and Brassica oleracea cv. Bronco. For this, both species were grown in hydroponic culture with different Zn doses: 10μM Zn as control and 0.01μM Zn as deficiency treatment. Zn deficiency treatment decreased foliar Zn concentration, although in greater extent in B. oleracea plants, and caused similar biomass reduction in both species. Zn deficiency negatively affected NO3(-) reduction and NH4(+) assimilation and enhanced photorespiration in both species. Pro and GB concentrations were reduced in L. sativa but they were increased in B. oleracea. Finally, the AAs profile changed in both species, highlighting a great increase in glycine (Gly) concentration in L. sativa plants. We conclude that L. sativa would be more suitable than B. oleracea for growing in soils with low availability of Zn since it is able to accumulate a higher Zn concentration in leaves with similar biomass reduction. However, B. oleracea is able to accumulate N derived protective compounds to cope with Zn deficiency stress.

Accumulation of free polyamines enhances the antioxidant response in fruits of grafted tomato plants under water stress

Polyamines, small aliphatic polycations, have been suggested to play key roles in a number of biological processes. In this paper, attempts were made to investigate the possibility of improving antioxidant response of tomato fruits in relation with endogenous free polyamines content. We studied the reactive oxygen species and polyamines content, and antioxidant and polyamine-biosynthesis enzyme activities in fruits of ungrafted and grafted tomato plants under moderate water stress. We used a drought-tolerant cultivar (Zarina) and drought-sensitive cultivar (Josefina) to obtain reciprocal graft, selfgraft and ungraft plants. Fruits contained higher endogenous polyamine content during the course of the experiment relative to the control, coupled with higher arginine decarboxylase and spermine synthase activities in Zarina ungrafted and ZarxJos. In these cultivars, tomato fruits showed a lower reactive oxygen species generation and higher catalase and superoxide dismutase activities, suggesting that a higher content in polyamines (especially spermine) exerted a positive effect on antioxidant systems. All of these data suggest that spermine leads to more effective reactive oxygen species scavenging (less tissue damage) in tomato fruits, which may function collectively to enhance dehydration tolerance.

IL-6 blockade reverses the abnormal STAT activation of peripheral blood leukocytes from rheumatoid arthritis patients

Considering the interplay of multiple STATs in response to cytokines, we investigated how IL-6 and its blocking affect STAT signaling in rheumatoid arthritis (RA). Leukocytes obtained from RA patients before and after tocilizumab treatment and healthy donors (HDs) were cytokine-stimulated and STAT phosphorylation was analyzed by cytometry. RA patients had significantly fewer pSTAT1+, pSTAT3+, and pSTAT6+ monocytes and pSTAT5+ lymphocytes than HDs. After 24weeks of treatment, percentages of IFNγ-induced pSTAT1+ and IL-10-induced pSTAT3+ monocytes in RA patients increased, reaching levels comparable to HDs. pSTAT1+ and pSTAT3+ cells correlated inversely with RA disease activity index and levels of pSTAT+ cells at baseline were higher in patients with good EULAR response to tocilizumab. IFNγ-induced pSTAT1+ cells correlated inversely with memory T cells and anti-CCP levels. IL-10-induced pSTAT3+ cells correlated with Treg/Teff ratio. Our findings suggest that IL-6 blocking reduces the inflammatory mechanisms through the correction of STAT1 and STAT3 activation status.

A combined whelk watch suggests repeated TBT desorption pulses

Environmental quality in coastal Europe has improved since the complete 2003 ban on the use of tributyltin (TBT) in antifouling paints. However, there is evidence that TBT is entering the water column, presumably from illegal practices. We determined the concentration of butyltins (BTs: TBT and derivatives) in populations of two gastropods, the rock snail Nucella lapillus (n=17) and the mud snail Nassarius reticulatus (n=18) at regular intervals from pre-ban times until 2009 and 2011, respectively, in NW Spain. Although a substantial decline in TBT occurred shortly after the ban, no significant changes were observed in either species over the last 3-year period of study. In addition, the proportion of TBT relative to the sum of BTs (a marker of recent pollution) in the most recent rock snail samples unexpectedly increased; this proportion therefore showed a generally decreasing but oscillatory trend over time. The results are consistent with the theoretical expectation of BT desorption from sediments; however, this natural phenomenon is now interpreted as a recurrent episode rather than a unique, transient event. Evidence of this subtle input improves our understanding of TBT persistence in the environment in Europe and worldwide.

Genotype differences in the metabolism of proline and polyamines under moderate drought in tomato plants

Water stress is one of the most important factors limiting the growth and productivity of crops. The implication of compatible osmolytes such as proline and polyamines in osmotic adjustment has been widely described in numerous plants species under stress conditions. In the present study, we investigated the response of five cherry tomato cultivars (Solanum lycopersicum L.) subjected to moderate water stress in order to shed light on the involvement of proline and polyamine metabolism in the mechanisms of tolerance to moderate water stress. Our results indicate that the most water stress-resistant cultivar (Zarina) had increased degradation of proline associated with increased polyamine synthesis, with a higher concentration of spermidine and spermine under stress conditions. In contrast, Josefina, the cultivar most sensitive to water stress, showed a proline accumulation associated with increased synthesis after being subjected to stress. In turn, in this cultivar, no rise in polyamine synthesis was detected. Therefore, all the data appear to indicate that polyamine metabolism is more involved in the tolerance response to moderate water stress.

Role of GSH homeostasis under Zn toxicity in plants with different Zn tolerance

Tripepthide glutathione (GSH) is a pivotal molecule in tolerance to heavy metals, including Zinc (Zn). The aim of our work is to examine the role of GSH metabolism in two different horticultural plants under Zn toxicity in order to select and/or generate plants tolerant to Zn toxicity. We show a comparative analysis of the toxic effect of 0.5mM Zn between Lactuca sativa cv. Phillipus and Brassica oleracea cv. Bronco. In L. sativa the accumulation of Zn resulted in an increase in reactive oxygen species (ROS), while enzymes of GSH metabolism and the activities of the antioxidant enzymes were negatively affected. On the contrary, B. oleracea showed the existence of a detoxification mechanism of these ROS. Moreover, while in L. sativa increased the oxidized GSH (GSSG) and phytochelatins (PCs) concentration with the reduction of leaves biomass, in B. oleracea the higher concentration of reduced GSH and its use in the detoxification of ROS seems to be a major mechanism to provide tolerance to Zn toxicity without reducing leaf biomass. Our results suggested that under Zn toxicity, B. oleracea is more efficient and tolerant than L. sativa through the detoxification of lipid peroxidation products due to the reduced GSH.

Assessment of the abiotic and biotic effects of sodium metabisulphite pulses discharged from desalination plant chemical treatments on seagrass (Cymodocea nodosa) habitats in the Canary Islands

Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatments with sodium metabisulphite, which have potentially toxic effects to the environment for marine life, although no empirical and experimental evidence for this is yet available. The aim of this study was to characterise for the first time, the physico-chemical modification of the marine environment and its biological effects, caused by hypersaline plumes during these membrane cleaning treatments. The case study was the Maspalomas II desalination plant, located in the south of Gran Canaria (Canary Islands, Spain). Toxicity bioassays were performed on marine species characteristic for the infralittoral soft bottoms influenced by the brine plume (Synodus synodus and Cymodocea nodosa), and revealed a high sensitivity to short-term exposure to low sodium metabisulphite concentrations. The corrective measure of incorporating a diffusion system with Venturi Eductors reduced nearly all the areas of influence, virtually eliminating the impact of the disinfectant.

Beneficial effects of exogenous iodine in lettuce plants subjected to salinity stress

Salinity inhibits plant growth due to ionic and osmotic effects on metabolic processes and nutritional balance, leading to impaired physiological functions. Selenium (Se) and silicon (Si) can be partially alleviated by the effects wrought by NaCl on the plant metabolism. Iodine (I), applied as iodate (IO(3)(-)) in biofortification programmes, has been confirmed to improve the antioxidant response in lettuce plants. Thus, the aim of this study was to determine whether the application of IO(3)(-) can improve the response to severe salinity stress in lettuce (Lactuca sativa cv. Philipus). In this work, the application of IO(3)(-) (20-80 μM) in lettuce plants under salinity stress (100mM of NaCl) exerted a significantly positive effect on biomass and raised the levels of soluble sugars while lowering the Na(+) and Cl(-) concentrations as well as boosting the activity of antioxidant enzymes such as SOD, APX, DHAR and GR. Therefore, IO(3)(-) could be considered a possibly beneficial element to counteract the harmful effects of salinity stress.

Receptor screening technologies in the evaluation of Amazonian ethnomedicines with potential applications to cognitive deficits

ETHNOPHARMACOLOGICAL RELEVANCE

Amazonian peoples utilize a variety of psychoactive plants that may contain novel biologically active compounds. Efforts to investigate such remedies in terms of neuropharmacology have been limited.

AIM OF THIS STUDY

This study identified Amazonian ethnomedicines with potential for the treatment of cognitive deficits in schizophrenia and dementias, and characterized their interactions with CNS neurotransmitter receptors in vitro.

MATERIALS AND METHODS

Approximately 300 Amazonian species with folk uses or constituents indicative of central nervous system activity were incorporated into a database constructed from literature searches, herbarium surveys, and interviews with traditional practitioners. Approximately 130 of these targeted species were collected in Loreto province, Peru, and 228 fractions derived from them were screened in 31 radioreceptor assays via the resources of the NIMH Psychoactive Drug Screening Program. A subset was also screened in functional assays at selected serotonin, muscarinic, and adrenergic receptors.

RESULTS

Ninety-one samples displayed ≥60% inhibition of radioligand binding activity in receptor assays; 135 samples displayed agonist or antagonist activity (or both) in functional assays.

CONCLUSIONS

Potential CNS activity was detected in about 40% of the samples screened, with some correlations to both folk uses and phytochemical constituents. These results may point to novel and potentially therapeutic CNS active compounds.

The effect of environmental conditions on nutritional quality of cherry tomato fruits: evaluation of two experimental Mediterranean greenhouses

BACKGROUND

The aim of this study was to examine how different environmental factors (temperature, solar radiation, and vapour-pressure deficit [VPD]) influenced nutritional quality and flavour of cherry tomato fruits (Solanum lycopersicum L. cv. Naomi) grown in two types of experimental Mediterranean greenhouses: parral (low technology) and multispan (high technology).

RESULTS

Fruits were sampled three times during 3 years (2004, 2005 and 2006): at the beginning, middle and end of the fruit production period. Values for temperature, solar radiation, and VPD peaked in the third sampling in both greenhouses; values were higher in the parral-type greenhouse, triggering abiotic stress. This stress reduced the accumulation of lycopene and essential elements, augmenting the phytonutrient content and the antioxidant capacity of tomatoes. During the third sampling, sugars were increased while organic acid content diminished, producing tomatoes with a sweeter-milder flavour. The parral greenhouse produced tomatoes with higher phenolic compounds and ascorbic acid contents, together with a greater antioxidant capacity, without showing differences in flavour parameters.

CONCLUSION

The higher phytonutrients content and antioxidant activity during the environmental stress, more pronounced in parral than multispan greenhouse, together with the sweeter-milder flavour, conferred a notable nutritional benefit, which considerably improved the nutritional and organoleptic quality of these tomatoes.

Steric effects on alkyl cation affinities of maingroup-element hydrides

We have carried out an extensive exploration of gas-phase alkyl cation affinities (ACA) of archetypal anionic and neutral bases across the periodic system using zeroth order regular approximation-relativistic density functional theory at BP86/QZ4P//BP86/TZ2P. ACA values were computed for the methyl, ethyl, i-propyl and t-butyl cations and compared with the corresponding proton affinities (PA). One purpose of this work is to provide an intrinsically consistent set of values of the 298 K ACA of all anionic (XH (n-1)(-)) and neutral bases (XH(n)) constituted by maingroup-element hydrides of groups 14-17 and the noble gases (group 18) along the periods 1-6. Another purpose is to determine and rationalize the trend in affinity for a cation as the latter varies from proton to t-butyl cation. This undertaking is supported by quantitative bond energy decomposition analyses. Correlations are established between PA and ACA values.

[Holmium laser enucleation of the prostate. Experience in Hospital Germans Trias i Pujol]

OBJECTIVES

Evaluate the introduction of the enucleation with Holmium laser in our center, including the surgeon's learning curve by the analysis of the patients.

MATERIALS AND METHODS

150 procedures have been analyzed in a retrospective manner with an average follow-up of 11 months. Qmax, IPSS and Qol have been determined before surgery, at 6 months and 12 months, realizing their statistic analysis. PSA was measured before surgery and after 3 months. Complications, surgical time and hospital stay have been analyzed.

RESULTS

Average patient age was 72, 4 years. Average prostatic size was of 71,3 gr (18-150). Average hospital stay was of 22 h. Qmax before surgery, 6 months, 12 months was of 7,53 ml/s, 23,24 ml/s and 21,62 ml/s being statistically significant (p<0,01). Transfusion rate was of 1,3% and urethral stenosis rate of 4%. IPSS improvement at 6 and 12 months was statistically significant as well (p<0, 01).

CONCLUSIONS

Enucleation with Holmium laser is a safe and effective technique with lower complication rate than TURP, included during the learning curve.

Response of nitrogen metabolism in lettuce plants subjected to different doses and forms of selenium

BACKGROUND

Currently, biofortification programmes are being carried out with selenium (Se), since it is an essential element for humans and its ingestion depends partly on a vegetable diet, this not being so for plants. In this sense, few studies have tested the effect that Se has on some of the main plant metabolisms, such as nitrogen (N) metabolism. Thus the aim of this study was to establish the effect of the application of different doses (5, 10, 20, 40, 60, 80 and 120 micromol L(-1)) and forms (selenate and selenite) of Se on the reduction of nitrate (NO3-) and subsequent assimilation of ammonium (NH4+).

RESULTS

The results showed an increase in all enzyme activities analysed (nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase (GOGAT)), especially with application of the selenite form, in addition to a decline in foliar NO3- concentration.

CONCLUSION

Se applied in both forms increased N metabolism, with selenite inducing this physiological process more strongly, since it prompted a stronger activation of NR, GS and GOGAT as well as a greater concentration of total reduced N.