Distribution of PAHs and trace elements in Spartina densiflora and associated sediments from low to highly contaminated South American estuarine saltmarshes.

Estuarine saltmarshes from South America are exposed to several anthropogenic impacts due to diverse human activities that occur in both Atlantic/Pacific coastal environments. Primarily, chemical and petrochemical industries negatively impact saltmarshes generating inputs/deposition of non-essential trace elements (NTEs) and polycyclic aromatic hydrocarbons (PAHs) in sediments. The native cordgrass Spartina densiflora inhabits a wide range of environments, from non-impacted to highly impacted areas. It is important to know its performance towards pollution in different environmental settings in South America. The content of Cd, Hg, Pb, and PAHs was determined in the roots and leaves of S. densiflora, bulk sediments (Bs), and rhizosediments (Rs) of estuaries from Argentina, Brazil, and Chile. Differences in NTEs and PAHs levels were observed between Bs, Rs, and Spartina tissues from different saltmarsh areas. Differences in Rs/Bs (RHICF; rhizosediments concentration factors), roots/Bs (RCF; roots concentration factors) and leaves/roots (TF; translocation factors) factors were also found. In terms of NTEs, S. densiflora showed a high capability to increase levels in their Rs (RHICF>1) and bioconcentrate Cd in roots (RCF > 1), while no general translocation (TF < 1) was observed. Conversely, in cordgrass tissues, Bs and Rs, PAHs contents showed RCF and TF > 1, which was in line with lower levels in Rs related to Bs (RHICF<1) in most sites. These findings showed the S. densiflora capacity to retain, remove and/or translocate priority contaminants depending on intrinsic chemical characteristics and the level of contamination. The present study enables future considerations regarding the biomonitoring and phytoremediation/stabilization capabilities of Spartina in coastal environments.

Effect of biological and anthropogenic habitat sounds on oxidative stress biomarkers and behavior in a key crab species.

Soundscapes are characterized by a combination of natural and anthropogenic sounds. This study evaluated the stress effect of biological and anthropogenic sounds characterizing a Man and Biosphere UNESCO wetland, by assessing the protein content, oxidative biomarkers, and behavior of a key crab species (Neohelice granulata), through a tank-laboratory experiment. Biological sounds corresponded to predators of N. granulata (fish and crustacean stimuli), while anthropogenic ones belonged to motorboat passages (boat stimulus). Biochemical results showed differences depending on the sound stimuli used and the crab tissue analyzed. Protein content was higher in hemolymph when crabs were exposed to fish and boat stimuli, and in gills when exposed to boat stimulus. The enzymatic activity in hemolymph showed a decreased GST (fish stimulus) and CAT (fish and boat stimuli) activity, in hepatopancreas a higher GST (crustacean stimulus) and CAT (crustacean and boat stimuli) activity was found, and in gills a higher CAT activity was also observed (crustacean and boat stimuli). Lipid peroxidation was higher only in hemolymph (fish and crustacean stimuli). Protein oxidation was higher in gills (fish stimulus) and hepatopancreas (crustacean stimulus). Behavioral analysis demonstrated that the crab locomotion activity diminished when exposed to diverse sound stimuli. Thus, both sound sources caused physiological and behavioral stress in this species. The results contribute important data to be used in the development of management plans considering the habitat importance in terms of biodiversity, the ecosystem services provided and the role of the studied species.

Spatial and temporal distribution of Persistent Organic Pollutants and current use pesticides in the atmosphere of Argentinean Patagonia.

XAD-based passive air samplers (PAS) were used to evaluate organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and some current use pesticides (chlorotalonil, trifluralin and dichlofluanid) in the atmosphere of Argentinian Patagonia. The PAS were deployed for 12 months during three consecutive years along a longitudinal (Rio Negro watershed) and a latitudinal (Patagonian coast) transect. Endosulfan, trifluralin and DDT-related substances were the most prevalent pesticides in the Rio Negro watershed, an intensive agricultural basin, consistent with ongoing use of endosulfan at the time of sampling. Concentrations of industrial contaminants were low (mean 25 pg/m3 and 1.9 pg/m3 for Σ38 PCBs, and Σ5PBDEs, respectively) and similar among sites. However, along the Patagonian coast, air concentrations of total contaminants were highly variable (14-400 pg/m3) with highest values recorded at Bahia Blanca, an important industrial area that is also downwind of the most intensively agriculturally used area of Argentina. Contaminant levels decreased toward the south, with the exception of the southernmost sampling site (Rio Gallegos) where a slight increase of total pollutant levels was observed, mainly due to the lower chlorinated PCB congeners. Interannual variability was small, although the last year tended to have slightly higher levels for different contaminant groups at most sampling sites. This large-scale spatial atmospheric monitoring of POPs and some CUPs in the South of Argentina highlights the important and continuing role of rural and urban areas as emission sources of these chemicals.

Impacts of dietary supplementation with p-coumaric acid and indole-3-acetic acid on survival and biochemical response of honey bees treated with tau-fluvalinate.

Pollinator populations are in decline worldwide. Multiple factors have been cited as potential causes to these declines. In honey bees, a combination of stressors is known to cause colony losses. Adequate nutrition is a key factor for honey bee growth and colony development. Several studies show that the nutritional quality of the diet is directly proportional to the ability of the bee to face challenges or stressors. We explored the effect of p-coumaric (600 µM) and indole-3-acetic acid (2, 20 or 200 µM) supplementation on the survival and activity of key detoxification enzymes of honey bees exposed to tau-fluvalinate. The dietary supplementation with p-coumaric and indole-3-acetic acids (20 µM) enhanced the survival of bees exposed to tau-fluvalinate (approximately 20%). We also showed that dietary p-coumaric acid increased the levels of cytochrome P450 and glutathione reductase activity in bees treated with tau-fluvalinate, as well as in the untreated controls, while glutathione-S-transferase activity was lower in treated bees than in untreated. In bees fed with indole-3-acetic acid, cytochrome P450 showed increased levels, however, glutathione-S-transferase showed the lowest activity. Moreover, the results showed that supplementation with p-coumaric and indole-3-acetic acids did not alter acetyl cholinesterase activity, nor did treatment with tau-fluvalinate. Altogether, the enzymatic changes related to the detoxification mechanisms observed in bees that were fed with p-coumaric and indole-3-acetic acids could be responsible for the increased survival of bees treated with tau-fluvalinate compared to those that received a control diet. The results presented in this study, together with previous studies, provide evidence of the importance of dietary phytochemicals in the response of honey bees to pesticide exposure. Moreover, these results are the first report of the beneficial effect of the phytohormone indole-3-acetic acid on the survival of honey bees treated with tau-fluvalinate.

DDTs-induced antioxidant responses in plants and their influence on phytoremediation process.

Phytoremediation is a low cost technology based on the use of plants to remove a wide range of pollutants from the environment, including the insecticide DDT. However, some pollutants are known to enhance generation of reactive oxygen species (ROS), which can generate toxic effects on plants affecting the phytoremediation efficiency. This study aims to analyze the potential use of antioxidant responses as a measure of tolerance to select plants for phytoremediation purposes. Tomato and zucchini plants were grown for 15 days in soils contaminated with DDTs (DDT + DDE + DDD). Protein content, glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and catalase (CAT) activities were measured in plant tissues. Exposure to DDTs did not affect protein content or CAT activity in any of the species. GST, GR and GPx activity showed different responses in exposed and control tomato plants. After DDTs exposure, tomato showed increased GR and GPX activity in stems and leaves, respectively, and a decrease in the GST activity in roots. As no effects were observed in zucchini, results suggest different susceptibility and/or defense mechanisms involved after pesticide exposure. Finally, both species differed also in terms of DDTs uptake and translocation. The knowledge about antioxidant responses induced by pesticides exposure could be helpful for planning phytoremediation strategies and for the selection of tolerant species according to particular scenarios.

Antioxidant responses in soybean and alfalfa plants grown in DDTs contaminated soils: Useful variables for selecting plants for soil phytoremediation?

Phytoremediation is a low-cost alternative technology based on the use of plants to remove pollutants from the environment. Persistent organic pollutants such as DDTs with a long half-life in soils are attractive candidates for remediation. This study aimed to determine the potential of antioxidant response use in the evaluation of plants' tolerance for selecting species in phytoremediation purposes. Alfalfa and soybean plants were grown in DDT contaminated soils. After 60days, growth, protein content, antioxidant capacity, GST activity, concentration of proteic and non-proteic thiol groups, chlorophyll content and carotenoid content were measured in plant tissues. Results showed no effect on alfalfa or soybean photosynthetic pigments but different responses in the protein content, antioxidant capacity, GST activity and thiol groups on roots, stems and leaves, indicating that DDTs affected both species. Soybean showed higher susceptibility than alfalfa plants due to the lower antioxidant capacity and GST activity in leaves, in spite of having the lowest DDT accumulation. This study provides new insights into the role of oxidative stress as an important component of the plant's response to DDT exposure.

Potential use of edible crops in the phytoremediation of endosulfan residues in soil.

Endosulfan is a persistent and toxic organochlorine pesticide of banned or restricted use in several countries. It has been found in soil, water, and air and is bioaccumulated and magnified in ecosystems. Phytoremediation is a technology that promises effective and inexpensive cleanup of contaminated hazardous sites. The potential use of tomato, sunflower, soybean and alfalfa species to remove endosulfan from soil was investigated. All species were seeded and grown in endosulfan-spiked soils (8000 ng g(-1) dry weight) for 15 and 60 days. The phytoremediation potential was evaluated by studying the endosulfan levels and distribution in the soil-plant system, including the evaluation of soil dehydrogenase activity and toxic effects on plants. Plant endosulfan uptake leads to lower insecticide levels in the rhizosphere with regards to bulk soil or near root soil at 15 days of growth. Furthermore, plant growth-induced physical-chemical changes in soil were evidenced by differences in soil dehydrogenase activity and endosulfan metabolism. Sunflower showed differences in the uptake and distribution of endosulfan with regard to the other species, with a distribution pesticide pattern of aerial tissues > roots at 15 days of growth. Moreover, at 60 days, sunflower presented the highest pesticide levels in roots and leaves along with the highest phytoextraction capacity. Lipid peroxidation levels correlated positively with endosulfan accumulation, reflecting the negative effect of this insecticide on plant tissues. Considering biomass production and accumulation potential, in conjunction with the reduction of soil pesticide levels, sunflower plants seem to be the best phytoremediation candidate for endosulfan residues in soils.

Effects of amendments on soil availability and phytoremediation potential of aged p,p'-DDT, p,p'-DDE and p,p'-DDD residues by willow plants (Salix sp.).

Combining technologies offer a great potential to phytoremediate contaminated soils. As sequestration occurs, pollutants availability decline and organic amendments could counterbalance that situation. This work studies the potential of willow plants to phytoremediate soil containing p,p'-DDT (101.3 ng g(-1)) and p,p'-DDE (381.4 ng g(-1)) residues. The effect of root exudates, Tween 80 and citric and oxalic acids on DDTs desorption and availability from soil was tested together with the plant uptake and translocation. Treatments increased the p,p'-DDE/p,p'-DDT ratio when compared with control (water) soil. Watering with carboxylic acids led to a significant enhancement of the quantities of p,p'-DDT and p,p'-DDE desorbed from soil that was related with an increase of organic carbon in solution. Willow plants accumulated DDTs under all treatments although plants watered with carboxylic acids showed the highest leaves translocation factor for both p,p'-DDT and p,p'-DDE. Results indicate that the addition of carboxylic acids enhanced DDTs bioavailability which further increases plant uptake and translocation. The effect of surfactants on the soil-plant systems needs to be better assessed for this particular soil and plant species. The enhancement of soluble organic carbon is crucial at the moment of evaluating DDTs release from soil as well as to establish cleaning strategies.

Phloem sap of tomato plants contains a DIR1 putative ortholog.

Arabidopsis thaliana defective in induced resistance 1 (At-DIR1) has been characterized as a protein responsible for the generation or transmission of the still unknown signal involved in systemic acquired resistance. This acidic apoplastic protein is a member of the family of lipid transfer proteins and was detected in vascular fluids. To our knowledge, no DIR1-like protein has been described in other plant species. Hence, we have performed data mining to identify a putative ortholog of DIR1 in tomato. This strategy allowed the detection of a few gene products displaying sequence similarity to At-DIR1 whose structural features were further analysed in silico. The best match (unigene SGN-327306) encoded a protein with an acidic pI, a peculiar characteristic of DIR1 among lipid transfer proteins, and was hence selected as a putative tomato ortholog of At-DIR1. This sequence, named Le-DIR1, served for the design of a specific antigenic peptide and the generation of polyclonal antibodies. The antiserum anti-Le-DIR1 recognized a peptide of the expected size (7kDa) in phloem sap of tomato plants, hence confirming the existence of the predicted protein in vascular fluids. This result supports the notion of the existence of common systemic acquired resistance (SAR) signaling molecules in different species.