خيارات البحث
النتائج 1091 - 1100 من 4,042
Absence of selenium protection against methylmercury toxicity in harbour seal leucocytes in vitro النص الكامل
2016
Dāsa, Kr̥shṇā | Dupont, Aurélie | De Pauw-Gillet, Marie- Claire | Debier, Cathy | Siebert, Ursula
Absence of selenium protection against methylmercury toxicity in harbour seal leucocytes in vitro النص الكامل
2016
Dāsa, Kr̥shṇā | Dupont, Aurélie | De Pauw-Gillet, Marie- Claire | Debier, Cathy | Siebert, Ursula
Previous studies described high concentrations of mercury (Hg) and selenium (Se) in the blood of harbour seals, Phoca vitulina from the North Sea. In the present study, we evaluated the in vitro potential protective effects of sodium selenite (Na2SeO3) and selenomethionine (SeMet) on cell proliferation of harbour seal lymphocytes exposed to MeHgCl 0.75μM. In vitro exposure of ConA-stimulated T lymphocytes resulted in severe inhibition of DNA synthesis, likely linked to severe loss of mitochondrial membrane potential at 0.75μM. Neither selenite nor SeMet showed a protective effect against MeHg toxicity expressed at the T lymphocyte proliferation level for harbour seals. Selenite and SeMet did not show negative effects regarding lymphocyte proliferation and mitochondrial membrane potential.To conclude, our results clearly demonstrated that MeHg affected in vitro immune cells exposure with no protective effects of selenium at a molar ratio Hg:Se of 1:10 in harbour seals from the North Sea.
اظهر المزيد [+] اقل [-]Absence of selenium protection against methylmercury toxicity in harbour seal leucocytes in vitro النص الكامل
2016
Das, Krishna | Dupont, Aurélie | De Pauw-Gillet, Marie-Claire | Debier, Cathy | Siebert, Ursula | MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
peer reviewed | Previous studies described high concentrations of mercury (Hg) and selenium (Se) in the blood of harbour seals, Phoca vitulina from the North Sea. In the present study, we evaluated the in vitro potential protective effects of sodium selenite (Na2SeO3) and selenomethionine (SeMet) on cell proliferation of harbour seal lymphocytes exposed to MeHgCl 0.75 µM. In vitro exposure of ConA-stimulated T lymphocytes resulted in severe inhibition of DNA synthesis, likely linked to severe loss of mitochondrial membrane potential at 0.75 µM. Neither selenite nor SeMet showed a protective effect against MeHg toxicity expressed at the T lymphocyte proliferation level for harbour seals. Selenite and SeMet did not show negative effects regarding lymphocyte proliferation and mitochondrial membrane potential. To conclude, our results clearly demonstrated that MeHg affected in vitro immune cells exposure with no protective effects of selenium at a molar ratio Hg:Se of 1:10 in harbour seals from the North Sea.
اظهر المزيد [+] اقل [-]Plastic litter in sediments from a marine area likely to become protected (Aeolian Archipelago's islands, Tyrrhenian sea) النص الكامل
2016
Fastelli, Paolo | Blašković, Andrea | Bernardi, Giulia | Romeo, Teresa | Čižmek, Hrvoje | Andaloro, Franco | Russo, Giovanni F. | Guerranti, Cristiana | Renzi, Monia
This research aims to define for the first time levels and patterns of different litter groups (macro, meso and microplastics) in sediments from a marine area designed for the institution of a new marine protected area (Aeolian Archipelago, Italy). Microplastics resulted the principal group and found in all samples analyzed, with shape and colours variable between different sampling sites. MPs levels measured in this study are similar to values recorded in harbour sites and lower than reported in Adriatic Sea, while macroplastics levels are notably lower than in harbor sites. Sediment grain-size and island extent resulted not significant in determining levels and distribution of plastic debris among islands. In the future, following the establishment of the MPA in the study area, these basic data will be useful to check for potential protective effects on the levels and distribution of plastic debris.
اظهر المزيد [+] اقل [-]Reynolds number scaling to predict droplet size distribution in dispersed and undispersed subsurface oil releases النص الكامل
2016
Li, Pu | Weng, Linlu | Niu, Haibo | Robinson, Brian | King, Thomas | Conmy, Robyn | Lee, Kenneth | Liu, Lei
This study was aimed at testing the applicability of modified Weber number scaling with Alaska North Slope (ANS) crude oil, and developing a Reynolds number scaling approach for oil droplet size prediction for high viscosity oils. Dispersant to oil ratio and empirical coefficients were also quantified. Finally, a two-step Rosin-Rammler scheme was introduced for the determination of droplet size distribution. This new approach appeared more advantageous in avoiding the inconsistency in interfacial tension measurements, and consequently delivered concise droplet size prediction. Calculated and observed data correlated well based on Reynolds number scaling. The relation indicated that chemical dispersant played an important role in reducing the droplet size of ANS under different seasonal conditions. The proposed Reynolds number scaling and two-step Rosin-Rammler approaches provide a concise, reliable way to predict droplet size distribution, supporting decision making in chemical dispersant application during an offshore oil spill.
اظهر المزيد [+] اقل [-]Active biomonitoring of mussels Mytilus galloprovincialis with integrated use of micronucleus assay and physiological indices to assess harbor pollution النص الكامل
2016
Gherras Touahri, Hamida | Boutiba, Zitouni | Benguedda, Wacila | Shaposhnikov, Sergey
The mussels Mytilus galloprovincialis collected from a noncontaminated site (Chaib Rasso) were transplanted during one, three and six months at Ghazaouet harbor (GH), areas with a strong gradient of pollution. The micronucleus test (MN) was selected to monitor the impact of contamination, along with physiological indexes (condition index CI and organo-somatic indexes RI and GSI). The results show a negative correlation of MN variation in gill cells with CI but a positive correlation with transplantation duration. However, a significant correlation was found between the indexes. Moreover, the findings indicate that MN in the hemolymph and gills of transplanted mussels for one, three and six months at GH are significantly higher than those of the reference site. However, no significant differences were noted between the three transplants at the two organs. Monitoring the physiological status of mussels, in parallel with the biomarker measurements, is useful in assessing the impact of contaminants.
اظهر المزيد [+] اقل [-]The new Landsat 8 potential for remote sensing of colored dissolved organic matter (CDOM) النص الكامل
2016
Slonecker, E Terrence | Jones, Daniel K. | Pellerin, Brian A.
Due to a combination of factors, such as a new coastal/aerosol band and improved radiometric sensitivity of the Operational Land Imager aboard Landsat 8, the atmospherically-corrected Surface Reflectance product for Landsat data, and the growing availability of corrected fDOM data from U.S. Geological Survey gaging stations, moderate-resolution remote sensing of fDOM may now be achievable. This paper explores the background of previous efforts and shows preliminary examples of the remote sensing and data relationships between corrected fDOM and Landsat 8 reflectance values. Although preliminary results before and after Hurricane Sandy are encouraging, more research is needed to explore the full potential of Landsat 8 to continuously map fDOM in a number of water profiles.
اظهر المزيد [+] اقل [-]Environmental dynamics of red Noctiluca scintillans bloom in tropical coastal waters النص الكامل
2016
Baliarsingh, S.K. | Lotliker, Aneesh A. | Trainer, Vera L. | Wells, Mark L. | Parida, Chandanlal | Sahu, Biraja K. | Srichandan, Suchismita | Sahoo, Subhashree | Sahu, K.C. | Kumar, T Sinivasa
An intense bloom of red Noctiluca scintillans (NS) occurred off the Rushikulya estuarine region along the east coast of India, an important site for mass nesting events of the vulnerable Olive Ridley sea turtle. At its peak, densities of NS were 3.3×105 cells-l−1, with low relative abundance of other phytoplankton. The peak bloom coincided with high abundance of gelatinous planktivores which may have facilitated bloom development by their grazing on other zooplankton, particularly copepods. Ammonium concentrations increased by approximately 4-fold in the later stages of bloom, coincident with stable NS abundance and chlorophyll concentrations in the nano- and microplankton. This increase likely was attributable to release of intracellular ammonium accumulated through NS grazing. Dissolved oxygen concentrations decreased in sub-surface waters to near hypoxia. Micro-phytoplankton increasingly dominated chlorophyll-a biomass as the bloom declined, with diminishing picoplankton abundance likely the result of high predation by the ciliate Mesodinium rubrum. Together, these data illustrate factors that can disrupt ecosystem balance in this critically important Indian coastal region.
اظهر المزيد [+] اقل [-]Impact of prolonged storm activity on the Ecological Status of intertidal benthic habitats within oyster (Crassostrea gigas) trestle cultivation sites النص الكامل
2016
O'Carroll, Jack P.J. | Quinn, Christina | Forde, James | Patterson, Adrian | O'Beirn, Francis X. | Kennedy, Robert
The Ecological Status (ES; sensu the Water Framework Directive) of intertidal benthic communities within six oyster trestle cultivation sites was found to be negatively impacted along the access routes to trestles in a 2013 study. All cultivation sites occur within Natura 2000 sites.The current study revisited four of the 2013 cultivation sites in February 2014 one month after the storm activity of winter 2013/14 to test if the compaction effect along access routes persisted after the storms.Three levels of the fixed factor treatment were sampled; immediately below the trestles, along the access route and 300m away from any anthropogenic activity.The compaction effect at the Access treatment persisted in spite of the major storm activity. The current study showed the IQI to be effective for assessing the impacts of aquaculture and highlights the IQI as a tool for monitoring Conservation Status of intertidal communities under the Habitats Directive.
اظهر المزيد [+] اقل [-]Suspended particulate matter fluxes along with their associated metals, organic matter and carbonates in a coastal Mediterranean area affected by mining activities النص الكامل
2016
Helali, Mohamed Amine | Zaaboub, Noureddine | Oueslati, Walid | Added, Ayed | Aleya, Lotfi
A study of suspended particulate matter (SPM) fluxes along with their associated metals, organic matter and carbonates, was conducted off the Mejerda River outlet in May 2011 and in March and July 2012 at depths of 10, 20 and 40m using sediment traps. SPM fluxes are more significant near the Mejerda outlet, especially in winter, but dissipate further offshore. Normalization reveals that the Mejerda is a major source of Pb, Zn, Cd, Cu, Ni, and Co, all of which are the result of human activities. In contrast, Fe, Mn and N are of authigenic origin. The enrichment factor shows that Pb, Zn and especially Cd are the most highly polluting metals off the Mejerda outlet. This confirms the trend observed on the shores of the Mejerda prodelta and is consistent with the type of mining activities conducted in the Mejerda catchment.
اظهر المزيد [+] اقل [-]Direct evidences on bacterial growth pattern regulating pyrene degradation pathway and genotypic dioxygenase expression النص الكامل
2016
Chen, Baowei | Huang, Jinyin | Yuan, Ke | Lin, Li | Wang, Xiaowei | Yang, Lihua | Luan, Tiangang
Pyrene degradation by Mycobacterium sp. strain A1-PYR was investigated in the presence of nutrient broth, phenanthrene and fluoranthene, respectively. Fast bacterial growth in the nutrient broth considerably enhanced pyrene degradation rate, whereas degradation efficiency per cell was substantially decreased. The addition of nutrient broth could not alter the transcription levels of all dioxygenase genotypes. In the PAH-only substrates, bacterial growth completely relied on biological conversion of PAHs into the effective carbon sources, which led to a higher degradation efficiency of pyrene per cell than the case of nutrient broth. Significant correlations were only observed between nidA-related dioxygenase expression and pyrene degradation or bacterial growth. The highest pyrene degradation rate in the presence of phenanthrene was consistent with the highest transcription level of nidA and 4,5-pyrenediol as the sole initial metabolite. This study reveals that bacterial growth requirement can invigorate degradation of PAHs by regulating metabolic pathway and genotypic enzyme expression.
اظهر المزيد [+] اقل [-]Under pressure: Investigating marine resource-based livelihoods in Jakarta Bay and the Thousand Islands النص الكامل
2016
Baum, Gunilla | Kusumanti, Ima | Breckwoldt, Annette | Ferse, Sebastian C.A. | Glaser, Marion | Dwiyitno, | Adrianto, Luky | van der Wulp, Simon | Kunzmann, Andreas
Jakarta Bay, next to the Jakarta Metropolitan Area with around 30 million inhabitants, is facing extreme pollution. Although local coral reefs are degraded and marine resources heavily exploited, they provide livelihoods for millions of people. This study investigates anthropogenic pressures on local fisheries resources and associated livelihoods. Questionnaire surveys were conducted in 15 coastal communities (10 coastal neighborhoods in Jakarta Bay on the mainland and 5 of the offshore Thousand Islands). The most economically valuable species were Caesio cuning (Redbelly yellowtail fusilier) on the islands and Rastrelliger kanagurta (Indian mackerel) on the mainland. Over 80% of all interviewed fishermen regarded the current state of marine resources as declining, mainly due to pollution and overexploitation. While perceptions of declining resources were equally high on the islands and the mainland, pollution was listed as the principal cause of degradation significantly more on the mainland. Findings are discussed in the context of coastal livelihood vulnerability.
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