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Resultados 1331-1340 de 5,098
Interactive responses of primary producers and grazers to pollution on temperate rocky reefs
2018
Fowles, Amelia E. | Stuart-Smith, Rick D. | Hill, Nicole A. | Thomson, Russell J. | Strain, Elisabeth M.A. | Alexander, Timothy J. | Kirkpatrick, James | Edgar, Graham J.
Macroalgal beds provide important habitat structure and support primary production for rocky reef communities, but are increasingly degraded as a result of human pressures. Various sources of pollution can have both direct and interactive effects on stressed ecosystems. In particular, interactions involving invertebrate grazers could potentially weaken or strengthen the overall impact of pollution on macroalgal beds. Using a paired impact-control experimental design, we tested the effects of multiple pollution sources (fish farms, marinas, sewerage, and stormwater) on translocated and locally established algal assemblages, while also considering the influence of invertebrate grazers. Marinas directly affected algal assemblages and also reduced densities of amphipods and other invertebrate mesograzers. Fish farms and sewerage outfalls tended to directly increase local establishment of foliose and leathery algae without any indication of changes in herbivory. Overall, pollution impacts on algae did not appear to be strongly mediated by changes in grazer abundance. Instead, mesograzer abundance was closely linked to availability of more complex algal forms, with populations likely to decline concurrently with loss of complex algal habitats. Macrograzers, such as sea urchins, showed no signs of a negative impact from any pollution source; hence, the influence of this group on algal dynamics is probably persistent and independent of moderate pollution levels, potentially adding to the direct impacts of pollution on algal beds in urbanised environments.
Mostrar más [+] Menos [-]OTA induces intestinal epithelial barrier dysfunction and tight junction disruption in IPEC-J2 cells through ROS/Ca2+-mediated MLCK activation
2018
Wang, Hong | Zhai, Nianhui | Chen, Ying | Fu, Chongyang | Huang, Kehe
Ochratoxin A (OTA) is a frequent contaminant of feed and food worldwide. The toxicity of OTA on intestinal barrier was investigated in porcine intestinal epithelial cells (IPEC-J2). We observed that OTA induced intestinal barrier dysfunction as indicated by the reduction in transepithelial electrical resistance (TEER) and elevation in paracellular permeability to 4 kDa dextran. The barrier dysfunction was accompanied with tight junction disruption including a down-regulation in ZO-1 expression and redistribution of Occludin and ZO-1. Moreover, OTA exposure increased reactive oxygen species (ROS) generation, elevated the intracellular calcium level ([Ca²⁺]c) and activated myosin light chain kinase (MLCK). Simultaneously, NAC, a ROS scavenger, blocked OTA-induced ROS generation, [Ca²⁺]c elevation, barrier dysfunction and tight junction disruption, suggesting that OTA-induced ROS generation may act as a trigger. Next, we found that OTA-induced MLCK activation was inhibited by BAPTA-AM, the cytosolic Ca²⁺ chelator, demonstrating that OTA-induced MLCK activation is dependent on [Ca²⁺]c elevation. Furthermore, inhibition of MLCK with ML-7 or inhibition of [Ca²⁺]c elevation with BAPTA-AM markedly prevented OTA-induced barrier dysfunction and tight junction disruption. Taken together, our results indicated that OTA induces ROS generation, and then elevates the [Ca²⁺]c and MLCK activity in turn, which finally induces barrier dysfunction and disrupts tight junction in IPEC-J2 cell monolayers.
Mostrar más [+] Menos [-]Occurrence of tetrabromobisphenol a (TBBPA) and hexabromocyclododecane (HBCD) in soil and road dust in Chongqing, western China, with emphasis on diastereoisomer profiles, particle size distribution, and human exposure
2018
Lu, Jun-Feng | He, Ming-Jing | Yang, Zhi-Hao | Wei, Shi-Qiang
Currently, the HBCDs were listed in Annex A by the Stockholm Convention, and the knowledge on the contamination of TBBPA and HBCDs in soil and road dust in China is still limited, and it is unclear what role is played by dust particle size distribution. In this study, a total of 81 soil and 43 road dust samples were analyzed with TBBPA and ΣHBCDs concentrations ranging from < LOQ to 33.8 ng/g dw (dry weight) and 0.43–15.2 ng/g dw in soil, and from < LOQ to 74.1 ng/g dw and 7.25–14.0 ng/g dw in road dust, respectively. TBBPA and HBCDs exhibited different spatial distribution patterns in soil, where relatively high levels of HBCDs were found in industrial area and commercial area, while high levels of TBBPA were detceted in residential area. However, no distinct variation in spatial distribution of these two compounds was observed in road dust. Different diastereoisomer profiles of HBCDs were also found with γ-HBCD predominating in soil and α-HBCD occupying a large proportion in road dust. The α-/γ-HBCD values in road dust were significantly greater (T-test, P < 0.05) than those in soil, which suggested that γ-HBCD in road dust were likely to transform into α-HBCD compared with soil. The distribution of dust particle size showed that HBCDs levels were increasing with the decreasing in particle sizes, while the TBBPA showed some “accidental” peak values in specific diameter ranges. The estimated daily intakes (EDIs) of TBBPA and HBCDs were assessed through dust ingestion, dermal absorption and inhalation via road dust, and all the exposure estimates were well below the reference dose (RfD), but the toddlers were more vulnerable to TBBPA and HBCDs intakes, which should be paid more attention.
Mostrar más [+] Menos [-]Effects of arbuscular mycorrhizal symbiosis on growth, nutrient and metal uptake by maize seedlings (Zea mays L.) grown in soils spiked with Lanthanum and Cadmium
2018
Chang, Qing | Diao, Feng-wei | Wang, Qi-fan | Pan, Liang | Dang, Zhen-hua | Guo, Wei
Multiple contaminants can affect plant-microbial remediation processes because of their interactive effects on environmental behaviour, bioavailability and plant growth. Recent studies have suggested that arbuscular mycorrhizal fungi (AMF) can facilitate the revegetation of soils co-contaminated with rare earth elements (REEs) and heavy metals. However, little is known regarding the role of AMF in the interaction of REEs and heavy metals. A pot experiment was conducted to evaluate the effects of Claroideoglomus etunicatum on the biomass, nutrient uptake, metal uptake and translocation of maize grown in soils spiked with Lanthanum (La) and Cadmium (Cd). The results indicated that individual and combined applications of La (100 mg kg−1) and Cd (5 mg kg−1) significantly decreased root colonization rates by 22.0%–35.0%. With AMF inoculation, dual-metal treatment significantly increased maize biomass by 26.2% compared to single-metal treatment. Dual-metal treatment significantly increased N, P and K uptake by 20.1%–76.8% compared to single-metal treatment. Dual-metal treatment significantly decreased shoot La concentration by 52.9% compared to single La treatment, whereas AM symbiosis caused a greater decrease of 87.8%. Dual-metal treatment significantly increased shoot and root Cd concentrations by 65.5% and 58.7% compared to single Cd treatment and the La translocation rate by 142.0% compared to single La treatment, whereas no difference was observed between their corresponding treatments with AMF inoculation. Furthermore, AMF had differential effects on the interaction of La and Cd on metal uptake and translocation under the background concentrations of soil metals. Taken together, these results indicated that AMF significantly affected the interaction between La and Cd, depending on metal types and concentrations in soils. These findings promote a further understanding of the contributions of AMF to the phytoremediation of co-contaminated soil.
Mostrar más [+] Menos [-]Dose-dependent transcriptomic responses of zebrafish eleutheroembryos to Bisphenol A
2018
Martínez, Rubén | Esteve-Codina, Anna | Herrero-Nogareda, Laia | Ortiz-Villanueva, Elena | Barata, Carlos | Tauler, Romà | Raldúa, Demetrio | Piña, Benjamin | Navarro-Martín, Laia
Despite the abundant literature on the adverse effects of Bisphenol A (BPA) as endocrine disruptor, its toxicity mechanisms are still poorly understood. We present here a study of its effects on the zebrafish eleutheroembryo transcriptome at concentrations ranging from 0.1 to 4 mg L⁻¹, this latter representing the lowest observed effect concentration (LOEC) found in our study at three different macroscopical endpoints (survival, hatching and swim bladder inflation). Multivariate data analysis methods identified both monotonic and bi-phasic patterns of dose-dependent responses. Functional analyses of genes affected by BPA exposure suggest an interaction of BPA with different signaling pathways, being the estrogenic and retinoid receptors two likely targets. In addition, we identified an apparently unrelated inhibitory effect on, among others, visual function genes. We interpret our data as the result of a sum of underlying, independent molecular mechanisms occurring simultaneously at the exposed animals, well below the macroscopic LOEC, but related to at least some of the observed morphological alterations, particularly in eye size and yolk sac resorption. Our data supports the idea that the physiological effects of BPA cannot be only explained by its rather weak interaction with the estrogen receptor, and that multivariate analyses are required to analyze the effects of toxicants like BPA, which interact with different cellular targets producing complex phenotypes.
Mostrar más [+] Menos [-]Impact of cold temperature on Euro 6 passenger car emissions
2018
Suarez-Bertoa, Ricardo | Astorga, Covadonga
Hydrocarbons, CO, NOx, NH₃, N₂O, CO₂ and particulate matter emissions affect air quality, global warming and human health. Transport sector is an important source of these pollutants and high pollution episodes are often experienced during the cold season. However, EU vehicle emissions regulation at cold ambient temperature only addresses hydrocarbons and CO vehicular emissions. For that reason, we have studied the impact that cold ambient temperatures have on Euro 6 diesel and spark ignition (including: gasoline, ethanol flex-fuel and hybrid vehicles) vehicle emissions using the World-harmonized Light-duty Test Cycle (WLTC) at −7 °C and 23 °C. Results indicate that when facing the WLTC at 23 °C the tested vehicles present emissions below the values set for type approval of Euro 6 vehicles (still using NEDC), with the exception of NOx emissions from diesel vehicles that were 2.3–6 times higher than Euro 6 standards. However, emissions disproportionally increased when vehicles were tested at cold ambient temperature (−7 °C). High solid particle number (SPN) emissions (>1 × 10¹¹ # km⁻¹) were measured from gasoline direct injection (GDI) vehicles and gasoline port fuel injection vehicles. However, only diesel and GDI SPN emissions are currently regulated. Results show the need for a new, technology independent, procedure that enables the authorities to assess pollutant emissions from vehicles at cold ambient temperatures.Harmful pollutant emissions from spark ignition and diesel vehicles are strongly and negatively affected by cold ambient temperatures. Only hydrocarbon, CO emissions are currently regulated at cold temperature. Therefore, it is of great importance to revise current EU winter vehicle emissions regulation.
Mostrar más [+] Menos [-]Bioavailability and uptake of smelter emissions in freshwater zooplankton in northeastern Washington, USA lakes using Pb isotope analysis and trace metal concentrations
2018
Child, A.W. | Moore, B.C. | Vervoort, J.D. | Beutel, M.W.
The upper Columbia River and associated valley systems are highly contaminated with metal wastes from nearby smelting operations in Trail, British Columbia, Canada (Teck smelter), and to a lesser extent, Northport, Washington, USA (Le Roi smelter). Previous studies have investigated depositional patterns of airborne emissions from these smelters, and documented the Teck smelter as the primary metal contamination source. However, there is limited research directed at whether these contaminants are bioavailable to aquatic organisms. This study investigates whether smelter derived contaminants are bioavailable to freshwater zooplankton. Trace metal (Zn, Cd, As, Sb, Pb and Hg) concentrations and Pb isotope compositions of zooplankton and sediment were measured in lakes ranging from 17 to 144 km downwind of the Teck smelter. Pb isotopic compositions of historic ores used by both smelters are uniquely less radiogenic than local geologic formations, so when zooplankton assimilate substantial amounts of smelter derived metals their compositions deviate from local baseline compositions toward ore compositions. Sediment metal concentrations and Pb isotope compositions in sediment follow significant (p < 0.001) negative exponential and sigmoidal patterns, respectively, as distance from the Teck smelting operation increases. Zooplankton As, Cd, and Sb contents were related to distance from the Teck smelter (p < 0.05), and zooplankton Pb isotope compositions suggest As, Cd, Sb and Pb from historic and current smelter emissions are biologically available to zooplankton. Zooplankton from lakes within 86 km of the Teck facility display isotopic evidence that legacy ore pollution is biologically available for assimilation. However, without water column data our study is unable to determine if legacy contaminants are remobilized from lake sediments, or erosional pathways from the watershed.
Mostrar más [+] Menos [-]Linking the contents of hydrophobic PAHs with the canopy water storage capacity of coniferous trees
2018
Anna, Klamerus-Iwan | Emanuel, Gloor | Anna, Sadowska-Rociek | Błońska, Ewa | Lasota, Jarosław | Łagan, Sylwia
The canopy water storage capacity (S) is an important parameter for the hydrological cycle in forests. One factor which influences the S is leaf texture, which in turn is thought to be affected by the contents of polycyclic aromatic hydrocarbons (PAHs). In order to improve our understanding of S we simulated rainfall and measured the S of coniferous species growing under various conditions. The contents of 18 PAHs were measured in the needles. The species chosen were: Scots pine (Pinus sylvestris L), Norway spruce (Picea abies (L.) H. Karst) and silver fir (Abies Alba Mill.). Sample branches were collected in 3 locations: A - forest; B - housing estate; C - city center. We found that PAHs have a significant impact on the S of tree crowns. The increase in the total content of all of polycyclic aromatic hydrocarbons (SUM.PAH) translates into an increase of S for all species. The S is the highest for the P. abies species, followed by P. sylvestris and A. alba at all locations. Within the same species, an increase in the value of S is associated with an increase in the PAH content in needles measured by gas chromatography. For A.alba, the average S increased from 11.54% of the total amount of simulated rain (ml g⁻¹) at location A, to 17.10% at location B, and 21.02% at location C. Similarly for P. abies the S was 21.78%, 29.06% and 34.36% at locations A, B and C respectively.The study extends the knowledge of the mechanisms of plant surface adhesion and the anthropogenic factors that may modify this process as well as foliage properties.
Mostrar más [+] Menos [-]Increased risk of phthalates exposure for recurrent pregnancy loss in reproductive-aged women
2018
Liao, Kai-Wei | Guo, Baolin | Huang, Han-Bin | Chang, Jung-Wei | Chiang, Hung-Che | Huang, Po-Chin
Recurrent pregnancy loss (RPL) is the termination of pregnancies, usually before 20 weeks of gestation, and is defined as the loss of two or more pregnancies. In Taiwan, after 2011 di-2-ethylhexyl phthalate (DEHP) exposure episode, more reproductive-aged women still expose to high levels of DEHP and di-butyl phthalate (DBP) than have women of other age groups. Phthalates might be involved in the RPL pathogenesis. This study assessed the association of phthalate exposure with RPL risk in reproductive-aged Taiwanese women.This study recruited 103 patients diagnosed by a physician with RPL of unknown etiology and 76 controls from the Department of Obstetrics and Gynecology at a medical center in southern Taiwan between August 2013 and August 2017. Urine samples were analyzed for 11 phthalate metabolites through liquid chromatography–tandem mass spectrometry; subsequently, principal component analysis (PCA) and hierarchical clustering analysis were performed to determine the main sources of phthalate exposure. Finally, multivariate logistic regression was used to determine the RPL risk.The creatinine-unadjusted median levels of mono-iso-butyl phthalate (MiBP), mono-n-butyl phthalate (MnBP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) in RPL/control were 9.8/5.3, 27.2/13.1, 11.4/8.1, and 12.9/9.5 ng/mL, respectively; furthermore, ΣDBPm and ΣDEHPm in RPL/control were 0.18/0.10 and 0.15/0.12 nmol/mL, respectively. PCA revealed three primary components of phthalate exposure: diethyl phthalates (DEP), DEHP, and DBP. Plastic food container use and medication were identified as the main phthalate exposure sources. After adjustment for potential confounding factors (urinary creatinine, age, age at menarche, education, and plastic food container use), we found that the urinary level of ΣDBPm was significantly associated with elevated risk for RPL (OR = 2.85, p = 0.045).Our findings supported the hypothesis that exposure to phthalates increases RPL risk. The development of a strategy to reduce phthalate exposure among reproductive-aged women should be emphasized.
Mostrar más [+] Menos [-]Contaminants of emerging concern presence and adverse effects in fish: A case study in the Laurentian Great Lakes
2018
Jorgenson, Zachary G. | Thomas, Linnea M. | Elliott, Sarah M. | Cavallin, Jenna E. | Randolph, Eric C. | Choy, Steven J. | Alvarez, David A. | Banda, Jo A. | Gefell, Daniel J. | Lee, K. E. (Kathy E.) | Furlong, Edward T. | Schoenfuss, Heiko L.
The Laurentian Great Lakes are a valuable natural resource that is affected by contaminants of emerging concern (CECs), including sex steroid hormones, personal care products, pharmaceuticals, industrial chemicals, and new generation pesticides. However, little is known about the fate and biological effects of CECs in tributaries to the Great Lakes. In the current study, 16 sites on three rivers in the Great Lakes basin (Fox, Cuyahoga, and Raquette Rivers) were assessed for CEC presence using polar organic chemical integrative samplers (POCIS) and grab water samplers. Biological activity was assessed through a combination of in vitro bioassays (focused on estrogenic activity) and in vivo assays with larval fathead minnows. In addition, resident sunfish, largemouth bass, and white suckers were assessed for changes in biological endpoints associated with CEC exposure. CECs were present in all water samples and POCIS extracts. A total of 111 and 97 chemicals were detected in at least one water sample and POCIS extract, respectively. Known estrogenic chemicals were detected in water samples at all 16 sites and in POCIS extracts at 13 sites. Most sites elicited estrogenic activity in bioassays. Ranking sites and rivers based on water chemistry, POCIS chemistry, or total in vitro estrogenicity produced comparable patterns with the Cuyahoga River ranking as most and the Raquette River as least affected by CECs. Changes in biological responses grouped according to physiological processes, and differed between species but not sex. The Fox and Cuyahoga Rivers often had significantly different patterns in biological response Our study supports the need for multiple lines of evidence and provides a framework to assess CEC presence and effects in fish in the Laurentian Great Lakes basin.
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