خيارات البحث
النتائج 431 - 440 من 3,208
Transgenerational inheritance of heart disorders caused by paternal bisphenol A exposure النص الكامل
2015
Lombó, Marta | Fernández-Díez, Cristina | González-Rojo, Silvia | Navarro, Claudia | Robles, Vanesa | Herráez, María Paz
Bisphenol A (BPA) is an endocrine disruptor used in manufacturing of plastic devices, resulting in an ubiquitous presence in the environment linked to human infertility, obesity or cardiovascular diseases. Both transcriptome and epigenome modifications lie behind these disorders that might be inherited transgenerationally when affecting germline. To assess potential effects of paternal exposure on offspring development, adult zebrafish males were exposed to BPA during spermatogenesis and mated with non-treated females. Results showed an increase in the rate of heart failures of progeny up to the F2, as well as downregulation of 5 genes involved in cardiac development in F1 embryos. Moreover, BPA causes a decrease in F0 and F1 sperm remnant mRNAs related to early development. Results reveal a paternal inheritance of changes in the insulin signaling pathway due to downregulation of insulin receptor β mRNAs, suggesting a link between BPA male exposure and disruption of cardiogenesis in forthcoming generations.
اظهر المزيد [+] اقل [-]Distribution of persistent organic pollutants (PAHs, Me-PAHs, PCBs) in dissolved, particulate and sedimentary phases in freshwater systems النص الكامل
2015
Rabodonirina, Suzanah | Net, Sopheak | Ouddane, Baghdad | Merhaby, Dima | Dumoulin, David | Popescu, Tudor | Ravelonandro, Pierre
The occurrence of three groups of hazardous organic contaminants (PCBs, PAHs, Me-PAHs) in fifteen watercourses and rivers located in highly urbanized and industrialized zones was studied. The distribution of 62 organic contaminants was determined in three matrices: in the dissolved phase, associated with suspended solid matter (SSM) and in sediment. Their distributions in the aquatic environment depend strongly on their physicochemical properties. Low molecular weight PAHs were predominant in the dissolved phase while those with high molecular weight accumulated preferentially in SSM and sediments. Among the 28 PCBs congeners, only PCB153 was detected. The results showed that the contamination of these areas originated mainly from combustion processes. The three the most polluted sites identified are surrounded by big cities. Ecotoxicological assessment based on the international Sediment Quality Guidelines (SQGs) showed that the toxic effects of the sediment in these watercourses and rivers occurred due to high levels of hydrocarbons.
اظهر المزيد [+] اقل [-]Biosorption of nonylphenol by pure algae, field-collected planktons and their fractions النص الكامل
2015
Zhang, Dainan | Ran, Yong | Cao, Xiaoyan | Mao, Jingdong | Cui, Jinfang | Schmidt-Rohr, Klaus
Algal samples were fractionated into lipid (LP), lipid free (LF), alkaline nonhydrolyzable carbon (ANHC), and acid nonhydrolyzable carbon (NHC) fractions, and were characterized by the quantitative 13C multiCP NMR technique. The biosorption isotherms for nonylphenol (NP) were established and compared with previously published data for phenanthrene (Phen). The log KOC values are significantly higher for the field-collected plankton samples than for the commercial algae and cultured algae samples, correlating with their lipid contents and aliphatic carbon structure. As the NHC fraction contains more poly(methylene) carbon, it exhibits a higher biosorption capacity. The sorption capacities are negatively related to the polarity index, COO/N–C=O, polar C and O-alkyl C concentrations, but are positively related to the H/O atomic ratios and poly(methylene) carbon. The higher sorption capacities observed for NP than for Phen on the investigated samples are explained by specific interactions such as hydrogen bonding and π–π interaction.
اظهر المزيد [+] اقل [-]Levels of short chain chlorinated paraffins in pine needles and bark and their vegetation-air partitioning in urban areas النص الكامل
2015
Wang, Thanh | Yu, Junchao | Han, Shanlong | Wang, Yawei | Jiang, Guibin
Short chain chlorinated paraffins (SCCPs) have been of considerable concern in recent years due to their high production volumes, environmental persistency and potential for long range atmospheric transport. Vegetation can take up considerable amounts of semivolatile organic compounds from the atmosphere and can act as indicators of local contamination. Paired pine needles and bark were sampled around Beijing during winter and summertime to investigate the distribution of SCCPs in urban areas. Levels in bark samples ranged 5.79–37.5 μg/g on a lipid normalized basis (lw) with a geometric mean (GM) of 16.9 μg/g lw whereas levels were 3.03–40.8 (GM 11.8) μg/g lw for needles. Average congener group abundance profiles showed equal contribution of all four carbon groups (C10–13) in wintertime whereas higher abundances of C10 and C11 groups were found during summer. Uptake of SCCPs occurred mainly via kinetically limited gaseous deposition and particle bound deposition in the investigated area.
اظهر المزيد [+] اقل [-]Responses of primary production, leaf litter decomposition and associated communities to stream eutrophication النص الكامل
2015
Dunck, Bárbara | Lima-Fernandes, Eva | Cássio, Fernanda | Cunha, Ana | Rodrigues, Liliana | Pascoal, Cláudia
We assessed the eutrophication effects on leaf litter decomposition and primary production, and on periphytic algae, fungi and invertebrates. According to the subsidy-stress model, we expected that when algae and decomposers were nutrient limited, their activity and diversity would increase at moderate levels of nutrient enrichment, but decrease at high levels of nutrients, because eutrophication would lead to the presence of other stressors and overwhelm the subsidy effect. Chestnut leaves (Castanea sativa Mill) were enclosed in mesh bags and immersed in five streams of the Ave River basin (northwest Portugal) to assess leaf decomposition and colonization by invertebrates and fungi. In parallel, polyethylene slides were attached to the mesh bags to allow colonization by algae and to assess primary production. Communities of periphytic algae and decomposers discriminated the streams according to the trophic state. Primary production decomposition and biodiversity were lower in streams at both ends of the trophic gradient.
اظهر المزيد [+] اقل [-]Whole-tree seasonal nitrogen uptake and partitioning in adult Fagus sylvatica L. and Picea abies L. [Karst.] trees exposed to elevated ground-level ozone النص الكامل
2015
Weigt, R.B. | Häberle, K.H. | Rötzer, T. | Matyssek, R.
The effect of long-term exposure of twice-ambient O3 (2 × O3) on whole-tree nitrogen (N) uptake and partitioning of adult beech and spruce was studied in a mixed forest stand, SE-Germany. N uptake as 15N tracer and N pools were calculated using N concentrations and biomass of tree compartments. Whole-tree N uptake tended to be lower under 2 × O3 in both species compared to trees under ambient O3 (1 × O3). Internal partitioning in beech showed significantly higher allocation of new N to roots, with mycorrhizal root tips and fine roots together receiving about 17% of new N (2 × O3) versus 7% (1 × O3). Conversely, in spruce, N allocation to roots was decreased under 2 × O3. These contrasting effects on belowground N partitioning and pool sizes, being largely consistent with the pattern of N concentrations, suggest enhanced N demand and consumption of stored N with higher relevance for tree-internal N cycling in beech than in spruce.
اظهر المزيد [+] اقل [-]Storage and source of polycyclic aromatic hydrocarbons in sediments downstream of a major coal district in France النص الكامل
2015
Bertrand, O. | Mondamert, L. | Grosbois, C. | Dhivert, E. | Bourrain, X. | Labanowski, J. | Desmet, M.
During the 20th century, the local economy of the Upper Loire Basin (ULB) was essentially based on industrial coal mining extraction. One of the major French coal districts with associated urban/industrial activities and numerous coking/gas plants were developed in the Ondaine-Furan subbasins, two tributaries of the upper Loire main stream. To determine the compositional assemblage, the level and the potential sources of contamination, the historical sedimentary chronicle of the 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) has been investigated. PAH concentrations were determined using gas chromatography/mass spectrometry (GC/MS) in a dated core, sampled in the Villerest flood-control reservoir located downstream of the Ondaine-Furan corridor (OFC). The most contaminated sediments were deposited prior to 1983 (Σ16PAHs ca. 4429–13,348 ng/g) and during flood events (Σ16PAHs ca. 6380 ng/g – 1996 flood; 5360 ng/g – 2003 flood; 6075 ng/g – 2008 flood), especially in medium and high molecular weight PAHs. Among them, typical pyrogenic PAHs such as FLT, PYR, BbF and BaP were prevalent in most of the core samples. In addition, some PAHs last decade data is available from the Loire Bretagne Water Agency and were analyzed using high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC/FLD). These results confirm that the most highly contaminated sediments were found downstream of OFC (Σ16PAHs ca. 2264–7460 ng/g). According to the observed molecular distribution, PAHs are originated largely from high-temperature pyrolytic processes. Major sources of pyrogenic PAHs have been emphasized by calculation of specific ratios and by comparison to reported data. Atmospheric deposition of urban and industrial areas, wood combustion and degraded coal tar derived from former factories of coking/gas plants seem to be the major pyrogenic sources. Specifically, particular solid transport conditions that can occur during major flood events lead us to emphasize weathering of former contamination sources, such as more preserved coal tar.
اظهر المزيد [+] اقل [-]Acute and chronic toxicity of short chained perfluoroalkyl substances to Daphnia magna النص الكامل
2015
Barmentlo, S Henrik | Stel, Jente M. | van Doorn, Marijn | Eschauzier, Christian | Voogt, Pim de | Kraak, Michiel H.S.
The aim of this study was to evaluate the aquatic toxicity of a C4–C6 chemistry based fluoroalkylated polymer and the perfluoroalkyl carboxylic acids, PFBA, PFHxA and PFOA to Daphnia magna. The acute toxicity decreased with decreasing carbon chain length, but the polymer did not show a dose related effect. In a chronic toxicity test performed with PFHxA, mortality was observed at similar concentrations as in the acute toxicity test, indicating that toxicity did not increase with increasing exposure time. Effects on mortality, reproduction and population growth rate occurred at similar concentrations, indicating no specific effect of PFHxA on sublethal endpoints. C4–C6 chemistry is thus less hazardous to daphnids than C7–C8 chemistry. Yet, these compounds are persistent, hard to remove from the environment and production volumes are increasing.
اظهر المزيد [+] اقل [-]Ovarian cancer mortality and industrial pollution النص الكامل
2015
García-Pérez, Javier | Lope, Virginia | López-Abente, Gonzalo | González Sánchez, Mario | Fernández-Navarro, Pablo
We investigated whether there might be excess ovarian cancer mortality among women residing near Spanish industries, according to different categories of industrial groups and toxic substances. An ecologic study was designed to examine ovarian cancer mortality at a municipal level (period 1997–2006). Population exposure to pollution was estimated by means of distance from town to facility. Using Poisson regression models, we assessed the relative risk of dying from ovarian cancer in zones around installations, and analyzed the effect of industrial groups and pollutant substances. Excess ovarian cancer mortality was detected in the vicinity of all sectors combined, and, principally, near refineries, fertilizers plants, glass production, paper production, food/beverage sector, waste treatment plants, pharmaceutical industry and ceramic. Insofar as substances were concerned, statistically significant associations were observed for installations releasing metals and polycyclic aromatic chemicals. These results support that residing near industries could be a risk factor for ovarian cancer mortality.
اظهر المزيد [+] اقل [-]A comparison of Reduced Life Expectancy (RLE) model with Haber's Rule to describe effects of exposure time on toxicity النص الكامل
2015
Verma, Vibha | Yu, Qiming J. | Connell, D. W.
The Reduced Life Expectancy (RLE) Model (LC50 = [ln(NLE) – ln(LT50)]/d) has been proposed as an alternative to Haber's Rule. The model is based on a linear relationship between LC50 (Lethal Exposure Concentration) and lnLT50 (Lethal Exposure Time) and uses NLE (Normal Life Expectancy) as a limiting point as well as a long term data point (where d is a constant). The purposes of this paper were to compare the RLE Model with Haber's Rule with available toxicity data and to evaluate the strengths and weaknesses of each approach. When LT50 is relatively short and LC50 is high, Haber's Rule is consistent with the RLE model. But the difference between the two was evident in the situation when LT50 is relatively long and LC50 is low where the RLE model is a marked departure from Haber's Rule. The RLE Model can be used to appropriately evaluate long term effects of exposure.
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