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881.
David N. Skilleter 《毒物与环境化学》2013,95(3):213-228
The carcinogenicity of beryllium to several animal species is well established and evidence exists which strongly suggests that this is the case in human exposure. In this review several biochemical properties of the metallocarcinogen are considered including, the causation of cell transformation, and infidelity of DNA synthesis, inhibition of cell division and enzyme induction, and interference with regulatory mechanisms controlling gene expression. These effects are discussed in relation to beryllium chemistry, cellular accumulation mechanisms and distribution to subcellular organdies and molecular targets. It is suggested that the ultimate location and interactions of the metal ion in cell nuclei and its selective inhibition of certain protein phosphorylation reactions in particular are the biochemical effects potentially most relevant to induction of beryllium carcinogenesis. 相似文献
882.
Alan R. Katritzky Petia A. Shipkova Ming QI David H. Powell Michael Siskin David T. Ferrughelli 《毒物与环境化学》2013,95(1-4):239-249
Arsenic compounds, and especially organo‐arsenic derivatives, are highly toxic and many have been manufactured as chemical warfare agents. This study was designed to provide background information relevant to the potential application of aquathermolysis techniques for the detoxification of such potent military warfare agents. Six arsenic‐containing compounds with structural features which mimic known agents were studied in neutral superheated water: 4‐aminophenylarsine oxide, 4‐arsanilic acid, 4‐nitrophenylarsonic acid, 5, 10‐dihydro‐10‐ethylphenarsazine, tetraphenylarsonium chloride hydrate, and (3‐cyanopropyl)dimethyl(2‐phenethyl)arsonium bromide. Most of these compounds were moderately susceptible to hydrolysis for 1h at 300°C. o‐ and p‐Aminosubsituted arsenic compounds were more reactive than compounds with an electron‐withdrawing group substituent. Aromatic C—As bonds were more resistant to cleavage than aliphatic C—As bonds. 相似文献
883.
Ellie Owen Francis Daunt Colin Moffat David A. Elston Sarah Wanless Paul Thompson 《Marine Biology》2013,160(4):987-999
A key challenge in ecology is to find ways to obtain complete and accurate information about the diets of animals. To respond to this challenge in seabirds, traditional methods (usually stomach content analysis or observations of prey at nests) have been supplemented with indirect methods or molecular trophic markers. These techniques have the potential to extend the period of investigation outside the few short months of breeding and avoid biases. Here, we use an analysis of fatty acids (FAs) and fatty alcohols (FALs) from blood, adipose tissue and stomach oil to investigate how the diets of male and female common guillemots (Uria aalge), black-legged kittiwakes (Rissa tridactyla) and northern fulmars (Fulmarus glacialis) differed through the sampling period (prelaying and breeding season) and by sex. Diets of both sexes of all three species generally varied across the season, but sex differences were apparent only in fulmars during prelaying. Our study shows that FA/FAL analysis can provide significant insights into diets of seabirds, in particular periods of the annual cycle which are not readily studied using traditional methods. 相似文献
884.
Georg H. Engelhard Julia L. Blanchard John K. Pinnegar Jeroen van der Kooij Ewen D. Bell Steven Mackinson David A. Righton 《Marine Biology》2013,160(2):299-308
Lesser sandeels Ammodytes marinus are eaten by a range of predatory fishes including commercially fished species, but are also exploited at large scale by industrial fisheries. Is availability of sandeels, as key prey source, linked to the body condition of predatory fishes? In the North Sea, the largest sandeel biomass is concentrated in the Dogger Bank region. Here we studied predator–sandeel interactions at two sites differing widely in sandeel abundance and local sandeel fishing effort. Surveys took place in 2004, 2005, and 2006, years when local sandeel densities observed at these sites were low, intermediate, and high, respectively. Five predator species––whiting, lesser weever, grey gurnard, plaice, and haddock––showed better body condition indices in either the years or study area (or both) characterised by higher local sandeel densities, when compared to sandeel-poorer conditions. Moreover, whiting, weever, and gurnard condition was better for those individuals actually observed to have eaten sandeels (based on stomach contents) than for those that had not. As body condition relates to growth, reproduction, and survival, predators in sandeel-rich conditions may be inferred to have a higher fitness. These links between sandeel availability, sandeel consumption, and predator condition hint that, if large-scale localised depletions of sandeels were to occur, negative indirect effects on predatory fish might become apparent, underlining the importance of considering the sandeel fishery in an ecosystem context. 相似文献
885.
The present study was conducted to establish the relationship between selected oxidative stress parameters and ultrastructural responses in liver tissue of Labeo rohita fingerlings exposed to cypermethrin. Fish were exposed to lethal (4.0 μg L?1) and sublethal (0.4 μg L?1) concentrations of cypermethrin for a period of 24, 48, 72 and 96 h for acute studies and 1, 5, 10 and 15 days for subacute studies, respectively. Results showed increased catalase (CAT) and protease activity, hydrogen peroxide (H2O2), malondialdehyde (MDA), protein carbonyls and free amino acid (FAA) levels at both concentrations. This suggests participation of free-radical-induced oxidative cell injury in mediating the hepatotoxicity of cypermethrin. In corroboration of this, ultrastructural lesions witnessed a reduction in the number of cell organelles, swollen, vacuolated and condensed mitochondria, dilated rough endoplasmic reticulum, and reduced numbers of smooth enodplasmic reticulum, peroxisomes and lysosomes at the lethal (4.0 μg L?1) concentration. At the sublethal (0.4 μg L?1) concentration, cytoplasmic vacuolation, condensed, vacuolated and swollen mitochondria, dilated rough endoplasmic reticulum and an absence of hepatocyte microvilli were prominent. Ultrastructural changes were exhibited as subcellular responses due to the imbalance in cellular oxidative status by means of oxidative damage. 相似文献
886.
As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources. 相似文献
887.
The pH of machine-made snow and its effect on an acid-sensitive watershed in Vermont were studied. Spring runoff from snowmaking was found to be less acidic and to contain less dissolved inorganic aluminum. Dissolved inorganic aluminum has been associated with damage to aquatic life. The extensive use of machine-made snow by the ski industry in most of the northeast region of the US may be beneficial to aquatic life. 相似文献
888.
David L. Nieland Charles A. Wilson John W. Fleecer Bin Sun Ronald F. Malone Shulin Chen 《Chemistry and Ecology》2013,29(3-4):305-319
Phosphogypsum (PG), a solid by-product of phosphoric acid production, contains radionuclides and trace metals in concentrations which may pose a potential hazard to human health and the environment. to investigate the possibility of bioaccumulation of radium and six heavy metals over time when aquatic organisms experience both trophic and environmental exposure to PG, we designed a laboratory experiment representing three levels of an aquatic food chain. During the 135 day experiment, a meiobenthic copepod species (Amphiascoides atopus) was cultured in the presence of PG. the copepods were subsequently fed to grass shrimp (Palaemonetes vulgaris and P. pugio) which were in turn fed to gulf killifish (Fundulus grandis); both the grass shrimp and the killifish also experienced an environmental PG exposure. Other than elevated radium levels in the experimental grass shrimp, the experiment demonstrated little effect of environmental or trophic exposure to PG on microinvertebrates, macroinvertebrates, or fishes that could be attributed to PG. in all cases where increased concentrations were indicated within the experimental group, roughly equivalent increases in metal concentrations also occurred in the control group. 相似文献
889.
David C. Natcher 《国际发展与全球生态学杂志》2013,20(4):363-374
Recognizing the limitations common to both centralized and privatized management regimes, institutionalized resource management is beginning to incorporate the knowledge and skills of local resource users, coupled with the enabling policies and legislation of state systems, to arrive at cooperative approaches to resource management. These varying and dynamic approaches to resource management have been compelled largely through the recognition of the limited capabilities of existing management systems to adapt effectively to ecosystem change and the evolving needs of resource users. These cooperative approaches to management should not, however, be considered an institutional end-point, but rather a phase in the perpetual transition of a social system; each unique in character and individually variable depending on the resource being managed, the political climate in which management occurs, as well as the differing strategies employed by resource users to enact institutional change. Drawing from the experiences of the Whitefish Lake First Nation of Alberta, Canada, this paper presents a brief overview of the evolution of resource management theory, grounded in the real-world formation of the Whitefish Lake First Nation — Province of Alberta Cooperative Management Agreement. 相似文献
890.
Mohammad Salehi Bardia Panahbehagh Afshin Parvardeh David R. Smith Yuancai Lei 《Environmental and Ecological Statistics》2013,20(4):571-590
Adaptive two-stage sequential sampling (ATSSS) design was developed to observe more rare units and gain higher efficiency, in the sense of having a smaller variance estimator, than conventional sampling designs with equal effort for rare and spatially cluster populations. For certain rare populations, incorporating auxiliary variables into a sampling design can further improve the observation of rare units and increase efficiency. In this article, we develop regression-type estimators for ATSSS so that auxiliary variables can be incorporated into the ATSSS design when warranted. Simulation studies on two populations show that the regression-type estimators can significantly increase the efficiency of ATSSS and the detection of more rare units as compared to conventional sampling counterparts. Simulation of sampling of desert shrubs in Inner Mongolia (one of the two populations studied) showed that by incorporating a GIS auxiliary variable into ATSSS with the regression estimators resulted in a gain in efficiency over ATSSS without the auxiliary variable. Further, we found that the use of the GIS auxiliary variable in a conventional two-stage design with a regression estimator did not show a gain in efficiency. 相似文献