The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes   总被引：1，自引：0，他引：1  

Codi King S  Hassell K  Nugegoda D  Kristiansen SI 《Marine environmental research》2008,66(1):116-118

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds.  相似文献   

Effect of hydrocarbon volatility and adsorption on source-rock pyrolysis     

Martha E. Tarafa  John M. Hunt  Inger Ericsson 《Journal of Geochemical Exploration》1983,18(1):75-85

Petroleum source-rock evaluations by pyrolysis are based on the concept that free hydrocarbons in rock samples are volatilized below 300°C while hydrocarbons cracked from kerogen come off at higher temperatures. The pyrolysis of pure hydrocarbons with different mineral matrices shows that free hydrocarbons containing 16 or more carbon atoms may not be evolved eblow 300°C, but at varying higher temperatures. The extent to which this occurs depends on the hydrocarbon volatility, the mineral matrix and the pyrolysis instrument design. Source-rock parameters which use the P₁ (S₁) peak may be not be reproducible between instruments if the rock contains appreciable amounts of high molecular weight hydrocarbons.  相似文献   

Decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy: A test on 3C 120     

Sebastin F. Snchez  Begoa García-Lorenzo  Knud Jahnke  Evencio Mediavilla  Jos Ignacio Gonzlez-Serrano  Lise Christensen  Lutz Wisotzki 《New Astronomy Reviews》2006,49(10-12):501

We have developed a new technique to decouple the spectra of the host and the nucleus of type I AGNs using integral field spectroscopy data. The technique is a simple extension of methods widely tested in 2D imaging. We present here the results from applying the technique to data taken with INTEGRAL at the 4.2 m William Herschel Telescope on the Seyfert 1 radio-galaxy 3C 120. We obtained, for the first time, a clean spectrum of the host galaxy, without contamination from the nuclear source.  相似文献   

Pressure solution - The importance of the electrochemical surface potentials     

Kai Kristiansen  George W. Greene  Jacob N. Israelachvili 《Geochimica et cosmochimica acta》2011,75(22):6882-6892

“Pressure solution”, frequently found in clay-rich sandstone, is characterized by enhanced quartz dissolution at inter-grain contacts. The origin of pressure solution and many other related dissolution processes remains elusive. Using an Electrochemical Surface Forces Apparatus we visualized and measured the dissolution of silica glass surfaces close to an electrode surface. The dissolution rates correlate quantitatively with the electrode potential via the Butler-Volmer equation for corrosion. Our experimental results demonstrate that at low temperature, apparent pressure solution and many other mineral dissolution phenomena can be driven by electrochemical processes rather than a pressure-driven process. This finding highlights the role of electrochemical surface potentials in dissolution phenomena at dissimilar material interfaces, and provides new perspectives on pressure solution in particular and a new theoretical basis for predictive control of dissolution phenomena in general.  相似文献   

Decadal and seasonal development of embryo dunes on an accreting macrotidal beach: North Lincolnshire,UK     

Anne‐Lise Montreuil  Joanna E. Bullard  Jim H. Chandler  Jon Millett 《地球表面变化过程与地形》2013,38(15):1851-1868

Embryo dunes are often ephemeral, but can develop to become established coastal foredunes. In 2001 a patch of embryo dunes 13.11 m² appeared on a beach in north Lincolnshire, UK and had expanded to over 3600 m² by 2011. The rate of expansion is linked to storm occurrence, where expansion is slowed during years with a higher incidence of storm surges. From July 2009–October 2010 seasonal changes in dune field topography were determined using terrestrial laser scanning (TLS) data. Vegetation is important in the development of embryo dunes, but can cause errors in TLS data. Tests evaluating the impact of vegetation on the TLS data suggest the minimum elevation value from the TLS point cloud within a 0.05 m grid cell gives a good approximation of the ground surface. Digital elevation models (DEMs) of the dunes constructed using filtered data showed the embryo dunes underwent a classic seasonal cycle of erosion during the winter and accretion during the summer. For example from October 2009 to April 2010 over 375 m³ of sediment was eroded from the dunes whereas during spring and summer 2010 the dune field gained over 600 m³ of sand. The overall magnitude of change in dune height and volume from season to season exceeded the errors associated with the construction of the DEM from the TLS data and the vegetation filtering process, which suggests TLS can be useful for documenting topographic change in vegetated dunes. After 10 years, the patch of embryo dunes is still expanding but has not yet merged with more established foredunes to landward. Aeolian process measurements indicate that, at present, the embryo dunes do not prevent sand from reaching the foredunes, however the rate of foredune progradation has slowed concurrently with the expansion of the embryo dune field. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Evaluating explanatory models of the spatial pattern of surface climate trends using model selection and bayesian averaging methods     

Ross McKitrick  Lise Tole 《Climate Dynamics》2012,39(12):2867-2882

We evaluate three categories of variables for explaining the spatial pattern of warming and cooling trends over land: predictions of general circulation models (GCMs) in response to observed forcings; geographical factors like latitude and pressure; and socioeconomic influences on the land surface and data quality. Spatial autocorrelation (SAC) in the observed trend pattern is removed from the residuals by a well-specified explanatory model. Encompassing tests show that none of the three classes of variables account for the contributions of the other two, though 20 of 22 GCMs individually contribute either no significant explanatory power or yield a trend pattern negatively correlated with observations. Non-nested testing rejects the null hypothesis that socioeconomic variables have no explanatory power. We apply a Bayesian Model Averaging (BMA) method to search over all possible linear combinations of explanatory variables and generate posterior coefficient distributions robust to model selection. These results, confirmed by classical encompassing tests, indicate that the geographical variables plus three of the 22 GCMs and three socioeconomic variables provide all the explanatory power in the data set. We conclude that the most valid model of the spatial pattern of trends in land surface temperature records over 1979–2002 requires a combination of the processes represented in some GCMs and certain socioeconomic measures that capture data quality variations and changes to the land surface.  相似文献   

Quantifying historic skew surges: an example for the Dunkirk Area,France     

Giloy  Nathalie  Hamdi  Yasser  Bardet  Lise  Garnier  Emmanuel  Duluc  Claire-Maire 《Natural Hazards》2019,98(3):869-893

Natural Hazards - As instrumental records often cover only short time periods, historical information is the main source of data in order to extend natural disaster catalogs. This study...  相似文献   

Metamorphic evolution of the Sesia-Lanzo Zone,Western Alps: time constraints from multi-system geochronology   总被引：6，自引：0，他引：6  

S. Inger  W. Ramsbotham  R. A. Cliff  D. C. Rex 《Contributions to Mineralogy and Petrology》1996,126(1-2):152-168

 The Sesia-Lanzo Zone is a polymetamorphic unit containing Hercynian granulite relics overprinted by eclogite and greenschist facies metamorphism and deformation during the Alpine orogeny. Different parts of the unit record different stages on the P-T-deformation evolution, allowing multi-system isotopic studies to unravel the precise timing of the metamorphic history. New Rb–Sr white mica and U–Pb sphene data constrain the age of eclogite facies metamorphism and deformation to 60–70 Ma. This substantially alters the common view of early- to mid-Cretaceous eclogite facies metamorphism in this unit. The new results are more consistent with the established geotectonic framework for the Alpine orogeny, since they do not require a prolonged period of depressed geothermal gradient at a time when the region was in extension. It is also more concordant with recent studies of other units that demonstrate post-Cretaceous high-pressure metamorphism. Step-heated ⁴⁰Ar–³⁹Ar analysis of phengites yields good plateaux giving ages older than the corresponding Rb–Sr age. Such anomalously high ages indicate the presence of radiogenic argon-rich fluids in the grain boundary network under the fluid/pressure conditions acting during this high-pressure metamorphic event. The U–Pb sphene ages are variable in polymetamorphic rocks, and show inheritance of older Pb or sphene crystals into the high-pressure event. Two monometamorphic assemblages yield concordant ages at 66±1 Ma, reflecting crystallisation of the eclogite facies assemblage. The Gneiss Minuti Complex (GMC) lies structurally below the Eclogitic Micaschists, and its pervasive greenschist facies fabric yields tightly clustered Rb–Sr white mica ages at 38–39 Ma. This greenschist event did not affect the majority of the EMC. The ⁴⁰Ar–³⁹Ar ages of micas formed at this time were very disturbed, whereas micas surviving from an earlier higher pressure assemblage had their ⁴⁰Ar–³⁹Ar system reset. The greenschist event did not strongly affect U–Pb systematics in Hercynian age sphenes, suggesting that the GMC did not uniformly suffer an eclogite facies metamorphism during the Alpine cycle, but was juxtaposed against the EMC later in the orogeny. This model still requires that the locus of deformation and metamorphism (and possibly fluid flux) moved outboard with time, leaving the Sesia-Lanzo basement as a shear-bounded unreactive block within the orogenic wedge. Received: 12 October 1995/Accepted:25 June 1996  相似文献   

Past and future climate variations in the Norwegian Arctic: overview and novel analyses   总被引：1，自引：1，他引：1  

Eirik J. Førland  Inger Hanssen-Bauer 《Polar research》2003,22(2):113-124

Sparse stations and serious measuring problems hamper analyses of climatic conditions in the Arctic. This paper presents a discussion of measuring problems in the Arctic and gives an overview of observed past and projected future climate variations in Svalbard and Jan Mayen. Novel analyses of temperature conditions during precipitation and trends in fractions of solid/liquid precipitation at the Arctic weather stations are also outlined. Analyses based on combined and homogenized series from the regular weather stations in the region indicate that the measured annual precipitation has increased by more than 2.5% per decade since the measurements started in the beginning of the 20th century. The annual temperature has increased in Svalbard and Jan Mayen during the latest decades, but the present level is still lower than in the 1930s. Downscaled scenarios for Svalbard Airport indicate a further increase in temperature and precipitation. Analyses based on observations of precipitation types at the regular weather stations demonstrate that the annual fraction of solid precipitation has decreased at all stations during the latest decades. The reduced fraction of solid precipitation implies that the undercatch of the precipitation gauges is reduced. Consequently, part of the observed increase in the annual precipitation is fictitious and is due to a larger part of the "true" precipitation being caught by the gauges. With continued warming in the region, this virtual increase will be measured in addition to an eventual real increase.  相似文献   

Dry deposition of reactive nitrogen to marine environments: recent advances and remaining uncertainties     

Pryor SC  Sørensen LL 《Marine pollution bulletin》2002,44(12):1336-1340

Many highly productive marine ecosystems exhibit nitrogen limitation or co-limitation. This article is a status review of research into the exchange of nitrogen between the atmosphere and these ecosystems with a particular focus on reactive nitrogen compounds. A summary of research conducted over the past ten years is presented and a perspective given as to remaining uncertainities and research needs. Looking toward development of coastal management modeling tools, we illustrate the processes that need to be resolved in order to accurately simulate the flux from the atmosphere and provide guidance on the required resolution of such models.  相似文献