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   

The influence of tectonic plates on mantle convection patterns, temperature and heat flow   总被引：1，自引：0，他引：1  

Julian P. Lowman  Scott D. King  Carl W. Gable 《Geophysical Journal International》2001,146(3):619-636

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Radon anomalies on three kinds of faults in California   总被引：1，自引：0，他引：1  

Ch-Yu King  Wei Zhang  Bi-Shia King 《Pure and Applied Geophysics》1993,141(1):111-124

Radon emanation is known to be anomalously high along active faults in many parts of the world. We tested this relationship in California during July and early August 1992, using a portable radonmeter to conduct soil-air radon surveys at 5 sites across three kinds of faults: Creeping, locked, and freshly broken.Along a 350-m long survey line across a creeping segment of the San Andreas fault at Nyland Ranch in San Juan Bautista, we found anomalous radon concentrations not in the creep zone itself as determined by a creepmeter, but on the adjacent sides, 10 and 30 meters from the center line of the fault. The anomalous values were 5 times higher than the background values measured farther away from the fault. A similar radon anomaly was observed along a 420-m long survey line across a creeping segment of the Calaveras fault near 7th Street in Hollister. There, the anomalous values were about 6 to 11 times the background values and about 40 and 50 m from the center line of the fault. The double-peaked featire of the anomalies may be indicative of a relatively low gas permeability of the fault-gouge materials in the creeping zones and high permeability of fractured rocks in the adjacent shear zones.Along a 144-m survey line across the currently locked segment of the San Andreas fault at the Earthquake Trail near Olema, the radon concentration was indeed anomalously high in the fault zone, by a factor of two above background values. However, the maximum values (3 to 6 times background) again were recorded about 10 meters from the center line.Three weeks after the magnitude 7.5 Landers earthquake of 28 June 1992, we conducted a survey along a 300-m line across the earthquake fault alongside Encantado Road in the epicenter area. The radon values measured at the two main fault breaks were an order of magnitude higher than the background values. A similar result was found along a 420-m line alongside Reche Road about 1.7 km south of Encantado Road.  相似文献   

Heat and water vapour fluxes and scalar roughness lengths over an Antarctic ice shelf   总被引：1，自引：0，他引：1  

J. C. King  P. S. Anderson 《Boundary-Layer Meteorology》1994,69(1-2):101-121

We present eddy-correlation measurements of heat and water vapour fluxes made during the Antarctic winter. The surface layer was stably stratified throughout the period of observation and sensible heat fluxes were always directed downwards. However, both upward and downward water vapour fluxes were observed. Their magnitude was generally small and the latent heat flux was not a significant fraction of the surface energy budget. The variation of heat and water vapour fluxes with stability is well described by Monin-Obukhov similarity theory but the scalar roughness lengths for heat and water vapour appear to be much larger than the momentum roughness length. Possible explanations of this effect are discussed.  相似文献   

A synthesis of post-glacial diatom records from Lake Baikal     

J. Platt Bradbury  Ye. V. Bezrukova  G. P. Chernyaeva  S. M. Colman  G. Khursevich  J. W. King  Ye. V. Likoshway 《Journal of Paleolimnology》1994,10(3):213-252

The biostratigraphy of fossil diatoms contributes important chronologic, paleolimnologic, and paleoclimatic information from Lake Baikal in southeastern Siberia. Diatoms are the dominant and best preserved microfossils in the sediments, and distinctive assemblages and species provide inter-core correlations throughout the basin at millennial to centennial scales, in both high and low sedimentation-rate environments. Distributions of unique species, once dated by radiocarbon, allow diatoms to be used as dating tools for the Holocene history of the lake. Diatom, pollen, and organic geochemical records from site 305, at the foot of the Selenga Delta, provide a history of paleolimnologic and paleoclimatic changes from the late glacial (15 ka) through the Holocene. Before 14 ka diatoms were very rare, probably because excessive turbidity from glacial meltwater entering the lake impeded productivity. Between 14 and 12 ka, lake productivity increased, perhaps as strong winds promoted deep mixing and nutrient regeneration. Pollen evidence suggests a cold shrub — steppe landscape dominated the central Baikal depression at this time. As summer insolation increased, conifers replaced steppe taxa, but diatom productivity declined between 11 and 9 ka perhaps as a result of increased summer turbidity resulting from violent storm runoff entering the lake via short, steep drainages. After 8 ka, drier, but more continental climates prevailed, and the modern diatom flora of Lake Baikal came to prominence. On Academician Ridge, a site of slow sedimentation rates, Holocene diatom assemblages at the top of 10-m cores reappear at deeper levels suggesting that such cores record at least two previous interglacial (or interstadial?) periods. Nevertheless, distinctive species that developed prior to the last glacial period indicate that the dynamics of nutrient cycling in Baikal and the responsible regional climatic environments were not entirely analogous to Holocene conditions. During glacial periods, the deep basin sediments of Lake Baikal are dominated by rapidly deposited clastics entering from large rivers with possibly glaciated headwaters. On the sublacustrine Academician Ridge (depth = 300 m), however, detailed analysis of the diatom biostratigraphy indicates that diastems (hiatuses of minor duration) and (or) highly variable rates of accumulation complicate paleolimnologic and paleoclimatic reconstructions from these records.  相似文献   

A model for the quantitative estimation of mineral liberation by grinding     

R.P. King 《International Journal of Mineral Processing》1979,6(3):207-220

An exact expression is derived for the fraction of particles of mesh size D that contain less than a prescribed fraction of any particular mineral. The expression is obtained entirely in terms of the distributions of linear intercept lengths of the minerals in the ore. These distributions can be obtained by line traverses across a section of the ore. No other statistical information regarding the mineral grain sizes is required. The theory is completely free of empirical constants or other parameters and in particular no assumptions are made regarding the shape of the mineral grains in the ore or of the particles.The theory predicts that the fractional liberation of mineral at mesh size D is given by: where F(l) is the distribution of linear intercept lengths for the mineral and μ is the mean linear intercept length for the mineral. N(l/D) is the linear intercept distribution function for particles of mesh size D and Du is the largest intercept length across any particle of mesh size D.The theory was confirmed experimentally for the liberation of pyrite from Witwatersrand quartzite.  相似文献   

Holocene environmental changes in the alpine zone,northern San Juan Mountains,Colorado: Evidence from bog stratigraphy and palynology   总被引：1，自引：0，他引：1  

J.T. Andrews  P.E. Carrara  F.B. King  R. Stuckenrath 《Quaternary Research》1975,5(2):173-197

Cores from five high alpine basins in the northern San Juan Mountains show several fluctuations in lithology. Typically, peats are interbedded with coarser clastic sediments or else woody peats alternate with fibrous peat. Twenty ¹⁴C dates provide radiometric control. Sediment rates averaged about 2.5 cm/100 yr but varied at the different sites between 1.19 and 50 cm/100 yr. Rates were lower during the middle of the Holocene. Basal radiocarbon dates indicate that these high (ca. 3600 m a.s.l.) northeasterly facing cirques were icefree by 9000 BP. There is some evidence in the cores for a short climatic reversal sometime between 8000 and 7000 BP. A major change occurred in the high basins very close to 5000 BP and thereafter there are several intervals of increased clastic sedimentation which may be related to Neoglacial climatic fluctuations. Analysis of a 2.15 m core near Hurricane Basin indicates significant fluctuation of pollen and macrofossils occurred during the 9000 ± year record. The Picea/Pinus ratios are used to delimit changes in the apparent elevation of the site: the ratios indicate that a short drop of “treeline” occurred about 8000 BP and then remained near present level until about ≥1800 BP when the apparent elevation of the site rose. Macrofossils indicate that spruce was present in the Hurricane Basin (and others) at specific periods and confirms the general results of the Picea/Pinus ratios. The San Juan Mountains do not possess a glacial Neoglacial record but the stratigraphy of these high cirque basins can be used to define glacial stades (cf. Jardine, 1972). The interpreted climatic response record on vegetation and sediment flux has both similarities and differences from other records in the western mountains of North America.  相似文献   

The composition and evolution of primordial solutions on Mars, with application to other planetary bodies     

P.L. King  D.T. Lescinsky 《Geochimica et cosmochimica acta》2004,68(23):4993-5008

We examine a model for Mars involving bulk primordial solutions (oceans and lakes) that were relatively Mg-rich and SO₄/(SO₄ + Cl)-rich. Such solutions could be produced when (1) volatiles leached a planet (or portions of a planet) with an ultramafic-mafic composition in a process called “planetary leaching”; and/or by (2) “impactor leaching” where meteoritic and/or cometary impactor fragments were leached. When Mg-SO₄/(SO₄ + Cl)-rich solutions are concentrated, we predict that the following sequence of salts precipitates: phosphates; carbonates; gypsum; epsomite; bloedite; halite; hexahydrite; and, finally bischofite. This sequence is modified slightly if appreciable Fe-, Mg- or Na-carbonates, Fe-sulfates, Mg-phosphate, or other halide salts crystallized before the Mg-Na-sulfate salts, or if HCO₃+CO₃ concentrations vary due to other effects (e.g., atmosphere CO₂ levels change).On Mars, the initial primordial solutions would have been relatively salt-rich and water-poor; therefore, the surface solutions formed Mg-Na-SO₄-Cl salts (cements, veneers, and dust) and subsurface solutions or ice (solid H₂O). This model is supported by the compositions of cements in the regolith on Mars (high Mg, Na, S, and Cl) and geochemical and petrographic evidence that the salts precipitated in the predicted sequence. We suggest that the partial pressure of oxygen was above the hematite-magnetite buffer where Fe³⁺-(hydrous)-oxides are stable and SO₄^2- or HSO₄^- are solutes in any solution. Such a partial pressure of oxygen may have been attained via H₂-loss.In contrast, on the Galilean satellites (Europa, Ganymede, and Callisto) surface solutions were relatively water-rich and formed ice, Mg-SO₄-rich salts, and solutions, thereby producing surface features dependent on the initial water content and the crystallization path. Unlike the Na-Cl-rich oceans on Earth, the solutions of these planetary bodies likely did not change greatly from their bulk primordial Mg-rich, SO₄/(SO₄ + Cl)-rich compositions; hence they did not attain compositions similar to modern seawater.  相似文献   

Geochemical characterization, correlation, and optical dating of tephra in alluvial sequences of central western Argentina   总被引：1，自引：0，他引：1  

Phillip S Toms  Matthew King  Rob A Kemp 《Quaternary Research》2004,62(1):60-75

The synthesis of paleoclimatic archives provided by loess and alluvial sequences of central Argentina has been hindered by the lack of a cohesive lithostratigraphic framework extending across the Chaco-Pampean plains and catchments of the Rios Desaguadero, Colorado, and Negro. This condition originates in part from the dearth of absolute chronological controls. The occurrence of discrete tephra layers across this region may provide an opportunity to address this deficiency if a tephrochronological framework can be established. The potential of such a project is assessed within the context of a pilot study constrained within alluvial sequences of central western Argentina proximal to potential source vents in the Southern Volcanic Zone. The intersite discrimination and correlation of tephra layers on a geochemical basis is examined, with indirect chronological control for the eruption of each generated by optical dating. Alluvial sediments on either side of each of five tephra units at a type site were dated using the optically stimulated luminescence of fine-silt-sized quartz, thus providing an age control on each tephra (ca. 24,000, 30,000, 32,000, 39,000, and 48,000 yr). The geochemical composition of each tephra was derived. Using these data, tephra layers at other sites in the study area were geochemically analyzed and, in instances of statistical concordance in major oxide structure, correlated to the type site and therefore ascribed ages. This methodology identified a further sixth volcanic event between ca. 24,000 and 30,000 yr not registered by type-site tephras. The extension of this initial tephrochronological framework beyond the alluvial sequences of central western Argentina is encouraged by the occurrence of geochemically distinct tephra verified and dated in this study.  相似文献   

Choice of optimal averaging radii for temporal GRACE gravity solutions, a comparison with GPS and satellite altimetry   总被引：3，自引：0，他引：3  

Matt King  Philip Moore  Peter Clarke    David Lavallée 《Geophysical Journal International》2006,166(1):1-11

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