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1.
We have previously demonstrated that medaka CYP3A is associated with metabolism of several endobiotics including steroids and bile acids. In this study, we demonstrate that medaka CYP3A catalysis exhibits unusual kinetic behaviors consistent with allosteric interaction which cannot be described by hyperbolic kinetic models. Using 7-benzyloxy-4-(trifluoromethyl)-coumarin (BFC) and nonylphenol as CYP3A substrates, we describe both homotropic and heterotropic cooperative interactions. Given the role of CYP3A in maintaining the homeostatic balance for numerous endobiotics, enzymatic activation/inhibition by endocrine disruptors (EDCs) represents a putative (non-genomic) mechanism for endocrine disruption. 相似文献
2.
SW Evans N Cole H Kylin NS Choong Kwet Yive V Tatayah J Merven 《African Journal of Marine Science》2016,38(3):317-327
A survey of seabirds and turtles at St Brandon’s Rock, 400 km north of Mauritius, was undertaken in 2010. We estimated that 1 084 191 seabirds comprising seven breeding species and excluding non-breeders were present at the archipelago and we counted 279 turtle tracks and nesting pits of green turtles Chelonia mydas. Hawksbill turtles Eretmochelys imbricata were also present. Analyses of 30 different islets that make up the atoll showed that the seabird species mostly partitioned their use of islets based on islet size, with four species preferring larger islets and two species preferring smaller islets. Alien species introduced historically are still present and other threats, such as shipwrecks, remain. We propose conservation and other measures that should adequately protect the birds, turtles and coral reef by treating the atoll as a system. 相似文献
3.
Altitudinal tree- and forest-limits of mountain birch ( Betula pubescens Ehrh. ssp. tortuosa (Ledeb.) Nyman) were measured (m a.s.l.) on 229 sites forming a regional network of sites intended for long-term monitoring. Regional and local topographical variables used for correlations with the recorded elevations included slope aspect, inclination, morphology, snow depth and shortest distance to the sea. No relationship between past human utilization of natural resources and the vertical extension (width) and position of the tree-limit ecotone was found and thus the ecotone is regarded as natural. It is concluded that tree- and forest-limit altitudes are regionally controlled by macroclimate, and correlate negatively with the degree of maritimity. On a more local scale, snow conditions, and microtopography, are important for tree- and forest-limit altitudinal position. The ecotone is wider in snow accumulation areas than in deflation areas, and tree- and forest-limit altitudes are generally higher on slopes with a varied micro-topography than on flat slopes. Slope aspect and inclination are also important, and the highest tree- and forest-limit altitudes are generally found on steep, SE-W-facing slopes. Tree height at the tree-limit is independent of the analysed topographical parameters and fairly constant at 2.7 m, suggesting a strong common environmental control. Many of the results presented in this paper are confirmations of the results of earlier, small-scale investigations or of surveys lacking statistically treated data. 相似文献
4.
Hinton DE Kullman SW Hardman RC Volz DC Chen PJ Carney M Bencic DC 《Marine pollution bulletin》2005,51(8-12):635-648
In this age of modern biology, aquatic toxicological research has pursued mechanisms of action of toxicants. This has provided potential tools for ecotoxicologic investigations. However, problems of biocomplexity and issues at higher levels of biological organization remain a challenge. In the 1980s and 1990s and continuing to a lesser extent today, organisms residing in highly contaminated field sites or exposed in the laboratory to calibrated concentrations of individual compounds were carefully analyzed for their responses to priority pollutants. Correlation of biochemical and structural analyses in cultured cells and tissues, as well as the in vivo exposures led to the production and application of biomarkers of exposure and effect and to our awareness of genotoxicity and its chronic manifestations, such as neoplasms, in wild fishes. To gain acceptance of these findings in the greater environmental toxicology community, “validation of the model” versus other, better-established often rodent models, was necessary and became a major focus. Resultant biomarkers were applied to heavily contaminated and reference field sites as part of effects assessment and with investigations following large-scale disasters such as oil spills or industrial accidents.
Over the past 15 years, in the laboratory, small aquarium fish models such as medaka (Oryzias latipes), zebrafish (Danio rerio), platyfish (Xiphophorus species), fathead minnow (Pimephales promelas), and sheepshead minnow (Cyprinodon variegatus) were increasingly used establishing mechanisms of toxicants. Today, the same organisms provide reliable information at higher levels of biological organization relevant to ecotoxicology. We review studies resolving mechanisms of toxicity and discuss ways to address biocomplexity, mixtures of contaminants, and the need to relate individual level responses to populations and communities. 相似文献
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6.
Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos 总被引：1，自引：0，他引：1
Michael W. Carney Kyle Erwin Ron Hardman Bonny Yuen David C. Volz David E. Hinton Seth W. Kullman 《Marine pollution bulletin》2008,57(6-12):255
Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations. 相似文献
7.
内蒙古太平川铜钼矿成矿斑岩时代、地球化学及地质意义 总被引：27，自引：9，他引：18
内蒙古太平川Cu-Mo矿床位于得尔布干成矿带北段额尔古纳地区,为新近发现的斑岩型矿床。矿区内发育环带状热液蚀变,由内向外主要为硅化-绢云母化和泥化。热液蚀变围绕花岗闪长斑岩分布,Cu-Mo矿化主要受控于硅化-绢云母化蚀变,主要分布在花岗闪长斑岩中。本文获得成矿斑岩岩浆锆石U-Pb谐和年龄为202±5.7Ma,指示该矿床可能形成于晚三叠世。同时在样品中也发现继承锆石(784Ma),表明该地区可能存在晚元古基底。成矿斑岩的元素地球化学数据表明,主量元素SiO2(65.86%～68.84%)56%、Al2O3(15.18%～16.28%)15%、MgO(0.84%～1.06%)3%、Na2O/K2O1;微量元素亏损重稀土,Sr(471×10-6～513×10-6)400×10-6、Y(15.0×10-6～17.9×10-6)18×10-6、Yb(1.27×10-6～1.81×10-6)1.9×10-6,表明该花岗闪长斑岩具有明显的埃达克质岩石的地球化学特征。同时成矿斑岩具有相对高的SiO2、Yb含量和Th/Nb、Ce/Nb比值,而相对低的Al2O3、TiO2、MgO、Sr、Th含量和Th/Ce比值,这些特征与源于俯冲板片的埃达克岩相似。然而成矿斑岩(87Sr/86Sr)i(0.70943～0.71019)较大,εNd(t)为-3.4～-3.9,我们推测额尔古纳地块在岩浆上升过程中贡献了部分物质。结合区域构造演化,我们认为该矿区成矿斑岩岩浆形成于俯冲洋壳的部分熔融,矿床形成背景为早中生代蒙古-鄂霍茨克洋向额尔古纳地块俯冲的陆缘弧环境。 相似文献
8.
华宁暮车露天矿开采对周边地质环境影响评价 总被引：1，自引：0，他引：1
现场调查评价区地裂缝特征和成因机制,对形成地裂缝的直接原因——采矿诱发斜坡的失稳进行了定性、定量评价,提出不稳定斜坡的相应防治对策。 相似文献
9.
ROBERT O''BRIEN BIMAL K.SINHA WILLIAM P.SMITH Statistical Policy Branch Environmental Protection Agency M St. SW Washington DC U.S.A. 《地理学报(英文版)》1991,(3)
The object of this paper is to develop a suitable statistical procedure to evaluate clean-up standards athazardous waste sites.Under the assumptions that contaminant masses at a site follow a gammadistribution and that the data from the pre-remediation baseline sample as well as from the interim orfinal sample taken after a certain period of operation are both distributed as gamma with the same shapeparameter but different scale parameters,we derive a uniformly most powerful unbiased test of thehypothesis that a specified percentage of contaminant mass has been reduced.A large-sampleapproximation of the exact test procedure and a comparison with the likelihood ratio test are provided. 相似文献
10.
Carney MW Erwin K Hardman R Yuen B Volz DC Hinton DE Kullman SW 《Marine pollution bulletin》2008,57(6-12):255-266
Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA>2H1NA>2H3NA>6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations. 相似文献