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Despite the fact that BaP is a carcinogen, mammalian immunosuppressant, and ubiquitous aquatic pollutant, knowledge regarding the effects of BaP on the immune system of fish is still lacking. To begin to fill this gap, studies were conducted in medaka to examine the effects and mechanisms by which BaP exposure might alter host immunocompetence. Fish, exposed by IP injection of BaP (2-600 microg/g BW), were examined after 48 h for effects upon immune function and CYP1A expression/activity. Benzo[a]pyrene, at a concentration below that which increased levels of CYPIA expression/activity (2 microg BaP/g BW) suppressed lymphocyte proliferation. Concentrations of BaP at 20 and 200 microg/g BW. suppressed antibody-forming cell (AFC) numbers, superoxide production, and host resistance against bacteria. In contrast, exposure to the low affinity aryl hydrocarbon receptor (AhR) agonist, benzo[e]pyrene (BeP), neither induced CYP1A expression nor altered immune function. Given the lack of immunosuppressive effects produced by BeP, and the fact that exposure to the AhR antagonist (and CYP1A inhibitor) alpha-naphthoflavone (ANF) ameliorated the suppressive effects of BaP upon AFC numbers, the AhR pathway (including CYP1A-mediated production of reactive BaP metabolites) appears important in mediating BaP-induced immunotoxicity in fish, as in mammals. In the past, the medaka has proven a successful model for assessing carcinogenic agents. These studies have demonstrated its utility for also determining the immunosuppressive effects of an important aquatic contaminant. 相似文献
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利用相当位涡诊断条件性对称不稳定区 总被引：2，自引：0，他引：2
条件性对称不稳定（ＣＳＩ）是一个用于诊断和预报冬季气旋内中等到强降水的中尺度雨带的重要的大气特征．在ＣＳＩ区域内，倾斜对流能够增大狭窄区域内的降雪总量．典型的情况是，在一个垂直于对流层中层热成风方向的剖面上，利用Ｍｇ（绝对地转动量）和θｅ（相当位温）来进行ＣＳＩ的估算，在等Ｍｇ面比等θｅ面坡度小的区域为ＣＳＩ区．本文描述了一种量度ＣＳＩ的客观方法，称为相当位涡（ＥＰＶ）方法，它可以快速有效地计算ＣＳＩ。通过两次实例比较了Ｍｇ剖面对θｅ剖面的方法和ＥＰＶ方法，从而说明了利用ＥＰＶ剖面诊断ＣＳＩ的有效性．上述实例还说明了倾斜对流与垂直对流的区别。 相似文献
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Finnish strategies for reduction and control of effluents to the marine environment--examples from agriculture,municipalities and industry 总被引：1，自引：0，他引：1
Kohonen JT 《Marine pollution bulletin》2003,47(1-6):162-168
The most serious environmental problem encountered in the Baltic Sea is eutrophication. Finland finalised in spring 2002 its national Programme for the Protection of the Baltic Sea. The programme contains more than 30 measures for improving the state of the Baltic Sea and protecting the marine environment. Total national investments during the next 10-15 years will amount to EUR 300-370 million. The highest annual cost will be environmental support to agriculture. The bulk of the rest of the money will be used for nitrogen purification of municipal wastewater, improvement of water protection in dispersed settlement areas, and investments to improve maritime safety and decrease the risks of oil spills. 相似文献
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Summary results from a pilot study conducted around an oil production platform on the Northwest Shelf of Australia 总被引：3，自引：0，他引：3
King SC Johnson JE Haasch ML Ryan DA Ahokas JT Burns KA 《Marine pollution bulletin》2005,50(11):1163-1172
The Australian Institute of Marine Science (AIMS) conducted a pilot study around the Harriet A oil production platform on the Northwest Shelf of Australia. We evaluated hepatic ethoxyresorufin-O-deethylase (EROD) activity, fluorescent aromatic compounds (FACs) in bile and immunodetection of CYP1A-like proteins in two Australian tropical fish species, Gold-Spotted Trevally (Carangoides fulvoguttatus) and Bar-Cheeked Coral Trout (Plectropomus maculatus) to assess exposure to petroleum hydrocarbons associated with produced formation water (PFW). Additionally, the incidence of hydrocarbon-degrading bacteria isolated from the liver and bile of all fish captured was examined. Low EROD activity was found in both species, with EROD activity in C. fulvoguttatus showing significant site differences. FACs and CYP1A protein levels in C. fulvoguttatus showed a clear trend in hydrocarbon exposure consistent with hydrocarbon chemistry data: Harriet A>Harriet C>reference site. P. maculatus showed elevated levels of FACs at Harriet A as compared to the reference site and demonstrated detectable levels of CYP1A-like proteins at these two sites. Hydrocarbon-degrading bacteria were found in the liver and bile of both species, yet there was no correlation by sites. Our results demonstrate that C. fulvoguttatus and P. maculatus have potential as indicator species for assessing the effects from exposure to petroleum hydrocarbons. Both FACs and CYP1A are providing warning signs that there is potential for biological effects on fish populations exposed to PFW around the Harriet A production platform. 相似文献
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Magnetite in the oxidized CV chondrite Allende mainly occurs as spherical nodules in porphyritic-olivine (PO) chondrules, where it is associated with Ni-rich metal and/or sulfides. To help constrain the origin of the magnetite, we measured oxygen isotopic compositions of magnetite and coexisting olivine grains in PO chondrules of Allende by an in situ ion microprobe technique. Five magnetite nodules form a relatively tight cluster in oxygen isotopic composition with delta 18O values from -4.8 to -7.1% and delta 17O values from -2.9 to -6.3%. Seven coexisting olivine grains have oxygen isotopic compositions from -0.9 to -6.3% in delta 18O and from -4.6 to -7.9% in delta 17O. The delta 17O values of the magnetite and coexisting olivine do not overlap; they range from -0.4 to -2.6%, and from -4.0 to -5.7%, respectively. Thus, the magnetite is not in isotopic equilibrium with the olivine in PO chondrules, implying that it formed after the chondrule formation. The delta 17O of the magnetite is somewhat more negative than estimates for the ambient solar nebula gas. We infer that the magnetite formed on the parent asteroid by oxidation of metal by H2O which had previously experienced minor O isotope exchange with fine-grained silicates. 相似文献
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Copper isotope fractionation during surface adsorption and intracellular incorporation by bacteria 总被引：1，自引：0，他引：1
Copper isotopes may prove to be a useful tool for investigating bacteria-metal interactions recorded in natural waters, soils, and rocks. However, experimental data which attempt to constrain Cu isotope fractionation in biologic systems are limited and unclear. In this study, we utilized Cu isotopes (δ65Cu) to investigate Cu-bacteria interactions, including surface adsorption and intracellular incorporation. Experiments were conducted with individual representative species of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as with wild-type consortia of microorganisms from several natural environments. Ph-dependent adsorption experiments were conducted with live and dead cells over the pH range 2.5-6. Surface adsorption experiments of Cu onto live bacterial cells resulted in apparent separation factors (Δ65Cusolution-solid = δ65Cusolution − δ65Cusolid) ranging from +0.3‰ to +1.4‰ for B. subtilis and +0.2‰ to +2.6‰ for E. coli. However, because heat-killed bacterial cells did not exhibit this behavior, the preference of the lighter Cu isotope by the cells is probably not related to reversible surface adsorption, but instead is a metabolically-driven phenomenon. Adsorption experiments with heat-killed cells yielded apparent separation factors ranging from +0.3‰ to −0.69‰ which likely reflects fractionation from complexation with organic acid surface functional group sites. For intracellular incorporation experiments the lab strains and natural consortia preferentially incorporated the lighter Cu isotope with an apparent Δ65Cusolution-solid ranging from ∼+1.0‰ to +4.4‰. Our results indicate that live bacterial cells preferentially sequester the lighter Cu isotope regardless of the experimental conditions. The fractionation mechanisms involved are likely related to active cellular transport and regulation, including the reduction of Cu(II) to Cu(I). Because similar intracellular Cu machinery is shared by fungi, plants, and higher organisms, the influence of biological processes on the δ65Cu of natural waters and soils is probably considerable. 相似文献
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Neolithic culture series in the Yishu River Basin developed in the order of Beixin culture-Dawenkou culture-Longshan culture-Yueshi culture. During the early and middle stage of Longshan culture （4600-4300 cal. yr BP）, the climate in the Yishu River Basin was warm and wet. Paddy-oriented agriculture planted paddy was very developed. The society was flourishing with great amount of archaeological sites. The cooling starting in 4200 cal. yr BP made the paddies shortfall in output or even no seeds were gathered. This situation intensified the discrepancy between population and resource. The scarcity in natural resource led to substantial decrease in population and subsequent drop in archaeological sites. About 4000 cal. yr BP Longshan culture was displaced by Yueshi culture which was relatively un- derdeveloped, simple and unsophisticated. 相似文献
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Forcada A Bayle-Sempere JT Valle C Sánchez-Jerez P 《Marine environmental research》2008,66(5):536-547
Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas. 相似文献
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长江三峡库区玉溪遗址地层沉积特征研究 总被引：1，自引：0，他引：1
在考古断代和AMS14C测年基础上,通过对洪水沉积环境以及三峡库区中坝遗址1981年洪水沉积和玉溪疑似古洪水沉积的粒度对比分析,发现它们的平均粒径、分选系数、偏度和峰度都在同一值域范围内;概率累积曲线都呈明显的三段式,从而推断出玉溪遗址的文化间隙层为古洪水沉积。 相似文献