Perturbation of gene expression and steroidogenesis with in vitro exposure of fathead minnow ovaries to ketoconazole

Ketoconazole is a fungicidal drug that inhibits function of cytochrome P450s in the synthesis of steroids. To examine if inhibition of P450 function affects gene expression in a dynamic manner, we conducted in vitro exposures of ovary tissue from fathead minnows (Pimephales promelas) to 0.5 microM ketoconazole to investigate effects on steroid production and gene expression over time. Expression of four key steroidogenesis genes was examined at 1, 6, and 12h of exposure. 11 beta- and 20 beta-hydroxysteroid dehydrogenases were down regulated at 1h and Cytochrome P450 17 was down-regulated at 12h, consistent with the absence of steroid production. In contrast, cytochrome P450 19A was up-regulated at 6h, indicating feedback regulation. Microarray analysis of 12h exposures indicated enrichment of biological processes involved in neurotransmitter secretion, lymphocyte cell activation, sodium ion transport, and embryonic development. These data suggest that, with the exception of cytochrome P450 19A, these steroid metabolic genes are regulated in a feed forward manner and that the effects of ketoconazole may be broader than anticipated based on the mechanism of action alone.     

SZF型波浪浮标系统

文中介绍了SZF型波浪浮标的系统组成、主要工作原理及系统的主要功能,给出了该型号浮标的测量指标及技术参数,介绍了该浮标的应用情况。     

基于ANP-SWOT模型的城市应急避难场所发展规划——以兰州市为例

合理的规划和建设城市应急避难场所可以增强城市抗灾能力,提高城市灾害韧性,降低灾害带来的人员伤亡和财产损失。在对兰州市应急避难场所的建设现状进行详细调研的基础上,利用ANP-SWOT模型对其发展规划进行分析。首先运用SWOT分析方法确定兰州市应急避难场所未来发展的内部优势和劣势、外部机会和威胁;其次运用ANP分析法构建兰州市应急避难场所发展规划的网络层次结构,结合专家咨询,通过赋值和对比分析确定最佳发展策略。结果显示,分布不均、数量不足、尚未形成专门的应急预案是制约兰州市应急避难场所发展的关键问题;最佳发展策略是加快推进兰州市应急避难场所的标准化规范化。     

陕甘宁盆地北部下白垩统潜水氧化带型铀矿成矿远景研究

陕甘宁盆地的北部下白垩统出露相当广泛,下白垩经沉积之后,伴随有大面积的竽隆升,根据沉积地层的岩性岩相特征、新构造运动的表现形式,可以区分出Ｋ２－Ｅ２以及Ｎ１－现代两个主要的氧化剥蚀作用期,在这两个氧化剥蚀作用期间,产生了大规模的面状氧化作用,有意思的是根据石油钻孔的ｒ测井资料和实地调研证实：这种氧化作用所形成的潜水氧化带都与铀矿化有关,同时,现代陕甘宁盆地北部所呈现出的高原型自治水盆地的水动力特征,暗示出在陕甘盆地的北部下白垩统中浅部层位（一般）〉２００ｍ）中的铀矿化以潜水氧化带型为主。     

平面Radon变换的反演公式

本文借助球面平均法和Ｈｉｌｂｅｒｔ空间算子理论,给出了平面上Ｒａｄｏｎ变换的反演公式,此公式是具体的、构造性的,便于数值计算,或者进一步探讨重建图象的性质。     

Airborne and groundbased spectrophotometry of comet P/Halley from 5-13 micrometers

Spectrophotometry from 5-10 micrometers (delta lambda/lambda approximately 0.02) of comet Halley was obtained from the Kuiper Airborne Observatory on 1985 December 12.1 and 1986 April 8.6 and 10.5, UT. 8-13 micrometers data were obtained on 17.2 December 1985 from the Nickel Telescope at Lick Observatory. The spectra show a strong broad emission band at 10 micrometers and a weak feature at 6.8 micrometers. We do not confirm the strong 7.5 micrometers emission feature observed by the Vega 1 spacecraft. The 10 micrometers band, identified with silicate materials, has substructure indicative of crystalline material. The band can be fitted by combining spectra data from a sample of interplanetary dust particles. The primary component of the silicate emission is due to olivine. The 6.8 micrometers emission feature can be due either to carbonates or the C-H deformation mode in organic molecules. The lack of other emission bands is used to place limits on the types of organic molecules responsible for the emission observed by others at 3.4 micrometers. Color temperatures significantly higher than the equilibrium blackbody temperature indicate that small particles are abundant in the coma. Significant spatial and temporal variations in the spectrum have been observed and show trends similar to those observed by the spacecraft and from the ground. Temporal variability of the silicate emission relative to the 5-8 micrometers continuum suggests that there are at least two physically separated components of the dust.     

Petrography and bulk chemistry of Martian orthopyroxenite ALH84001: implications for the origin of secondary carbonates

New petrologic and bulk geochemical data for the SNC-related (Martian) meteorite ALH84001 suggest a relatively simple igneous history overprinted by complex shock and hydrothermal processes. ALH84001 is an igneous orthopyroxene cumulate containing penetrative shock deformation textures and a few percent secondary extraterrestrial carbonates. Rare earth element (REE) patterns for several splits of the meteorite reveal substantial heterogeneity in REE abundances and significant fractionation of the REEs between crushed and uncrushed domains within the meteorite. Complex zoning in carbonates indicates nonequilibrium processes were involved in their formation, suggesting that CO2-rich fluids of variable composition infiltrated the rock while on Mars. We interpret petrographic textures to be consistent with an inorganic origin for the carbonate involving dissolution-replacement reactions between CO2-charged fluids and feldspathic glass in the meteorite. Carbonate formation clearly postdated processes that last redistributed the REE in the meteorite.     

Ar-Ar chronology of the Martian meteorite ALH84001: evidence for the timing of the early bombardment of Mars

ALH84001, a cataclastic cumulate orthopyroxenite meteorite from Mars, has been dated by Ar-Ar stepped heating and laser probe methods. Both methods give ages close to 3,900 Ma. The age calculated is dependent on assumptions made about 39Ar recoil effects and on whether significant quantities of 40Ar from the Martian atmosphere are trapped in the meteorite. If, as suggested by xenon and nitrogen isotope studies, Martian atmospheric argon is present, then it must reside predominantly in the K-rich phase maskelynite. Independently determined 129Xe abundances in the maskelynite can be used to place limits on the concentration of the atmospheric 40Ar. These indicate a reduction of around 80 Ma to ages calculated on the assumption that no Martian atmosphere is present. After this correction, the nominal ages obtained are: 3940 +/- 50, 3870 +/- 80, and 3970 +/- 100 Ma. by stepped heating, and 3900 +/- 90 Ma by laser probe (1 sigma statistical errors), giving a weighted mean value of 3,920 Ma. Ambiguities in the interpretation of 39Ar recoil effects and in the contribution of Martian atmospheric 40Ar lead to uncertainties in the Ar-Ar age which are difficult to quantify, but we suggest that the true value lies somewhere between 4,050 and 3,800 Ma. This age probably dates a period of annealing of the meteorite subsequent to the shock event which gave it its cataclastic texture. The experiments provide the first evidence of an event occurring on Mars coincident with the time of the late heavy bombardment of the Moon and may reflect a similar period of bombardment in the Southern Highlands of Mars. Whether the age determined bears any relationship to the time of carbonate deposition in ALH84001 is not known. Such a link depends on whether the temperature associated with the metasomatic activity was sufficient to cause argon loss from the maskelynite and/or whether the metasomatism and metamorphism were linked in time through a common heat source.     

铀的微生物成矿作用研究进展

铀的微生物成矿作用研究尚处于实验研究阶段。微生物富集铀的机制可分为代谢性和非代谢性两类。前与代谢产生的酶、化学配位体、排泄物对铀酰的络合、还原有关；后是由细胞的负电位与带正电荷的UO2^2 间产生生理-化学作用，导致铀的生物吸附、吸收、离子交换和沉淀。它与微生物的代谢、活力无关。综述了厌氧菌、喜氧菌富集铀的实验结果、富集机制和今后研究的发展趋向。