四环素胁迫对Shigella flexneri细菌四环素抗性基因抗性表达的影响过程

四环素(TC)抗生素在不同环境介质中已被广泛检出,为研究其对四环素抗性基因(TC-ARGs)丰度变化及表达水平的影响过程,以从活性污泥中筛选和纯化分离获得的弗氏志贺氏菌(Shigella flexneri)为研究对象,考察了不同浓度TC对其生长过程的作用影响,采用荧光定量PCR和逆转录PCR方法定量检测了不同抗性机制TC-ARGs,包括tetC、tetO和tetX基因的丰度变化及表达水平,并探讨了TC浓度与TC-ARGs丰度及其表达水平之间的相关关系.结果表明,在培养周期内(24 h),TC胁迫对Shigella flexneri细菌的生长具有抑制作用,细菌细胞浓度增长速率随TC暴露浓度的升高而降低,但对TC-ARGs丰度变化影响较小.TC胁迫能够促进Shigella flexneri细菌TC-ARGs的转录表达,tetC、tetO和tetX基因表达水平在整个培养周期内均先升高后降低.由相关性分析可知,TC浓度与TC-ARGs丰度及其表达水平之间相关关系不显著,但tetC和tetO基因丰度与其转录表达水平之间存在显著的正相关关系,表明其基因丰度一定程度上可用来衡量和评价其抗性表达水平.     

监测分析中结果的表达─兼谈环境监测标准化

对环境监测中的数据、统计、有效数字、修约，以及计量单位、结果表达、原始数据的记录等既平常又十分重要易被忽略的重要问题作了概述，这些问题的解决才能保证监测结果的准确性和可靠性．     

镉铅对小麦醇脱氢酶(ADH)基因表达影响的初步研究

经过镉，铅４５ｈ污染处理，运用Ｎｏｒｔｈｅｉｎ斑点杂分析和酶活性测定的方法探测萌发期小麦ＡＤＨ酶基因的表达情况。实验结果表明，ＡＤＨ基因表达在ＲＮＡ和酶活性两个层次均有变化，并且呈现相似的变化趋势，反映得金属的影响是来源于基因转录水平。     

全氟辛烷磺酸(PFOS)对斑马鱼卵黄蛋白原mRNA水平的影响

为了研究环境低剂量全氟辛烷磺酸（perfluorooctane sulfonate,PFOS）对水生生物的内分泌干扰效应和可能的作用机制,测定了PFOS对斑马鱼（Brachydanio rerio）肝脏中卵黄蛋白原（vitellogenin,VTG）mRNA水平的影响.将斑马鱼暴露于4个PFOS的环境低剂量浓度组（0.1、1、10、100μg.L-1）中进行21d毒性试验,收集肝脏样品,提取RNA,采用荧光定量PCR（qRT-PCR）分别检测VTG1和VTG3的mRNA水平.结果表明：①PFOS暴露引起雄性斑马鱼肝脏VTG1和VTG3 mRNA水平升高,VTG1 mRNA水平升高与剂量呈正相关,在100μg.L-1暴露浓度处与对照组呈现显著性差异;VTG3的mRNA水平变化与剂量呈倒U型曲线,呈现典型的毒物刺激荷尔蒙效应,在10和100μg.L-1暴露浓度处与对照组呈现显著性差异;②PFOS暴露引起雌性斑马鱼肝脏中VTG1 mRNA水平升高,在10μg.L-1暴露浓度处与对照组呈现显著性差异,但在高浓度（10和100μg.L-1）处试验结果误差较大;VTG3 mRNA水平只在10μg.L-1暴露浓度处升高,但相比于对照组均没有显著性差异.试验结果表明PFOS暴露对斑马鱼的内分泌干扰作用明显,其毒性作用机制可能是类雌激素效应,而肝脏中VTG1和VTG3mRNA水平可能作为PFOS内分泌干扰效应评价的敏感生物标志物,但VTG1和VTG3 mRNA水平的响应曲线呈现基因亚型和性别差异.     

镉对长江华溪蟹金属硫蛋白mRNA表达的诱导及低分子量壳聚糖的联合作用

采用实时荧光定量PCR法,研究了不同浓度镉（Cd2＋）对长江华溪蟹（Sinopotamon yangtsekiense）金属硫蛋白（metallothionein,简称MT）在肝胰腺、鳃、肌肉和心脏中mRNA表达的诱导作用及低分子量壳聚糖（lowmolecular weight chitosan,简称LMWC）的联合作...     

Molecular characterization and developmental expression patterns of thyroid hormone receptors (TRs) and their responsiveness to TR agonist and antagonist in Rana nigromaculata

Considering some advantages of Rana nigromaculata as an experimental species, we propose that this species, like Xenopus laevis, could be used to assay thyroid hormone（TH） signaling disrupting actions. To validate the utilizability of R. nigromaculata, we investigated the responsiveness of R. nigromaculata to a TH receptor（TR） agonist（T3） and antagonist（amiodarone） by analyzing expression, based on characterizing TR cDNA and developmental expression patterns. With high levels of identity with the corresponding genes in X. laevis, both TRα and TRβ in R. nigromaculata exhibited roughly similar developmental expression patterns to those of X. laevis, in spite of some species-specific differences. Both TRα and TRβ expression had greater changes in the liver and intestine than in the tail and brain during metamorphosis. T3 exposure for 2 days induced more dramatic increases of TRβ expression in stage 27 than in stage34 tadpoles but not in stage 42 tadpoles, showing that the responsiveness of R. nigromaculata to TH decreased with development and disappeared at the onset of metamorphic climax.Corresponding to greater changes of TRβ expression in the liver and intestine than in the tail and brain during metamorphosis, the liver and intestine had higher responsiveness to exogenous T3 than the tail and brain. Amiodarone inhibited T3-induced TRβ expression. Our results show that R. nigromaculata can be used as a model species for assaying TH signaling disrupting actions by analyzing TRβ expression, and intestine tissues at stage 27 are ideal test materials due to high responsiveness and easy accessibility.     

2,2',4,4'-四溴联苯醚对赤子爱胜蚓的抗氧化酶、代谢酶及其基因表达的影响

多溴联苯醚(PBDEs)是广泛存在于环境中的一种新型持久性有机污染物.四溴联苯醚同分异构体中的BDE-47是多溴联苯醚中最重要的单体之一.试验采用人工土壤培养法,通过亚急性试验,研究了在不同暴露时间阶段下,不同BDE-47剂量对赤子爱胜蚓(Eisenia fetida)抗氧化酶(过氧化氢酶CAT)、代谢酶(谷胱甘肽转移酶GST)以及二者基因表达的影响.结果表明,在暴露14 d和28 d时,CAT活性被诱导上升并且差异显著;GST活性变化差异不显著;CAT基因表达水平在第14 d时呈现抑制效应,在后续的第28 d和第42 d基因表达水平上调;GST基因表达水平整体呈现诱导效应,并且差异显著,随着暴露时间的增加,低毒处理组(10、50 mg·kg-1)的基因表达水平逐渐下调至低于对照组的水平,高毒处理组(100、200 mg·kg-1)的基因表达量仍高于对照组水平;在BDE-47的暴露试验中,CAT与GST活性及其基因表达水平两项指标对低毒处理组较高毒处理组更为敏感.     

Correlation of foliar MT2b expression with Cd and Zn concentrations in hybrid aspen (Populus tremula × tremuloides) grown in contaminated soil

Metal uptake and its effect on foliar metallothionein 2b (MT2b) mRNA levels were studied in hybrid aspen (Populus tremula × tremuloides) in field conditions. The trees were planted on a site contaminated with several metals, including cadmium (mean 5.1 mg kg⁻¹), chromium (80 mg kg⁻¹), copper (180 mg kg⁻¹), nickel (81 mg kg⁻¹), vanadium (240 mg kg⁻¹) and zinc (520 mg kg⁻¹). Of the ten trace elements analyzed, only Cd and Zn accumulated in the leaves with maximal foliar concentrations of 35 and 2400 mg kg⁻¹ (dry weight), respectively. There was a strong correlation between Cd and Zn concentrations and bioaccumulation factors (concentration in plant/soil) in the leaves, branches and roots, suggesting similar transport mechanisms for these two metals. The levels of MT2b correlated with Cd and Zn concentrations in the leaves, demonstrating that increased MT2b expression is one of the responses of hybrid aspen to chronic metal exposure.     

Expression of alkane monooxygenase (alkB) genes by plant-associated bacteria in the rhizosphere and endosphere of Italian ryegrass (Lolium multiflorum L.) grown in diesel contaminated soil

For phytoremediation of organic contaminants, plants have to host an efficiently degrading microflora. To assess the role of endophytes in alkane degradation, Italian ryegrass was grown in sterile soil with 0, 1 or 2% diesel and inoculated either with an alkane degrading bacterial strain originally derived from the rhizosphere of Italian ryegrass or with an endophyte. We studied plant colonization of these strains as well as the abundance and expression of alkane monooxygenase (alkB) genes in the rhizosphere, shoot and root interior. Results showed that the endophyte strain better colonized the plant, particularly the plant interior, and also showed higher expression of alkB genes suggesting a more efficient degradation of the pollutant. Furthermore, plants inoculated with the endophyte were better able to grow in the presence of diesel. The rhizosphere strain colonized primarily the rhizosphere and showed low alkB gene expression in the plant interior.     

基于模糊神经网络的机动车驾驶教练员职业适宜性研究

提出应用模糊神经网络系统,建构教练员职业适宜性的3个要素(即心理素质、驾驶技能和知识的表达阐述能力)的学习样本,分析"三要素"的8项特征参数指标——场依存性、速度估计能力、交通安全意识、简单反应、选择反应、跟踪能力、行车注意力、表达阐述能力等,使用K-均值法对实验样本进行初始分类,形成标准学习样本,使用该样本对所构建系统进行训练和调试。利用经调试训练后的系统,依据所测教练员的心理、心理参数对其职业适宜性进行评价。试验表明:建立的教练员职业适宜性仿真模型能取得很好的评价效果。