Cotransport of the heterodimeric small subunit of the Saccharomyces cerevisiae ribonucleotide reductase between the nucleus and the cytoplasm

Ribonucleotide reductase (RNR) catalyzes the rate-limiting step in de novo deoxyribonucleotide biosynthesis and is essential in DNA replication and repair. Cells have evolved complex mechanisms to modulate RNR activity during normal cell cycle progression and in response to genotoxic stress. A recently characterized mode of RNR regulation is DNA damage-induced RNR subunit redistribution. The RNR holoenzyme consists of a large subunit, R1, and a small subunit, R2. The Saccharomyces cerevisiae R2 is an Rnr2:Rnr4 heterodimer. Rnr2 generates a diferric-tyrosyl radical cofactor required for catalysis; Rnr4 facilitates cofactor assembly and stabilizes the resulting holo-heterodimer. Upon DNA damage, Rnr2 and Rnr4 undergo checkpoint-dependent, nucleus-to-cytoplasm redistribution, resulting in colocalization of R1 and R2. Here we present evidence that Rnr2 and Rnr4 are transported between the nucleus and the cytoplasm as one protein complex. Tagging either Rnr2 or Rnr4 with a nuclear export sequence causes cytoplasmic localization of both proteins. Moreover, mutations at the Rnr2:Rnr4 heterodimer interface can affect the localization of both proteins without disrupting the heterodimeric complex. Finally, the relocalization of Rnr4 appears to involve both active export and blockage of nuclear import. Our findings provide new insights into the mechanism of DNA damage-induced RNR subunit redistribution.     

Development of quartz-crystal-microbalance-based immunosensor array for clinical immunophenotyping of acute leukemias

An integrated piezoelectric immunosensor array has been developed to immunophenotype acute leukemias in clinic. Each quartz crystal microbalance (QCM) was fabricated with plasma-polymerized film of n-butylamine, nanogold particles, and protein A (PA) to be used to immobilize antibodies in orientation. Leukemic lineage-associated monoclonal antibodies were separately immobilized onto the nanogold-PA-modified surface of the crystals, which were constructed by a 2 x 2 type of probes forming a QCM-based immunosensor array. The main detection conditions were investigated, including the immobilization amount of antibodies, pH, immunoreaction time, sample dilution ratio, etc. The immunophenotyping feasibility of the new technique was investigated through simultaneously analyzing Jurkat cells by the immunosensor array method, immunohistochemistry, and flow cytometry. It was found that the developed technique could readily identify leukemia samples in 5 min and might monitor dynamically the immunoreaction processes. Moreover, comparison studies were carried out for CD antigens expressed on the nucleated cells isolated from 96 acute leukemic patients and 24 normal subjects using the QCM-based immunosensor method and the fluoroimmunoassay. Results obtained by immunophenotyping patients' samples with the immunosensor-based method achieved the rate of 88.93% in 768 groups of numerical data, where no significant statistical difference was observed between the two methods when checked by chi2 analysis (chi2 = 3.4, p > 0.05). This new immunosensor array showed the merits of high sensitivity, high specificity, good reproducibility, easy operation, and low cost. The results of specimen evaluation indicated that it might be clinically suitable for quantifying human differentiated leukocytes and immunophenotyping of acute leukemias.     

蝗虫生境评价信息系统的设计与实现

主要论述了蝗虫生境评价信息系统的设计目标、数据流程及结构设计、数据库设计、模型库设计及功能设计,并简要说明了所建系统的实现。研究表明,基于GIS技术所建立的蝗虫生境评价信息系统,可对影响蝗虫发生的生境因子进行综合分析以及针对蝗虫潜在发生可能性对蝗虫生境进行定量评价,从而为蝗虫发生和成灾的监测和防治提供强有力的技术手段。蝗虫生境评价信息系统除了应具备信息系统的基本功能和一般统计分析功能外,还应重点加强其生境评价功能,如评价因子选择和权重管理,评价指标量化,评价等级划分,评价指标的加权求和,以及总分值的划分。     

海洋放线菌124092细胞毒活性和化学成分研究

采用MTT法对海洋放线菌124092正己烷提取物进行细胞毒活性筛选,结果显示对小鼠B16黑色素瘤细胞有一定的生长抑制活性。用硅胶真空柱层析法将正己烷提取物粗分为6个组分（Fr1～Fr6）,细胞毒活性追踪显示Fr6组分为活性部分。为确定其中的活性成分,运用GC／MS对脯组分的化学成分进行了分析,结果显示其主要成分为：棕榈酸（Palmitic acid,11．76％）、油酸（Oleic acid,12．16％）、亚油酸（Linoleic acid．14．77％）和乳杆（菌）酸（Lactobacillic acid,61．31％）。据文献报道棕榈酸、油酸、亚油酸均对小鼠腹水瘤细胞具有细胞毒活性,亚油酸还对人肺腺癌细胞具有抑制作用。     

Uptake and exudation behavior of perchlorate in smartweed

Perchlorate uptake has been reported in a variety of vascular plants, but the mechanisms affecting the uptake, translocation, and exudation of ClO4(-) in plants are not well known. The uptake and transport behavior of ClO4(-) was studied in smartweed (Polygonum spp.) grown in aerated hydroponic ClO4(-) solutions with or without other common anions. Uptake followed first-order kinetics (0.017 +/- 0.003 day(-1)) and there was no apparent competitive effect on ClO4(-) uptake for up to 500 mg L(-1) of NO3(-) -N, SO4(2-), PO4(3-), or Cl(-). The net ClO4(-) mass uptake was proportional to transpiration but with some exclusion of ClO4(-) from the transpiration stream. Up to 4% of the ClO4(-) in plants after a 30-d exposure to a 10-mg/L solution of ClO4(-) was exuded from the roots within 15 d after the exposure was ended. Perchlorate exudation followed first-order kinetics with a rate coefficient of 0.0018 +/- 0.0006 (day(-1) Results obtained in this study indicate that evapotranspiration may be the critical variable to predict accumulation potential in plants and that phytoremediation strategies should take into account the re-release potential of ClO4(-) via exudation.     

基于地形因素的新疆荒漠植被-气候模型应用研究

本研究在新疆荒漠植被型分类的基础上,用植被与气候Holdridge生命带模型进行荒漠植被型的模拟,并用Kappa检验系数进行结果检验,模拟结果很差(0.19),将地形作为模拟模型具体考虑的一个因素,对重新分类的气候区进行二次植被模拟。二次模拟结果Kappa检验系数平均值为0.45,二次模拟整体荒漠植被型模拟结果的Kappa检验系数为0.64,极大地提高了模型模拟的准确度。模型模拟准确度的提高在于将影响新疆水分分配的地形因素作为改进Holdridge生命带模型的参数,该参数的引入为提高Holdridge生命带模型的准确度提供了新的思路,也为较准确地模拟新疆地区的植被提供了新途径。     

一种基于特征筛选的原核生物启动子判别分析方法

启动子识别是研究基因转录调控的重要环节,但目前方法的识别正确率偏低。在深入分析原核启动子特征的基础上,提出了一种基于特征筛选的原核启动子判别分析方法,首先在启动子序列的组成特征、信号特征和结构特征中选取备选特征,为每个特征建立适当的描述模型,并对主要的保守模式采用复合模式模型;再通过模型计算对备选特征进行逐步筛选,优化特征集,将序列表示为组合特征向量;最终利用二次判别分析实现识别。对大肠杆菌和枯草杆菌实际启动子数据进行的刀切法测试验证了方法的有效性和通用性。对于大肠杆菌非编码区(70启动子,识别的平均正确率达到了85.8%,优于其它几种典型识别方法;对于大肠杆菌编码区内部)70启动子和其它几种原核启动子,平均正确率也都超过了80%。方法框架还具有良好的可扩展性,能够方便地容纳新特征,使识别性能不断提高。     

中老年奶粉对肠道菌群、血清免疫球蛋白及钙的影响

目的了解中老年奶粉对中老年人肠道菌群、血清免疫球蛋白及钙的影响。方法用培养方法检测肠道菌群,速率散射浊度法测血清免疫球蛋白,化学法测血清钙。结果服用中老年奶粉后,中老年人肠道内双歧杆菌明显增加（P〈0．01）,血清IgG,IgA、IgM含量及血清钙水平也显著提高（分别为P〈0．001,P〈0．001,P〈0．01和P〈0．001）。结论中老年奶粉对调整中老年人肠道菌群、增加免疫力、预防脱钙等具有一定的作用。     

东方田鼠的同工酶与异构蛋白生化基因位点

目的观察四类东方田鼠在10个同工酶与异构蛋白生化基因位点上的基因分布特征,以研究它们间的遗传关系。方法应用乙酸纤维素膜电泳对四类东方田鼠的同工酶与异构蛋白生化基因位点进行测定分析。结果与结论黑龙江小体型东方田鼠与其他三类东方田鼠的电泳结果差异较大,在6个位点上都存在其所特有的等位基因,并且在其中的3个位点上它的基因型与其他三类鼠完全不同;湖南、宁夏和黑龙江大体型东方田鼠三者间的遗传距离在0.0633~0.2107之间,而黑龙江小体型东方田鼠与其他三类鼠的遗传距离在0.7068~0.8953之间;UPGMA聚类分析显示,湖南、宁夏和黑龙江大体型东方田鼠聚为一类,亲缘关系较近,而黑龙江小体型东方田鼠单独为一类,与其他三种鼠的亲缘关系均相对较远。     

准分子激光原位角膜磨镶术前术后客观验光和主观验光的比较

目的比较准分子激光原位角膜磨镶术前后客观验光和主观验光的准确性和相关性。方法对在我中心接受LASIK手术69例123眼,在术前和术后一个月进行客观验光(NIDEKARK-700)和主观验光(RODENSTOCK综合验光头),对获得的数据进行相关分析。结果LASIK术后,客观验光的准确性较术前下降,客观验光和主观验光测量结果的差值明显增加;术前近视度越高,术后客观验光和主观验光测量结果的差别越大。在测量散光中,术后1月,客观验光和主观验光测量散光的差值明显增加,客观验光不能准确测量散光的量和轴向。结论LASIK术前用自动验光仪进行的客观验光可靠性较高,与主观验光法测量屈光不正的结果接近;术后,客观验光的准确性较术前下降,不能有效评判屈光不正的性质和量。