Specific negative effects resulting from elevated levels of the recombinational repair protein Rad54p in Saccharomyces cerevisiae

RAD54 is an important gene in the RAD52 group that controls recombinational repair of DNA damage in Saccharomyces cerevisiae. Rad54p is a DNA‐dependent ATPase and shares seven conserved sequence motifs with proteins of the Swi2p/Snf2p family. Genetic analysis of mutations in motif IA, the putative ATP‐binding fold of Rad54p, demonstrated the functional importance of this motif. Overexpression of these mutant proteins resulted in strong, dominant‐negative effects on cell survival. High levels of full‐length wild‐type Rad54p or specific parts of Rad54p also resulted in negative effects, dependent on the ploidy of the host cell. This differential effect was not under a /α mating‐type control. Deletion of the RAD54 gene led to a small but significant increase in the mutation rate. However, the negative overexpression effects in haploid cells could not be explained by an accumulation of (recessive) lethal mutations. All negative overexpression effects were found to be enhanced under genotoxic stress. We suggest that the negative overexpression effects are the result of unbalanced protein–protein interactions, indicating that Rad54p is involved in multiple interactions, dependent on the physiological situation. Diploid wild‐type cells contained an estimated 7000 Rad54p molecules/cell, whereas haploid cells about 3500/cell. Rad54p levels were highest in actively growing cells compared to stationary phase cells. Rad54 protein levels were found to be elevated after DNA damage. Copyright © 1999 John Wiley & Sons, Ltd.     

基于龙芯一号IP核的EJTAG调试

在嵌入式系统中,片上调试是一种非常重要及有效的调试手段,而EJTAG就是其中一个重要的分支。本文从处理器的体系结构上讨论了EJTAG的设计、组成及工作原理,并针对龙芯一号处理器IP核,给出了GS32S处理器EJTAG调试的实现方法。经过项目的实际验证,在该方法的基础上实现的仿真器产品,不仅满足龙芯一号处理器的调试要求,而且满足标准的MIPS处理器的调试要求,扩展了MIPS仿真器产品的使用范围。     

多坐标系设置在墙板类零件加工中的应用

加工中心机床是实现多品种、小批次零件生产的理想设备,零件的一次装夹可完成多种工序的连续自动加工。工件坐标系的合理设置是实施自动加工前须认真考虑的重要问题,而充分利用数控系统的坐标系功能和机床工作台整个区域来实现零件的自动化加工,是提高自动加工效率的措施之一。文章主要讨论了利用多坐标系设置的方法来提高加工中心机床的墙板加工效率的具体措施和步骤,并实现仅在一套程序控制下的自动加工,同时给出了墙板类零件加工程序,实践检验结果表明该方法较单组零件一套程序加工提高效率一倍以上,具有一定应用价值。     

崇启长江公路大桥中上海与江苏平面坐标系统转换的实现

首先介绍了崇启长江公路大桥的概况,然后根据崇启长江公路大桥这个实例介绍了不同坐标系之间转换的方法,最后通过编程的方法实现了崇启长江公路大桥中上海与江苏平面坐标系统转换。     

Exposing water samples to ultraviolet light improves fluorometry for detecting human fecal contamination

Fluorometry identifies human fecal contamination by detecting optical brighteners in environmental waters. Because optical brighteners are sensitive to sunlight, we determined if we could improve fluorometry by exposing water samples to ultraviolet (UV) light to differentiate between optical brighteners and other fluorescing organic compounds. Optical brighteners were likely present when the relative percentage difference in fluorometric value of the water before and after UV light exposure was >30% (glass cuvettes, 30 min exposure) or >15% (polymethacrylate cuvettes, 5 min exposure). In a blind study, we correctly identified the presence or absence of optical brighteners in 178 of 180 (99%) of the samples tested with a more expensive field fluorometer and in 175 of 180 (97%) of the samples tested with a less expensive handheld fluorometer. In the field, the method correctly identified two negative and three positive locations for human fecal contamination. When combined with counts of fecal bacteria, the new fluorometric method may be a simple, quick, and easy way to identify human fecal contamination in environmental waters.     

UK experience of utility regulation since 2003 and outlook

Regulatory practice continues to be criticised and challenged. Issues which were concerning Government, regulators, companies and consumers in 2003 are, in many respects, still unresolved. There is a risk that too many decisions on developments in regulatory policy will be taken by Ministers rather than regulators, working with companies and consumers in the sectors they regulate, and that Ministers will be unduly influenced by “DIY economics”. The main challenge for the next ten years is, therefore, likely to be the relationship between regulators and government.     

浅析图书馆金属瓦屋面系统的选用和安装

校图书馆工程采用GS新型屋面系统,一是屋面的施工速度大大加快,满足工程工期要求,二是凸显了图书馆稳重庄重大气的品质,在工程验收中得到了验收专家和学校领导一致好评。     

中原油田φ101.6mm套管延迟注水泥技术

通过地面模拟试验和现场施工对比,找出了小间隙双层套管固井质量的解释方法和提高固井质量的技术措施,指出验套,套管回插,加焊扶正块等是提高固井一次成功率和合格率的根本保障.经过现场15口井的应用,固井质量合格率100%,优质井段达71.2%,投产投注效果良好.     

河道砂油藏开发中后期配产配注方法及应用

针对河道砂油藏连片性相对较差、面积相对较小、基础资料相对欠缺、油藏数值模拟方法难以有效应用的实际情况,从油藏自身的动态规律出发,确立了河道砂油藏注采指标的统计规律-累积产液量与时间的双对数直线规律和累积产液量、累积注水量与累积产油量的半对数直线规律。以此为基础推导出了累积产液量、月产油量、月注水量及月注采比与开发时间的关系。建立了一整套配产配注公式,可反映在稳定水驱阶段,累积产液量、月注水量及月注采比随时间的递增规律和月产油量随时间的递减规律。在老河口油田桩106-54砂体的应用表明,月产油量呈现出明显的逐月递减趋势,而日注水量和月注采比均呈现出逐月递增趋势,符合水驱砂岩油藏的开发规律。目前该配产配注结果已在现场应用,对老河口油田桩106-54砂体实际生产起到了有效的指导作用,目前该砂体生产态势平稳,开发效果较为理想。