Frequent mtDNA mutations and its role in gastric carcinogenesis

In order to disclose the relationship between mutations of mitochondrial DNA (mtDNA) and gastric carcinogenesis, we screened the entire mtDNA sequence in 30 cases of human gastric cancer and matched normal tissues by using denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing. Our data showed that high frequency (66.7%, 20/30) of mitochondrial genome mutation occurred in gastric cancer. Among these variants, 17 cases (56.7%, 17/30) were identified to be somatic mutation. High level mutant frequency was found in ND4, ND5 coding genes and D-loop control region, which was 36.7%, 26.7% and 30% respectively. Comparing with complexes Ⅲ, Ⅳ and Ⅴof the electron transport chain, we found that variants appeared to be more frequent in the subunit genes of complexⅠ. Most of mutations were base substitutions (85.4%, 41/48). Our results suggested that mutations of subunit genes encoding complexⅠ, especially ND3, ND4 and ND5 genes, might contribute to human gastric carcinogenesis.     

Colorectal cancer: mutations in a signalling pathway

Protein kinases are enzymes that are important for controlling cellular growth and invasion, and their malfunction is implicated in the development of some tumours. We analysed human colorectal cancers for genetic mutations in 340 serine/threonine kinases and found mutations in eight genes, including in three members of the phosphatidylinositol-3-OH kinase (PI(3)K) pathway. The discovery of this mutational activation of a key cell-signalling pathway may provide new targets for therapeutic intervention.     

Ha-ras hypervariable alleles in myelodysplasia

The somatic mutation of one of the ras oncogenes is now considered to be a critical step in the pathogenesis of many tumours. Circumstantial evidence also suggests that some individuals may be genetically predisposed to malignancy and a general method used to analyse such disease susceptibility is the study of restriction fragment length polymorphisms (RFLPs) at particular loci. The Harvey ras (Ha-ras) locus includes a hypervariable region (HVR) which consists of a series of 28-base-pair (bp) tandem repeats 3' to the gene. This arrangement gives rise to alleles of a wide range of sizes, making such genetic analysis possible. A previous study reported that white blood cell DNA from cancer patients frequently showed allelic restriction fragments at the Ha-ras locus which were found only rarely in normal unaffected individuals, and it was concluded that the inheritance of such unusual alleles may be linked to a susceptibility to cancer. As this conclusion has major implications we sought to investigate whether this association could be confirmed in patients with myelodysplasia, a common haematological malignancy reported to have the highest frequency of rare alleles. The Ha-ras alleles were characterized in normal healthy individuals and compared with those found in patients with myelodysplasia (MDS). Our results, reported here, show that the distribution of Ha-ras alleles in myelodysplastic patients is not significantly different from that in normal individuals.     

Electrophoresis of ribonucleoproteins reveals an ordered assembly pathway of yeast splicing complexes

Three splicing complexes formed with a yeast pre-messenger RNA during in vitro splicing can be resolved by non-denaturing gel electrophoresis after incubation in the presence of non-specific competitor RNA. The time course of the appearance of these complexes and their composition suggest that they represent an ordered pathway of splicing complex assembly.     

FLUENT在动力机械中的应用

FLUENT是用于模拟计算流体流动以及热传导问题的CFD通用软件,广泛应用于动力机械领域.介绍了FLUENT模拟的特点,并以混合管道内部流动为例,利用该软件模拟了管道内部流动的情况,以便更好地改善其运行的经济性、安全性和可靠性.     

Frequent mutation of histone-modifying genes in non-Hodgkin lymphoma

Follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) are the two most common non-Hodgkin lymphomas (NHLs). Here we sequenced tumour and matched normal DNA from 13 DLBCL cases and one FL case to identify genes with mutations in B-cell NHL. We analysed RNA-seq data from these and another 113 NHLs to identify genes with candidate mutations, and then re-sequenced tumour and matched normal DNA from these cases to confirm 109 genes with multiple somatic mutations. Genes with roles in histone modification were frequent targets of somatic mutation. For example, 32% of DLBCL and 89% of FL cases had somatic mutations in MLL2, which encodes a histone methyltransferase, and 11.4% and 13.4% of DLBCL and FL cases, respectively, had mutations in MEF2B, a calcium-regulated gene that cooperates with CREBBP and EP300 in acetylating histones. Our analysis suggests a previously unappreciated disruption of chromatin biology in lymphomagenesis.     

Translational control of intron splicing in eukaryotes

Most eukaryotic genes are interrupted by non-coding introns that must be accurately removed from pre-messenger RNAs to produce translatable mRNAs. Splicing is guided locally by short conserved sequences, but genes typically contain many potential splice sites, and the mechanisms specifying the correct sites remain poorly understood. In most organisms, short introns recognized by the intron definition mechanism cannot be efficiently predicted solely on the basis of sequence motifs. In multicellular eukaryotes, long introns are recognized through exon definition and most genes produce multiple mRNA variants through alternative splicing. The nonsense-mediated mRNA decay (NMD) pathway may further shape the observed sets of variants by selectively degrading those containing premature termination codons, which are frequently produced in mammals. Here we show that the tiny introns of the ciliate Paramecium tetraurelia are under strong selective pressure to cause premature termination of mRNA translation in the event of intron retention, and that the same bias is observed among the short introns of plants, fungi and animals. By knocking down the two P. tetraurelia genes encoding UPF1, a protein that is crucial in NMD, we show that the intrinsic efficiency of splicing varies widely among introns and that NMD activity can significantly reduce the fraction of unspliced mRNAs. The results suggest that, independently of alternative splicing, species with large intron numbers universally rely on NMD to compensate for suboptimal splicing efficiency and accuracy.     

论工程机械的智能化发展

针对工程机械智能化的问题,对机器人化工程机械需要研究的内容进行论述,即电液比例控制技术、状态监测及故障诊断技术、自动变速技术、卫星定位技术等.机械工业的智能化不仅可释解人类的体力劳动,而且更重要的是可替代人类的脑力劳动,从而实现脑力劳动的机械化、自动化.可见,智能化是机械工业发展的必然趋势.     

基于不确定数据的频繁项查询算法

频繁项的查询是一项非常重要的技术,但在新兴的不确定数据领域却是一项新的研究课题.基于不确定数据,提出了一种新的频繁项定义,并提出了两条过滤规则,可以有效地减少检测数据的数量.最后提出高效的频繁项查询算法UFI,该算法通过找到概率求解中的递推规律,极大提高了单点检测效率.实验结果显示:提出的方法可以有效地减少候选集,降低...     

在卷烟成型设备上实现高速任务处理

控制系统常常需要处理一些快速任务,介绍几种在卷烟成型设备上使用专用或通用器件的实现方法.对于使用通用控制器件的方法,则通过一些例子进行了较为详细的说明.ZJ17机组使用高速布尔处理器FM352-5,使用分频测算的方法测量设备运行的线速度.ZL26A机组使用伺服控制器simotion D1435完成废品剔除功能.所有的实现方法,已经在设备控制系统中应用并可以满足功能要求.     

高压甲铵预热器频繁爆管原因分析

对高压甲铵预热器爆管原因进行了分析,通过对高压甲铵预热器管壁涡流检测堵管和高压氨预热器的投用,彻底解决了高压甲铵预热器爆管给整个水溶液全循环法尿素胺装置带来危害的问题.     

桩基工程中常见事故分析处理与预防

桩基工程是土木工程中最常见的隐蔽工程之一,施工工艺涉及成孔、灌注。在成孔阶段,可能出现塌孔或缩径以及孔底留泥等。在灌注阶段,可能出现夹泥和断桩,这些事故均可导致灌注桩承载力缺陷,不能满足设计要求。根据工程实践经验,分析总结了我省近年来钻孔灌注桩施工过程中常见的工程事故及其产生原因,建议了相应的处理措施,具有一定的工程意义。     

Mining Maximal Frequent Patterns in a Unidirectional FP-tree

Becausemining complete set of frequent patterns from dense database could be impractical, an interesting alternative has been proposed recently. Instead of mining the complete set of frequent patterns, the new model only finds out the maximal frequent patterns, which can generate all frequent patterns. FP-growth algorithm is one of the most efficient frequent-pattern mining methods published so far. However,because FP-tree and conditional FP-trees must be two-way traversable, a great deal memory is needed in process of mining. This paper proposes an efficient algorithm Unid_FP-Max for mining maximal frequent patterns based on unidirectional FP-tree. Because of generation method of unidirectional FP-tree and conditional unidirectional FP-trees, the algorithm reduces the space consumption to the fullest extent. With the development of two techniques：single path pruning and header table pruning which can cut down many conditional unidirectional FP-trees generated recursively in mining process, Unid_ FP-Max further lowers the expense of time and space.     

基于机器视觉的农业机械无人驾驶研究

为实现农业机械的无人驾驶,研究基于机器视觉的农业机械运动控制具有重要的意义.本文介绍了基于机器视觉的农业机械无人驾驶的工作原理和实现方法.通过对视频图像的处理,识别出农业作业环境的路径特征的位置和方向,采用模糊控制方法实现了农业机械的运动控制.试验证明了基于机器视觉的农业机械无人驾驶系统的可行性及控制算法的可靠性.     

对高校教务秘书频繁更换的思索

教务秘书的频繁更换不利于高校教学和管理工作的正常开展,并将对其他员工产生负面效应.我们应当积极采取稳定对策,加大关怀力度,构建一支稳定的、高素质的教务秘书队伍.     

A role for branchpoints in splicing in vivo

The nucleotides immediately surrounding intron/exon junctions of genes transcribed by RNA polymerase B can be derived from 'consensus' sequences for donor and acceptor splice sites by only a few base changes. Studies in vivo have underlined the importance of these junction nucleotides for splicing. In higher eukaryotes, no evidence has been found for specific internal intron sequences involved in splicing. However, the recent discovery that, in vitro, introns are excised in a lariat form where the 5' end of the intron is joined via a 2'-5'-phosphodiester linkage to an A residue (branchpoint acceptor) close to the 3' end of the intron, suggests that internal intron sequences may nonetheless be important for splicing. Indeed, in yeast nuclear genes, the internal sequence 5'-TACTAAC-3' (or close homologue) is essential for splicing in vivo. A proposed consensus sequence for branchpoints in mammalian introns is 5'-CT(A/G)A(C/T)-3'. This sequence resembles the essential yeast internal sequence. Are branchpoints involved in the splicing of introns of higher eukaryotes in vivo? We show here that a branchpoint sequence from a human globin gene (5'-CTGACTCTCTCTG-3') greatly enhances the efficiency of splicing of a 'synthetic' intron in HeLa cells. A mutated branchpoint sequence, 5'-CTCCTCTCTCTG-3', in which the branchpoint acceptor nucleotide A has been deleted and the neighbouring purine G mutated to a C, does not exhibit this enhancing capability. We conclude that branchpoints have an important function in the splicing process in vivo.