Telomere dysfunction impairs DNA repair and enhances sensitivity to ionizing radiation

Telomeres are specialized nucleoprotein complexes that serve as protective caps of linear eukaryotic chromosomes. Loss of telomere function is associated with rampant genetic instability and loss of cellular viability and renewal potential. The telomere also participates in processes of chromosomal repair, as evidenced by the 'capture' or de novo synthesis of telomere repeats at double-stranded breaks and by the capacity of yeast telomeres to serve as repositories of essential components of the DNA repair machinery, particularly those involved in non-homologous end-joining (NHEJ). Here we used the telomerase-deficient mouse, null for the essential telomerase RNA gene (Terc), to assess the role of telomerase and telomere function on the cellular and organismal response to ionizing radiation. Although the loss of telomerase activity per se had no discernable impact on the response to ionizing radiation, the emergence of telomere dysfunction in late-generation Terc-/- mice imparted a radiosensitivity syndrome associated with accelerated mortality. On the cellular level, the gastrointestinal crypt stem cells and primary thymocytes showed increased rates of apoptosis, and mouse embryonic fibroblasts (MEFs) showed diminished dose-dependent clonogenic survival. The radiosensitivity of telomere dysfunctional cells correlated with delayed DNA break repair kinetics, persistent chromosomal breaks and cytogenetic profiles characterized by complex chromosomal aberrations and massive fragmentation. Our findings establish a intimate relationship between functionally intact telomeres and the genomic, cellular and organismal response to ionizing radiation.     

The Immersive Cockpit System for Capturing Natural Heritage

1 Introduction1 Preserving natural heritage has been identified as an important task in many countries. However, if damage to such heritage is unavoidable during the development, we may want to record the natural heritage before damaging it. One way is to acquire the 3D geometric information of the natural heritage. So that we can render it later. However, if the natural heritage is very large in scale and very complex in geometry, acquisition of such large-scale environment is infeasible an…     

灌浆对地下连续墙及邻近土体变形的影响

在地下连续墙深基坑开挖工程中,开挖前常用灌浆的方法来加固将被挖去的软土,从而减少地下连续墙的变形,增加开挖稳定性,保证工程安全,但是,在灌浆过程中,灌浆的作用机制以及对地下连续墙及邻近土体变形的影响原理还没有得到很好的研究,以新加坡艺术中心地下连续墙深基坑开挖工程为背景。实测了灌浆施工过程中,地下连续墙的变形、超孔隙水压力以及地下水位的变化;再结合有限元的理论分析方法,研究了灌浆施工对地下连续墙及     

大型企业库存管理中的数学模型——转库流向优化及时间推荐

在供应—生产—销售的供销环节中 ,大型企业的出厂决策问题是非常重要和难解决的。本文以某钢铁厂出厂决策支持系统为背景 ,对其中业务管理中的库存管理建立起数学模型体系。分析了模型的特点 ,由于 0— 1归划为 NP—难问题 ( NP—完全问题 )及一些问题属于大规模资源优化问题 ,当问题规模增大时求解变得极其困难。针对这些问题的特点介绍了求解模型的算法 :现有程序包、启发式算法和线性规划与启发混合的算法。这些算法在应用中取得了较好的效果。     

Cloning of cDNA for the major DNA-binding protein of the erythroid lineage through expression in mammalian cells

Genes expressed in erythroid cells contain binding sites for a cell-specific factor believed to be an important regulator for this haematopoietic lineage. Using high-level transient expression in mammalian cells, we have identified complementary DNA encoding the murine protein. The factor, a new member of the zinc-finger family of DNA-binding proteins, is restricted to erythroid cells at the level of RNA expression and is closely homologous between mouse and man.     

固化条件对改性环氧树脂混凝土中橡胶分散相形态的影响

通过改变固化工艺，采用显微图相分析手段，探讨了改性环氧树脂混凝土中橡胶分散相在不同工艺条件下的形态和相界面。     

SCHEDULING TWO GROUPS OF JOBS WITH INCOMPLETE INFORMATION

In real world situations, most scheduling problems occur neither as complete off-line nor ascomplete on-line models. Most likely a problem arises as an on-line model with some partialinformation. In this article, we consider such a model. We study the scheduling problem P(n_1,n_2),where two groups of jobs are to be scheduled. The first job group is available beforehand. As soon asall jobs in the first group are assigned, the second job group appears. The objective is to minimize thelongest job completion time(makespan). We show a lower bound of 3/2 even for very special cases.Best possible algorithms are presented for a number of cases. Furthermore, a heuristic is proposed forthe general case. The main contribution of this paper is to discuss the impact of the quantity ofavailable information in designing an on-line algorithm. It is interesting to note that the absence ofeven a little bit information may significantly affect the performance of an algorithm.