Broad phylogenomic sampling improves resolution of the animal tree of life

Long-held ideas regarding the evolutionary relationships among animals have recently been upended by sometimes controversial hypotheses based largely on insights from molecular data. These new hypotheses include a clade of moulting animals (Ecdysozoa) and the close relationship of the lophophorates to molluscs and annelids (Lophotrochozoa). Many relationships remain disputed, including those that are required to polarize key features of character evolution, and support for deep nodes is often low. Phylogenomic approaches, which use data from many genes, have shown promise for resolving deep animal relationships, but are hindered by a lack of data from many important groups. Here we report a total of 39.9 Mb of expressed sequence tags from 29 animals belonging to 21 phyla, including 11 phyla previously lacking genomic or expressed-sequence-tag data. Analysed in combination with existing sequences, our data reinforce several previously identified clades that split deeply in the animal tree (including Protostomia, Ecdysozoa and Lophotrochozoa), unambiguously resolve multiple long-standing issues for which there was strong conflicting support in earlier studies with less data (such as velvet worms rather than tardigrades as the sister group of arthropods), and provide molecular support for the monophyly of molluscs, a group long recognized by morphologists. In addition, we find strong support for several new hypotheses. These include a clade that unites annelids (including sipunculans and echiurans) with nemerteans, phoronids and brachiopods, molluscs as sister to that assemblage, and the placement of ctenophores as the earliest diverging extant multicellular animals. A single origin of spiral cleavage (with subsequent losses) is inferred from well-supported nodes. Many relationships between a stable subset of taxa find strong support, and a diminishing number of lineages remain recalcitrant to placement on the tree.     

The turnover of F-actin-bound ADP in vivo

Summary A procedure for estimating the rate of turnover of F-actin-bound ADP in vivo is described. A turnover rate of 0.88 h^–1 was determined for mouse muscle F-actin. The validity of the method when used to estimate the turnover rate of F-actin per se is discussed in relation to the possible exchange of F-actin-bound ADP.Acknowledgments. The invaluable technical assistance of Mr L. Carrington is gratefully acknowledged.     

泥沙颗粒微结构的GIS表达

在受污染的水体环境中,泥沙颗粒发生越来越复杂的物理、化学和生物变化过程,泥沙颗粒微结构研究成为研究这些复杂过程的基础.本文借助高分辨率扫描电镜等先进手段对泥沙微结构进行研究,结合图像处理软件和数学工具定量描述泥沙颗粒的平面投影形状、表面凹凸和污染元素分布特征.以GIS为平台,将这些成果形象直观地表达出来,同时进行二次开发,提供泥沙颗粒的三维建模和工程泥沙模型应用数据接口.     

Structure of the insulin receptor ectodomain reveals a folded-over conformation

The insulin receptor is a phylogenetically ancient tyrosine kinase receptor found in organisms as primitive as cnidarians and insects. In higher organisms it is essential for glucose homeostasis, whereas the closely related insulin-like growth factor receptor (IGF-1R) is involved in normal growth and development. The insulin receptor is expressed in two isoforms, IR-A and IR-B; the former also functions as a high-affinity receptor for IGF-II and is implicated, along with IGF-1R, in malignant transformation. Here we present the crystal structure at 3.8 A resolution of the IR-A ectodomain dimer, complexed with four Fabs from the monoclonal antibodies 83-7 and 83-14 (ref. 4), grown in the presence of a fragment of an insulin mimetic peptide. The structure reveals the domain arrangement in the disulphide-linked ectodomain dimer, showing that the insulin receptor adopts a folded-over conformation that places the ligand-binding regions in juxtaposition. This arrangement is very different from previous models. It shows that the two L1 domains are on opposite sides of the dimer, too far apart to allow insulin to bind both L1 domains simultaneously as previously proposed. Instead, the structure implicates the carboxy-terminal surface of the first fibronectin type III domain as the second binding site involved in high-affinity binding.     

开放式模块化通用数控系统软件设计

由于数控系统软件设计中存在设计不规范，可靠性与可维护性差等缺点，出现了多品种、低档次的数控系统软件。为此，提出一种开放式，模块化软件设计方法，它基于ＤＯＳ操作系统，采用Ｃ语言和汇编语言混合编程，调用０８Ｈ号中断前后台结构，实现管理和控制同步进行，从而实现“宏观并行，微观分时处理”，同时，建立插补库以及将扩展内存（ＸＭＳ）的使用引入数控系统软件设计，在实际软件开发过程中，取得良好的效果。     

科学基金绩效评估方案设计中的若干问题研究

本文概述了国家自然科学基金绩效评估工作的背景、实践意义及若干关键问题，提出了以国家自然科学基金绩效评估方案设计中的目标设定、结构分析出发构造评估指标体系等思路，为全面开展科学基金绩效评估工作进行了部分理论探讨。     

数控铣-立式加工中心综合实训项目的设计

设计并采用综合加工试切件的方式,将数控铣-立式加工中心各单项实训项目有机衔接起来,整合为综合实训项目,满足数控机床操作实训练习课题的针对性要求,并测量加工后试切件的精度, 检验机床的工作精度及可靠性,较全面地掌握数控铣-立式加工中心操作过程中的主要实训内容,为项目教学、过程教学提供一项参考实例,方便师生综合演练,降低数控铣-立式加工中心操作演练实训成本。