Enterotypes of the human gut microbiome

Our knowledge of species and functional composition of the human gut microbiome is rapidly increasing, but it is still based on very few cohorts and little is known about variation across the world. By combining 22 newly sequenced faecal metagenomes of individuals from four countries with previously published data sets, here we identify three robust clusters (referred to as enterotypes hereafter) that are not nation or continent specific. We also confirmed the enterotypes in two published, larger cohorts, indicating that intestinal microbiota variation is generally stratified, not continuous. This indicates further the existence of a limited number of well-balanced host-microbial symbiotic states that might respond differently to diet and drug intake. The enterotypes are mostly driven by species composition, but abundant molecular functions are not necessarily provided by abundant species, highlighting the importance of a functional analysis to understand microbial communities. Although individual host properties such as body mass index, age, or gender cannot explain the observed enterotypes, data-driven marker genes or functional modules can be identified for each of these host properties. For example, twelve genes significantly correlate with age and three functional modules with the body mass index, hinting at a diagnostic potential of microbial markers.     

Structure and mechanism of the chromatin remodelling factor ISW1a

Site-specific recognition of DNA in eukaryotic organisms depends on the arrangement of nucleosomes in chromatin. In the yeast Saccharomyces cerevisiae, ISW1a and related chromatin remodelling factors are implicated in establishing the nucleosome repeat during replication and altering nucleosome position to affect gene activity. Here we have solved the crystal structures of S. cerevisiae ISW1a lacking its ATPase domain both alone and with DNA bound at resolutions of 3.25?? and 3.60??, respectively, and we have visualized two different nucleosome-containing remodelling complexes using cryo-electron microscopy. The composite X-ray and electron microscopy structures combined with site-directed photocrosslinking analyses of these complexes suggest that ISW1a uses a dinucleosome substrate for chromatin remodelling. Results from a remodelling assay corroborate the dinucleosome model. We show how a chromatin remodelling factor could set the spacing between two adjacent nucleosomes acting as a 'protein ruler'.     

INTELLIGENT EARLY-WARNING SUPPORT SYSTEM FOR ENTERPRISE FINANCIAL CRISIS BASED ON CASE-BASED REASONING

Case-based reasoning （CBR） is an important reasoning technique of expert system. In this paper, the authors introduce CBR to intelligent early-warning support system, which could warn quantitatively for enterprise financial crisis and could warn qualitatively by expert＇s knowledge and experience. Furthermore, genetic algorithm is applied to case-based reasoning in CBR-IEWSS, which improves accuracy and efficiency of case retrieval. Last, the structure of CBR-IEWSS is given.     

魏晋南北朝时期的历法

该文是著者《中国的天文历法》一书的第三章，主要内容为：（１）三国时代历法；（２）晋代历法；（３）南北朝时代历法。     

教育环境与儿童空间认知的城镇空间组成研究

文中从发展对儿童适宜的生活环境的观点出发来研究城市住房项目．该项研究是针对Makahari湾城镇的中层住宅及附属教育设施的公寓区展开的．文中采用草图来确定Makahari湾城镇中儿童生活与其环境之间的关系．1999年进行首次研究，接着在2003年进行第二次研究，此间该镇的建设有所发展．具体研究是利用儿童凭记忆点出的关于他们的住宅、学校、玩耍场地和其它较多被注意的场所的草图来进行的．在两次研究期间，该地区发生了许多实体环境的变化，这些变化能从儿童的草图的许多元素中反映出来．将这些草图中的变化加以对照、分析，并将环境的改变与儿童的空间认知的关系加以探讨，同时注意分析比较体现在草图中的区域范围。结果表明，儿童早期对目标物的了解能从Makahari湾的空间结构以及环境变化中得到增强，而两者都由方格的模式构成．经验、每目的生活以及对小学和儿童游戏场所的空间认知与儿童的生活环境息息相关．此项分析揭示了在一个发展中的住宅区中儿童对其生活环境的空间认知与其附属教育设施之间的关系．     

Combined Structural,Electrochemical and Thermodynamic Investigations on Various Li_xMPO_4 Olivine Compounds

1 Results As tremendous increase of interest towards the application of LiFePO4 for lithium battery cathode,the mechanism of the intrinsic transport of lithium ions and electrons in LixFePO4 is becoming the intensive and exciting research subject.In the present paper,we will mainly focus on dimension of the transport and the role of solid solution as they seem to be key issues to understand charge movement in the olivine structure.Although one-demensional lithium motion along b-axis has been theoretical...     

Reconstitution of functional receptor for human interleukin-2 in mouse cells

Interleukin-2 (IL-2) has a key role in the antigen-specific clonal growth of T lymphocytes, by virtue of its interaction with a specific cell-surface receptor (IL-2R). The growth signal seems to be delivered by IL-2 bound to the high-affinity, but not the low-affinity, receptor. Genes encoding IL-2 and its receptor (that is, Tac-antigen) have been cloned and analysed in detail. We have now achieved cell-type-specific reconstitution of the high-affinity human IL-2R by expressing the complementary DNA cloned from normal lymphocytes. A mouse T-lymphocytic line, EL-4, expressed human IL-2R with high (dissociation constant (Kd) = 160-220 pM) and low (Kd = 2.1-2.2 nM) affinity for recombinant human IL-2, while mouse L929 cells expressed only a single class of the IL-2R with lower affinity (Kd = 34.5 nM) for the ligand. We also show that the human IL-2R expressed in EL-4 cells responds to IL-2 and mediates reversed signal transduction: growth of the EL-4 cells harbouring the IL-2R is inhibited specifically by human recombinant IL-2. The approach described here may provide a general experimental framework for elucidating the molecular basis of signal transduction mediated by specific receptor-ligand interaction.