The intervening sequence RNA of Tetrahymena is an enzyme

A shortened form of the self-splicing ribosomal RNA (rRNA) intervening sequence of Tetrahymena thermophila acts as an enzyme in vitro. The enzyme catalyzes the cleavage and rejoining of oligonucleotide substrates in a sequence-dependent manner with Km = 42 microM and kcat = 2 min-1. The reaction mechanism resembles that of rRNA precursor self-splicing. With pentacytidylic acid as the substrate, successive cleavage and rejoining reactions lead to the synthesis of polycytidylic acid. Thus, the RNA molecule can act as an RNA polymerase, differing from the protein enzyme in that it uses an internal rather than an external template. At pH 9, the same RNA enzyme has activity as a sequence-specific ribonuclease.     

加入世界贸易组织是中国与世贸组织的共同需要

本文阐述了中国加入世贸组织的迫切性和必要性，以及对全球经济发展进程的重大影响。     

不同轮作制的秸秆全量直接还田技术

通过 4年的试验示范 ,证明秸秆还田能有效提高土壤有机质含量 ,改善土壤理化性状和提高作物产量。稻草覆盖小麦、蚕豆能提高土壤表层湿度和温度 ,提早出苗 ,早生快发     

A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity

Obesity is a serious international health problem that increases the risk of several common diseases. The genetic factors predisposing to obesity are poorly understood. A genome-wide search for type 2 diabetes-susceptibility genes identified a common variant in the FTO (fat mass and obesity associated) gene that predisposes to diabetes through an effect on body mass index (BMI). An additive association of the variant with BMI was replicated in 13 cohorts with 38,759 participants. The 16% of adults who are homozygous for the risk allele weighed about 3 kilograms more and had 1.67-fold increased odds of obesity when compared with those not inheriting a risk allele. This association was observed from age 7 years upward and reflects a specific increase in fat mass.     

云南省冬季发展亚麻的优势及栽培技术

亚麻纤维是最优良的植物纺织纤维,其吸湿强、散热快、无静电、抑菌保健、色调柔和等独特优点为其它纤维所不能替代,亚麻纤维可纯纺,也可与其它纤维混纺,制成各种高级服装面料及家庭、宾馆装饰用品,因而受到越来越多的消费者青睐,使其制品成为国际市场的紧俏商品.     

以农业良好操作规程(GAP)应对日本肯定列表制度

日本食品残留农业化学品肯定列表制度（以下简称肯定列表制度）是迄今为止世界上最庞大的食品、农产品、兽药残留标准体系，已于2006年5月29日正式实施。浙江省众多农产品、食品出口企业应怎样面对，反应不一，归纳起来大致有四种情况：第一种类型是积极主动型，他们得到的相关信息比较早，[第一段]     

高油玉米花粉直感等遗传效应对普通玉米籽粒性状的影响

用高油玉米杂交种高油115为父本,与5个普通玉米杂交种进行杂交,研究了杂交当代籽粒的千粒重、胚重比和胚体积比。结果表明:胚重比、胚体积比和千粒重比普通玉米都有显著增加,增加量依次为1.79 %,1.99 %,10.34 %。筛选出了2个较好的组合为:郑单958×高油115,豫玉22×高油115。千粒重分别增加:33.00 g,29.13 g,胚重比分别增加:1.57 %,2.25 %,胚体积比分别增加:3.07 %,1.17 %,表明:高油玉米的花粉直感效应以及它们之间的杂种优势效应在玉米生产上有着广阔的应用前景。     

The 1990 to 1991 Sudan earthquake sequence and the extent of the East african rift system

One of the largest earthquakes ever recorded in Africa (surface wave magnitude M(s) = 7.2) occurred about 50 kilometers east of the Upper River Nile on 20 May 1990. Four days later, two more large earthquakes (M(s) = 6.4 and 7.0) occurred about 50 kilometers to the northwest in the Nile Valley. In the following months, a further 60 events were recorded by seismic stations worldwide. The earthquakes are associated with two fault systems: one east of the Nile with azimuth southeast and one along the Nile Valley with azimuth north-northeast. The activity alternated between the two fault systems and indicates that the northern extremity of the western branch of the East African Rift System extends at least 350 kilometers north of Lake Albert.     

中国北方主要树种对光肩星天牛抗性序列研究

通过对我国东北、西北、华北等地140种(包括杂交种、变种、变型及栽培品种)主要栽培的林木、果树、花卉树种被光肩星天牛为害情况调查,确定抗性序列。结果表明,调查树种中对光肩星天牛高感树种41种;感虫树种4种;抗虫树种16种;免疫树种79种。     

The proteasome of Mycobacterium tuberculosis is required for resistance to nitric oxide

The production of nitric oxide and other reactive nitrogen intermediates (RNI) by macrophages helps to control infection by Mycobacterium tuberculosis (Mtb). However, the protection is imperfect and infection persists. To identify genes that Mtb requires to resist RNI, we screened 10,100 Mtb transposon mutants for hypersusceptibility to acidified nitrite. We found 12 mutants with insertions in seven genes representing six pathways, including the repair of DNA (uvrB) and the synthesis of a flavin cofactor (fbiC). Five mutants had insertions in proteasome-associated genes. An Mtb mutant deficient in a presumptive proteasomal adenosine triphosphatase was attenuated in mice, and exposure to proteasomal protease inhibitors markedly sensitized wild-type Mtb to RNI. Thus, the mycobacterial proteasome serves as a defense against oxidative or nitrosative stress.     

The neostriatal mosaic: striatal patch-matrix organization is related to cortical lamination

The basal ganglia, of which the striatum is the major component, process inputs from virtually all cerebral cortical areas to affect motor, emotional, and cognitive behaviors. Insights into how these seemingly disparate functions may be integrated have emerged from studies that have demonstrated that the mammalian striatum is composed of two compartments arranged as a mosaic, the patches and the matrix, which differ in their neurochemical and neuroanatomical properties. In this study, projections from prefrontal, cingulate, and motor cortical areas to the striatal compartments were examined with the Phaseolus vulgaris-leucoagglutinin (PHA-L) anterograde axonal tracer in rats. Each cortical area projects to both the patches and the matrix of the striatum; however, deep layer V and layer VI corticostriatal neurons project principally to the patches, whereas superficial layer V and layer III and II corticostriatal neurons project principally to the matrix. The relative contribution of patch and matrix corticostriatal projections varies among the cortical areas examined such that allocortical areas provide a greater number of inputs to the patches than to the matrix, whereas the reverse obtains for neocortical areas. These results demonstrate that the compartmental organization of corticostriatal inputs is related to their laminar origin and secondarily to the cytoarchitectonic area of origin.     

高校实践科学发展观的着力点在于建设和谐校园

高等学校开展深入学习实践科学发展观活动应着眼于促进高校各项事业的科学发展、构建和谐校园。作为一个复杂的系统工程,建设和谐校园必须坚持以科学发展观为指导,必须坚持以人为本、促进师生员工及其与校园环境之间的协调与和谐发展,必须坚持高校党委的统筹领导及方向作用。