Helicobacter exploits integrin for type IV secretion and kinase activation

Integrins are important mammalian receptors involved in normal cellular functions as well as pathogenesis of chronic inflammation and cancer. We propose that integrins are exploited by the gastric pathogen and type-1 carcinogen Helicobacter pylori for injection of the bacterial oncoprotein cytotoxin-associated gene A (CagA) into gastric epithelial cells. Virulent H. pylori express a type-IV secretion pilus that injects CagA into the host cell; CagA then becomes tyrosine-phosphorylated by Src family kinases. However, the identity of the host cell receptor involved in this process has remained unknown. Here we show that the H. pylori CagL protein is a specialized adhesin that is targeted to the pilus surface, where it binds to and activates integrin alpha5beta1 receptor on gastric epithelial cells through an arginine-glycine-aspartate motif. This interaction triggers CagA delivery into target cells as well as activation of focal adhesion kinase and Src. Our findings provide insights into the role of integrins in H.-pylori-induced pathogenesis. CagL may be exploited as a new molecular tool for our further understanding of integrin signalling.     

RAID在线数据重建方法仿真器设计

在磁盘系统仿真器DiskSim的基础上,提出了一种独立冗余磁盘阵列在线数据重建方法仿真器的设计方案和实现机制.该仿真器以事件驱动的方式与主磁盘系统仿真器进行信息交互,并支持对2种常用的磁盘阵列重建方法(流水重建方法和面向磁盘的重建方法)的功能和性能仿真.仿真结果证明了磁盘阵列在线数据重建方法仿真器的有效性.     

Rapid,quantitative adipose conversion of chicken fibroblasts by high concentrations of chicken serum or plasma

Summary Rapid, quantitative adipose conversion of chicken fibroblasts occurs when these cells are cultured in undiluted commercial chicken serum or plasma. Fresh serum and plasma acquire this property after ageing.These studies were carried out with grants from the Richardson Foundation, the National Cancer Institute of Canada, and the Canadian Heart Foundations.To whom requests for reprints should be sent.     

基于 VAR 模型的重庆市大气污染物分析及研究

目的 研究重庆市首要空气污染物 PM2. 5 与 PM10 、SO2 、NO2 、CO、O3 的动态影响关系,为政府制定防治大气 污染措施及相关政策提供有价值的建议。 方法 收集重庆市 2021-05-01—2021-10-31 日的 PM2. 5 、PM10 、SO2 、 NO2 、CO、O3 这 6 项大气污染物的日浓度数据,利用 Eviews8. 0 软件,对原始数据进行序列平稳性检验;根据 Granger 因果检验结果选择变量,建立时间序列 VAR 模型,并检验模型的稳定性;利用广义脉冲响应分析和方差分 解分析,研究各污染物浓度对 PM2. 5 的动态影响及相对重要性。 结果 Granger 因果检验表明:PM10 、SO2 、NO2 、O3 是 PM2. 5 的 Granger 原因, CO 不是 PM2. 5 的 Granger 原因;广义脉冲响应分析表明:NO2 对 PM2. 5 的影响最大;方差 分解分析表明:NO2 的浓度对 PM2. 5 的影响最大;O3 对 PM2. 5 的影响次之,对 SO2 的影响作用最小。 所以,从长期 影响效应看,NO2 对 PM2. 5 具有长期较大的影响,SO2 对 PM2. 5 的影响最弱。 结论 防治 PM2. 5 对重庆市空气的污染 应着重控制 NO2 的污染,因此,政府应大力发展绿色交通,控制交通污染;大力监管高污染行业,将烟雾、粉尘、颗粒 物等排放量较大的行业作为工业污染源治理的重点;大力发展清洁能源,加快化石燃料替代资源的开发利用。     

The cosmological density of baryons from observations of 3He+ in the Milky Way.

Primordial nucleosynthesis after the Big Bang can be constrained by the abundances of the light elements and isotopes 2H, 3He, 4He and 7Li (ref. 1). The standard theory of stellar evolution predicts that 3He is also produced by solar-type stars, so its abundance is of interest not only for cosmology, but also for understanding stellar evolution and the chemical evolution of the Galaxy. The 3He abundance in star-forming (H II) regions agrees with the present value for the local interstellar medium, but seems to be incompatible with the stellar production rates inferred from observations of planetary nebulae, which provide a direct test of stellar evolution theory. Here we develop our earlier observations, which, when combined with recent theoretical developments in our understanding of light-element synthesis and destruction in stars, allow us to determine an upper limit for the primordial abundance of 3He relative to hydrogen: 3He/H = (1.1 +/- 0.2) x 10(-5). The primordial density of all baryons determined from the 3He data is in excellent agreement with the densities calculated from other cosmological probes. The previous conflict is resolved because most solar-mass stars do not produce enough 3He to enrich the interstellar medium significantly.     

Carbon loss by deciduous trees in a CO2-rich ancient polar environment

Fossils demonstrate that deciduous forests covered the polar regions for much of the past 250 million years when the climate was warm and atmospheric CO2 high. But the evolutionary significance of their deciduous character has remained a matter of conjecture for almost a century. The leading hypothesis argues that it was an adaptation to photoperiod, allowing the avoidance of carbon losses by respiration from a canopy of leaves unable to photosynthesize in the darkness of warm polar winters. Here we test this proposal with experiments using 'living fossil' tree species grown in a simulated polar climate with and without CO2 enrichment. We show that the quantity of carbon lost annually by shedding a deciduous canopy is significantly greater than that lost by evergreen trees through wintertime respiration and leaf litter production, irrespective of growth CO2 concentration. Scaling up our experimental observations indicates that the greater expense of being deciduous persists in mature forests, even up to latitudes of 83 degrees N, where the duration of the polar winter exceeds five months. We therefore reject the carbon-loss hypothesis as an explanation for the deciduous nature of polar forests.     

Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations

Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma.     

Long-term effects of tebuthiuron on Bromus tectorum

Use of herbicides to thin dense stands of Artemisia spp. (sagebrush) can free up resources for herbaceous plants and increase forage production, but may also facilitate weed invasion. We revisited a sagebrush thinning experiment in a north central Wyoming big sagebrush–grassland 11 years after application of tebuthiuron (N-[5-(1,1- dimethylethyl)-1,3,4-thiadiazol-2-yl]-N-N′-dimethylurea) to determine the long-term responses of shrubs, available soil resources, perennial grasses, and Bromus tectorum L. (downy brome). Tebuthiuron reduced shrub cover by more than half, from 31% in untreated plots to 15% in treated plots ( P = 0.002), and increased downy brome cover approximately 4-fold, from 0.9% in untreated plots to 3.5% in treated plots ( P = 0.02). Treatment with tebuthiuron also resulted in marginally significant increases in cover of perennial grasses (from 9% to 12.3%; P = 0.07) and bare ground (from 39.1% to 43.9%; P = 0.08). In comparisons of resource availability among microsites, available NO 3 was higher under dead sagebrush than under live sagebrush ( P = 0.03). No significant differences in soil water content were detected. The relatively recent expansion of downy brome populations at this site and the high NO 3 –N levels observed under dead sagebrush suggest that conditions facilitating downy brome invasion may persist for many years following sagebrush thinning. We demonstrate that sagebrush thinning can cause increases in downy brome populations years after initial treatment and suggest that managers should use caution when considering thinning sagebrush if downy brome is present, even if initial populations are small.