SGT1正调控橡胶树白粉菌在拟南芥上激活的抗病性

通过在拟南芥野生型Col-0和突变体sgt1b、eds1上接种橡胶树白粉菌Oidium heveae HN1106,分析了白粉菌细胞进入率、叶片发病症状、菌丝生长状态、细胞死亡和活性氧产生等表型。结果表明,与野生型Col-0相比,橡胶树白粉菌在拟南芥sgt1b上激发的早期抗病性、后期抗病性以及抗病反应部分降低,暗示着SGT1在稳定识别橡胶树白粉菌的抗性蛋白方面发挥着非常重要的作用。     

Positive regulation of T cell activation and integrin adhesion by the adapter Fyb/Slap

The molecular adapter Fyb/Slap regulates signaling downstream of the T cell receptor (TCR), but whether it plays a positive or negative role is controversial. We demonstrate that Fyb/Slap-deficient T cells exhibit defective proliferation and cytokine production in response to TCR stimulation. Fyb/Slap is also required in vivo for T cell-dependent immune responses. Functionally, Fyb/Slap has no apparent role in the activation of known TCR signaling pathways, F-actin polymerization, or TCR clustering. Rather, Fyb/Slap regulates TCR-induced integrin clustering and adhesion. Thus, Fyb/Slap is the first molecular adapter to be identified that couples TCR stimulation to the avidity modulation of integrins governing T cell adhesion.     

Living with lethal PIP3 levels: viability of flies lacking PTEN restored by a PH domain mutation in Akt/PKB

The phosphoinositide phosphatase PTEN is mutated in many human cancers. Although the role of PTEN has been studied extensively, the relative contributions of its numerous potential downstream effectors to deregulated growth and tumorigenesis remain uncertain. We provide genetic evidence in Drosophila melanogaster for the paramount importance of the protein kinase Akt [also called protein kinase B (PKB)] in mediating the effects of increased phosphatidylinositol 3,4,5-trisphosphate (PIP3) concentrations that are caused by the loss of PTEN function. A mutation in the pleckstrin homology (PH) domain of Akt that reduces its affinity for PIP3 sufficed to rescue the lethality of flies devoid of PTEN activity. Thus, Akt appears to be the only critical target activated by increased PIP3 concentrations in Drosophila.     

Dissociation of gp120 from HIV-1 virions induced by soluble CD4

The CD4 antigen is the high affinity cellular receptor for the human immunodeficiency virus type-1 (HIV-1). Binding of recombinant soluble CD4 (sCD4) or the purified V1 domain of sCD4 to the surface glycoprotein gp120 on virions resulted in rapid dissociation of gp120 from its complex with the transmembrane glycoprotein gp41. This may represent the initial stage in virus-cell and cell-cell fusion. Shedding of gp120 from virions induced by sCD4 may also contribute to the mechanism by which these soluble receptor molecules neutralize HIV-1.     

Blocking of HIV-1 infectivity by a soluble, secreted form of the CD4 antigen

The initial event in the infection of human T lymphocytes, macrophages, and other cells by human immunodeficiency virus (HIV-1) is the attachment of the HIV-1 envelope glycoprotein gp120 to its cellular receptor, CD4. As a step toward designing antagonists of this binding event, soluble, secreted forms of CD4 were produced by transfection of mammalian cells with vectors encoding versions of CD4 lacking its transmembrane and cytoplasmic domains. The soluble CD4 so produced binds gp120 with an affinity and specificity comparable to intact CD4 and is capable of neutralizing the infectivity of HIV-1. These studies reveal that the high-affinity CD4-gp120 interaction does not require other cell or viral components and may establish a novel basis for therapeutic intervention in the acquired immune deficiency syndrome (AIDS).     

城市湿地热环境调节功能的定量研究

以Landsat TM和MODIS多源遥感数据反演的城市地表温度和2007年北京湿地普查数据为基础,采用GIS空间分析技术和相关分析方法研究了城市湿地对城市热环境的调节能力并建立了定量模型。结果表明:1)由于湿地景观与城市其他下垫面的性质具有明显差异,湿地分布与城市低温区在空间分布上呈现出非常好的正相关。2)湿地调节指数可以较好地反映城市湿地对城市热环境调节能力的大小。分析其与湿地周长、面积、形状指数和内缘比等单元景观特征指数之间的相关性,发现城市湿地对周边区域的热环境调节能力主要取决于湿地的面积,且可以利用三次多项式来定量描述湿地热调节半径与湿地面积之间的关系。     

脂肪组织分泌产物及其对脂肪形成的调控

脂肪组织产生和分泌一系列以自/旁分泌或内分泌方式起作用的细胞因子,参与脂肪组织局部及整个机体能量代谢,并和与肥胖相关的多种代谢综合征有关.阐明脂肪组织分泌因子的生理学作用,有助于更好的理解脂肪形成的机制.本文主要阐述了脂肪组织分泌因子白细胞介素-6、肿瘤坏死因子-α、纤溶酶原激活物抑制因子-1、血管紧张素Ⅱ和抵抗素的功能特性及其对脂肪形成的影响.     

可溶性Sox2-11R重组蛋白的制备与鉴定

旨在通过原核表达制备可溶性Sox2-11R重组蛋白,并验证其穿膜能力。首先,采用增强型绿色荧光蛋白(enhanced green fluorescent protein, EGFP)与蛋白转导域11聚精氨酸（11 arginine, 11R）的融合表达和与成纤维细胞的共孵育验证11R的穿膜能力。其次,将目的基因Sox2-11R在原核表达载体pET30a中表达,通过优化表达条件获取可溶性Sox2-11R重组蛋白。最后,利用Ni柱纯化重组蛋白,SDS-PAGE及Western blotting对其进行鉴定;并用免疫荧光染色验证重组蛋白是否具有进入细胞核的能力。结果表明,成功构建了pET30a-Sox2-11R原核表达载体,纯化的Sox2-11R重组蛋白具有穿膜能力,且在细胞培养基中具有较高溶解度,这为制备其他重编程因子的重组蛋白提供了参考,也为外源蛋白诱导iPSCs奠定了基础。     

Recognition of histone H3 lysine-4 methylation by the double tudor domain of JMJD2A

Biological responses to histone methylation critically depend on the faithful readout and transduction of the methyl-lysine signal by "effector" proteins, yet our understanding of methyl-lysine recognition has so far been limited to the study of histone binding by chromodomain and WD40-repeat proteins. The double tudor domain of JMJD2A, a Jmjc domain-containing histone demethylase, binds methylated histone H3-K4 and H4-K20. We found that the double tudor domain has an interdigitated structure, and the unusual fold is required for its ability to bind methylated histone tails. The cocrystal structure of the JMJD2A double tudor domain with a trimethylated H3-K4 peptide reveals that the trimethyl-K4 is bound in a cage of three aromatic residues, two of which are from the tudor-2 motif, whereas the binding specificity is determined by side-chain interactions involving amino acids from the tudor-1 motif. Our study provides mechanistic insights into recognition of methylated histone tails by tudor domains and reveals the structural intricacy of methyl-lysine recognition by two closely spaced effector domains.     

基于IP的网络考试视频监察系统设计

针对考试违纪行为较多这一问题,提出了低硬件成本的考试视频监察系统的设计方案,采用分层的C/S模式设计,介绍了系统应具备的主要功能模块。     

聚苯胺在LiFePO4/C正极中的双重功能

锂离子电池(LIB)中正极活性材料的导电率σ都很低, 要减小正极的极化程度, 增大活性材料的比充、放电容量和充、放电电流密度, 最有效方法之一是选用高导电率的导电剂, 与粘结剂混合在一起在正极中组成良好的导电网络. 测试结果表明:聚苯胺(PAn)的导电率(σPAn=18.39 S/cm)大于正极中常用导电剂乙炔黑(AB)的导电率(σAB=7.77 S/cm). 以PAn作为正极活性材料, 不添加其他导电剂, 对其进行恒电流充、放电试验(电流密度I=15 mA/g)时, 其第3循环的比放电容量D3=60.8 mAh/g,充、放电效率η3=94.56 %, 试验结果表明: PAn在正极中兼有导电剂和活性材料的功能. 以LiFePO4/C含碳复合材料作为正极活性材料, 以PAn替代AB作为导电剂进行了恒电流充、放电试验, 在电流密度为15 mA/g,30 mA/g,45 mA/g,60 mA/g,75 mA/g,90 mA/g和120 mA/g时,LiFePO4/C的比充、放电容量都增加了, 表明正极的极化程度减小了. 正极在经过较大电流密度(120 mA/g)充、放电后, 再以小电流密度(15 mA/g)进行充、放电时, 比充、放电容量几乎没有变化, 表明经大电流(120 mA/g)充、放电后LiFePO4/C的贮锂结构没有变化.     

Inactivation by ultraviolet light of an acriflavine-sensitive gene function in phage T4D

Mutants of phage T4D can be isolated which multiply in the presence of concentrations of acriflavine inhibitory to the growth of wild-type phage. Bacteria mixedly infected with resistant and sensitive phage are unproductive in the presence of acriflavine. Irradiation of the sensitive phage with ultraviolet light results in inactivation of the function of the gene for acriflavine sensitivity, permitting the mixedly infected complexes to yield phage. This function is inactivated in an exponential manner and has a cross section comparable to cross sections of other gene functions in T4D.     

Inhibition of T cell receptor expression and function in immature CD4+CD8+ cells by CD4

Most immature CD4+CD8+ thymocytes express only a small number of T cell receptor (TCR) molecules on their surface, and the TCR molecules they do express are only marginally capable of transducing intracellular signals. TCR expression and function was not intrinsically low in immature CD4+CD8+ thymocytes, but was found to be actively inhibited by CD4-mediated signals. Indeed, release of CD4+CD8+ thymocytes from CD4-mediated signals resulted in significant increases in both TCR expression and signaling function. These results suggest that, in CD4+CD8+ cells developing in the thymus, increased TCR expression and function requires release from CD4-mediated inhibition.     

鸟氨酸脱羧酶结构、功能及表达调控研究进展

多胺对细胞生长、存活以及增殖具有重要的调控作用,体内多胺水平变化与疾病和衰老的关系密切。鸟氨酸脱羧酶(Ornithine decarboxylase,ODC)是多胺生物合成途径中的第一个限速酶,能催化细胞内鸟氨酸脱羧转化成腐胺。因此,ODC可通过对细胞内多胺水平的调节来参与调控细胞增殖过程。近年来,对ODC功能的研究取得了一定的进展,特别是在ODC调控多胺水平、细胞增殖、癌症以及ODC表达调控等方面研究较多。文章对ODC结构、功能及其表达调控的研究进行了评述,并对今后ODC的深入研究进行了展望。     

LIPI-4 EII对单核细胞增生性李斯特菌关键毒力因子转录调控的影响

为探究单核细胞增生性李斯特菌(LM)毒力岛4(LIPI-4)中膜透性酶(EII)对LM毒力基因表达的调控作用,本研究分别构建EII缺失株(LM928ΔEII)、强启动子回补株(CLM928ΔEII-P_help)和天然启动子回补株(CLM928ΔEII-P_native),测定各菌株在体外培养中的生长曲线和在永生化人脑微血管内皮细胞(HCMEC/D3)内的增殖情况;RT-qPCR检测体外培养和HCMEC/D3细胞内各菌株9个关键毒力基因的转录水平。结果显示:1)EII基因缺失株LM928ΔEII构建成功,重组回补质粒pIMK2-EII和pIMK2-EII-P_native及回补株CLM928ΔEII-P_help和CLM928ΔEII-P_native构建成功。2)在体外培养下,EII对LM的生长曲线没有影响。但在侵染HCMEC/D3后,LM928ΔEII在8和12 h的胞内细菌量显著高于LM928(P<0.05),2和4 h的胞内细菌量极显著高于LM928(P<0.01),CLM928ΔEII-P_native在2、4和6 h恢复至野生株水平(P>0.05),而CLM928ΔEII-P_help在2、4、6、8、10和12 h均极显著低于野生株(P<0.01)。3)体外培养条件下,相比于野生株,LM928ΔEII中66.7%(6/9)的毒力基因转录水平极显著上调(P<0.01);CLM928ΔEII-P_help中66.7%(6/9)的基因转录水平上升1~4倍,CLM928ΔEII-P_native中88.9%(8/9)的基因转录水平倍数变化在1倍以内。在HCMEC/D3细胞内,相比于野生株,LM928ΔEII中66.7%(6/9)的毒力基因转录水平极显著上调(P<0.01);CLM928ΔEII-P_help中33.3%(3/9)的基因转录水平上调1~3倍,CLM928ΔEII-P_native中基因转录水平倍数变化在1倍以内。综上,LIPI-4 EII对LM关键毒力因子的转录具有负调控作用。本研究为系统探究LIPI-4参与LM致病性机制奠定基础。     

共轭亚油酸对动物免疫调节功能的影响

近年来,人们对CLA对动物的抗癌、抗动脉粥样硬化的机制以及对动物免疫系统的影响进行了广泛的研究.共轭亚油酸具有广泛的生物学功能,对增加动物体液免疫球蛋白的含量、免疫细胞的增殖、细胞因子的产生、吞噬细胞的功能和基因表达都具有不同的调节作用.