Molecular Requirement for Sterols in Herpes Simplex Virus Entry and Infectivity

Herpes simplex virus 1 (HSV-1) required cholesterol or desmosterol for virion-induced membrane fusion. HSV successfully entered DHCR24^−/− cells, which lack a desmosterol-to-cholesterol conversion enzyme, indicating that entry can occur independently of cholesterol. Depletion of desmosterol from these cells resulted in diminished HSV-1 entry, suggesting a general sterol requirement for HSV-1 entry and that desmosterol can operate in virus entry. Cholesterol functioned more effectively than desmosterol, suggesting that the hydrocarbon tail of cholesterol influences viral entry.     

鸡减蛋综合征病毒(EDSV)基因组右末端结构的分析

从中国发病鸡中分离的鸡减蛋综合征病毒（ＥｇｇＤｒｏｐＳｙｎｄｒｏｍＶｉｒｕｓ,ＥＤＳＶ）弱毒株（ＡＡ－２）,其基因组全长约为３３ｋｂ。用限制性内切酶ＨｉｎｄⅢ水解ＥＤＳＶ全基因组,构建了以ｐＢｌｕｅｓｃｒｉｐｔⅡ（ＫＳ＋）为载体的右末端片段的克隆（约４．２ｋｂ）,对其进行了序列测定和结构分析。该片段全长４１８３个碱基对（ｂｐ）,位于基因组右末端８７．３ｍ．ｕ．－１００ｍ．ｕ．。结果显示,该片段与哺乳动物腺病毒右末端Ｅ４区结构不同,与禽Ⅰ型腺病毒代表株ＣＥＬＯ右末端片段亦无同源性。本文为深入了解ＥＤＳＶ基因组结构特点,ＥＤＳＶ与其他腺病毒基因结构与功能的进化关系和ＥＤＳＶ载体的构建奠定了分子生物学基础     

冻结速率对血小板冷冻干燥保存的影响

冷冻干燥法是使血小板能够长期保存的一种理想方法。冻结过程对血小板的冻干保存至关重要。采用梯度降温、搁板预冷、液氮冻结等三种冻结方式,研究了冻结速率对血小板冷冻干燥保存恢复率的影响。实验结果表明用搁板预冷的方式冻结并干燥的血小板复水后的恢复率最高,达到(93.0.2)%,此时的冻结速度约为10℃/min。扫描电镜照片显示冻干复水后的血小板保持了完整的细胞结构,但与新鲜血小板相比略呈球形。冻干复水后的血小板对1U/ml凝血酶的最大聚集率接近于新鲜血小板,但聚集速度比新鲜血小板慢。     

Affinity biosensor for avidin using a double functionalized dendrimer monolayer on a gold electrode

We have developed an affinity biosensor system based on avidin-biotin interaction on a gold electrode. As the building block of an affinity-sensing monolayer, a fourth-generation (G4) poly(amidoamine) dendrimer having partial ferrocenyl-tethered surface groups was prepared and used. The unmodified surface amine groups from dendrimers were functionalized with biotinamidocaproate, and the biotinylated and electroactive dendritic monolayer was constructed on a gold electrode for the affinity-sensing surface interacting with avidin. An electrochemical signal from the affinity biosensor was generated by free glucose oxidase in electrolyte, depending on the degree of coverage of the sensing surface with avidin. The sensor signal decreased correlatively with increasing avidin concentration and approached a minimum level when the sensing surface was fully covered with avidin. The detection limit of avidin was about 4.5 pM, and the sensor signal was linear ranging from 1.5 pM to 10 nM under optimized conditions. From the kinetic analysis using the biotinylated glucose oxidase, an active enzyme coverage of 2.5 x 10(-12) mol/cm(2) on the avidin-pretreated surface was registered, which demonstrates the formation of a spatially ordered and compact protein layer on the derivatized electrode surface.     

The Role of Monoacylglycerol Lipase (MAGL) in the Cancer Progress

In recent years, metabolism is talked highly important in cancer research, especially the lipid metabolism. Researchers believe that the de novo fatty acid synthesis plays an important role in tumor development, while many studies illustrated that Endocannabinoids have anti-tumorigenic actions, including anti-proliferation, apoptosis induction, and anti-metastatic effects, MAGL as an important decomposing enzyme of both lipid metabolism and endocannabinoids system, additionally as a part of a gene expression signature contributes to different aspects of tumourigenesis.     

Interactions of annexins with membrane phospholipids.

The annexins are proteins that bind to membranes and can aggregate vesicles and modulate fusion rates in a Ca2(+)-dependent manner. In this study, experiments are presented that utilize a pyrene derivative of phosphatidylcholine to examine the Ca2(+)-dependent membrane binding of soluble human annexin V and other annexins. When annexin V and other annexins were bound to liposomes containing 5 mol % acyl chain labeled 3-palmitoyl-2-(1-pyrenedecanoyl)-L-alpha-phosphatidylcholine, a decrease in the excimer-to-monomer fluorescence ratio was observed, indicating that annexin binding may decrease the lateral mobility of membrane phospholipids without inducing phase separation. The observed increases of monomer fluorescence occurred only with annexins and not with other proteins such as parvalbumin or bovine serum albumin. The extent of the increase of monomer fluorescence was dependent on the protein concentration and was completely and rapidly reversible by EDTA. Annexin V binding to phosphatidylserine liposomes was consistent with a binding surface area of 59 phospholipid molecules per protein. Binding required Ca2+ concentrations ranging between approximately 10 and 100 microM, where there was no significant aggregation or fusion of liposomes on the time scale of the experiments. The polycation spermine also displaced bound annexins, suggesting that binding is largely ionic in nature under these conditions.     

瘦素诱导体外培养大鼠脂肪间充质干细胞凋亡

为观察瘦素诱导体外培养大鼠脂肪间充质干细胞凋亡的作用, 采用胶原酶消化法分离培养大鼠附睾脂肪垫间充质干细胞, 第3代细胞用于实验。细胞免疫荧光化学方法鉴定CD105、Vimentin表达阳性率约80%以上, 10-6 mol/L的瘦素作用细胞48 h、72 h后激光共聚焦显微镜观察分别可见早期及中晚期特征表现; 0 mol/L、10-8 mol/L、10-7 mol/L、10-6 mol/L瘦素分别作用于细胞48 h后, 应用AnnexinⅤ/PI双染色法流式细胞仪检测早期凋亡率分别为2.50%±0.72%、6.78%±1.99%、11.99%±1.58%、17.93%±4.82% (P<0.05); 随着瘦素浓度的增加和作用时间的延长, Caspase-3的活性逐渐增高, 至48 h时达到高峰。说明瘦素可以直接诱导脂肪间充质干细胞凋亡, 从数量上减少脂肪组织的含量。     

生长温度对烟草叶片环式电子传递活性的影响（英文）

高等植物的光合机构在环境胁迫条件下非常容易产生光抑制,环式电子传递在光合机构的光保护中发挥着重要的作用。但是,生长温度对环式电子传递的影响并不清楚。本研究测定了在24/18℃和32/26℃条件下生长40天的烟草(K326)叶片的气体交换、叶绿素荧光和P700氧化还原态的光响应曲线。结果表明,烟草叶片在两种生长温度下的的光合能力、光化学淬灭、非光化学淬灭和通过光系统II的电子传递速率(ETR II)均没有差异。但是,在强光条件下,生长在24/18℃的叶片比生长在32/26℃的具有更高的通过光系统I的电子传递速率(ETR I)和ETR I/ETR II比值。短时间的强光处理后,生长在24/18℃的叶片具有较高的光系统II最大量子产额(Fv/Fm),表明环式电子传递活性的上调有助于缓解生长在24/18℃的叶片光系统II受到的光损伤。综上所述,环式电子传递活性的增强是植物适应较低生长温度的重要策略。     

Detection of an intermediate during the unfolding process of the dimeric ketosteroid isomerase

Failure to detect the intermediate in spite of its existence often leads to the conclusion that two-state transition in the unfolding process of the protein can be justified. In contrast to the previous equilibrium unfolding experiment fitted to a two-state model by circular dichroism and fluorescence spectroscopies, an equilibrium unfolding intermediate of a dimeric ketosteroid isomerase (KSI) could be detected by small angle X-ray scattering (SAXS) and analytical ultracentrifugation. The sizes of KSI were determined to be 18.7A in 0M urea, 17.3A in 5.2M urea, and 25.1A in 7M urea by SAXS. The size of KSI in 5.2M urea was significantly decreased compared with those in 0M and 7M urea, suggesting the existence of a compact intermediate. Sedimentation velocity as obtained by ultracentrifugation confirmed that KSI in 5.2M urea is distinctly different from native and fully-unfolded forms. The sizes measured by pulse field gradient nuclear magnetic resonance (NMR) spectroscopy were consistent with those obtained by SAXS. Discrepancy of equilibrium unfolding studies between size measurement methods and optical spectroscopies might be due to the failure in detecting the intermediate by optical spectroscopic methods. Further characterization of the intermediate using (1)H NMR spectroscopy and Kratky plot supported the existence of a partially-folded form of KSI which is distinct from those of native and fully-unfolded KSIs. Taken together, our results suggest that the formation of a compact intermediate should precede the association of monomers prior to the dimerization process during the folding of KSI.     

The Drosophila caspase Ice is important for many apoptotic cell deaths and for spermatid individualization, a nonapoptotic process

Caspase family proteases play important roles in the regulation of apoptotic cell death. Initiator caspases are activated in response to death stimuli, and they transduce and amplify these signals by cleaving and thereby activating effector caspases. In Drosophila, the initiator caspase Nc (previously Dronc) cleaves and activates two short-prodomain caspases, Dcp-1 and Ice (previously Drice), suggesting these as candidate effectors of Nc killing activity. dcp-1-null mutants are healthy and possess few defects in normally occurring cell death. To explore roles for Ice in cell death, we generated and characterized an Ice null mutant. Animals lacking Ice show a number of defects in cell death, including those that occur during embryonic development, as well as during formation of adult eyes, arista and wings. Ice mutants exhibit subtle defects in the destruction of larval tissues, and do not prevent destruction of salivary glands during metamorphosis. Cells from Ice animals are also markedly resistant to several stresses, including X-irradiation and inhibition of protein synthesis. Mutations in Ice also suppress cell death that is induced by expression of Rpr, Wrinkled (previously Hid) and Grim. These observations demonstrate that Ice plays an important non-redundant role as a cell death effector. Finally, we demonstrate that Ice participates in, but is not absolutely required for, the non-apoptotic process of spermatid differentiation.