核苷酸转换因子的特性及其在植物中的研究现状

热激蛋白HSP70是一类细胞必需的具有ATPase活性的分子伴侣。ADP的脱离是HSP70分子伴侣体系能够完成其功能循环的限速步骤,该反应步骤由核苷酸交换因子（NEFs）加速,因此,NEFs是HSP70分子伴侣体系中的一类关键辅助因子。本文总结了有关NEFs的研究成果以及植物NEFs的最新研究进展。     

A Computationally Guided Protein-Interaction Screen Uncovers Coiled-Coil Interactions Involved in Vesicular Trafficking

Mapping protein-protein interactions at a domain or motif level can provide structural annotation of the interactome. The α-helical coiled coil is among the most common protein-interaction motifs, and proteins predicted to contain coiled coils participate in diverse biological processes. Here, we introduce a combined computational/experimental screening strategy that we used to uncover coiled-coil interactions among proteins involved in vesicular trafficking in Saccharomyces cerevisiae. A number of coiled-coil complexes have already been identified and reported to play important roles in this important biological process. We identify additional examples of coiled coils that can form physical associations. The computational strategy used to prioritize coiled-coil candidates for testing dramatically improved the efficiency of discovery in a large experimental screen. As assessed by comprehensive yeast two-hybrid assays, computational prefiltering retained 90% of positive interacting pairs and eliminated > 60% of negatives from a set of interaction candidates. The coiled-coil-mediated interaction network elucidated using the combined computational/experimental approach comprises 80 coiled-coil associations between 58 protein pairs, among which 21 protein interactions have not been previously reported in interaction databases and 26 interactions were previously known at the protein level but have now been localized to the coiled-coil motif. The coiled-coil-mediated interactions were specific rather than promiscuous, and many interactions could be recapitulated in a green fluorescent protein complementation assay. Our method provides an efficient route to discovering new coiled-coil interactions and uncovers a number of associations that may have functional significance for vesicular trafficking.     

真盐生植物盐地碱蓬根系边缘细胞在耐盐中的作用初探

以黄河三角洲潮间带盐地碱蓬种子生成的幼苗为材料,研究了NaCl胁迫对盐地碱蓬生长与根系边缘细胞的影响。盐地碱蓬的第一个边缘细胞几乎与根尖同步产生,当根长达到13mm时,边缘细胞数目达到最大值。NaCl胁迫抑制边缘细胞的活性,但低浓度的NaCl处理增加边缘细胞的数目。低浓度NaCl处理时果胶甲基酯酶（PME）的活性比对照有明显增加,超氧化物歧化酶（SOD）活性随着NaCl浓度的增加呈现先上升后下降的趋势,低浓度NaCl可以增加盐地碱蓬根内过氧化氢酶（CAT）的活性,NaCl处理时间和处理浓度都对过氧化物酶（POD）活性的影响不明显。这些结果表明,盐地碱蓬至少部分通过增加调控活性氧（ROS）水平增加PME活性及根系边缘细胞数目来抵抗NaCl胁迫。     

绿藻假根羽藻色素-蛋白复合物的分离及其特性研究

采用聚丙烯酰胺凝胶电泳(PAGE)和蔗糖密度梯度超速离心方法分离了假根羽藻(Bryopsis corticulans)的色素-蛋白复合物,并对其特性进行分析。结果表明:采用PAGE分离得到7条色素-蛋白复合物带,分别是CPⅠa1、CPⅠa2、CPⅠ、LHCP₁、LHCP₂、CPa、LHCP₃₊₃,和2条游离色素(free pigment,FP)FCa、FC。用改进的不连续蔗糖密度梯度离心法分离到五条带。区带Ⅰ是FP;区带Ⅱ主要是小分子量的PSⅡ捕光复合物LHCP₃₊₃;区带Ⅲ以PSⅡ捕光复合物的聚集体LHCP1为主,区带Ⅱ和Ⅲ的吸收光谱中除了Chla外,还含有大量的Chlb和管藻黄素,是管藻黄素-Chla/b-蛋白质复合物;区带Ⅳ在PAGE中只显示一条带,光谱中有Chlb吸收肩峰,含有66和56kDa两种多肽,是较小的PSⅠ复合物CPⅠa。     

生态系统中流动路径多样性的测度

路径作为生态网络组成的一个基本单元,是生态系统中物质、能量流动的通道。生态系统的结构和功能是通过生态系统中不同路径上能量和物质的流动来实现的。路径多样性是反映生态系统营养结构多样性的一个重要侧面。本文在定义基路径和等价基路径的基础上,给出了生态系统中流动路径多样性的测度     

三种藻胆蛋白在复合累积LB膜中的能量传递

制备了R-藻红蛋白(R-PE)、C-藻蓝蛋白(C-PC)及变藻蓝蛋白(APC)的单组分累积LB膜及三组分复合累积LB膜. 吸收及荧光光谱测定表明三种蛋白的LB膜的光谱重叠性质与他们在水溶液中的性质相同. 结构测定表明, 三种蛋白在其LB膜中排列有序, 且由它们组装的复合累积LB膜结构类似于藻类植物中的藻胆体结构. 通过稳态荧光光谱及其光谱解叠, 观察到了三种蛋白在复合累积LB膜中的激发能量传递现象. 根据给体荧光峰的猝灭, 计算出在复合累积LB膜中从给体R-PE经C-PC到受体APC的能量传递效率为51%.     

Investigation on the Sensitivity and FOM of Ag Nanoparticles and Nanoarrays

The localized surface plasmon resonance (LSPR) spectroscopy of Ag nanoparticles (NPs) is sensitive to the changes of the surrounding medium, which enables the NPs to serve as plasmonic nanosensors. In this paper, the refractive index (RI) sensitivity and figure of merit (FOM) of individual NPs and nanoarrays are investigated by employing the finite difference time domain (FDTD) method. The influence of shape and size are analyzed for individual NPs, and the influence of particle spacing is analyzed for nanoarrays. It is found that the NP with shorter size in incident direction or longer size in polarization direction exhibits better sensing performance. And when the a_eff is between 20 and 60 nm, the larger NP exhibits higher sensitivity but lower FOM. The results of nanoarrays show that when particle spacing is large, the sensitivity of nanoarrays is large, and the sensitivity of nanoarrays decreases first and then increases as particle spacing decreases. In addition, the FOM of nanoarrays exhibits the similar trend.

     

Preparation of a light-sensitive and reversible dissolution copolymer and its application in lysozyme purification

A novel light-sensitive and cation-exchange copolymer (PNBCC) has been synthesized by random copolymerization of chlorophyllin sodium copper salt, crylic acid, n-butyl acrylate, and N-isopropylacrylamide. The PNBCC copolymer showed reversible dissolution and could be precipitated by 488 nm laser irradiation with the least light density of 1.70 x 10(5) W/m(2). By optimizing the ratio of monomers, pH, and ion concentration, over 95% copolymer was recovered by laser irradiation. The copolymer was used to purify lysozyme as light-sensitive cation exchanger, and its adsorption matched a Langmuir adsorption isotherm with maximum adsorption capacity of 98,900 U/g and dissociated constant of 852 U/mL. By applying the copolymer to the separation of lysozyme from egg white, the specific activity of lysozyme was improved from 399 to 6346 U/mg and the recovery of lysozyme achieved 81.3%.     

神经元迁移的细胞和分子机制

在脑的发育过程中,神经元的正确迁移是正常脑组织发生的一个必不可少的环节。在过去的几十年中,通过不同的学科方法,对于神经元迁移的机制有了较好的理解。在细胞水平上,神经元迁移需要3个重复事件的精确调控;在分子水平,与神经元迁移相关的胞外信号分子已经被鉴定,而且大量的胞内信号通路也已经被阐明。     

硫酸糖肽的生物活性及药理作用

黏多糖类物质独特的生物活性已成为生物化学和医学领域的热点。硫糖肽作为黏多糖类的一种,具有广泛的抗炎、抗溃疡作用,尤其是预防和治疗溃疡方面的优势引起人们越来越多的关注,具有广阔的药物开发和应用前景。本文就硫糖肽的生物活性及其药理作用展开综述,并结合硫糖肽的市场需求和研究现状进行了展望。