蛋白质-蛋白质相互作用的实验检测方法

生物体内的蛋白质分子常常通过与其他蛋白质分子发生相互作用来发挥其生物功能.因此,研究蛋白质-蛋白质相互作用(protein-protein interaction,PPI)对于阐明蛋白质分子的生物功能以及分子作用机理具有重要的意义.主要介绍基于生物物理和生物化学原理的检测蛋白质-蛋白质相互作用的实验研究方法,并对发展趋...     

土-箱形基础-结构动力相互作用的模态试验分析

进行了野外大比例(1：2)土-箱形基础-框架结构动力相互作用模型的试验研究．在假定环境激励是有限带宽白噪声的前提下,用NEXT法测试并分析了该7层框架结构模型脉动响应信号及其动力特性．借助在Matlab环境下编制的程序计算各点响应的功率谱,得到了模型前5阶自振频率．通过现场实测值与底部固结假定下结构三维有限元计算理论值的比较发现,考虑土-结构动力相互作用(SSI)时的自振频率比不考虑土-结构动力相互作用时结柏第一阶自振频率最大降低8．5％．     

轴对称有狭窄弹性管流固耦合模型及数值模拟

建立了求解厚壁,有狭窄,大管壁变形的血管及管内血液流动的流固耦合问题的数值计算模型。血管的几何形状、物质特性及模型的有关物理参数由模拟颈动脉血流及血管壁塌陷的实验获得。流体采用Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程,用广义有限差分方法求解。     

Linear surface capillary-gravity short-crested waves on a current

One of the forward situations in the study of water waves is the basic three-dimensional surface wave motion of short-crested waves. Capillary waves result in rich effects concerned closely with remote sensing in the open ocean. Ocean currents experience a complete process in surface wave motion. Based on the above ideas, a linear dynamical system of surface capillary-gravity short-crested waves is developed by considering the current effects, thus leading to the following analytical expressions of the kinematic and dynamic variables： the wave height, the wave steepness, the phase velocity, the wave-particle velocities, accelerations and trajectories and the wave pressure. A number of the classical, typical and latest special wave cases can arise from these expressions.     

密度泛函算法中基组效应对SiOSi链节的结构、能量和非共价键作用的影响

以二硅氧烷（H3 SiOSiH3）为聚硅氧烷中SiOSi骨架的模型分子，以它与水分子形成1∶1氢键复合物作为Si-OSi骨架参与非共价相互作用的模型分子，对二重裂分基组6-31G和三重裂分基组6-311G与不同极化函数和弥散函数组合下对二硅氧烷的几何结构、SiOSi线性化能垒及其非键相互作用的预测能力进行了测评。以B3LYP算法来测试基组效应对几何结构和SiOSi线性化能垒的影响，以PBE1PBE算法来考查基组对非共价相互作用的影响。结果表明：1）二硅氧烷的几何结构与线性化能垒对角动量的依赖性较强，至少要使用（3df ，p ）以上的角动量才会达到收敛；2）二硅氧烷的非共价相互作用同样也要使用（3df ，p）以上的角动量才会达到收敛，同时需要包含零点校正能才能得到合理的结合能，但基组叠加效应对结合能的影响则可忽略。     

Luminescence research and its relation to ultraweak cell radiation

Summary The fundamental laws of photochemistry and the essential results of experimental research on ultraweak cell radiation are presented. By comparing all the facts it can be concluded that the phenomena discussed may arise from a variety of possible reactions and sources. Recombination reactions of certain radicals actually do release sufficient energy to generate UV-photons of the intensity under consideration. On the other hand, stimulated emission cannot be excluded in view of the distinct deviation of the radiation field from thermal equilibrium. There exist, however, various other candidates, such as direct emitters like flavins, indoles, porphyrins, carbonyl derivatives and aromatic compounds, and molecular oxygen and its various species, as well as collective molecular interactions, e.g. dimole or exciplex transitions, triplet-triplet annihilation, collective hydrolysis, electric field effects in membranes, etc.Careful biochemical and biophysical experiments are still necessary to find answers to all the questions that remain; not only individual problems have to be solved, but it is important to keep in mind the interrelationships between certain reactions.     

Ascorbate content of foliage of eucalypts and conifers utilized by some Australian and North American mammals

Summary Ascorbate content of foliage of five species of Australian eucalypts and 10 species of North American conifers exhibited similar seasonal variation within the range of 100–350 mg per 100 g fresh weight.     

Chemical and tactile communication between the root aphid parasitoidParalipsis enervis and trophobiotic ants: consequences for parasitoid survival

Females of the aphid parasitoidParalipsis enervis received liquid food by regurgitation (trophallaxis) from workers of the ant speciesLasius niger, but were not fed by workers ofMyrmica laevinodis andTetramorium caespitum. WhileP. enervis was not treated aggressively by workers of any of these species,Lasius flavus workers killed the parasitoid. This different ant behaviour resulted in a different parasitoid longevity. WhileP. enervis survived for only 10 min in the presence ofL. flavus (due to ant aggression) or for approximately one day in the presence ofT. caespitum andM. laevinodis (due to lack of trophallaxis), survival increased significantly to more than five days in the presence ofL. niger, which provided food regularly to the parasitoids. Our study suggests thatP. enervis mimics behavioural signals ofL. niger, as well as odor cues of its host aphidAnoecia corni, to avoid aggression byL. niger.     

Production of insulin-like growth factor I (IGF-I) and IGF-binding proteins by rat intestinal stromal cells in vitro

To determine if intestinal stromal cells secrete diffusible factors such as insulin-like growth factors (IGFs) capable of regulating epithelial cell growth in vitro, stromal cells were isolated by enzymatic digestion of rat intestine. Incorporation of [³H]thymidine into DNA and [¹⁴C]leucine into protein of IEC-6 cells, a model intestinal epithelial cell line, was significantly increased (two- to threefold) when the IEC-6 cells were co-cultured with stromal cells, relative to IEC-6 cells grown alone. Medium conditioned by stromal cells stimulated DNA synthesis of IEC-6 cells in a dose-dependent manner. Analysis of the conditioned medium revealed that intestinal stromal cells secreted IGF-I, but little IGF-II, in addition to an M _r 32,000 IGF-binding protein (IGFBP-2) and an IGFBP having M _r∼ 24,000. We conclude that rat intestinal stromal cells secrete one or more diffusible factors, which may include IGF-I and IGFBPs, capable of stimulating proliferation of IEC-6 cells in vitro. Received 25 August 1997; received after revision 7 November 1997; accepted 20 November 1997