电荷耦合器件荧光成象研究膜上受体扩散

冷却慢扫描电荷耦合器件照相机附在荧光显微镜上组成了一个系统,可把一系列成象进行贮存,通过标记颗粒的位置,强度以及强度分布的差别,在每幅象上可区分５００个荧光点。荧光点的运动可以跟踪,通过分析可区分不同的运动方式。在人上皮成纤维细胞上跟踪观察了流感病毒受体在膜上的侧向扩散,实验结果表示在２４℃受体存在定向扩散、随机扩散和局部随机扩散三种运动方式。扩散系数Ｄ为１０－１２ｃｍ２ｓ－１的量级     

新型CCD摄像头在医疗中的应用

电荷耦合器件(Charge Coupled Device)简称CCD。CCD是一种大规模集成电路工艺制作的半导体光电元件,它在半导体硅片上制有成千上万个光敏元,这些光敏元组成线阵或面阵呈有规律地排列,当物体通过镜头成像于半导体平面上时。这些光敏元就产生与照在它上面的光强成正比的电荷。CCD器件具有自扫描能力,即将光敏元上产生的光生电荷依次有规模地串行输出,它的值与光     

尼罗红在测定细菌细胞中聚-β-羟基丁酸和其他脂类贮藏物质中的应用

通过对含有PHB和非PHB(脂类贮存物质(NPLD)的细菌细胞的尼罗红染色和荧光显微观察,证实尼罗红是一种很好的细菌细胞内贮存的脂类物质的荧光染色剂,灵敏度较高.可用于PHB和非PHB脂类贮藏物质荧光显微观察,并能在一定程度上将两者区分开来.     

尼罗红在测定细菌细胞中聚-β-羟基丁酸和其他脂类贮藏物质中的应用

通过对含有PHB和非PHB(脂类贮存物质(NPLD)的细菌细胞的尼罗红染色和荧光显微观察,证实尼罗红是一种很好的细菌细胞内贮存的脂类物质的荧光染色剂,灵敏度较高.可用于PHB和非PHB脂类贮藏物质荧光显微观察,并能在一定程度上将两者区分开来.     

鼠脑微透析液痕量氨基酸的激光诱导荧光检测

使用自制微透析探针和活动体位生化取样装置以及自行组装的毛细管电泳-增强型电荷耦合器件-激光诱导荧光系统,对鼠脑透析液中的痕量氨基酸以异硫氢酸荧光黄(FITC)进行柱前衍生后进行了分离和检测. 鼠脑海马CA₃区微透析液中游离氨基酸的浓度为10^-8～10^-6 mol/L, 并将其用于学习与记忆的研究, 为无损伤研究活体脑内神经递质和其他痕量生化物质的动态变化提供了一种新方法.     

细胞核内蛋白质动态变化研究进展

漂白后荧光恢复和漂白荧光丢失技术是蛋白质动态变化研究中常用的两项技术.近年来,利用这两项技术对细胞核内蛋白质动态变化的研究表明：一些蛋白质在细胞核内是运动的,能和各自所在的区域快速结合和解离;并且这种运动主要以被动扩散的方式进行,不消耗代谢的能量;另外蛋白质的共价修饰可对某些蛋白质的运动产生影响.细胞核内蛋白质的动态变化对细胞核的结构组成和基因表达的调控都具有重要的意义,但详细的机制还有待于进一步的研究.     

植物光诱导延迟荧光与光合作用的内在关联性研究

光合作用是地球上最重要的化学反应,植物内源性光诱导延迟荧光是光合作用原初过程中光系统Ⅱ作用中心P680处电荷分离效率的内在探针。本文从实验上证明了延迟荧光的产生与光合作用存在本质必然的联系。实验结果表明,延迟荧光激发谱与光合作用谱存在着明显的相似,延迟荧光强度随着激发光源光强的变化表现出类似的光抑制现象,以及在室温条件下延迟荧光强度与光合速率有着很好的相关性。为从植物光诱导延迟荧光技术来研究植物的光合作用提供了重要的实验证据。     

刀豆球蛋白A对Ehrlich腹水癌细胞的膜电位和表面电荷的影响

本文报告用荧光探剂diS-C_3—(5)和细胞电泳技术研究刀豆球蛋白A(ConA)作用于Ehrlich腹水癌细胞引起的膜电位和表面电荷的变化.ConA与细胞膜相应受体结合,导致在膜上的diS-C_3-(5)的荧光强度增加,表明细胞去极化.经用缬氨霉素诱导的钾扩散电位校正,与光学讯号变化相应的膜电位变化约是20mv.细胞经G毒毛旋化苷处理后,ConA引起的去极化程度比未处理过的细胞大.ConA作用于Ehrlich腹水癌细胞使细胞电泳迁移率变小.表明细胞表面负电荷数目减少.本文对这些变化的可能机制和相互关系进行了讨论.     

基于单分子定位的超分辨显微中荧光激发密度的优化

基于单分子定位的超分辨显微技术中,荧光点的中心位置可通过对每个荧光点进行单点扩散函数(point spread function,PSF)逐个拟合定位或对多个荧光点进行多PSF同时拟合定位获得。定位误差以及图像采样时间与荧光激发密度直接相关。为定量得到基于这两种算法的最优荧光激发密度,模拟了成像与定位过程,比较了常见的几种荧光分子在采用基于单PSF逐个拟合和多PSF同时拟合两种算法定位时的中心定位误差、荧光获取比率、获取的有效荧光点数与荧光激发密度间的关系,进而得到了采用这两种算法对不同荧光染剂进行超分辨成像时的最优荧光激发密度。该结果对单分子成像过程中荧光激发密度的选择和激发激光的强度控制具有指导意义。     

栀子提取物ZG对单纯疱疹病毒1型细胞吸附的影响

采用负染技术,借助高倍电子显微镜观察栀子提取物ZG作用后,病毒颗粒及其病毒吸附蛋白(virus attach-ment protein,VAP)的变化,考察药物是否直接改变或破坏病毒包膜蛋白的结构,使其失去感染性;采用异硫氰酸荧光素(fluorescein isothiocyanate,FITC)标记病毒,以肝素钠为参照,借助冷却慢扫描电荷耦合器件荧光成象技术,用Aquacomos软件进行图象分析,以探讨栀子提取物ZG不同加药方式对HSV-1吸附量的影响。结果表明栀子提取物ZG对HSV-1包膜表面的VAP无直接破坏作用,不影响病毒对Hep-2细胞的感染性;先加入肝素钠再进行病毒吸附及肝素钠病毒同时加入培养细胞这两种用药方式可明显减少细胞表面病毒的吸附量;栀子提取物ZG各种不同加药方式均能阻止HSV-1对Hep-2细胞表面的吸附,使病毒吸附量减少。     

Profile matching and profile subtraction: application of computer-based image analysis system for two-dimensional electrophoresis gels

The microcomputer-based image analysis system IB-1000 (developed by Indiana Biotech, Highland, IN) for two-dimensional electrophoresis gels has been described previously (9). It allows the user to compare protein spots between two profiles and identify those spots that are commonly shared in both profiles. This report describes two applications of the system's global comparison routine-profile matching and profile subtraction. This application is able to subtract commonly shared spots from one profile, creating a new profile made up by the unmatched spots in the other profile. These applications can be employed in a large variety of research projects.     

Restricted diffusion of DNA segments within the isolated Escherichia coli nucleoid

To study the dynamics and organization of the DNA within isolated Escherichia coli nucleoids, we track the movement of a specific DNA region. Labeling of such a region is achieved using the Lac-O/Lac-I system. The Lac repressor-GFP fusion protein binds to the DNA section where tandem repeats of the Lac operator are inserted, which allows us to monitor the motion of the DNA. The movement of such a GFP spot is followed at 48 ms temporal resolution during 12s. The spots are found to diffuse within a confined space, so that the nucleoid appears to behave like a viscoelastic network. The distribution of the "particle" position in time can be fitted to a Gaussian function indicating that the motion of the particle is Brownian. An average self-diffusion constant Ds=0.12 microm(2) s-1 is derived via the time auto-correlation functions of the displacement and is compatible with the collective diffusion coefficient measured previously by dynamic light scattering. Restriction of a DNA sequence to a small region of the nucleoid is tentatively related to the existence of so-called supercoiling domains.     

A physiologically discrete population of chromatophres in Octopus vulgaris (Mollusca)

Specimens of Octopus vulgaris (Cuvier) immersed in cold sea-water (4°C) exhibit a flashing display of brown chromatophores that we call "brown spots". The spots, which flashed approximately once every three seconds, are distributed over the dorsal skin of the head, mantle and arms and correspond mainly with the distribution of the white spots and white streaks previously described, and appear to act as a screen for the patches composing the white spots. Flashing brown spots could be evoked in animals with the supraoesophageal brain removed but not in animals with local denervation of the skin.
The precise site of action of the cold is unknown but it is proposed that the nerves supplying the brown spot units are normally tonically inhibited and that the cooling process removes this inhibition and allows the spots to flash. They are particularly useful for the in vivo study of the control of chromatophores because they can be reliably activated and isolated from responses of other chromatophores.     

A mechanical supination sprain simulator for studying ankle supination sprain kinematics

This study presents a free-fall mechanical supination sprain simulator for evaluating the ankle joint kinematics during a simulated ankle supination sprain injury. The device allows the foot to be in an anatomical position before the sudden motion, and also allows different degrees of supination, or a combination of inversion and plantarflexion. Five subjects performed simulated supination sprain trials in five different supination angles. Ankle motion was captured by a motion analysis system, and the ankle kinematics were reported in plantarflexion/dorsiflexion, inversion/eversion and internal/external rotation planes. Results showed that all sprain motions were not pure single-plane motions but were accompanied by motion in other two planes, therefore, different degrees of supination were achieved. The presented sprain simulator allows a more comprehensive study of the kinematics of ankle sprain when compared with some previous laboratory research designs.     

Software for quantitation and visualization of expression array data

Software is described that facilitates the analysis of phosphoimages from large array hybridizations. The Macintosh PowerPC-compatible application and its manual are available at no charge from http:?people.bu.edu/strehlow. The software is compatible with both custom formats and array filters from three commercial manufacturers. It allows the rapid quantitation of every spot on images of hybridizations to large arrays. The user drags grids of squares over the spots on the image to define the coordinates of each spot, then aligns and edits the position of the grid. The software then corrects the positions as necessary and quantitates up to 27,000 spots per image. It stores the numerical values for each signal in a format called the fingerprint file. Fingerprint files can be directly averaged or compared, allowing the user to find mean values or differences in data from independent hybridization experiments. Data can be recalled from the fingerprint file and can be output in a variety of spreadsheet formats with several options for background correction. Finally, the software offers an output format that allows the convenient visualization of data points using animated, three-dimensional graphs.     

Responses to worm-like-wriggling models by the praying mantis: effects of amount of motion on prey recognition

Adult females of the mantis, Tenodera angustipennis, were presented with a wriggling model, consisting of six circular spots positioned in a row horizontally and adjacently. During presentation, this model wriggled like a worm by moving some spots. When the motion of the model was small (the number of moving spots ≤2), the mantis sometimes stalked the model with peering movements but seldom struck it. When the motion was large (the number of moving spots ≥3), the mantis frequently fixated, rapidly approached, and struck the model. These results suggest that the mantis changes its approach behavior depending on the amount of prey motion. Disappearance of some terminal spots at the stationary end hardly affected the rates of fixation, peering, and strike. The model that wriggled at each end elicited lower rates of fixation and strike than the model that wriggled at one end. These results suggest that the mantis responds to only the fastest moving part of the wriggling model when the motion of the model is large. Electronic Publication     

The fundamental mechanism of motion detection in the insect visual system

The basic principle of motion detection by fibers of the optic lobes of flies were studied with a pair of small spots and a variety of paired intensity variations. These show that the process of correlation of adjacent field regions to detect motion is confined to a small area. The presence of small field units with small field adjacent inhibition in the system was detected. The optimum spot spacing for maximum reactions corresponded to the facet spacings. Selective motion detection responses from minimum information consisting of evaluating the difference between the spot intensities and the rate of change of the trailing spot relative to the motion direction was shown. However, additional properties best determined by white-noise experiments designed from this study were found.     

Docking of flexible ligands to flexible receptors in solution by molecular dynamics simulation

In this paper, a method of simulating the docking of small flexible ligands to flexible receptors in water is reported. The method is based on molecular dynamics simulations and is an extension of an algorithm previously reported by Di Nola et al. (Di Nola et al., Proteins 1994;19:174-182). The method allows a fast exploration of the receptor surface, using a high temperature of the center of mass translational motion, while the ligand internal motions, the solvent, and the receptor are simulated at room temperature. In addition, the method allows a fast center of mass motion of the ligand, even in solution. The dampening effect of the solvent can be overcome by applying different weights to the interactions between system subsets (solvent, receptor, and ligand). Specific ligand-receptor distances have been used to compare the results of the simulations with the crystal structure. The method is applied, as a test system, to the docking of the phosphocholine to the immunoglobulin McPC603. The results show the similarity of structure between the complex in solution and in the crystal.     

The feasibility of modal testing for measurement of the dynamic characteristics of goat vertebral motion segments

Structural vibration testing might be a promising method to study the mechanical properties of spinal motion segments as an alternative to imaging and spinal manipulation techniques. Structural vibration testing is a non-destructive measurement technique that measures the response of a system to an applied vibration as a function of frequency, and allows determination of modal parameters such as resonance frequencies (ratio between stiffness and mass), vibration modes (pattern of motion) and damping. The objective of this study was to determine if structural vibration testing can reveal the resonance frequencies that correspond to the mode shapes flexion-extension, lateroflexion and axial rotation of lumbar motion segments, and to establish whether resonance frequencies can discriminate specific structural alterations of the motion segment. Therefore, a shaker was used to vibrate the upper vertebra of 16 goat lumbar motion segments, while the response was obtained from accelerometers on the transverse and spinous processes and the anterior side of the upper vertebra. Measurements were performed in three conditions: intact, after dissection of the ligaments and after puncturing the annulus fibrosus. The results showed clear resonance peaks for flexion-extension, lateral bending and axial rotation for all segments. Dissection of the ligaments did not affect the resonance frequencies, but puncturing the annulus reduced the resonance frequency of axial rotation. These results indicate that vibration testing can be utilised to assess the modal parameters of lumbar motion segments, and might eventually be used to study the mechanical properties of spinal motion segments in vivo.