Imaging the dynamics of intracellular protein translocation by photoconversion of phamret-cybr/ROM

Cybr/Reduced On-random Motile (ROM) is a scaffold protein, containing a postsynaptic density protein-95/discs-large/ZO-1 (PDZ) domain, a LEU region and a PDZ domain binding region at the C-terminus. In the immune system, Cybr/ROM was found to localize in vesicles and at the plasma membrane, through interactions with cytohesin-1. In this investigation, we reported Cybr/ROM as occurring in vesicles, the cytoplasm and at membrane ruffles of H1299 lung cancer cells. Its localization at the ruffles was dependent on intact actin structures as indicated by latrunculin A treatment, which abrogated ruffle formation and staining of Cybr/ROM at the cells' periphery. Transfection of truncation mutants consisting of either the PDZ or LEU domain showed that the LEU domain of ROM was localized to membrane ruffles, vesicles and the cytoplasm, whereas, the PDZ domain localized to the membrane ruffles and cytoplasm only. There was therefore, domain/molecular segregation of Cybr/ROM in different cellular compartments. Cybr/ROM was subcloned into a plasmid carrying the photoactivation-mediated resonance energy transfer (Phamret) protein. The photoconversion experiments demonstrated the diffusion of ROM from the cytoplasm to the membrane ruffling sites and conversely from membrane ruffles to the cytoplasm. Large variances in the transport velocity of Cybr/ROM in the cytoplasm suggested that its movements were facilitated by other mechanisms in addition to diffusion.     

Morphological studies on the mechanisms of pigmentary organelle transport in fish xanthophores and melanophores

Pigmentary organelle translocations within fish chromatophores undergo physiological color changes when exposed to external signals. Chromatophores can be isolated in high yields, and their pigmentary organelles can be tracked readily by microscopy. The combined efforts of morphology and biomolecular chemistry have led to the identification of and determination of the interrelationships between cytoskeletal elements and accessory proteins, motor molecules, cytomatrix, and pigmentary organelles of various sizes. Fish chromatophores have been classified as fast, intermediate, and slow translocators, based on the relative numbers of microtubules. Studies on cultured goldfish (Carassius auratus L.) xanthophores for over 20 years have demonstrated that in this slow translocator, tubulovesicular structures of the smooth endoplasmic reticular (SER) cisternae are involved in the disperson and aggregation of associated carotenoid droplets (CD) with some involvement of cytoskeletal elements. Killifish (Fundulus heteroclitus L.) melanophore, a fast translocator, was also examined. Recent work demonstrates a bright fluorescent "starburst"-like spot that we call an actin filament-organizing center (AFOC) with radiating microfilaments, akin to the microtubule-organizing center (MTOC) with radiating microtubules. Melanosomes translocate single-file on microtubules and are not associated with SER cisternae. Slower CD dispersion or aggregation in goldfish xanthophores seems to be predominantly microfilament-based transport, or microfilament- and microtubule-based transport, respectively. Faster melanosome translocations in killifish melanophores are based on microtubules, with our evidence indicating microfilament involvement. Neural crest-derived chromatophores are models for vesicular transport in axons, and immunocytochemical and imaging technologies may help to elucidate the cellular transport mechanisms.     

Role of parietal and principal gastric mucosa cells in the phenomenon of concentration of aluminum and indium

The subcellular behavior of aluminum and indium, used in medical and industrial fields, was studied in the gastric mucosa and the liver after their intragastric administration to rats, using, two of the most sensitive methods of observation and microanalysis, the transmission electron microscopy, and the secondary ion mass spectrometry. The ultrastructural study showed the presence of electron dense deposits, in the lysosomes of parietal and principal gastric mucosa cells but no loaded lysosomes were observed in the different studied hepatic territories. The microanalytical study allowed the identification of the chemical species present in those deposits as aluminum or indium isotopes and the cartography of their distribution. No modification was observed in control rats tissues. In comparison to previous studies describing the mechanism of aluminum concentration in the gastric mucosa and showing that this element was concentrated in the lysosomes of fundic and antral human gastric mucosa, our study provided additional informations about the types of cells involved in the phenomenon of concentration of aluminum and indium, which are the parietal and the principal cells of the gastric mucosa. Our study demonstrated that these cells have the ability to concentrate selectively aluminum and indium in their lysosomes, as a defensive reaction against intoxication by foreign elements.     

基于OpenGL的弹簧卷绕过程仿真系统研究

根据目前数控卷簧机编程中存在的问题,对弹簧成形过程、弹簧及卷簧机床三雏建模进行了研究。以OpenGL和VisualC＋＋为开发工具,实现了弹簧卷绕过程的动态显示,为弹簧加工程序的正确性提供了保障。     

Morphological studies on the gills of the European hake (Merluccius merluccius,Linnaeus, 1758)

The current work gives concern to study the morphology of the Merluccius merluccius gills by using gross morphology, scanning electron microscopy (SEM), and light microscopy. The findings of the present study revealed that the gill system consisted of four pairs of gill arches which carry the gill filaments on the convex border and gill rakers on the concave border of them. SEM results revealed that the rakers and the spines distribution on the first gill arch differed from that of the other three gill arches on the lateral and medial surfaces. On the surface the gill filaments, there were longitudinal ridges that carried pores of chloride cells and mucous cells. The histological examination revealed that, the gill arch composed of hyaline cartilage that presented in the form of cups. Each cup consisted of central cartilagenous core and peripheral cartilagenous matrix. The gill filaments composed of cartilaginous bar of peripheral cartilaginous matrix and central cartilaginous core extended from the gill arches and covered by an epithelial layers with a few mucous cells permeate it, and chloride cells were straggly in the interlamellar epithelium. Each gill filament carried several leaves like secondary lamellae on both sides of it. The epithelium, which lined the secondary lamellae, composed of epithelial pavement cells, some mucous cells, and pillar cells.     

Morphological changes of the human gastric mucosa under long-term proton pump inhibitor therapy and their clinical relevance

Proton pump inhibitors are potent drugs for the treatment of acid-related diseases. The moderate hypergastrinaemia observed during therapy is a physiological response to low intragastric pH and the increase is limited to the first months of therapy with no further changes thereafter. Reports on endocrine cell changes in the antral mucosa under chronic PPI therapy are controversial and lack clinical relevance. In contrast, in the oxyntic mucosa hyperplastic argyrophil cell changes have been reported, dependent on the degree and duration of hypergastrinaemia, the severity of oxyntic mucosal gastritis, especially atrophy, and the presence of H. pylori infection. Current data do not support a progression from hyperplastic to dysplastic argyrophil cell lesions in humans in the absence of additional genetic factors. Data on the progression of oxyntic gastritis under chronic PPI treatment in comparison to untreated controls could not be confirmed in more recent studies including a well-matched control population. The main factor for gastritis progression is the presence of Helicobacter pylori infection. The bacterium not only causes a chronic inflammation of the gastric mucosa, resulting in atrophy and intestinal metaplasia, but also influences endocrine cell populations involved in the regulation of gastric acid secretion. The clinical benefit of H. pylori eradication in reflux esophagitis patients is still a matter of debate. The complex relations in humans between hypergastrinaemia, (oxyntic) gastritis and atrophy, H. pylori infection, argyrophil cell hyperplasia, and the effects of long-term PPI treatment of acid-related diseases do not allow a quantification of the contribution of each single factor for the observed changes.     

Rodent nerve-muscle cell culture system for studies of neuromuscular junction development: refinements and applications

Understanding of vertebrate neuromuscular junction (NMJ) development has been advanced by experimentation with cultures of dissociated embryonic nerve and skeletal muscle cells, particularly those derived from Xenopus and chick embryos. We previously developed a rodent (rat) nerve-muscle coculture system that is characterized by extensive induction of acetylcholine receptor (AChR) aggregation at sites of axonal contact with myotubes (Dutton et al., 1995). In this article, we report modifications of this culture system and examples of its application to the study of NMJ development: (1) We describe improved methods for the enrichment of myoblasts to give higher yields of myotubes with equal or greater purity. (2) We demonstrate lipophilic dye labeling of axons in cocultures by injection of dye into neuron aggregates and show the feasibility of studying the growth of living axons on myotubes during synapse formation. (3) We describe the preparation of a better-defined coculture system containing myotubes with purified rat motoneurons and characterize the system with respect to axon-induced AChR aggregation. (4) We demonstrate dependence of the pattern of axon-induced AChR aggregation on muscle cell species, by the use of chick-rat chimeric co-cultures. (5) We provide evidence for the role of alternatively-spliced agrin isoforms in synapse formation by using single cell RT-PCR with neurons collected from co-cultures after observation of axon-induced AChR aggregation. Microsc. Res. Tech. 49:26-37, 2000. Published 2000 Wiley-Liss, Inc.     

A new approach for high-pressure freezing of primary culture cells: the fine structure and stimulation-associated transformation of cultured rabbit gastric parietal cells

A newly designated procedure for high‐pressure freezing of primary culture cells provided excellent ultrastructure of rabbit gastric parietal cells. The isolated parietal cells were cultivated on Matrigel‐coated aluminium plates for conventional subsequential cryoimmobilization by high‐pressure freezing. The ultrastructure of different organelles (Golgi apparatus, mitochondria, multivesicular bodies, etc.) was well preserved compared to conventional chemical fixation. In detail, actin filaments were clearly shown within the microvilli and the subapical cytoplasm. Another striking finding on the cytoskeleton system is the abundance of microtubules among the tubulovesicles. Interestingly, some microtubules appeared to be associating with tubulovesicles. A large number of electron‐dense coated pits and vesicles were observed around the apical membrane vacuoles in cimetidine‐treated resting parietal cells, consistent with an active membrane uptake in the resting state. Immunogold labelling of H⁺/K⁺‐ATPase was seen on the tubulovesicular membranes. When stimulated with histamine, the cultured parietal cells undergo morphological transformation, resulting in great expansion of apical membrane vacuoles. Immunogold labelling of H⁺/K⁺‐ATPase was present not only on the microvilli of expanded apical plasma membrane vacuoles but also in the electron‐dense coated pits. The present findings provide a clue to vesicular membrane trafficking in cultured gastric parietal cells, and assure the utility of the new procedure for high‐pressure freezing of primary culture cells.     

Theoretical and experimental studies on the interface phenomena during the engagement of automatic transmission clutch

Mathematical models for predicting the temperature and thermal degradation have been developed, which include all important phenomena during the engagement of wet friction clutch. The thermal model consists of heat balance for the separator, friction lining, core plate, and ATF in the clearance. The degradation mechanism and constants for the selected friction material obey the zeroth order reaction. The model predictions show good agreement with experimental measurements. This revised version was published online in June 2006 with corrections to the Cover Date.     

Numerical studies on the dynamic characteristics of a wet multi-disc clutch during the disengaging process

Journal of Mechanical Science and Technology - A comprehensive numerical model was proposed to investigate the disengaging process of a wet multi-disc clutch, which included the hydrodynamic...     

基于合作目标的姿态测量系统建模及精度的蒙特卡罗估计

通过在飞行器表面安装x型的激光发射装置作为合作目标,用于飞行器近景姿态测量.该方法将飞行器姿态变化进行了有效放大,提高了测量精度.建立相应的数学模型以确定飞行器的外部姿态.针对系统的测量函数关系式具有隐式、非线性的特点,且相关系数估计困难,提出了基于蒙特卡罗统计仿真的不确定度估计方法.通过静态实验测得各输入坐标的不确定度及其误差服从的概率分布.用计算机模拟抽样各分量代入测量数学模型中,得到三维姿态的估计值和系统的总不确定度.从而有效地回避了由于测量方程的限制而对测量不确定度估计所造成的困难.使不确定度评定更为有效.仿真结果为实际测量的精度估算奠定基础.     

Electron diffraction studies of the peptidoglycan of bacterial cell walls.

Peptidoglycan of the gram-positive bacterium Lactobacillus plantarum was adsorbed onto hydrophilic crystalline films of graphitic oxide. Destruction by radiation damage was reduced by using a device which permitted scanning of the specimen for several hours through a focussed electron beam of low current density (2.5 X 10(-5) A/cm2). In additition to the sharp Debye-Scherrer rings caused by graphitic oxide, peptidoglycan causes a diffuse Debye-Scherrer ring in the region of 4.5 A. This can be interpreted as the packing periodicity of the peptidoglycan within the planes of the peptidoglycan sacculi.     

基于AMESim的电液伺服系统仿真与优化研究

AMESim是法国IMAGINE公司开发的高级工程系统仿真建模环境，为机械、液压、控制等工程系统提供一个较完善的综合仿真环境。目前该软件已广泛地被GM、Ford、LG、ZF、Bosch等公司采用，成为在汽车、液压和航空航天等研发部门的理想选择。文章首先介绍了AMESim软件的功能与特点，以典型的电液伺服控制系统为例，探讨了基于AMESim的液压系统建模与仿真的方法，研究了基于AMESim／DesignExploration模块和AMESim／matlab接口对AMESim仿真系统进行优化设计的方法，并给出了仿真与优化的结果。利用此方法，借助于AMESim所提供的多领域软件接口．可方便实现大型机电液一体化系统的联合仿真与优化研究．     

振动系统机电耦合研究的现状与展望

振动机械从诞生开始，经过近半个世纪的发展，已经奠定了雄厚的理论基础。由两台感应电动机分别驱动的自同步振动机时，需要对振动系统机电耦合及同步控制等进行更加深入的研究，为解决多机传动机械系统的同步控制作好准备。     

基于PROFIBUS的污水处理智能控制系统研究

从实际情况出发,为中小城市污水处理系统组建了一个基于PROFIBUS现场总线的控制网络,设计了一套用于指导污水处理厂日常运行的故障诊断及决策系统,实现了对污水处理的智能控制。     

Analyze the thermal dynamic images during the processing based on the causation system

Journal of Mechanical Science and Technology - The information and data from “visible temperature” can be used as a comprehensive fault detection system. In the past, most of the...     

Morphological observations of small granule-containing (Chromaffin) cells in the celiac ganglion of the guinea pig,with emphasis on cell contacts

Utilizing electron microscopic observation, several contacts between small, granule-containing cells (SGC) and postganglionic neurons (PGN) in the celiac ganglion of the guinea pig have been observed. A SGC in very close association with a PGN was seen to receive a distinct synaptic contact that contained many vesicles with dense cores. This contact was morphologically unlike cholinergic synapses previously reported on chromaffin cells. Because the SGC and PGN were clearly separated by a thin rim of satellite cell cytoplasm mutual to both cells, it is not known how or if the SGC would possibly exert a synaptic or paracrine effect on the PGN. Also, intraganglion SGC existed as large well-vascularized islands within the celiac ganglion. These intraganlion clusters sometimes contained more than 50 cells and perhaps could be considered to function as localized neuroendocrine components within the ganglion by secreting granule products into the nearby blood vessels for local or distant effects, although this certainly is not known. This work reports a unique synaptic ending upon a single-occurring SGC, which, in turn, closely approximates a ganglion neuron in a soma-somatic relationship. In addition, a very close association (but no actual contact) was observed between granule-containing processes, presumably emanating from the intraganglion clusters, and PGN. Whatever the function of ganglionic SGC may be, the exact relationship between SGC and PGN presumably would be of great interest and potential importance. © 1994 Wiley-Liss, Inc.     

Synapses on the mauthner cell of the goldfish: Thin section,freeze-fracture,and immunocytochemical studies

Large myelinated club ending and small-vesicle bouton synapses on the distal part of the lateral dendrite of the goldfish Mauthner cell were investigated with thin section, freeze-fracture, and immunocytochemical electron microscopic methods. Large myelinated club endings form mixed synapses, having both gap junctions and chemical synaptic junctions. The correlation of the number of gap junction particles (connexons) and the data from electrophysiological studies of single large myelinated club ending synapses suggest that only a small fraction of gap junction channels are open at any given time during electrical synaptic transmission. The chemical synaptic junctions at the large myelinated club ending synapse have large, round synaptic vesicles, indicating that they are excitatory. This result is in agreement with electrophysiological data demonstrating the excitatory nature of this chemical synapse. Freeze-fracture of these excitatory chemical synaptic junctions reveals the presence of the intramembrane particle aggregates in the postsynaptic E face. Small-vesicle boutons form chemical synaptic junctions with small, flat or oval synaptic vesicles. These structural data, in combination with previous electrophysiological studies, suggest that the small-vesicle bouton synapses are inhibitory. In support of this theory, the cytoplasmic side of the postsynaptic membrane of some of these synapses show positive immunocytochemical reaction to monoclonal antibodies against the rat glycine receptor. Freeze-fracture data reveal intramembrane particle aggregates in the postsynaptic P face of some small-vesicle bouton synapses which could possibly represent glycine receptor aggregates.