Live imaging of yeast Golgi cisternal maturation

There is a debate over how protein trafficking is performed through the Golgi apparatus. In the secretory pathway, secretory proteins that are synthesized in the endoplasmic reticulum enter the early compartment of the Golgi apparatus called cis cisternae, undergo various modifications and processing, and then leave for the plasma membrane from the late (trans) cisternae. The cargo proteins must traverse the Golgi apparatus in the cis-to-trans direction. Two typical models propose either vesicular transport or cisternal progression and maturation for this process. The vesicular transport model predicts that Golgi cisternae are distinct stable compartments connected by vesicular traffic, whereas the cisternal maturation model predicts that cisternae are transient structures that form de novo, mature from cis to trans, and then dissipate. Technical progress in live-cell imaging has long been awaited to address this problem. Here we show, by the use of high-speed three-dimensional confocal microscopy, that yeast Golgi cisternae do change the distribution of resident membrane proteins from the cis nature to the trans over time, as proposed by the maturation model, in a very dynamic way.     

Development of glomerular pattern visualized in the olfactory bulbs of living mice

Many regions of the mammalian brain are characterized by iterated ensembles of nerve cells which can be distinguished anatomically and physiologically. A particularly striking example is the pattern of glomeruli in the olfactory bulbs; other instances are columns and 'blobs' in the visual cortex, barrels and columns in the somatosensory cortex, and striasomes and cell islands in the neostriatum. Understanding the generation of these neuronal ensembles has a bearing on a variety of important neurobiological problems, including the nature of critical periods, the age-dependent response of the nervous system to injury and the manner in which neural information is stored. Analysis of these issues has usually been restricted to studies of the brains of different individuals at various ages. Many questions about the formation of such units, however, can only be answered by observing the same brain repeatedly in a living animal. This strategy would enable a direct assessment of how these units are assembled, whether the initial ensembles persist and whether units are lost or gained as an animal matures. We have succeeded in studying the pattern of glomeruli in the mouse olfactory bulb on two separate occasions during postnatal development. Comparison of the patterns observed at intervals of up to three weeks show that this part of the brain is gradually constructed by the addition of new glomeruli to a persisting population.     

An essential role for a phospholipid transfer protein in yeast Golgi function

Progression of proteins through the secretory pathway of eukaryotic cells involves a continuous rearrangement of macromolecular structures made up of proteins and phospholipids. The protein SEC14p is essential for transport of proteins from the yeast Golgi complex. Independent characterization of the SEC14 gene and the PIT1 gene, which encodes a phosphatidylinositol/phosphatidylcholine transfer protein in yeast, indicated that these two genes are identical. Phospholipid transfer proteins are a class of cytosolic proteins that are ubiquitous among eukaryotic cells and are distinguished by their ability to catalyse the exchange of phospholipids between membranes in vitro. We show here that the SEC14 and PIT1 genes are indeed identical and that the growth phenotype of a sec14-1ts mutant extends to the inability of its transfer protein to effect phospholipid transfer in vitro. These results therefore establish for the first time an in vivo function for a phospholipid transfer protein, namely a role in the compartment-specific stimulation of protein secretion.     

可视化程序模块结构设计技术

具有面向过程方式编程经验的软件开发人员 ,在使用可视化开发工具时 ,其开发工作大多数是以 E-DP方式展开的。在讨论事件驱动程序设计 ( E-DP)的特点的基础上 ,以医院信息管理系统为实例 ,分析事件驱动程序系统的结构 ,提出一种以容器为框架的事件驱动程序结构设计及表示方法。     

一种可视化的时态推理方法

给出了一种集成定性与定量的约束的可视时态概念模型,通过该模型使得每个时态对象可以转子平面上的一个可视实体,并且在一些假设下引进一种有效的可视时态约束传递算法。     

Neuronal pacemaker for breathing visualized in vitro.

Breathing movements in mammals arise from a rhythmic pattern of neural activity, thought to originate in the pre-B?tzinger complex in the lower brainstem. The mechanisms generating the neural rhythm in this region are unknown. The central question is whether the rhythm is generated by a network of bursting pacemaker neurons coupled by excitatory synapses that synchronize pacemaker activity. Here we visualized the activity of inspiratory pacemaker neurons at single-cell and population levels with calcium-sensitive dye. We developed methods to label these neurons retrogradely with the dye in neonatal rodent brainstem slices that retain the rhythmically active respiratory network. We simultaneously used infrared structural imaging to allow patch-clamp recording from the identified neurons. After we pharmacologically blocked glutamatergic synaptic transmission, a subpopulation of inspiratory neurons continued to burst rhythmically but asynchronously. The intrinsic bursting frequency of these pacemaker neurons depended on the baseline membrane potential, providing a cellular mechanism for respiratory frequency control. These results provide evidence that the neuronal kernel for rhythm generation consists of a network of synaptically-coupled pacemaker neurons.     

Golgi biogenesis in Toxoplasma gondii

Two models have been put forward to explain the growth of new Golgi during the cell cycle. The first suggests that a new Golgi grows out of the endoplasmic reticulum by de novo synthesis. The second suggests that a pre-existing Golgi is needed for the growth of a new one, that is, the Golgi is an autonomously replicating organelle. To resolve this issue, we have exploited the simplicity of the apicomplexan parasite Toxoplasma gondii, which has only a single Golgi stack. Here we show, by using video fluorescence microscopy and three-dimensional reconstructions of serial thin sections, that the Golgi grows by a process of lateral extension followed by medial fission. Further fission leads to the inheritance by each daughter of a pair of Golgi structures, which then coalesce to re-form a single Golgi. Our results indicate that new Golgi grow by autonomous duplication and raise the possibility that the Golgi is a paired structure that is analogous to centrioles.     

MCNP可视化输入程序的开发

MCNP(Monte Carlo N-particle)输入文件格式较复杂,特别是对相关物体几何参数的描写更难,不仅书写麻烦,而且很容易出错。为方便用户准确得到输入文件,进行了MCNP可视化输入程序的开发。程序运行于Windows平台下,使用VC 和OpenGL语言编译。应用该程序,用户能够在一个三维可视化环境中创建几何体并定义区域,描写数据卡,最后直接得到符合MCNP输入文件格式要求的inp文件。     

假设检验的可视化教学

利用大家熟悉的ExceI软件,解决假设检验的相关问题。     

HDFS可视化操作研究与实现

Hadoop是一个由Java语言实现的软件框架,在一个计算机集群中对海量数据进行分布式计算,这个集群可以支持上千个节点和PB级别的数据.HDFS是专门为Hadoop设计的分布式文件系统,作为Hadoop最基本的构成元素,保证内容的完整性与可用性.但是HDFS的操作界面并不友好,必须通过命令行或者IDE插件来实现对文件的操作.在研究HDFS的架构的基础上,设计实现了基于WEB的HDFS可视化文件访问系统.     

SEC21 is a gene required for ER to Golgi protein transport that encodes a subunit of a yeast coatomer.

Non-clathrin coated vesicles have been implicated in early steps of intercompartmental transport. A distinct set of coat proteins are peripherally associated with the exterior of purified mammalian intra-Golgi transport vesicles. The 'coatomer', a cytosolic complex containing a similar subunit composition to and sharing at least one subunit (beta-COP) with the coat found on vesicles, has been postulated to be the precursor of this non-clathrin coat. Here we describe the characterization of SEC21, an essential gene required for protein transport from the endoplasmic reticulum to the Golgi in the yeast Saccharomyces cerevisiae. The 105K product of this gene, Sec21p, participates in a cytosolic complex that we show to be a yeast homologue of the mammalian coatomer. These observations demonstrate that a non-clathrin coat protein plays an essential role in intercompartmental transport.     

基于Web交互式的DS-CAI可视化算法实现

该文是对DS-CAI（数据结构CAI）程序的具体实现．首先介绍程序可视化原理并回顾了程序相关的数据结构知识——BF匹配算法，接着对算法程序可视化进行详细描述，最后采用基于Web的JavaApplet技术实现了可视化算法演示程序．     

活性自由基聚合的研究进展

活性自由基聚合是近来新发展的一种合成聚合物的方法。本文对活性自由基聚合物动力学行为在制备特定结构高分子方面的应用作了概括性的介绍，并展望且了它的发展趋势。     

Sustained oscillations in living cells

Glycolytic oscillations in yeast have been studied for many years simply by adding a glucose pulse to a suspension of cells and measuring the resulting transient oscillations of NADH. Here we show, using a suspension of yeast cells, that living cells can be kept in a well defined oscillating state indefinitely when starved cells, glucose and cyanide are pumped into a cuvette with outflow of surplus liquid. Our results show that the transitions between stationary and oscillatory behaviour are uniquely described mathematically by the Hopf bifurcation. This result characterizes the dynamical properties close to the transition point. Our perturbation experiments show that the cells remain strongly coupled very close to the transition. Therefore, the transition takes place in each of the cells and is not a desynchronization phenomenon. With these two observations, a study of the kinetic details of glycolysis, as it actually takes place in a living cell, is possible using experiments designed in the framework of nonlinear dynamics. Acetaldehyde is known to synchronize the oscillations. Our results show that glucose is another messenger substance, as long as the glucose transporter is not saturated.     

基于可视化分层递阶表示模型的社会和谐评价方法

以中国城市和谐发展指数为例,提出了一种多维数据的分层递阶表示模型,它具有鲜明的可视化特点。应用该模型对41个城市的和谐发展进行整体评价分析,实现了社会和谐多维数据分层信息融合的评价和评价结果的可视化,为社会科学的定量研究提供了一种新方法。基于多元图的可视化信息融合不仅给出系统整体状态的定量表达,而且可以从不同层次图形的几何形状确定评价指标的优劣程度。