生态系统健康评价方法初探

生态系统是维持人类环境的最基本单元,生态系统功能主要体现在两个方面：一是生态服务功能（service);二是价值功能（goods)这两种功能是人类生态和发展的基础,生态系统健康是保证生态系统功能正常发挥的前提,结构和功能的完整性,具有抵抗干扰和恢复能力（resilience)、稳定和可持续性是生态系统健康的特征,生态系统健康评价需要基于生态系统的结构、功能过程来确定指标,包括生态系统的完整性,适应性和效率,生态系统健康评价主要有两种方法：一是指示物种评价,二是结构功能指标评价,结构功能指标评价包括单指标评价,复合指标评价和指标体系评价,指标体系评价中又包括自然指标体系评价,社会－经济－自然复合生态系统指标体系评价,本文针对生态系统健康的不同评价方法进行了对比研究,同时,针对不同的生态系统类型应选择其健康评价方法方面进行了简要的阐述。     

nsf is essential for organization of myelinated axons in zebrafish

BACKGROUND: Myelinated axons are essential for rapid conduction of action potentials in the vertebrate nervous system. Of particular importance are the nodes of Ranvier, sites of voltage-gated sodium channel clustering that allow action potentials to be propagated along myelinated axons by saltatory conduction. Despite their critical role in the function of myelinated axons, little is known about the mechanisms that organize the nodes of Ranvier. RESULTS: Starting with a forward genetic screen in zebrafish, we have identified an essential requirement for nsf (N-ethylmaleimide sensitive factor) in the organization of myelinated axons. Previous work has shown that NSF is essential for membrane fusion in eukaryotes and has a critical role in vesicle fusion at chemical synapses. Zebrafish nsf mutants are paralyzed and have impaired response to light, reflecting disrupted nsf function in synaptic transmission and neural activity. In addition, nsf mutants exhibit defects in Myelin basic protein expression and in localization of sodium channel proteins at nodes of Ranvier. Analysis of chimeric larvae indicates that nsf functions autonomously in neurons, such that sodium channel clusters are evident in wild-type neurons transplanted into the nsf mutant hosts. Through pharmacological analyses, we show that neural activity and function of chemical synapses are not required for sodium channel clustering and myelination in the larval nervous system. CONCLUSIONS: Zebrafish nsf mutants provide a novel vertebrate system to investigate Nsf function in vivo. Our results reveal a previously unknown role for nsf, independent of its function in synaptic vesicle fusion, in the formation of the nodes of Ranvier in the vertebrate nervous system.     

放射治疗网络系统的设计和应用

目的:研发放射治疗计划和放射治疗信息管理系统。方法:放疗网络采用客户机服务器模式,Oracle 9i为数据库服务器;使用PowerBuilder9i为编程语言进行开发。结果:该系统包括医生模块(放射治疗计划模块)、技术员模块、物理师模块、放射治疗电子病历查询和统计模块、系统管理模块五个部分。结论:该系统运行稳定,数据安全可靠,操作简单,可作为科室信息化建设的重要组成部分。     

Identification and analysis of bacterial virulence genes in vivo

Signature-tagged mutagenesis is a mutation-based screening method for the identification of virulence genes of microbial pathogens. Genes isolated by this approach fall into three classes: those with known biochemical function, those of suspected function and some whose functions cannot be predicted from database searches. A variety of in vitro and in vivo methods are available to elucidate the function of genes of the second and third classes. We describe the use of some of these approaches to study the function of the Salmonella pathogenicity island 2 type III secretion system of Salmonella typhimurium. This virulence determinant is required for intracellular survival. Secretion by this system is induced by an acidic pH, and its function may be to alter trafficking of the Salmonella-containing vacuole. Use of a temperature-sensitive non-replicating plasmid and competitive index tests with other genes show that in vivo phenotypes do not always correspond to those predicted from in vitro studies.     

An E. coli 5S rRNA Deletion Mutant Useful for the Study of 5S rRNA Structure/Function Relationships

We report on the construction of a novel strain of E. coli that can be useful for studies on the structure/function relationship of 5S rRNAs. The bacterial strain is deficient in six of the eight naturally occurring 5S rRNA genes (operons B, D, H, G, E) and demonstrates a greatly reduced growth rate that can be compensated by the plasmid-encoded expression of 5S rRNA. The relatively large difference in growth rate between compensated and non-compensated mutants provides the basis for a quick and simple assaying system for both the evaluation and mass screening of divergent 5S rRNA sequences for function. We describe the construction of the 5S rRNA deletion mutant BDHGE and characterize the usefulness and limitations of the system for evaluating structure/function relationships of 5S rRNA sequence. Received: 20 August 2000 / Accepted: 2 January 2001     

Brain Ventricular System and Cerebrospinal Fluid Development and Function: Light at the End of the Tube

The brain ventricular system is a series of connected cavities, filled with cerebrospinal fluid (CSF), that forms within the vertebrate central nervous system (CNS). The hollow neural tube is a hallmark of the chordate CNS, and a closed neural tube is essential for normal development. Development and function of the ventricular system is examined, emphasizing three interdigitating components that form a functional system: ventricle walls, CSF fluid properties, and activity of CSF constituent factors. The cellular lining of the ventricle both can produce and is responsive to CSF. Fluid properties and conserved CSF components contribute to normal CNS development. Anomalies of the CSF/ventricular system serve as diagnostics and may cause CNS disorders, further highlighting their importance. This review focuses on the evolution and development of the brain ventricular system, associated function, and connected pathologies. It is geared as an introduction for scholars with little background in the field.     

Thermodynamic correlates of evolution

At any given time the ecosystem is roughly describable as an autocatalytic collection of substances in the steady state. The evolutionary behavior of such a system may be studied by making a thermodynamic analysis of the autocatalytic model. our main assumptions are: the energy input is constant; the dissipation is a function of the concentration of catalyst and the rate constants which characterize the reaction (the catalytic capacity); the dissipation function is time independent. Our main result is: the concentration of catalyst and catalytic capacity are complementary. This means that biomass and rate cannot both increase in the course of evolution. The stationary state which fulfills this complementarity condition is stable and unique, in the sense that the dissipation function along with the catalytic capacity is sufficient to determine the quantity of catalyst. Under quite general conditions changes in the catalytic capacity are positively correlated to changes in the turnover frequency of matter and energy and negatively correlated to changes in the free energy of the system. The spatial heterogeneity of the system plays an important role in determining the applicability of these conditions. Spatial heterogeneity stabilizes the catalytic capacity and biomass since it allows for net movements of catalyst which always oppose changes in these quantities.     

The vestibulo-ocular reflex of hypergravity rats

The vertebrate vestibular system detects linear (otolith organs) and angular (semicircular canals) acceleration. The function of the otolith system is twofold, 1: perception of linear acceleration of the head, and 2: assessment of the spatial orientation of the head relative to the vector of gravity. Because of the latter function, a change of gravity will affect the vestibular input which, in turn, may have a wide range of serious physiological effects, for instance on ocular reflexes. The function of the vestibulo-ocular reflex (VOR) is to stabilize the visual image on the retina. Measurement of this VOR provides a method to investigate the (processing within the) vestibular system. Discrimination between gravity and linear acceleration, caused by movement of the head, is not possible. Therefore, information from the otolith system must be constantly compared with additional information from other sensory systems in order to solve the inherent ambiguity between tilt and translation. In this processing, cues from the semicircular canals also play a role. During parabolic flight, experiments can be performed at altered gravity levels for brief periods of time. On earth, the only effective possibility to manipulate gravity for longer periods of time is a centrifuge. Together with experiments in weightlessness during orbital flight, these methods form useful tools to investigate the influence of gravity on physiology. In our laboratory, rats have been kept inside a centrifuge at 2.5 g during their entire life-span (i.e. including gestation).     

A stochastic model for a closed biochemical system at equilibrium

This paper presents a stochastic model, a theoretical multi-variate probability function describing concentrations of reactants in a closed biochemical system at equilibrium. The theory applies to the complete range of biochemical systems from single enzyme reactions to combinations of reactions to complete pathways. Prior to examining the general system, probability functions are derived for the following systems as examples: a reaction with a competitive inhibitor, a bisubstrate reaction using the ping-pong mechanism and a series of two mono-substrate reactions. The theory of Markov processes is used to derive the probability functions for each of the example systems and then for the general system which includes the example systems as special cases. The probability function for any appropriate biochemical system proves to be the product of independent Poisson probabilities conditioned on the conservation equations. Finally, the implications of the theory are briefly discussed and possible extensions proposed.     

Emergence and biological complexity

Biological networks possess an organization that expresses their potential information. A function, I(X:Y)N, called mutual information of integration, define, on a quantitative basis, three types of organization. If I(X:Y)N=0, the properties of the global system XY can be reduced to the properties of its component sub-systems X and Y. Hence, XY is not a real system displaying collective properties but the mere collection of X and Y. Its properties are the properties of the sub-systems X and Y. If I(X:Y)N>0, the system is integrated. Although it behaves as a coherent whole, it does not possess many collective properties. Last, if I(X:Y)N<0, the system possesses emergent collective properties and can be considered complex for it possesses many collective properties that cannot be predicted from the independent study of component sub-systems X and Y. In a biological system, the emergence of information usually means the emergence of a novel function. This is probably what is occurring with enzymes. If a protein binds two ligands able to interact, and if the condition above is fulfilled, then the protein behaves as an enzyme able to allow a catalytic reaction between the two reagents.     

一种猪模型的体外肺灌注系统的建立

目的:体外肺灌注技术(Ex vivo lung perfusion, EVLP)对于肺移植的实施意义重大,但成本昂贵。本文采用国产经济材料建立猪模型的EVLP系统,以探索保证系统性能的同时降低移植费用。方法:我们首先依据国产材料配置肺灌注液,并组装管道、连接仪器以建立EVLP系统;之后通过外科手段获得3头家猪的肺脏,并灌注肺灌注液,低温保存6小时;最后我们将肺脏连接到EVLP系统,通过血气分析和肺功能检查来评估肺脏随时间变化的状况。结果:离体并在低温保存6小时的猪肺脏,通过我们建立的相对经济的EVLP系统,可以在2小时内维持良好的氧合功能和肺生理指标:肺动脉压、气道峰压、平台压力、肺动脉氧气分压和二氧化碳分压和左心房的氧气分压和二氧化碳分压都保持稳定,同时肺脏具有正常的颜色和弹性,没有明显水肿和功能损害。结论:我们建立的EVLP系统可以有效地维护离体猪肺的生理功能,且降低了成本,从而为肺移植体外肺灌注技术的优化应用提供了研究基础。     

微机控制的穿棱箱双向主动回避反应实验系统

目的：研究动物的学习与记忆功能。方法：研制一种微机控制的穿梭箱双向主动回避反应实验系统,自动分析和记录实验结果。结果：实验结果客观、准确。结论：本系统自动化程度高,操作简便,能满足实验需求     

An efficient transgenic system by TA cloning vectors and RNAi for C. elegans

In the nematode, transgenic analyses have been performed by microinjection of DNA from various sources into the syncytium gonad. To expedite these transgenic analyses, we solved two potential problems in this work. First, we constructed an efficient TA-cloning vector system which is useful for any promoter. By amplifying the genomic DNA fragments which contain regulatory sequences with or without the coding region, we could easily construct plasmids expressing fluorescent protein fusion without considering restriction sites. We could dissect motor neurons with three colors in a single animal. Second, we used feeding RNAi to isolate transgenic strains which express lag-2::venus fusion gene. We found that the fusion protein is toxic when ectopically expressed in embryos but is functional to rescue a loss of function mutant in the lag-2 gene. Thus, the transgenic system described here should be useful to examine the protein function in the nematode.     

Biomechatronics--assisting the impaired motor system

Biomechatronics concerns the interdisciplinary field of interaction with the human neuromuscular-skeletal system with the objective to assist impaired human motor control. In this field technology is developed that integrates neuroscience, robotics, interface and sensor technology, dynamic systems and control theory. The primary issue in this field concerns the concepts of assisting impaired human motor function. The secondary, derived, issue concerns possible methods of interfacing with the human body at all hierarchical levels of the human motor system. The application of motor assist systems may serve several goals: it can take over part of the affected motor control, enable the physiological motor system to perform the desired function or aid in training the impaired physiological system. The progress in these issues are reviewed and their potential implications for assistance of the impaired human motor system are discussed.     

The nervous system has an absolute molecular species requirement for proper function

A considerable body of biological evidence has accumulated that suggests that docosahexaenoic acid (22:6n3) is an essential component in the nervous system. Moreover, it appears from these studies that long chain polyunsaturates of the n-6 family such as arachidonate (20:4n6) and docosapentaenoate (22:5n6) cannot substitute for 22:6n3. This evidence is briefly reviewed and two hypotheses centering upon either biochemical or biophysical aspects of polyunsaturate function are presented and discussed. It is concluded that a bioactive metabolite of 22:6n3 is not responsible for its function in brain and that the best hypothesis asserts that a membrane function of a 22:6n3-containing species of phospholipid, such as phosphatidylserine, is critical for optimal neural function. Moreover, data are presented indicating that the biophysical properties of various highly unsaturated species of phospholipid are distinguishable. It is further contended that these species are not randomly distributed in membranes and thus the differences in physical properties may be amplified. It is concluded that a conceptual framework is needed in which the distinct membrane roles of phospholipid species may be understood as a function of the positions and numbers of double bonds. Only then may the critical role of the highly unsaturated n-3 polyunsaturates in the brain and retina be understood.     

Visualizing function in the tumor-associated lymphatic system

The recent surge of interest in the lymphatic system can be attributed to two factors: the discovery of cytokines that induce the growth of new lymphatic capillaries and the identification of lymphatic endothelial-specific markers. In contrast to the above, there is a paucity of techniques for studying lymphatic function in vivo. This article reviews imaging and other techniques that allow the assessment of lymphatic function, particularly in the tumor microenvironment, and proposes novel solutions for probing the same in vivo.     

综述: 补体系统及其糖基化

补体系统是固有免疫系统的重要组成部分,同时也是连接固有免疫和适应性免疫系统的重要桥梁．补体系统由30多种蛋白质组成,且其中绝大多数都经过糖基化修饰．近年来对补体系统的研究,不断揭示出补体系统在抗击病原微生物入侵和维持有机体生理稳态过程中发挥着重要作用．然而补体系统需要严格的调控,不论是激活不足、抑或是过度激活都可能引起疾病的发生．本文概述了近年来对于补体系统的激活、调控和功能研究的最新进展,并首次从糖生物学角度对补体系统蛋白质组分的糖链结构及糖链对相应蛋白质功能的影响进行了综述和小结．