Exchange factors,effectors, GAPs and motor proteins: common thermodynamic and kinetic principles for different functions

In this article, we review the properties of several classes of proteins that interact with ATPases and GTPases involved in energy and signal transduction. We show that certain common basic thermodynamic principles apply to the manner in which the nucleotide hydrolases interact with their partner molecules, and that the principles involved in signal transduction can be quantitatively modified to give systems with the known properties of energy transducing systems. As an example, actin can be described as an exchange factor for myosin, with its exchange activity being specific for ATP or inorganic phosphate in the myosin.ADP.P(i) complex, in contrast to the unspecific exchange activity of guanosine nucleotide exchange factors operating on GTPases involved in signal transduction and regulatory processes. These common aspects are reflected in shared structural features, suggesting an evolutionary relationship between such systems.     

Art and the Twenty-First Century Gift: Corporate Philanthropy and Government Funding in the Cultural Sector

Marcel Mauss's work on the archaic gift contributes to understandings of corporate and government support of arts organisations, or ‘institutional funding’. His approach allows us to see institutional funding as a gift that is embedded in a system of exchange wherein gifts come with a variety of obligations, and self-interest and disinterestedness are inseparable. The institutional gift operates through money and contracts; nevertheless, it entails obligations to give, to receive, and to reciprocate. This system of obligations has been joined, in the contemporary institutional gift, by another obligation: the obligation to ask.

Institutional funding of the arts has acquired additional twenty-first-century elements. The article elaborates these, using the UK as an example. It also argues that the ambivalence felt by some members of the arts world about institutional funding stems, in large part, from the obligations inherent in the gift. The recent imposition of the neo-liberal model into the arts is an intrinsic part of the exchange between institutional funders and arts organisations. Given that Mauss's work is strongly anti-liberal and anti-utilitarian, it is ironic that his ideas should prove so useful for understanding a form of twenty-first-century gift in which neo-liberalism plays such a crucial role.     

Building the New Zion: Unfinished Conversations between the Jews of Venta Prieta, Mexico, and Their Neighbors to the North

In 1950, Raphael Patai published his research on Venta Prieta, a Mexican town in which some residents lived as Jews despite having little knowledge of Judaism. Like other visitors, Patai was perplexed. Why did they wish to live as Jews? While Patai never answered this question to his satisfaction, he believed the answer would be found by developing a psychological profile of the residents, an approach in keeping with culture and personality theorists of the day. The present article provides a different solution. Drawing on additional sources, and short visits, we argue that Venta Prieta was not only a stop on the Jewish tourist circuit by 1950 but also developed out of a unique exchange. While U.S. Jews, as evangelical Protestants before them, provided a model for upwardly mobile Mexicans, Venta Prieta enabled middle-class tourists to experience Judaism in a pastoral setting and to "repair the world" (tikkun). [Keywords: Judaism, tourism, dialogical anthropology, social change, social mobility]     

微生物学教学改革的几点思考

通过对30多年来在各种刊物上发表的微生物学教学改革论文的分析,针对论文作者们普遍关心的教学队伍建设、课程体系建设和教学内容的调整、教学方法的改进等进行了讨论,提出了我们的观点,与微生物学教学工作者进行交流。     

Modulation and experience of external stimuli: toward a science of experience and interoception

The concept of interoception can be found in various writing over the past 100 or more years dating back to Sherrington, James and Lange. Professor Gy?rgy Adám that made American scientists increasingly aware of the importance of interoception with his 1967 book Interoception and Behavior. In this article we want to discuss two areas of research from out laboratory that have been influenced from this perspective. First, we will focus on electrocortical correlates of error detection during visuo-motor task and examine the manner in which an individual becomes aware of making an error as well as the way in which this awareness directs behavior on an ongoing basis. Second, we will examine hypnotic modulation of the pain experience and describe the manner in which electrocortical processes reflect the modulation and experience of pain. In this discussion, we suggest the importance of the anterior cingulate in not only modulating these processes in particular but also in its more general role as an interface between the limbic system and the neocortex and the integration of cognitive with emotional stimuli.     

Martian Stable Isotopes: Volatile Evolution,Climate Change and Exobiological Implications

Measurements of the ratios of stable isotopes in the martian atmosphere and crust provide fundamental information about the evolution of the martian volatile and climate system. Current best estimates of the isotope ratios indicate that there has been substantial loss of gases to space and exchange of gases between the atmosphere and the crust throughout geologic time; exchange may have occurred through circulation of water in hydrothermal systems. Processes of volatile evolution and exchange will fractionate the isotopes in a manner that complicates the possible interpretation of isotopic data in terms of any fractionation that may have been caused by martian biota, and must be understood first. Key measurements are suggested that will enhance our understanding of the non-biological fractionation of the isotopes and of the evolution of the martian volatile system.     

中外模拟医学学科发展对比与思考

模拟医学是一门将成为未来医学实践教学主流的教育学科。我国模拟医学学科建设还处于起步阶段,与国外发达国家相比明显滞后。从模拟医学专业课程、专科医师培训、理论研究、相关学术组织和学术交流等方面对国外模拟医学学科发展现状进行了分析,并对比我国模拟医学学科发展现状,提出要积极借鉴国外先进经验,勇于创新,进一步完善我国模拟医学学科体系建设,搭建更多学术交流平台,扩大模拟医学理论体系的内涵和外延,以构建具有中国特色的模拟医学学科体系。     

From colonial liberation to Cold War liberalism: Walter White,the NAACP,and Foreign Affairs, 1941–1955

With the USA's entry into World War II, international politics again commanded significant attention from the National Association for the Advancement of Colored People [NAACP]. Walter White, the NAACP's secretary, actively promoted an international solidarity movement to pressure the USA and European powers to commit to a world without colonies. The NAACP's participation in this movement lasted through to 1948. By 1951 White and his association had abandoned that solidarity, cut its ties with the African-American left, and embraced liberal anti-Communism. In exchange for this support, the NAACP received an unkept promise of influence in the formulation of domestic race relations policy. This article examines the foreign policy choices that the NAACP made between 1941 and 1955; the leadership styles that facilitated these choices; and the Cold War pressures on black America that helped push White and the NAACP into the liberal anti-communists’ camp.     

Methionine transport in S37 cells. Substrate-dependent function of amino acid transport system A in exchange processes.

Methionine had been observed to interact with two principal transport systems for amino acids in mammalian cells, the A and L systems. The present study of methionine transport and of exchange processes through system A arose in the course of a study to define the specificity of a transinhibition effect caused by cysteine. Methionine uptake through two transport systems in the S37 cell was confirmed by the occurrence of a biphasic double-reciprocal plot for labeled methionine uptake. Preloading cells with methionine stimulated labeled histidine uptake through systems A and L. Efflux of labeled methionine from cells was stimulated by histidine in a biphasic manner, so that bothe systems A and L can be used for exchange when methionine is the intracellular amino acid. Aminocycloheptanecarboxylic acid elicited exchange efflux of labeled methionine only through system L. ALPHA-Aminoisobutyric acid and N-methyl-alpha-aminoisobutyric acid both stimulated efflux of labeled N-methyl-alpha-aminoisobutyric acid from S37 cells. These findings are interpreted a showing that transport system A is capable of functioning as an exchange system depending upon the identity of intracellular and extracellular substrates available.     

A flavour of Alzheimer's

This article describes how today in the United States neurologists diagnose forms of dementia, such as Alzheimer's disease and frontotemporal dementia. Taking as a starting‐point the pervasive context of uncertainty in the diagnosis of neurodegenerative diseases, it examines how uncertainty is not merely an epistemological obstacle to the making of knowledge. On the contrary, the article analyses how uncertainty positively incites the use of clinicians’ ‘feelings’ in diagnostic work. Drawing on observations of clinical consultations and team meetings, it studies how, alongside contemporary instruments of objectification, clinicians use, share, and discuss their ‘feelings’ to ultimately renew knowledge about brain diseases. In documenting the manner in which medical expertise is bound to a concrete experience of the world, this article further explores how experts’ ‘intuition’ can be grasped as a conscious and effortful process, rather than as something ineffable, resisting analysis, and confined to an unconscious background.     

Sacrifice, Plants, and Western Pharmaceuticals: Money and Health Care in Northern Ghana

In this article I discuss the role of money vis-à-vis health care among the Dagomba, an agrarian people living in northern Ghana, whose pluralistic medical culture involves the use of both plants and Western pharmaceuticals in the treatment of various symptoms. In Dagomba society monetary exchanges in the domain of healing cannot be equated with self-interest, and nonmonetary exchanges cannot be compared with altruism in any straightforward fashion. Exchanges and their purposes are made meaningful by the contexts in which they occur. Exchanges may involve money and be commoditized. However, the very fact that such an exchange is made in a "benevolent and considerate manner" (which often means selling/buying on credit) transforms otherwise impersonal relationships between medicine sellers and their customers into displays of solidarity with the communal (collective) goals of Dagomba society.     

Regulation of neuritogenesis and synaptic transmission by msec7-1, a guanine nucleotide exchange factor,in cultured Aplysia neurons

msec7-1, a mammalian homologue of yeast sec7p, is known as a GDP/GTP exchange factor (GEF) for the ADP ribosylation factor (ARF) family of small GTPases. Here, we report that msec7-1 overexpression in cultured Aplysia neurons leads to an extensive neuritogenesis in a GEF activity-dependent manner through the modulation of the actin cytoskeleton. Similarly, the overexpression of ARNO, another mammalin GEF, produces extensive neuritogenesis in Aplysia neurons. In addition, msec7-1 overexpression increases the number of varicosities with an altered size and shape in a GEF activity-dependent manner. The overexpression of msec7-1 in pre-synaptic sensory neurons co-cultured with post-synaptic target motor neurons leads to an increase in the amplitude of the excitatory post-synaptic potential through its GEF activity. Our results demonstrate that msec7-1 regulates neuritogenesis and synaptic transmission.     

Runa realism: Upper Amazonian attitudes to nature knowing

Stories about the forest recounted in a Quichua-speaking Runa village in Ecuador's Upper Amazon point to an element of ecological understandings that is rarely studied; these are primarily about capturing and sharing the experience of the process of knowing rather than trafficking in stabilized tokens of ecological knowledge. Runa understanding of nature is achieved through a poetic language rich in what philosopher Charles S. Peirce terms iconic and indexical signs. This way of talking about forest experience is advantageous because these forms of representation can capture qualities and events in the world in ways that what Peirce terms symbols cannot. Iconic and indexical signs mediate the world in distinctive ways. Accordingly, this article suggests some implications that iconically and indexically rich modes of communicating experience have for engaging with the nonhuman realm, acquiring knowledge of the world, and establishing a certain kind of interpersonal social intimacy.     

Differential effects of triphenyltin and 8-azido-ATP on the ATP synthesis, ATP-Pi exchange, and ATP hydrolysis in liposomes containing ATP synthase and bacteriorhodopsin

The ATP hydrolysis activity of purified ATP synthase reconstituted in liposomes was inhibited by triphenyltin in a manner different from that of other thiol-specific reagents. In liposomes containing ATP synthase and bacteriorhodopsin, ATP hydrolysis and ATP-Pi exchange were inhibited by triphenyltin to a greater extent than the ATP synthesis, in contrast to what was found with an F1-specific inhibitor, 8-azido-ATP. The possibility is discussed that ATP hydrolysis and ATP synthesis are differently coupled to proton conduction through F0.     

Protein aggregation and its consequences for human disease

Protein molecules have emerged through evolution so that they are able to remain in their functional and soluble states under normal physiological conditions, although in other situations they often have a high propensity to aggregate. Aggregation in vivo is associated with a wide range of human disorders, including Alzheimer's disease and type II diabetes, medical conditions that are becoming increasingly common in the modern world. In such diseases, aggregated proteins can often be observed as highly intractable thread-like species known as amyloid fibrils. This article provides an overview of our present knowledge of the nature of these fibrillar aggregates and the manner in which they form, and discusses the origins and potential means of suppression of the pathogenic properties with which they and their precursors are associated.     

Playing with perspectives: spirit possession,mimesis, and permeability in the buuta ritual in South India

The aim of this study is to investigate spirit possession through the lenses of mimesis, permeability, and perspectivity. Recent studies have explored the significance of perspective exchange as reciprocal subjectification. At the same time, the importance of reflexive self‐awareness amid perspective exchange has been noted. Linking studies on perspective exchange with those on spirit possession, this article tries to show an alternative understanding of perspective exchange as the de‐subjectification and generative transformation of self and other. Focusing on the buuta ritual in South India, I examine perspective exchange as the capability for freeing oneself from one's subjectivity enough to let various perspectives come and go through the permeable self. Being permeable and reflexive, the buuta impersonator plays with multiple perspectives to transform both his and others' perspectives to enable all to become ‘real’ humans in relation to the deity.     

Constrained trade and creative exchange on the barima river, guyana

This article examines entrepreneurial activities among Amerindian residents of the Barima River, Guyana. It argues that Barima residents create entrepreneurial opportunities by exploiting a trading system constructed by a French palm-heart processing company as rigidly non-negotiable. This mercantilism is further enabled by the fact that the river itself constitutes an artery of neighbouring economic zones, in which distinct regimes of production, exchange, and consumption dominate at different points along the waterway. By moving exchange goods along this river, entrepreneurs are able to use a particular location, a centre of small-scale gold-mining, as an economic amplifier which allows them to realize profits.     

Accounting for Fluorine: Production,Use, and Loss

Fluorine is an essential element to human health and to the chemical industry. In spite of our dependence on fluorine and fluorine compounds, we have yet to learn to use them wisely. Our fluorine history, which spans about a hundred years, has had negative effects such as hydrofluoric acid pollution caused by aluminum smelters and ozone depletion due to chlorofluorocarbon (CFC) emissions. More recent concerns center on greenhouse effects from CFCs, hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6). In this article we note also that fluorine is a nonrenewable resource that is nonsubstitutable for many purposes. This article tracks fluorine from sources through conversion processes to end uses, most of which are dissipative. We present a stock‐flow model of the fluorine system. Based on this model we consider some possible measures that could be taken to increase the degree of recovery. To mention one example, a large percentage of the world demand for fluorspar could be supplied by the phosphate rock (fertilizer) industry, which currently dissipates a great deal of recoverable fluorine in waste phospho‐gypsum.     

A thermoelectric, heat-flux-controlled cooling stage for measuring freezing parameters of small plants

A new cooling system was developed which permits the accurate recording of the freezing temperatures of small samples which contain less than 1 mg of water. The cooling system consists of a thermoelectric cooling stage with automatically controlled heat exchange between sample and coolant and of a sample-temperature recording unit. The heat exchange controller keeps the latent heat dissipation small during freezing, thus it is also possible to record an accurate freezing plateau in small samples like buds, leaves, conifer needles, short apices, and roots as well as small tissue samples like leaf disks, isolated bark, cambium or wood.Construction and performance of the system are discussed. Results of cooling experiments are presented to illustrate the system's performance as well as some of the problems encountered with test material of varying sizes and water contents. Based upon this experience we may recommend the use of this system for various cryobiological investigations.