Helminthosporoside,a host-specific toxin fromHelminthosporium sacchari: A structure revision and a new partial structure

Summary Reevaluation of the previously proposed structure of helminthosporoside, a host-specific toxin fromHelminthosporium sacchari, reveals a sesquiterpenoid bis-digalactoside. The carbohydrate portion of the toxin was characterized by¹³C-NMR spectroscopy, methylation analyses, FD and FAB mass spectroscopy. The ring size and anomeric configuration of the galactose moieties were determined by utilizing a¹³C-NMR structural analysis method. A new partial structure is proposed.Acknowledgment. We extend special thanks to C.E. Costello, Department of Chemistry, M.I.T., Cambridge, MA, for FD mass spectral analyses, and to C.E. Ballou, Department of Biochemistry, University of California, Berkeley, CA, for FAB mass spectral analyses. We submit sincere appreciation to both V.N. Reihold, Harvard Medical School, Boston, MA, and P. Albersheim, Department of Chemistry, University of Colorado, Boulder, CO, for methylation analyses. We thank J.S. Frye at the Colorado State University Regional NMR-Center, funded by National Science Foundation grant No. DHE 78-18581, Department of Chemistry, Colorado State University, Fort Collins, Co, for high resolution CMR and NMR, and we are grateful to P.W. Jennings, Department of Chemistry, Montana State University, Bozeman, Mt, for total carbon analyses. This work was supported in part by a Herman Frasch Foundation grant to G.A. Strobel, by NSF grant PCM-78-22517, and funds from the Montana Agricultural Experiment Station. B.P. Mundy acknowledges the partial support of NSF (ISP-801149).     

Karl Pearson's mathematization of inheritance: from ancestral heredity to Mendelian genetics (1895-1909)

Long-standing claims have been made for nearly the entire twentieth century that the biometrician, Karl Pearson, and colleague, W. F. R. Weldon, rejected Mendelism as a theory of inheritance. It is shown that at the end of the nineteenth century Pearson considered various theories of inheritance (including Francis Galton's law of ancestral heredity for characters underpinned by continuous variation), and by 1904 he 'accepted the fundamental idea of Mendel' as a theory of inheritance for discontinuous variation. Moreover, in 1909, he suggested a synthesis of biometry and Mendelism. Despite the many attempts made by a number of geneticists (including R. A. Fisher in 1936) to use Pearson's chi-square (X2, P) goodness-of-fit test on Mendel's data, which produced results that were 'too good to be true', Weldon reached the same conclusion in 1902, but his results were never acknowledged. The geneticist and arch-rival of the biometricians, Williams Bateson, was instead exceptionally critical of this work and interpreted this as Weldon's rejection of Mendelism. Whilst scholarship on Mendel, by historians of science in the last 18 years, has led to a balanced perspective of Mendel, it is suggested that a better balanced and more rounded view of the hereditarian-statistical work of Pearson, Weldon, and the biometricians is long overdue.     

Historical development of Teichmüller theory

Originally, the expression “Teichmüller theory” referred to the theory that Oswald Teichmüller developed on deformations and on moduli spaces of marked Riemann surfaces. This theory is not an isolated field in mathematics. At different stages of its development, it received strong impetuses from analysis, geometry, and algebraic topology, and it had a major impact on other fields, including low-dimensional topology, algebraic topology, hyperbolic geometry, geometric group theory, representations of discrete groups in Lie groups, symplectic geometry, topological quantum field theory, theoretical physics, and there are certainly others. Of course, the impacts on these various fields are not equally important, but in some cases (namely, low-dimensional topology, algebraic geometry, and physics) the impact was crucial. At the same time, Teichmüller theory established important connections between the fields mentioned. This, in part, is a consequence of the diversity and the richness of the structure that Teichmüller space itself carries. From a more subjective point of view, the result of pondering on these connections and applications demonstrates the unity of mathematics. The aim of this paper is to survey the origin of Teichmüller theory and the development of its early major ideas.     

The effect of abrin,anti-lymphocyte globulin and their conjugates on the immune response of mice to sheep red blood cells

Summary A chemical conjugate of anti-mouse lymphocyte globulin and abrin, is about twice as effective as a similar conjugate made with normal immunoglobulin and abrin, in suppressing the ability of the mouse to respond immunologically to an injection of sheep red blood cells.Acknowledgment. We thank Dr Stuart, Society of Herbalists, London, and Prof. G.C. Clark, Dept. of Botany, University of Ghana, for gifts ofAbrus precatorius seeds, and Mrs L. Bushby for help in the preparation of the horse anti-mouse lymphocyte globulin. D.C.E. is an external member of the staff of the Wellcome Foundation Ltd.     

Regulation of intestinal epithelial permeability by tight junctions

The gastrointestinal epithelium forms the boundary between the body and external environment. It effectively provides a selective permeable barrier that limits the permeation of luminal noxious molecules, such as pathogens, toxins, and antigens, while allowing the appropriate absorption of nutrients and water. This selective permeable barrier is achieved by intercellular tight junction (TJ) structures, which regulate paracellular permeability. Disruption of the intestinal TJ barrier, followed by permeation of luminal noxious molecules, induces a perturbation of the mucosal immune system and inflammation, and can act as a trigger for the development of intestinal and systemic diseases. In this context, much effort has been taken to understand the roles of extracellular factors, including cytokines, pathogens, and food factors, for the regulation of the intestinal TJ barrier. Here, I discuss the regulation of the intestinal TJ barrier together with its implications for the pathogenesis of diseases.     

Impaired nuclear translocation of glucocorticoid receptors: novel findings from psoriatic epidermal keratinocytes

Psoriasis is a chronic proliferative skin disease and is usually treated with topical glucocorticoids, which act through the glucocorticoid receptor (GR), a component of the physiological systems essential for immune responses, differentiation, and homeostasis. To investigate the possible role of GR in the pathogenesis of psoriasis, normal and psoriatic lesional skin were recruited. Firstly, the immunolocalization of GR in the skin and cultured epidermal keratinocytes were determined by immunofluorescence. In normal skin and cultured human epidermal keratinocytes, intracellular GR is localized in the nuclei, while in psoriatic skin and cultured keratinocytes, GR is in the cytoplasm. Next, we investigated possible factors associated with the cytoplasmic distribution. We found that VEGF and IFN-γ led to impaired nuclear translocation of GR through p53 and microtubule-inhibitor, vincristine, and inhibited nuclear uptake of GR in normal keratinocytes. In addition to dexamethasone, interleukin (IL)-13 was also able to transfer GR into nuclei of psoriatic keratinocytes. Furthermore, discontinuation of dexamethasone induced cytoplasmic retention of GR in normal keratinocytes. In contrast, energy depletion of normal epidermal keratinocytes did not change the nuclear distribution of GR. To confirm our findings in vivo, an imiquimod-induced psoriasis-like skin mouse model was included. IL-13 ameliorated (but vincristine exacerbated) the skin lesions on the mouse. Taken together, our findings define that impaired nuclear translocation of GR is associated with VEGF, IFN-γ, p53, and microtubule. Therapeutic strategies designed to accumulate GR in the nucleus, such as IL-13, may be beneficial for the therapy of psoriasis.     

Studies of the blood ofAscidia ceratodes. Total blood cell counts,differential blood cell counts,hematocrit values,seasonal variations,and fluorescent characteristics of blood cells

Summary Seasonal, and animal size and weight variations of the blood cells of the vanadium-containing ascidian,Ascidia ceratodes, were determined. The fluorescent properties of various cell types were ascertained, and discussed in terms of cell development, phylogenic position of the species, and chemicals in the cells.This investigation was supported by a grant from the Research Corporation and one of us (W.R.B.) received partial support from various University of California administrated fellowships. The current address of W.R.B. is Chevron Research Products, Richmond, CA. The use of the facilities at the Bodega Marine Laboratory, University of California are acknowledged.     

Vascular stem/progenitor cells: functions and signaling pathways

Vascular stem/progenitor cells (VSCs) are an important source of all types of vascular cells needed to build, maintain, repair, and remodel blood vessels. VSCs, therefore, play critical roles in the development, normal physiology, and pathophysiology of numerous diseases. There are four major types of VSCs, including endothelial progenitor cells (EPCs), smooth muscle progenitor cells (SMPCs), pericytes, and mesenchymal stem cells (MSCs). VSCs can be found in bone marrow, circulating blood, vessel walls, and other extravascular tissues. During the past two decades, considerable progress has been achieved in the understanding of the derivation, surface markers, and differentiation of VSCs. Yet, the mechanisms regulating their functions and maintenance under normal and pathological conditions, such as in eye diseases, remain to be further elucidated. Owing to the essential roles of blood vessels in human tissues and organs, understanding the functional properties and the underlying molecular basis of VSCs is of critical importance for both basic and translational research.     

陕北地区生态修复与粮食安全分析

生态修复是指利用自然界的自我修复能力,在适当人工措施辅助下,恢复生态系统原有的保持水土、调节小气候、维护生物多样性的生态功能和开发利用等经济功能。生态修复工程给黄土丘陵区提供了一次难得的生态重建历史机遇。粮食供需的总量平衡是我国面临的巨大的问题．且在人口净增长达到由正变负的拐点之前,问题的艰巨性将与日俱增。基于粮食问题是我国的根本问题,本文以生态修复学的基本原理为指导,利用生态经济学的基本观点,回顾了黄土丘陵区产的发展历史,探讨了生态修复过程中的粮食生产潜力;在此基础上,根据当地经济发展规划和远景目标,提出了相应的发展对策：稳住粮田面积、强化基础建设、加大投入力度、积极推动粮食产业化、控制人口增长、提高思想认识。     

Structure and function of biotin-dependent carboxylases

Biotin-dependent carboxylases include acetyl-CoA carboxylase (ACC), propionyl-CoA carboxylase (PCC), 3-methylcrotonyl-CoA carboxylase (MCC), geranyl-CoA carboxylase, pyruvate carboxylase (PC), and urea carboxylase (UC). They contain biotin carboxylase (BC), carboxyltransferase (CT), and biotin-carboxyl carrier protein components. These enzymes are widely distributed in nature and have important functions in fatty acid metabolism, amino acid metabolism, carbohydrate metabolism, polyketide biosynthesis, urea utilization, and other cellular processes. ACCs are also attractive targets for drug discovery against type 2 diabetes, obesity, cancer, microbial infections, and other diseases, and the plastid ACC of grasses is the target of action of three classes of commercial herbicides. Deficiencies in the activities of PCC, MCC, or PC are linked to serious diseases in humans. Our understanding of these enzymes has been greatly enhanced over the past few years by the crystal structures of the holoenzymes of PCC, MCC, PC, and UC. The structures reveal unanticipated features in the architectures of the holoenzymes, including the presence of previously unrecognized domains, and provide a molecular basis for understanding their catalytic mechanism as well as the large collection of disease-causing mutations in PCC, MCC, and PC. This review will summarize the recent advances in our knowledge on the structure and function of these important metabolic enzymes.     

能源互联网重要基础支撑:分布式储能技术的探索与实践

可再生能源分布式发电的能量波动性以及用户驱动的能量需求的时空随机性,导致能源互联网中能量流本身具有先天的不确定性与无秩序性,因此,分布式储能技术由于可以有效消除能量流的不确定性,并使能量的时空转移和能量流的有序流动成为可能,成为能源互联网重要基础支撑.分布式电池储能作为一种重要的储能方式,电池单体本身非线性特性与电池成组或成网后单体间的差异性,使得电池储能系统"管理好"成为真正"使用好"的基础.但是,电池成组或成网后将构成复杂巨系统,这对"管理好"带来巨大的挑战.因此,本文基于作者多年理论与技术的成果积累,总结了一套适用于分布式储能的大规模电池网络优化管理的理论与方法,包括:单体和电池组或电池网络的建模与状态参数精确估算;基于模糊测度的电池网络特征提取及快速计算;基于自适应动态规划的电池网络优化管理.随后,本文将基于能源互联网思想的分布式储能架构及其管理优化方法与技术引入数据中心,并给出了其在数据中心中实际应用原型系统介绍.本文工作可以为能源互联网的重要基础支撑—分布式储能技术—的研究与应用提供方法指导与技术支撑.     

基因工程改造噬菌体应用于细菌感染的研究进展

噬菌体作为细菌病毒，在细菌性感染尤其是多重耐药菌感染的治疗方面具有抗生素无法比拟的优势。目前人工改造噬菌体的理论和技术已趋成熟，研究者通过基因工程技术解决了噬菌体特异性高、半衰期短、释放内毒素等问题，使基因工程改造噬菌体具有了较强的临床应用潜力。本文主要就基因工程改造噬菌体在扩大宿主范围、增强抗生素疗效、延缓免疫清除、避免内毒素释放等方面所具有的优势，及其在剂量确定、细菌耐受、宿主安全性等方面可能会出现的问题进行了阐述。     

State of the field: Paper tools

Paper occupies a special place in histories of knowledge. It is the substrate of communication, the stuff of archives, the bearer of marks that make worlds. For the early-modern period in particular we now have a wealth of studies of ‘paper tools’, of the ways in which archives were assembled and put to use, of the making of lists and transcribing of observations, and so on. In other fields, too, attention has turned to the materiality of information. How far is it possible to draw a stable methodology out of the insights of literary and book historians, bibliographers, anthropologists, and those working in media studies? Do these diverse fields in fact refer to the same thing when they talk of paper, its qualities, affordances and limitations? In attempting to answer these questions, the present essay begins in the rich territory of early-modern natural philosophy – but from there opens out to take in recent works in a range of disciplines. Attending to the specific qualities of paper is only possible, I argue, if it is understood that paper can be both transparent and opaque depending on the social world it inhabits and helps to constitute. Paper flickers into and out of view, and it is precisely this quality that constitutes its sociomateriality.     

The CD40/CD154 receptor/ligand dyadRID="†"ID="†" Review

Until recently, the expression and primary function of the cell surface receptor CD40 and its ligand CD154 were considered restricted to B and T lymphocytes, and their interactions required for the thymus-dependent humoral response. However, current work from several groups challenges this view of the CD40/CD154 dyad as a mere mediator of lymphocyte communication. A variety of non-lymphocytic cell types express both receptor and ligand, including hematopoetic and non-hematopoetic cells, such as monocytes, basophils, eosinophils, dendritic cells, fibroblasts, smooth muscle, and endothelial cells. Accordingly, ligation of CD40 mediates a broad variety of immune and inflammatory responses, such as the expression of adhesion molecules, cytokines, matrix-degrading enzymes, prothrombotic activities, and apoptotic mediators. Consequently, CD40 signaling has been associated with pathogenic processes of chronic inflammatory diseases, such as autoimmune diseases, neurodegenerative disorders, graft-versus-host disease, cancer, and atherosclerosis. This review focuses on the synthesis and structure of CD40 and outlines CD154/CD40 signaling pathways, and emphasizes the previously unexpected importance of the CD40/CD154 receptor/ligand dyad in a spectrum of immunoregulatory processes and prevalent human diseases. Received 10 January 2000; revised 16 June 2000; accepted 5 July 2000 RID="†" ID="†" Review RID="*" ID="*" Corresponding author.     

多媒体取证

多媒体取证是信息安全领域的重要研究内容之一，主要应用于司法取证、刑侦取证，是电子证据鉴别等领域中的关键技术之一．目前篡改媒体内容大量涌现，严重危及个人隐私与社会稳定，多媒体取证已成为一项迫切需求的技术．本文概要介绍了多媒体取证技术的特点和原理，并且从媒体源辨识、内容篡改检测、处理历史分析、反取证四方面阐述多媒体取证的发展现状和趋势，分析了各种取证技术所面临的难点．最后展现了未来技术发展的若干问题与可能趋势．     

Lysozyme activity in female genital tissues of normal and genetically lysozyme-deficient rabbits

Summary The internal genitalia of female normal rabbits and mutant lysozyme-deficient rabbits, which lack genetically the leukocytic isozyme of lysozyme, were assayed for lysozyme activity. The ovaries, uteri, and vaginas of the lysozyme-deficient rabbits had less than 20% of the lysozyme activity of normals. The oviducts, and in particular the caudal portions of the oviducts, had lysozyme activities up to 71% of the levels in normal. These observations suggest that the lysozymes of oviduct and leukocytes of rabbits are under the control of different genes.Supported in part by grants RR00515, RR05465, K04-RR00003, and T32-GM07160 from the National Institutes of Health. We acknowledge the excellent technical assistance of LeeAndra Froseth.     

Determination of trace elements in peripheral lymphocytes from tumor-bearing rats

Summary Neutron activation, analysis of peripheral lymphocytes from healthy and Walker 256 carcinosarcoma-bearing rats resulted in the quantitative determination of Co, Cu, K, Mn, Rb, Se and Zn, and a qualitative determination of Au and Sb. From corresponding plasma samples, Co, Zn, Rb, Se and Cs were analyzed. Differences in trace element concentrations could only be detected in plasma of tumor-bearing animals which showed a decreased Zn and Co content of 50% and 30%, respectively, and a rise of Rb when compared to plasma of control animals.     

Reflections on the preservation of recent scientific heritage in dispersed university collections

The bulk of the significant recent scientific heritage of universities is not to be found in accredited science museums or collections employed in research. Rather it is located in a wide variety of more informal collections, assemblages and accumulations. The selection and documentation of such materials is very often unsystematic and many of them are vulnerable to changes of staff, relocation and, above all, shortage of space. Following a survey of views on the values of the recent material heritage of the sciences, I consider the many advantages—for teaching, engagement with wider communities, enhancement of institutional identity and work experience, celebration of scientific achievements, study of the recent history of the practices and fruits of the sciences, etc.—of “multi-site museums” formed through the coordination of such varied and scattered collections. I go on to reflect on ways in which the preservation and display of scientific heritage in dispersed collections may be enhanced and protected through institutional recognition and through provision of guidance and assistance in selection, documentation and digitisation, preservation and conservation, and display. The importance of adequate documentation of the contexts of production and use of objects is stressed, as are the benefits that can result from involvement of student “taskforces” and heritage-concerned scientists.