草地与农牧交错带退化生态系统重建及防治途径

草地不仅是草地畜牧业的基地，而且在生态环境保护与建设方面的作用尤为重要。草原与农牧交错带，即不同于西部牧区，也不同于东部农区。根据它在地理、气候、农林牧产业结构、生态、经济、文化、社会等方面具有自己独特地位的实际情况，因地制宜提出了相应之对策，为国家在西部大开发和草地与农牧交错带生态环境的恢复提供科学依据。     

The metabolism and function of sphingolipids and glycosphingolipids

Sphingolipids and glycosphingolipids are emerging as major players in many facets of cell physiology and pathophysiology. We now present an overview of sphingolipid biochemistry and physiology, followed by a brief presentation of recent advances in translational research related to sphingolipids. In discussing sphingolipid biochemistry, we focus on the structure of sphingolipids, and their biosynthetic pathways – the recent identification of most of the enzymes in this pathway has led to significant advances and better characterization of a number of the biosynthetic steps, and the relationship between them. We then discuss some roles of sphingolipids in cell physiology, particularly those of ceramide and sphingosine-1-phosphate, and mention current views about how these lipids act in signal transduction pathways. We end with a discussion of sphingolipids and glycosphingolipids in the etiology and pathology of a number of diseases, such as cancer, immunity, cystic fibrosis, emphysema, diabetes, and sepsis, areas in which sphingolipids are beginning to take a central position, even though many of the details remain to be elucidated. Received 13 February 2007; received after revision 19 April 2007; accepted 26 April 2007     

镁及镁合金的研究现状与进展

文献综述了镁及镁合金的性能特性，镁合金系列，国内外镁合金的研究现状，镁合金表面处理的各种方法以及镁合金在航空航天，汽车工业，电子工业及民用各个领域的广泛应用，展望了镁合金的应用前景。     

Structuralism and the conformity of mathematics and nature

Structuralists typically appeal to some variant of the widely popular ‘mapping’ account of mathematical representation to suggest that mathematics is applied in modern science to represent the world’s physical structure. However, in this paper, I argue that this realist interpretation of the ‘mapping’ account presupposes that physical systems possess an ‘assumed structure’ that is at odds with modern physical theory. Through two detailed case studies concerning the use of the differential and variational calculus in modern dynamics, I show that the formal structure that we need to assume in order to apply the mapping account is inconsistent with the way in which mathematics is applied in modern physics. The problem is that a realist interpretation of the ‘mapping’ account imposes too severe of a constraint on the conformity that must exist between mathematics and nature in order for mathematics to represent the structure of a physical system.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Upon amputation of the urodele limb, the epidermal cells surrounding the amputation plane migrate to heal the wound. The resulting wound epidermis (WE) induces the regeneration process, resulting in blastema formation, cell division, and ultimately repatterning into a new limb. Despite its central role in the initiation of limb regeneration, little is known about how the WE forms. Here we discuss various models of WE formation and the experimental data in support of each.     

Estimation of serotonin and its action on oviducts and uteri of some oviparous and viviparous insects

Summary Serotonin was not found in the oviducts ofBlabera gigantea, Clitumnus extradentatus nor in the uterus ofGlossina, but it is present in the uterus ofBlabera. It is also found in the central nervous system of all three insects. In vitro experiments confirm these data by showing that serotonin increases the contractions of the uterus ofBlabera, but has no effect on the uterus ofGlossina.     

Molecular and cellular pathogenesis of melanoma initiation and progression

Melanoma is a malignant tumor of melanocytes that can spread to other organs of the body, resulting in severe and/or lethal malignancies. Melanocytes are pigment-producing cells found in the deep layer of the epidermis and are originated from melanocytes stem cells through a cellular process called melanogenesis. Several genes and epigenetic and micro-environmental factors are involved in this process via the regulation and maintenance of the balance between melanocytes stem cells proliferation and their differentiation into melanocytes. Dysregulation of this balance through gain or loss of function of key genes implicated in the control and regulation of cell cycle progression and/or differentiation results in melanoma initiation and progression. This review aims to provide a comprehensive overview about the origin of melanocytes, the oncogenic events involved in melanocytes stem cells transformation, and the mechanisms implicated in the perpetuation of melanoma malignant phenotype.     

Linear and threshold forecasts of output and inflation using stock and housing prices

This study examines whether simple measures of Canadian equity and housing price misalignments contain leading information about output growth and inflation. Previous authors have generally found that the information content of asset prices in general, and equity and housing prices in particular, are unreliable in that they do not systematically predict future economic activity or inflation. However, earlier studies relied on simple linear relationships that would fail to pick up the potential nonlinear effects of asset price misalignments. Our results suggest that housing prices are useful for predicting GDP growth, even within a linear context. Meanwhile, both stock and housing prices can improve inflation forecasts, especially when using a threshold specification. These improvements in forecast performance are relative to the information contained in Phillips‐curve type indicators for inflation and IS‐curve type indicators for GDP growth. Copyright © 2008 John Wiley & Sons, Ltd.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Although early after birth the central nervous system is more plastic than in the adult, it already displays limited regenerative capability. This becomes severely impaired at specific stages of embryonic development; however, the precise cellular and molecular basis of this loss is not fully understood. The chick embryo provides an ideal model for direct comparisons of regenerating and non-regenerating spinal cord within the same species because of its accessibility in ovo, the extensive knowledge of chick neural development and the molecular tools now available. Regenerative ability in the chick is lost at around E13, a relatively advanced stage of spinal cord development. This is most likely due to a complex series of events: there is evidence to suggest that developmentally regulated changes in the early response to injury, expression of inhibitory molecules and neurogenesis may contribute to loss of regenerative capacity in the chick spinal cord.     

Exemplification and the use-values of cases and case studies

This paper provides an account of the ‘use-value’ of case-based research by showing how social scientists exploit cases, and case studies, in a variety of practices of inference and extension. The critical basis for making such extensions relies on the power of a case, or the account given of a case (the case-study account), to exemplify certain features of the social world in ways which prove valuable for further analysis: either of the same case, or in many domains beyond the original case study. Framing use-values in terms of exemplification compares favourably with understanding reasoning beyond the case either as a form of analogical reasoning or in taking cases as experimentable objects.     

Expression of the genes of interferons and other cytokines in normal and diseased tissues of man

Summary Specific interferon genes are transcribed at low levels in the spleen, liver, and peripheral blood leukocytes of normal individuals in the apparent absence of virus infection while other interferon genes remain unexpressed in the same tissues. In contrast, the genes of cytokines such as IL-1, IL-6 and TNF are expressed at relatively high levels in the organs of normal individuals. The level of expression of the IL-1, IL-6 and TNF genes is markedly reduced in the livers of patients with autoimmune liver disease compared to the level of expression in the liver of normal individuals, whereas the expression of interferon genes is similar in both normal and diseased liver, suggesting that a defect in the expression of specific cytokines is associated with severe liver disease.     

Structure and function of desmosomal proteins and their role in development and disease

Desmosomes represent major intercellular adhesive junctions at basolateral membranes of epithelial cells and in other tissues. They mediate direct cell-cell contacts and provide anchorage sites for intermediate filaments important for the maintenance of tissue architecture. There is increasing evidence now that desmosomes in addition to a simple structural function have new roles in tissue morphogenesis and differentiation. Transmembrane glycoproteins of the cadherin superfamily of Ca²⁺-dependent cell-cell adhesion molecules which mediate direct intercellular interactions in desmosomes appear to be of central importance in this respect. The complex network of proteins forming the desmosomal plaque associated with the cytoplasmic domain of the desmosomal cadherins, however, is also involved in junction assembly and regulation of adhesive strength. This re-view summarizes the structural features of these desmosomal proteins, their function during desmosome assembly and maintenance, and their role in development and disease.Received 5 February 2003; received after revision 14 March 2003; accepted 1 April 2003     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Cell plasticity and mesenchymal-epithelial interactions are regarded as a hallmark of embryonic development and are not believed to occur extensively in the adult. Recently, adult mesenchymal stem cells were reported to differentiate in culture into a variety of mature cell types, including epithelial cells. Progress in stem and progenitor cell biology and recognition of the unique properties of such cells may enable intelligent bioengineering design of replacement skin which allows regeneration to occur in vivo. Ideally, a scaffold-free environment which stimulates skin stem cells in situ to initiate cell signals that result in regeneration rather than scar formation is required. Various skin progenitor cell types are considered along with the signalling cascades that they affect. We also discuss a mammalian model of scar-free regeneration. Many of these mechanisms, if fully understood, could be harnessed after injury to perfectly restore the skin.     

The functioning and interrelationships of blood capillaries and lymphatics

Summary the structure and function of blood capillaries, as related to permeability, depends on tight, close and (in injured vessels) open junctional regions, small vesicles, vacuoles (in injured vessels) and fenestrae. The basement membrane presents a hindrance to the larger macromolecules, at high flow rates, but not to small molecules. The connective tissue channels are probably the paths by which macromolecules, and most of the small ones, pass from the arterial-limbs to the venous ones, and to the lymphatics. In some regions these channels are grouped in special systems: the prelymphatics. The initial lymphatics take up material via open junctions, which close during tissue-compression. The collecting lymphatics retain the lymph because they do not have open junctions.In the close junctional regions the motive force for water flow is the result of Starling's forces; diffusion is very important for other small molecules. The small vesicles transport macromolecules slowly by Brownian motion, as may the vacuoles, but possibly these latter are moved actively.There is much evidence that colloids can develop high effective osmotic pressures even across pores much larger than their molecules, and that proteins can be dragged up a concentration gradient by the resultant fluid flow. On the basis of this, hypotheses have been developed about the functioning of venous-limb fenestrae and the initial lymphatics, for which there is much theoretical, in vitro, and in vivo evidence. Thus, in fenestrae and regions there is held to be a large local circulation through the tissues, of which a quantitatively small, but qualitatively vital, part goes to the lymphatics. Material is considered usually to enter these latter because of the relative concentration of the lymph.It is becoming increasingly evident that in the study of the microvasculature, as with other systems, there is much to be gained by quantifying fine structural observations and by combining and contrasting this data, via physical laws, with that obtained by other methods where the characteristics of whole organs and regions are studied. Thus one can obtain interrelated information, which is not possible by either method alone, and which gives us a vital, comprehensive, perspective of the ways in which whole systems function, and how different systems interact. In this paper I shall show how this approach has yielded much that is new about the functioning of different kinds of blood capillaries, of the tissue channels, of the whole lymphatic system, and of the ways they affect each other.Most of the author's work reported here was financed by the Australian Research Grants Committee.     

药用植物羌活现状及其民族植物学调查

羌活为重要的传统中药和藏药常用药材，大量的汉藏药方和成药均作为重要的配伍药材加以使用。羌活传统产区主要是藏族、羌族和其它少数民族的聚居的高寒山区，经济较为落后，交通不便。由于难以驯化栽培，药材来源主要依赖野生资源采挖，但由于受到种子发育不完全、后熟期长等本身繁殖特性的限制，羌活繁殖和种群恢复主要是通过无性繁殖实现，野生资源恢复受到严重制约。道地产区的调查发现，羌活野生生境正受到前所未有的破坏，包括生境丧失、破碎化、土壤退化、土地利用模式改变和环境变化等；调查还发现近年来羌活药材价格与采挖量之间的关系，以及当地民族植物学方面的状况。羌活野生资源的破坏受到利益驱使、致使采挖时间和方式等利用模式发生改变，极不利于羌活野生资源的保存和种群恢复，若不规范羌活野生资源的利用和引种驯化，进行人工栽培，羌活野生资源不但难以实现可持续利用，而且还将遭到毁灭性破坏，并有灭绝的危险。本文最后提出了药用羌活属植物的保护性开发和可持续利用可能途径。     

Expression and immunolocalisation of odorant-binding and chemosensory proteins in locusts

We have identified, cloned and expressed a new chemosensory protein (CSP) in the desert locust Schistocerca gregaria belonging to a third sub-class of these polypeptides. Polyclonal antibodies stained a band of 14 kDa, as expected, in the extracts of antennae and palps of the adults, but not in the 4th and 5th instars. In the related species Locusta migratoria, instead, the same antibodies cross-reacted only with a band of apparent molecular mass of 35 kDa in the extract of 1st–5th instars, but not in the adults. The recombinant protein binds the fluorescent probe N-phenyl-1-naphthylamine, but none of the compounds so far reported as pheromones for S. gregaria. The expression of the odorant-binding protein (OBP) and of CSPs of sub-classes I and II was also monitored in antennae, tarsi, palpi, wings and other organs of solitary and gregarious locusts in their nymphal and adult stages. OBP was found to be antenna specific, where it is expressed at least from the 3rd instar in both solitary and gregarious locusts. CSPs, instead, appear to be more ubiquitous, with different expression patterns, according to the sub-class. Immunocytochemistry experiments revealed that OBP is present in the sensillum lymph of sensilla trichodea and basiconica, while CSP-I and CSP-III were found in the outer sensillum lymph of sensilla chaetica and in the sub-cuticular space between epidermis and cuticle of the antenna. Sensilla chaetica on other parts of the body showed the same expression of CSP-I as those on the antenna.Received 11 Janury 2005; received after revision 21 February 2005; accepted 18 March 2005X. Jin and A. Brandazza contributed equally to this work.     

Expression of the genes of interferons and other cytokines in normal and diseased tissues of man

Specific interferon genes are transcribed at low levels in the spleen, liver, and peripheral blood leukocytes of normal individuals in the apparent absence of virus infection while other interferon genes remain unexpressed in the same tissues. In contrast, the genes of cytokines such as IL-1, IL-6 and TNF are expressed at relatively high levels in the organs of normal individuals. The level of expression of the IL-1, IL-6 and TNF genes is markedly reduced in the livers of patients with autoimmune liver disease compared to the level of expression in the liver of normal individuals, whereas the expression of interferon genes is similar in both normal and diseased liver, suggesting that a defect in the expression of specific cytokines is associated with severe liver disease.     

Functions and pathologies of BiP and its interaction partners

The endoplasmic reticulum (ER) is involved in a variety of essential and interconnected processes in human cells, including protein biogenesis, signal transduction, and calcium homeostasis. The central player in all these processes is the ER-lumenal polypeptide chain binding protein BiP that acts as a molecular chaperone. BiP belongs to the heat shock protein 70 (Hsp70) family and crucially depends on a number of interaction partners, including co-chaperones, nucleotide exchange factors, and signaling molecules. In the course of the last five years, several diseases have been linked to BiP and its interaction partners, such as a group of infectious diseases that are caused by Shigella toxin producing E. coli. Furthermore, the inherited diseases Marinesco-Sj?gren syndrome, autosomal dominant polycystic liver disease, Wolcott-Rallison syndrome, and several cancer types can be considered BiP-related diseases. This review summarizes the physiological and pathophysiological characteristics of BiP and its interaction partners. Received 20 November 2008; received after revision 09 December 2008; accepted 12 December 2008     

Remodeling and dedifferentiation of adult cardiomyocytes during disease and regeneration

Cardiomyocytes continuously generate the contractile force to circulate blood through the body. Imbalances in contractile performance or energy supply cause adaptive responses of the heart resulting in adverse rearrangement of regular structures, which in turn might lead to heart failure. At the cellular level, cardiomyocyte remodeling includes (1) restructuring of the contractile apparatus; (2) rearrangement of the cytoskeleton; and (3) changes in energy metabolism. Dedifferentiation represents a key feature of cardiomyocyte remodeling. It is characterized by reciprocal changes in the expression pattern of “mature” and “immature” cardiomyocyte-specific genes. Dedifferentiation may enable cardiomyocytes to cope with hypoxic stress by disassembly of the energy demanding contractile machinery and by reduction of the cellular energy demand. Dedifferentiation during myocardial repair might provide cardiomyocytes with additional plasticity, enabling survival under hypoxic conditions and increasing the propensity to enter the cell cycle. Although dedifferentiation of cardiomyocytes has been described during tissue regeneration in zebrafish and newts, little is known about corresponding mechanisms and regulatory circuits in mammals. The recent finding that the cytokine oncostatin M (OSM) is pivotal for cardiomyocyte dedifferentiation and exerts strong protective effects during myocardial infarction highlights the role of cytokines as potent stimulators of cardiac remodeling. Here, we summarize the current knowledge about transient dedifferentiation of cardiomyocytes in the context of myocardial remodeling, and propose a model for the role of OSM in this process.     

Intragenic complementation and the structure and function of argininosuccinate lyase

Argininosuccinate lyase (ASL) catalyzes the reversible hydrolysis of argininosuccinate to arginine and fumarate, a reaction important for the detoxification of ammonia via the urea cycle and for arginine biosynthesis. ASL belongs to a superfamily of structurally related enzymes, all of which function as tetramers and catalyze similar reactions in which fumarate is one of the products. Genetic defects in the ASL gene result in the autosomal recessive disorder argininosuccinic aciduria. This disorder has considerable clinical and genetic heterogeneity and also exhibits extensive intragenic complementation. Intragenic complementation is a phenomenon that occurs when a multimeric protein is formed from subunits produced by different mutant alleles of a gene. The resulting hybrid protein exhibits greater enzymatic activity than is found in either of the homomeric mutant proteins. This review describes the structure and function of ASL and its homologue delta crystallin, the genetic defects associated with argininosuccinic aciduria and current theories regarding complementation in this protein.