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Escape
Kinds of Escape Terms modified by Escape Selected AbstractsPLANNING THROUGH INCLUSIVE DIALOGUE: NO ESCAPE FROM SOCIAL CHOICE DILEMMASECONOMIC AFFAIRS, Issue 4 2005Tore Sager The thrust of the theory of preference aggregation is that it is impossible to design institutions guaranteeing collective decisions that are both consistent and fair. Proponents of deliberative democracy have used this as an argument for decision-making based on dialogue rather than voting. Communicative public planning - producing plans through public participation exercises - is seen as an integral part of deliberative democracy. It is argued here, however, that the inclusive dialogue of this style of planning cannot promise escape from arbitrariness and does not necessarily deliver improved local decision-making. [source] RAPID EVOLUTIONARY ESCAPE BY LARGE POPULATIONS FROM LOCAL FITNESS PEAKS IS LIKELY IN NATUREEVOLUTION, Issue 6 2005Daniel M. Weinreich Abstract Fitness interactions between loci in the genome, or epistasis, can result in mutations that are individually deleterious but jointly beneficial. Such epistasis gives rise to multiple peaks on the genotypic fitness landscape. The problem of evolutionary escape from such local peaks has been a central problem of evolutionary genetics for at least 75 years. Much attention has focused on models of small populations, in which the sequential fixation of valley genotypes carrying individually deleterious mutations operates most quickly owing to genetic drift. However, valley genotypes can also be subject to mutation while transiently segregating, giving rise to copies of the high fitness escape genotype carrying the jointly beneficial mutations. In the absence of genetic recombination, these mutations may then fix simultaneously. The time for this process declines sharply with increasing population size, and it eventually comes to dominate evolutionary behavior. Here we develop an analytic expression for Ncrit, the critical population size that defines the boundary between these regimes, which shows that both are likely to operate in nature. Frequent recombination may disrupt high-fitness escape genotypes produced in populations larger than Ncrit before they reach fixation, defining a third regime whose rate again slows with increasing population size. We develop a novel expression for this critical recombination rate, which shows that in large populations the simultaneous fixation of mutations that are beneficial only jointly is unlikely to be disrupted by genetic recombination if their map distance is on the order of the size of single genes. Thus, counterintuitively, mass selection alone offers a biologically realistic resolution to the problem of evolutionary escape from local fitness peaks in natural populations. [source] Great EscApe: the great ape facility at Oklahoma City Zoological ParkINTERNATIONAL ZOO YEARBOOK, Issue 1 2000J. GRISHAM On 31 July 1993, after nearly 4 years of design and construction, Oklahoma City Zoological Park opened Great EscApe, a state-of-the-art exhibit for the maintenance and conservation of three species of great ape: Western lowland gorilla Gorilla gorilla gorilla, Sumatran orang-utan Pongo pygmaeus abelii and Chimpanzee Pan troglodytes. The 2,6 ha enclosure comprises a large support facility, four spacious outdoor exhibit areas, two visitor centres, a children's activity loop, an open-air pavilion and a research station. In addition, Great EscApe provides an educational experience for visitors covering all facets of great ape biology and the conservation challenges which these species present. Extensive landscaping with plants, many of which simulate the natural surroundings of the apes, was utilized throughout the exhibit. [source] Fixing the Hole in the Bucket: Household Poverty Dynamics in the Peruvian AndesDEVELOPMENT AND CHANGE, Issue 5 2006Anirudh Krishna ABSTRACT Achieving the Millennium Development Goal of halving poverty will require simultaneous action on two separate fronts: helping poor people escape from poverty, and stemming the flow of people into poverty. This article examines forty Peruvian communities, and finds that descents into poverty have occurred alongside escapes in every one of them. Escape and descent are asymmetric in terms of reasons: while one set of reasons is responsible for escapes from poverty, another and different set of reasons is associated with descent. Making progress in poverty reduction will require measures to accelerate escapes whilst at the same time slowing down descents. The article looks at the different policies which will be required to serve these two separate purposes. [source] Escape from natural enemies during climate-driven range expansion: a case studyECOLOGICAL ENTOMOLOGY, Issue 3 2008ROSA MENÉNDEZ Abstract 1.,A major, and largely unexplored, uncertainty in projecting the impact of climate change on biodiversity is the consequence of altered interspecific interactions, for example between parasitoids and their hosts. The present study investigated parasitism in the Brown Argus butterfly, Aricia agestis; a species that has expanded northward in Britain during the last 30 years in association with climate warming. 2.,Aricia agestis larvae suffered lower mortality from parasitoids in newly colonised areas compared with long-established populations. This result was consistent over four consecutive generations (2 years) when comparing one population of each type, and also when several populations within the historical and recently colonised range of the species were compared within a single year. Thus, A. agestis appears to be partially escaping from parasitism as it expands northwards. 3.,Reduced parasitism occurred despite the fact that several of the parasitoid species associated with A. agestis were already present in the newly colonised areas, supported predominantly by an alternative host species, the Common Blue butterfly, Polyommatus icarus. 4.,As the species expand their distributions into areas of increased climatic suitability, invasion fronts may escape from natural enemies, enhancing rates of range expansion. The results suggest that the decoupling of interspecific interactions may allow some species to exploit a wider range of environments and to do so more rapidly than previously thought possible. [source] Biodegradable Dextran Nanogels for RNA Interference: Focusing on Endosomal Escape and Intracellular siRNA DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 9 2009Koen Raemdonck Abstract The successful therapeutic application of small interfering RNA (siRNA) largely relies on the development of safe and effective delivery systems that are able to guide the siRNA therapeutics to the cytoplasm of the target cell. In this report, biodegradable cationic dextran nanogels are engineered by inverse emulsion photopolymerization and their potential as siRNA carriers is evaluated. The nanogels are able to entrap siRNA with a high loading capacity, based on electrostatic interaction. Confocal microscopy and flow cytometry analysis reveal that large amounts of siRNA-loaded nanogels can be internalized by HuH-7 human hepatoma cells without significant cytotoxicity. Following their cellular uptake, it is found that the nanogels are mainly trafficked towards the endolysosomes. The influence of two different strategies to enhance endosomal escape on the extent of gene silencing is investigated. It is found that both the application of photochemical internalization (PCI) and the use of an influenza-derived fusogenic peptide (diINF-7) can significantly improve the silencing efficiency of siRNA-loaded nanogels. Furthermore, it is shown that an efficient gene silencing requires the degradation of the nanogels. As the degradation kinetics of the nanogels can easily be tailored, these particles show potential for intracellular controlled release of short interfering RNA. [source] The Impact of Interferon Gamma Receptor Expression on the Mechanism of Escape From Host Immune Surveillance in Hepatocellular CarcinomaHEPATOLOGY, Issue 3 2000Mitsuo Nagao M.D. Interferon gamma (IFN-,) plays an important role in host defense mechanism and participates in the progression of chronic liver disease. IFN-, exerts its pleiotrophic effects by transcriptional regulation of expression of numerous genes, such as major histocompatibility complex (MHC) class I and Fas, through interaction with IFN-, receptor (IFN-,-R). Although hepatocytes in normal liver express weak or no IFN-,-R, those in acute and chronic liver disease up-regulate its expression. A study using IFN-,-R ,-chain knock-out mice revealed the actions of IFN-, on tumor cells as an extrinsic tumor-suppressor mechanism. However, it is unclear whether or how hepatocellular carcinoma (HCC) blocks the signal transduction of IFN-, to evade host immune surveillance. We examined the expression of IFN-,-R and IFN-,,inducible genes in 44 cases with HCC using real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. In noncancerous liver tissues (n = 38), IFN-,-R expression on the cell surface was up-regulated in 27 cases. In IFN-,-R,negative cases (n = 15), tumor size was larger (P = .032), serum ,-fetoprotein (AFP) level was higher (P = .001), intrahepatic and extrahepatic metastasis was more common (P = .044 and .013, respectively), and Ki-67 labeling index (LI) was higher (P = .041), compared with IFN-,-R,positive cases. Accordingly, the evasion mechanism may play an important role in progression, especially metastasis, in HCC. The significant correlation between the status of IFN-,-R and the expression of Fas and MHC implies that the loss of IFN-,-R might contribute to the mechanism of escape from host immune rejection in HCC. [source] Escape from microenvironmental control and progression of intraepithelial neoplasiaINTERNATIONAL JOURNAL OF CANCER, Issue 6 2005Weitian Zhang Abstract We previously reported that normal human keratinocytes controlled neoplastic progression of tumor cells at an early stage of transformation in stratified squamous epithelium. We now studied if cells at a more advanced stage of transformation were also subject to such microenvironmental control. To accomplish this, 3D human tissues that mimic intraepithelial neoplasia were fabricated by mixing genetically marked (,-gal), early-stage (II-4 cells) or advanced-stage (SCC13) transformed keratinocytes with normal keratinocytes, and tumor cell fate and phenotype were monitored in organotypic culture and after surface transplantation to nude mice. In vivo, SCC13 cells evaded local growth suppression to undergo connective tissue invasion at significantly lower tumor cell volumes (12:1, 50:1 normal:tumor cells) than II-4 cells. This behavior was explained by the growth suppression of II-4 cells, while advanced-stage tumor cells escaped this control and continued to undergo clonal expansion in mixed cultures to form large, intraepithelial tumor clusters. These communities of tumor cells underwent autonomous growth that was associated with altered expression of markers of differentiation (keratin 1) and cell,cell communication (connexin-43). Furthermore, significantly greater numbers of SCC13 cells expanded into a basal position after low-calcium stripping of suprabasal cells of mixed cultures compared to II-4 cells, suggesting that expansion of these cells enabled tumor cell invasion after transplantation. These findings demonstrated that early tumor development in human stratified squamous epithelium required escape from microenvironmental growth control that was dependent on the transformation stage of intraepithelial tumor cells during the premalignant stage of cancer progression. © 2005 Wiley-Liss, Inc. [source] Distributional Patterns of Diatoms and Limnodrilus Oligochaetes in a Kenyan Dry Streambed Following the 1999,2000 Drought ConditionsINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2005Jude M. Mathooko Abstract Drought is a natural phenomenon experienced by many intermittent and also seasonal lotic systems. It has diverse effects on the structure and distribution of biological communities through habitat transition from wetted to terrestrial conditions. The Njoro River, a tropical stream, was drought-stressed between late 1999 and mid 2000, providing an opportunity to sample and describe the distributional patterns of diatoms and Limnodrilus oligochaetes in the vertical sediment profile. The dispersion of Limnodrilus oligochaetes with sediment depth profile varied from quasi-random (i.e. exponent k of the negative binomial distribution >2.0 or <0) at the surface to strong aggregation (0 < k < 1.0) in the deeper sediments. Diatoms were heterogenous, with most species contributing less than 1% of all the diatoms collected from the riverbed. Contagious dispersion was a common feature among the diatom species. The distribution of Fragilaria ulna was largely quasi-random in all sites, with Nitzschia amphibia and Cocconeis placentula demonstrating quasi-random distribution in the Kerma vertical sediment profile. Escape from stranding to deeper sediment strata as the drought progressed was not a universal response among the diatom species. Our results showed that drought-stress altered the structure of biological assemblages and also emphasized the need for the management of tropical lotic systems and their catchments for flow permanence. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Escape of farmed tilapiines into the wild and entry of wild forms in fishponds, and the possible interactions between wild and farmed tilapiines from a sample of smallholder farms in Central UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009Matthew Tenywa Mwanja Abstract Seven smallholder fishponds in central Uganda were studied between 2000 and 2001 to investigate the interaction of farmed tilapiines with their wild conspecifics. Emphasis was on the features that facilitate escape of fish and/or entry of fish into the farms and interactions between the farmed and the wild. These included number of species, source of seed, connection between pond and natural watercourses, purpose of the farm, destination of cultured fish and interaction between farmed and wild fish. Fishponds had no screens against entry of wild fish into the farm or escape of farmed fish into the wild and occurred within wetlands close to natural watercourses. Ponds stocked with one fish species were found to have multispecies with some individuals that were apparently intermediate morphs between the species. Fry produced within the growout fishponds was shared with other farmers within and outside the watersheds. This study showed that smallholder farms with little or no control of escape or entry of fish out and into the fishponds, and little or no management present circumstances that facilitate continued movement of tilapiines within and across watersheds in Ugandan waters. The study also indicated possible genetic interaction between farmed and their wild conspecifics through interactions within fishponds. Résumé Sept viviers appartenant à de petits propriétaires ont étéétudiés entre 2000 et 2001 pour rechercher l'interaction entre les tilapiinés d'élevage et ceux qui vivent dans la nature. On insistait sur les caractéristiques qui facilitent la fuite et/ou l'entrée des poissons dans les fermes et les interactions entre les poissons d'élevage et les poissons sauvages. On a étudié le nombre d'espèces, la source de la progéniture, les connections entre les bassins et les cours d'eau naturels, la raison d'être des fermes, la destination des poissons d'élevage et l'interaction entre les poissons d'élevage et les poissons sauvages. Les réservoirs n'avaient pas de filtres pour empêcher l'entrée des poissons sauvages ou la fuite des poissons d'élevage et ils se trouvaient dans des zones humides proches de cours d'eau naturels. Les bassins qui avaient été stockés avec une seule espèce de poissons se sont avérés contenir plusieurs espèces, et certains individus semblaient avoir une morphologie intermédiaire entre différentes espèces. Le fretin produit dans les bassins de croissance était partagé avec d'autres éleveurs dans ou en dehors des bassins versants. Cette étude a montré que les petits élevages qui exercent peu de contrôles sur les entrées ou les sorties de poissons dans et hors des bassins et une gestion nulle ou très réduite, offrent des conditions qui facilitent le déplacement continu des tilapiinés au sein des bassins de rivières et entre eux, dans les eaux ougandaises. Cette étude indique aussi qu'il est possible qu'il existe des interactions génétiques entre les poissons d'élevage et les poissons sauvages de même espèce, au niveau des bassins d'élevage. [source] Aldosterone Excess or Escape: Treating Resistant HypertensionJOURNAL OF CLINICAL HYPERTENSION, Issue 5 2009Samira Ubaid-Girioli MD Aldosterone excess or "escape" can occur after treatment with medications that block the renin-angiotensin-aldosterone system or in undiagnosed primary aldosteronism. Spironolactone is thought to be an important addition to resistant hypertension (RH) treatment. In this study, resistant (RH) and controlled (CH) hypertensives and normotensive patients were submitted to echocardiography, flow-mediated vasodilation, carotid intima-media wall thickness studies, renin plasma activity, and aldosterone plasma levels and plasma and urinary sodium and potassium concentrations at baseline (pre-spironolactone phase). Subsequently, for only RH and CH groups, 25 mg/d spironolactone was added to preexisting treatments over 6 months. Afterwards, these parameters were reassessed (post-spironolactone phase). The RH and CH groups achieved reductions in blood pressure (P<.001), decreases in left ventricular hypertrophy (P<.001), improved diastolic function (Kappa index RH: 0.219 and Kappa index CH: 0.392) and increases in aldosterone concentrations (P<.05). The RH group attained improved endothelium-dependent (P<.001) and independent (P=.007) function. Optimized RH treatment with spironolactone reduces blood pressure and improves endothelial and diastolic function and left ventricular hypertrophy despite the presence of aldosterone excess or escape. [source] Escape in space from enemies: a comparison between stands with and without enhanced densities of the spruce bark beetleAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2007Leif Martin Schroeder Abstract 1,Populations of the spruce bark beetle, Ips typographus (L.), are known to grow rapidly in storm-disturbed stands as a result of relaxation from intraspecific competition. In the present study, it was tested whether a second mechanism, escape in space from natural enemies, also contributes to the rapid population increase. 2,The experiment was conducted during the initiation phase of five local outbreaks of I. typographus triggered by a storm-disturbance in November 1995 in southern Sweden. 3,The impact of natural enemies on the ratio of increase (number of daughters per mother) of I. typographus was compared pairwise between disturbed stands with high numbers of storm-felled trees and undisturbed stands without wind-felled trees. 4,Enemy impact was assessed by comparing the ratio of increase in uncaged (exposed to enemies) and caged (protected from enemies) bolts colonized by I. typographus prior to being placed in the stands. The experiment was conducted in the second and third summers after the storm-felling. 5,Enemy impact was about twice as high in stands without wind-felled trees compared with in stands with wind-felled trees in the second summer whereas there was no significant difference between the stand types in the third summer. 6,The result demonstrates that spatial escape from enemies contributes to the rapid population growth of I. typographus after storm-disturbances. [source] Escape from Germany: Disappearing Bodies and Postmodern Space in Christian Kracht's ProseTHE GERMAN QUARTERLY, Issue 1 2006Richard Langston First page of article [source] New Labour's Escape from Class PoliticsTHE JOURNAL OF THE HISTORICAL SOCIETY, Issue 1 2006James E. Cronin The connection between trade unions and parties of the left is traditionally close across Europe. In Britain the link is more than close: it is intimate, defining, and constitutive of what the Labour Party is and has been since its inception. This link allowed the party to survive during bad times and helped it to govern during good times, but during the 1970s it became less helpful, as policies backed by the unions not only failed to work but were also repudiated by union members themselves in what came to be known as the "winter of discontent" in 1979. New Labour was therefore built on the understanding that its past connection to the unions, and hence to a particular sort of "class politics," needed to be rethought and renegotiated. It is the new defining feature of the Labour Party. [source] Escape of bloodstained fluid during use of a B. Braun vasofix® safety intravenous cannulaANAESTHESIA, Issue 7 2009J. Dolan No abstract is available for this article. [source] Capitalism's Anxious Whole: Fear, Capture and Escape in the,GrundrisseANTIPODE, Issue 5 2008Vinay Gidwani Abstract:, Two Hegels inhabit the,Grundrisse. The first is conservative of the "selfsame" subject that continuously returns to itself as non-identical identity and propels "history". The other Hegel tarries with the "negative" he (which or variously calls "non-being", "otherness""difference") to disrupt this plenary subject to Marx's reading of a Hegel who is different-in-himself lends,Grundrisse its electric buzz: seizing Hegel's "negative" as the,not -value of value, i.e. "labor", Marx explains how capital must continuously enroll labor to its will in order to survive and expand. But this enrollment is never given; hence, despite its emergent structure of necessity, capital's return to itself as "self-animating value" is never free of peril. The most speculative aspect of my argument is that the figure of "labor" in,Grundrisse, because of its radically open formulation as not-value, anticipates the elusive subject of difference in postcolonial theory, "the subaltern",that figure which evades dialectical integration, and is in some ontological way inscrutable to the "master". Unexpectedly, then,Grundrisse gives us a way to think beyond the epistemic and geographic power of "Europe". [source] Cutting the bars: thoughts on ,prisoners and escapees' in BangladeshPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 2 2002Donald CurtisArticle first published online: 8 MAY 200 The idea that problems in governance have deep roots in social structure has been revisited by Geof Wood in a recent article in this journal. His article takes a position in relation to an ongoing debate about how to improve public administration and management in Bangladesh, a debate that seems to be almost as ,imprisoned' in incompatible values and premises as, he argues, are the various Bangladeshi actors in society. But behind this debate are some very practical issues about how the administration there might be persuaded to work better. Key to his contribution is the idea of ,room for manoeuvre' or conditions for ,escape'. This article argues that embedded institutions and values matter but that behaviour is also responsive to opportunity. ,Old' values can be put together into new institutional complexes if given a chance. The key to successful institutional change is effectiveness. ,Escape' is not only, or even primarily, a matter of changing values but of responding to circumstances and changing institutions,cutting the bars. A close look at institutional and organizational reform in any country, including the UK, shows that, whatever moral language and posture inform the reform agenda, it is constructive compromise that produces the structure that works. Copyright © 2002 John Wiley & Sons, Ltd. [source] Functions of glutamate transporters in cerebellar Purkinje cell synapsesACTA PHYSIOLOGICA, Issue 1 2009Y. Takayasu Abstract Glutamate transporters play a critical role in the maintenance of low extracellular concentrations of glutamate, which prevents the overactivation of post-synaptic glutamate receptors. Four distinct glutamate transporters, GLAST/EAAT1, GLT-1/EAAT2, EAAC1/EAAT3 and EAAT4, are distributed in the molecular layer of the cerebellum, especially near glutamatergic synapses in Purkinje cells (PCs). This review summarizes the current knowledge about the differential roles of these transporters at excitatory synapses of PCs. Data come predominantly from electrophysiological experiments in mutant mice that are deficient in each of these transporter genes. GLAST expressed in Bergmann glia contributes to the clearing of the majority of glutamate that floods out of the synaptic cleft immediately after transmitter release from the climbing fibre (CF) and parallel fibre (PF) terminals. It is indispensable to maintain a one-to-one relationship in synaptic transmission at the CF synapses by preventing transcellular glutamate spillover. GLT-1 plays a similar but minor role in the uptake of glutamate as GLAST. Although the loss of neither GLAST nor GLT-1 affects cerebellar morphology, the deletion of both GLAST and GLT-1 genes causes the death of the mutant animal and hinders the folium formation of the cerebellum. EAAT4 removes the low concentrations of glutamate that escape from uptake by glial transporters, preventing the transmitter from spilling over into neighbouring synapses. It also regulates the activation of metabotropic glutamate receptor 1 (mGluR1) in perisynaptic regions at PF synapses, which in turn affects mGluR1-mediated events including slow EPSCs and long-term depression. No change in synaptic function is detected in mice that are deficient in EAAC1. [source] Dynamics of Dislocations in a 2D Plasma CrystalCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4-5 2009V. Nosenko Abstract Recent experimental results on the dislocation dynamics in a two-dimensional plasma crystal are reviewed. A single layer of micron-size microspheres was suspended in the sheath of a capacitively coupled rf discharge. The particles self-organized in a triangular lattice. Edge dislocations were created in pairs in this plasma crystal when the internal shear stress built up above a threshold, due to the crystal's slow differential rotation. Basic stages of dislocation nucleation were identified and studied, from gradual pile-up of shear strain in the crystal to eventual escape of free dislocations. After nucleation, dislocations moved supersonically with respect to the shear waves and generated shear-wave Mach cones (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Balancing Self-interest and Altruism: corporate governance alone is not enoughCORPORATE GOVERNANCE, Issue 2 2004Sandra Dawson Governance has become a topic of unprecedented emotional significance and fundamental importance in the boardrooms of companies, partly as a result of a confluence of early 21st century corporate scandals, stock market falls and public rage about senior executive remuneration. A simple adherence to formal systems of corporate governance, in terms of structures, rules, procedures and codes of practice, whilst a starting point, will not alone win back confidence in markets and corporations. Consideration needs to be given to how to release entrepreneurial self interest within a moral context. This focuses attention on the role of other major social institutions which may more naturally be able to nurture a moral framework as well as the role of individual citizens and the responsibility of all of us to enact a moral framework for business activities. There is no escape from individual moral responsibility, and our part in creating and sustaining social institutions beyond corporations. [source] Fixing the Hole in the Bucket: Household Poverty Dynamics in the Peruvian AndesDEVELOPMENT AND CHANGE, Issue 5 2006Anirudh Krishna ABSTRACT Achieving the Millennium Development Goal of halving poverty will require simultaneous action on two separate fronts: helping poor people escape from poverty, and stemming the flow of people into poverty. This article examines forty Peruvian communities, and finds that descents into poverty have occurred alongside escapes in every one of them. Escape and descent are asymmetric in terms of reasons: while one set of reasons is responsible for escapes from poverty, another and different set of reasons is associated with descent. Making progress in poverty reduction will require measures to accelerate escapes whilst at the same time slowing down descents. The article looks at the different policies which will be required to serve these two separate purposes. [source] A role for innate immunity in type 1 diabetes?DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2003H. Beyan Abstract Two arms of the immune system, innate and adaptive immunity, differ in their mode of immune recognition. The innate immune system recognizes a few highly conserved structures on a broad range of microorganisms. On the other hand, recognition of self or autoreactivity is generally confined to the adaptive immune response. Whilst autoimmune features are relatively common, they should be distinguished from autoimmune disease that is infrequent. Type 1 diabetes is an immune-mediated disease due to the destruction of insulin secreting cells mediated by aggressive immune responses, including activation of the adaptive immune system following genetic and environmental interaction. Hypotheses for the cause of the immune dysfunction leading to type 1 diabetes include self-reactive T-cell clones that (1) escape deletion in the thymus, (2) escape from peripheral tolerance or (3) escape from homeostatic control with an alteration in the immune balance leading to autoimmunity. Evidence, outlined in this review, raises the possibility that changes in the innate immune system could lead to autoimmunity, by either priming or promoting aggressive adaptive immune responses. Hostile microorganisms are identified by genetically determined surface receptors on innate effector cells, thereby promoting clearance of these invaders. These innate effectors include a few relatively inflexible cell populations such as monocytes/macrophages, dendritic cells (DC), natural killer (NK) cells, natural killer T (NKT) cells and ,, T cells. Recent studies have identified abnormalities in some of these cells both in patients with type 1 diabetes and in those at risk of the disease. However, it remains unclear whether these abnormalities in innate effector cells predispose to autoimmune disease. If they were to do so, then modulation of the innate immune system could be of therapeutic value in preventing immune-mediated diseases such as type 1 diabetes. Copyright © 2002 John Wiley & Sons, Ltd. [source] Adaptive advantages of myrmecochory: the predator-avoidance hypothesis tested over a wide geographic rangeECOGRAPHY, Issue 5 2005Antonio J. Manzaneda The predator-avoidance hypothesis states that once released from the parent plant, myrmecochorous seeds are rapidly taken by ants to their nests, where they are protected from predators. Previous studies conducted to test this hypothesis have frequently neglected two major aspects necessary for its verification: 1) the influence of processes acting after the seed release and 2) the spatial evenness of such processes. Thus, large-scale variations in the mechanisms acting beyond seed release, and possibly influencing seed escape from predators, remain poorly documented. Here, we present the results of a post-dispersal seed-removal experiment on the myrmecochorous herb Helleborus foetidus, aimed at verifing the predator-avoidance hypothesis by considering two key post-release aspects of seed fate: seed destination (dispersed or nondispersed) and seed burial (buried or not buried). Experiments were performed in four different regions in the Iberian Peninsula. After three days of exposure of seeds to the main predator (fieldmice Apodemus sylvaticus), ca 30% of the seeds were removed. Seed destination affected the proportion of seeds escaping predation, but the sign, magnitude and statistical significance of the effect varied among the geographical regions. In the southern region (Cazorla), seeds dispersed in ant nests or intermediate destinations suffered scarcely any predation, but seeds under reproductive-age plants experienced losses ca 50%. Conversely, in the northern region (Caurel), seeds in nests suffered significantly greater losses than seeds under plants or intermediate destinations, suggesting that nests were especially unsafe destinations. Seed burial had a strong impact on seed escape from predators, and its effect was highly consistent among geographical regions. In view of the consistency of its effect at different spatial scales, seed burial was a more general mechanism for predation avoidance than seed relocation to ant nests, which was habitat- and/or ant-species-dependent. Our results thus only partially support the predator-avoidance hypothesis for the evolution of myrmecochory. [source] Tritrophic interactions and trade-offs in herbivore fecundity on hybridising host plantsECOLOGICAL ENTOMOLOGY, Issue 3 2004Maria V. Cattell Abstract., 1. Interspecific plant hybridisation can have important evolutionary consequences for hybridising plants and for the organisms that they interact with on multiple trophic levels. In this study the effects of plant hybridisation on the abundance of herbivores and on the levels of herbivore parasitism were investigated. 2. Borrichia frutescens, B. arborescens, and their hybrid (B. × cubana) were censused for Asphondylia borrichiae galls and Pissonotus quadripustulatus plant hoppers in the Florida Keys. Levels of egg parasitism were determined by dissecting parental and hybrid stems and galls for herbivore and parasite eggs and larvae. Stem toughness and gall size are plant-mediated modes of protection from parasitism and these were also measured. For gall midges, fly size was measured as an estimate of fecundity. 3. Field censuses indicated that herbivore abundances varied on hybrid hosts relative to parent plant species and that the different herbivore species exhibited different patterns of abundance. Asphondylia borrichiae gall numbers followed the additive pattern of abundance while P. quadripustulatus numbers most closely resembled the dominance pattern. 4. Parasitism of P. quadripustulatus eggs was high on B. frutescens and the hybrids, and low on B. arborescens, which also had significantly tougher stems. Asphondylia borrichiae suffered the highest levels of parasitism on B. frutescens, the host plant which produced the smallest galls. On B. arborescens, which produced the largest galls, levels of A. borrichiae parasitism were lowest. Both parasitism and gall size were intermediate on the hybrid plants. Galls on B. arborescens and hybrid plants produced significantly smaller flies then those from B. frutescens suggesting that, when selecting hosts from among parent species and hybrids, gall flies may face a trade-off between escape from natural enemies and maximising fecundity. [source] The angiosperm radiation revisited, an ecological explanation for Darwin's ,abominable mystery'ECOLOGY LETTERS, Issue 9 2009Frank Berendse Abstract One of the greatest terrestrial radiations is the diversification of the flowering plants (Angiospermae) in the Cretaceous period. Early angiosperms appear to have been limited to disturbed, aquatic or extremely dry sites, suggesting that they were suppressed in most other places by the gymnosperms that still dominated the plant world. However, fossil evidence suggests that by the end of the Cretaceous the angiosperms had spectacularly taken over the dominant position from the gymnosperms around the globe. Here, we suggest an ecological explanation for their escape from their subordinate position relative to gymnosperms and ferns. We propose that angiosperms due to their higher growth rates profit more rapidly from increased nutrient supply than gymnosperms, whereas at the same time angiosperms promote soil nutrient release by producing litter that is more easily decomposed. This positive feedback may have resulted in a runaway process once angiosperms had reached a certain abundance. Evidence for the possibility of such a critical transition to angiosperm dominance comes from recent work on large scale vegetation shifts, linking long-term field observations, large scale experiments and the use of simulation models. [source] Optimal eradication: when to stop looking for an invasive plantECOLOGY LETTERS, Issue 7 2006Tracey J. Regan Abstract The notion of being sure that you have completely eradicated an invasive species is fanciful because of imperfect detection and persistent seed banks. Eradication is commonly declared either on an ad hoc basis, on notions of seed bank longevity, or on setting arbitrary thresholds of 1% or 5% confidence that the species is not present. Rather than declaring eradication at some arbitrary level of confidence, we take an economic approach in which we stop looking when the expected costs outweigh the expected benefits. We develop theory that determines the number of years of absent surveys required to minimize the net expected cost. Given detection of a species is imperfect, the optimal stopping time is a trade-off between the cost of continued surveying and the cost of escape and damage if eradication is declared too soon. A simple rule of thumb compares well to the exact optimal solution using stochastic dynamic programming. Application of the approach to the eradication programme of Helenium amarum reveals that the actual stopping time was a precautionary one given the ranges for each parameter. [source] Microevolution in agricultural environments: how a traditional Amerindian farming practice favours heterozygosity in cassava (Manihot esculenta Crantz, Euphorbiaceae)ECOLOGY LETTERS, Issue 2 2005Benoît Pujol Abstract We demonstrate a novel case of selection for heterozygosity in nature, involving inadvertent human selection on a population of domesticated plants. Amerindian farmers propagate cassava (Manihot esculenta) clonally by cuttings. Seedlings also appear spontaneously in fields, and farmers allow them to grow, later using some for cuttings. These ,volunteers' contribute new genotypes. However, many are inbred, whereas multiplied clones are highly heterozygous. We demonstrate the selective retention of heterozygous volunteers. When farmers weeded fields, they killed small volunteers, but retained large ones. Plant size and heterozygosity were correlated, and both increased after weeding. The process we document allows maintenance of genotypically diverse and heterozygous clonal stocks. Demonstrating heterosis in nature usually requires large sample sizes, but novel features of our system allowed escape of this constraint. Traditional agroecosystems offer unusual opportunities for the microevolutionary studies required to give on-farm conservation of genetic resources a solid scientific basis. [source] Plant,soil biota interactions and spatial distribution of black cherry in its native and invasive rangesECOLOGY LETTERS, Issue 12 2003Kurt O. Reinhart Abstract One explanation for the higher abundance of invasive species in their non-native than native ranges is the escape from natural enemies. But there are few experimental studies comparing the parallel impact of enemies (or competitors and mutualists) on a plant species in its native and invaded ranges, and release from soil pathogens has been rarely investigated. Here we present evidence showing that the invasion of black cherry (Prunus serotina) into north-western Europe is facilitated by the soil community. In the native range in the USA, the soil community that develops near black cherry inhibits the establishment of neighbouring conspecifics and reduces seedling performance in the greenhouse. In contrast, in the non-native range, black cherry readily establishes in close proximity to conspecifics, and the soil community enhances the growth of its seedlings. Understanding the effects of soil organisms on plant abundance will improve our ability to predict and counteract plant invasions. [source] Genetic differences in growth of an invasive tree speciesECOLOGY LETTERS, Issue 6 2001Evan Siemann Invasive plants are often more vigorous in their introduced ranges than in their native ranges. This may reflect an innate superiority of plants from some habitats or an escape from their enemies. Another hypothesis proposes that invasive plants evolve increased competitive ability in their introduced range. We present the results of a 14-year common garden experiment with the Chinese Tallow Tree (Sapium sebiferum) from its native range (Asia), place of introduction to North America (Georgia) and areas colonized a century later (Louisiana and Texas). Invasive genotypes, especially those from recently colonized areas, were larger than native genotypes and more likely to produce seeds but had lower quality, poorly defended leaves. Our results demonstrate significant post-invasion genetic differences in an invasive plant species. Post-introduction adaptation by introduced plants may contribute to their invasive success and make it difficult to predict problem species. [source] PLANNING THROUGH INCLUSIVE DIALOGUE: NO ESCAPE FROM SOCIAL CHOICE DILEMMASECONOMIC AFFAIRS, Issue 4 2005Tore Sager The thrust of the theory of preference aggregation is that it is impossible to design institutions guaranteeing collective decisions that are both consistent and fair. Proponents of deliberative democracy have used this as an argument for decision-making based on dialogue rather than voting. Communicative public planning - producing plans through public participation exercises - is seen as an integral part of deliberative democracy. It is argued here, however, that the inclusive dialogue of this style of planning cannot promise escape from arbitrariness and does not necessarily deliver improved local decision-making. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||