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Local Environment (local + environment)
Selected AbstractsDifferences in Local Environment Determine the Site of Physiological Angiogenesis in Rat Skeletal MuscleEXPERIMENTAL PHYSIOLOGY, Issue 5 2003I. Badr The specificity in location of angiogenesis to either glycolytic or oxidative fibre types, or muscle regions, was examined in the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles of rat. Angiogenesis was induced by mechanical means either with (chronic muscle stimulation) or without (muscle stretch by overload) changes in blood flow, treatments which invoked only minor changes in fibre type and fibre size. Proliferation estimated by PCNA labelling of cells co-localised with capillaries was very rare in control muscles, where it occurred mainly in the glycolytic regions, but was increased in both models of angiogenesis. However, when labelled capillaries were scored according to the type of surrounding fibres, only muscle stimulation significantly accentuated proliferation of capillaries surrounded by glycolytic fibres. We conclude that while mechanical stimuli are important for proliferation in glycolytic regions in both models, capillary growth occurs specifically around glycolytic fibres in that region when the angiogenic stimulus includes increased blood flow and/or increased metabolic demand. [source] On the Influence of the Local Environment on the CO Stretching Frequencies in Native Myoglobin: Assignment of the B-States in MbCOCHEMPHYSCHEM, Issue 10 2006Markus Meuwly Prof. Dr. Frequency shifts: The influence of the local electrostatic environment on the ground vibrational level of photodissociated CO in native myoglobin is investigated by performing QM/MM calculations at the DFT level. The distribution of CO frequencies in the FeCO conformation occurs at higher wavenumbers than in the FeOC conformation (see figure). [source] The effects of fire, local environment and time on ant assemblages in fens and forestsDIVERSITY AND DISTRIBUTIONS, Issue 6 2005Jaime S. Ratchford ABSTRACT We investigated the effects of the abiotic environment, plant community composition and disturbance by fire on ant assemblages in two distinct habitat types in the Siskiyou Mountains in northern California and southern Oregon, USA. Sampling over 2 years in burned and unburned Darlingtonia fens and their adjacent upland forests, we found that the effects of disturbance by fire depended on habitat type. In forests, fire intensity predicted richness in ant assemblages in both years after the fire, and plant community composition predicted richness 2 years after the fire. No factors were associated with richness in the species-poor fen ant assemblages. Species-specific responses to both habitat type and disturbance by fire were idiosyncratic. Assemblage composition depended on habitat type, but not disturbance by fire, and the composition of each assemblage between years was more dissimilar in burned than unburned sites. [source] Species richness patterns and metapopulation processes , evidence from epiphyte communities in boreo-nemoral forestsECOGRAPHY, Issue 2 2006Swantje Löbel For several epiphyte species, dispersal limitation and metapopulation dynamics have been suggested. We studied the relative importance of local environmental conditions and spatial aggregation of species richness of facultative and obligate epiphytic bryophytes and lichens within two old-growth forests in eastern Sweden. The effect of the local environment was analyzed using generalized linear models (GLM). We tested whether species richness was spatially structured by fitting variogram models to the residuals of the GLM. In addition, we analyzed the species-area relationship (area=tree diameter). Different environmental variables explained the richness of different species groups (bryophytes vs lichens, specialists vs generalists, sexual vs asexual dispersal). In most groups, the total variation explained by environmental variables was higher than the variation explained by the spatial model. Spatial aggregation was more pronounced in asexually than in sexually dispersed species. Bryophyte species richness was only poorly predicted by area, and lichen species richness was not explained by area at all. Spatial aggregation may indicate effects of dispersal limitation and metapopulation dynamics on community species richness. Our results suggest that species groups differ in habitat requirements and dispersal abilities; there were indications that presence of species with different dispersal strategies is linked to the age of the host tree. Separate analyses of the species richness of species groups that differ in the degree of habitat specialization and dispersal ability give insights into the processes determining community species richness. The poor species-area relationship, especially in lichens, may indicate species turnover rather than accumulation during the lifetime of the host tree. Epiphyte species extinctions may be mainly caused by deterministic processes, e.g. changes in habitat conditions as the host tree grows, ages and dies, rather than by stochastic population processes. [source] Assessing environmental risks of transgenic plantsECOLOGY LETTERS, Issue 2 2006D. A. Andow Abstract By the end of the 1980s, a broad consensus had developed that there were potential environmental risks of transgenic plants requiring assessment and that this assessment must be done on a case-by-case basis, taking into account the transgene, recipient organism, intended environment of release, and the frequency and scale of the intended introduction. Since 1990, there have been gradual but substantial changes in the environmental risk assessment process. In this review, we focus on changes in the assessment of risks associated with non-target species and biodiversity, gene flow, and the evolution of resistance. Non-target risk assessment now focuses on risks of transgenic plants to the intended local environment of release. Measurements of gene flow indicate that it occurs at higher rates than believed in the early 1990s, mathematical theory is beginning to clarify expectations of risks associated with gene flow, and management methods are being developed to reduce gene flow and possibly mitigate its effects. Insect pest resistance risks are now managed using a high-dose/refuge or a refuge-only strategy, and the present research focuses on monitoring for resistance and encouraging compliance to requirements. We synthesize previous models for tiering risk assessment and propose a general model for tiering. Future transgenic crops are likely to pose greater challenges for risk assessment, and meeting these challenges will be crucial in developing a scientifically coherent risk assessment framework. Scientific understanding of the factors affecting environmental risk is still nascent, and environmental scientists need to help improve environmental risk assessment. [source] High-Zirconium-Content Nano-Sized Bimodal Mesoporous SilicasEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006David Ortiz de Zárate Abstract Silica-based nanoparticulated bimodal mesoporous materials with high Zr content (43 , Si/Zr , 4) have been synthesized by a one-pot surfactant-assisted procedure from a hydroalcoholic medium using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure-directing agent, and starting from molecular atrane complexes of Zr and Si as hydrolytic inorganic precursors. This preparative technique allows optimization of the dispersion of the Zr guest species in the silica walls. The bimodal mesoporous nature of the final high surface area nano-sized materials is confirmed by XRD, TEM, and N2 adsorption,desorption isotherms. The small intraparticle mesopore system (with pore sizes around 2,3 nm) is due to the supramolecular templating effect of the surfactant, while the large mesopores (around 12,24 nm) have their origin in the packing voids generated by aggregation of the primary nanometric mesoporous particles. The basicity of the reaction medium seems to be a key parameter in the definition of this last pore system. The effects induced by the progressive incorporation of Zr atoms on the mesostructure have been examined, and the local environment of the Zr sites in the framework has been investigated by UV/Vis spectroscopy. Observations based on the consequences of post-treatments of the as-synthesized materials with HCl/ethanol mixtures corroborate that the atrane method leads to Zr-rich materials showing enhanced site accessibility and high chemical homogeneity throughout the pore walls. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] X-Ray absorption fine structure analysis of the local environment of zinc in dentine treated with zinc compoundsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2005Tsutomu Takatsuka It has been reported that zinc oxide (ZnO) inhibits dentine demineralization. By using the X-ray absorption fine structure (XAFS) technique, our aims in this study were to provide information about the local environment of zinc atoms in dentine that had been treated with zinc compounds. We measured the Zn K-edge X-ray absorption near-edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) of dentine specimens treated with zinc chloride or ZnO. In XAFS analyses, the spectra of dentine specimens treated with ZnO (D-ZO) or with zinc chloride (D-ZC) were similar and obviously different from the reference ZnO spectrum. This suggests that most of the zinc atoms detected in D-ZO are not derived from particles of ZnO. The spectra of D-ZO and D-ZC were similar to the spectrum of the synthetic, zinc-containing hydroxyapatite, but were not similar to that of zinc in ZnCl2 -treated collagen. The results of this study suggest that most of the zinc atoms detected were attached to hydroxyapatite and not to collagen. [source] SELECTION IN HETEROGENEOUS ENVIRONMENTS MAINTAINS THE GENE ARRANGEMENT POLYMORPHISM OF DROSOPHILA PSEUDOOBSCURAEVOLUTION, Issue 12 2008Stephen W. Schaeffer Chromosomal rearrangements may play an important role in how populations adapt to a local environment. The gene arrangement polymorphism on the third chromosome of Drosophila pseudoobscura is a model system to help determine the role that inversions play in the evolution of this species. The gene arrangements are the likely target of strong selection because they form classical clines across diverse geographic habitats, they cycle in frequency over seasons, and they form stable equilibria in population cages. A numerical approach was developed to estimate the fitness sets for 15 gene arrangement karyotypes in six niches based on a model of selection,migration balance. Gene arrangement frequencies in the six different niches were able to reach a stable meta-population equilibrium that matched the observed gene arrangement frequencies when recursions used the estimated fitnesses with a variety of initial inversion frequencies. These analyses show that a complex pattern of selection is operating in the six niches to maintain the D. pseudoobscura gene arrangement polymorphism. Models of local adaptation predict that the new inversion mutations were able to invade populations because they held combinations of two to 13 local adaptation loci together. [source] HISTORIC CYCLES OF FRAGMENTATION AND EXPANSION IN PARNASSIUS SMINTHEUS (PAPILIONIDAE) INFERRED USING MITOCHONDRIAL DNAEVOLUTION, Issue 1 2004Eric G. DeChaine Abstract Climate oscillations of the Quaternary drove the repeated expansion and contraction of ecosystems. Alpine organisms were probably isolated in sky island refugia during warm interglacials, such as now, and expanded their range by migrating down-slope during glacial periods. We used population genetic and phylogenetic approaches to infer how paleoclimatic events influenced the distribution of genetic variation in the predominantly alpine butterfly Parnassius smintheus. We sequenced a 789 bp region of cytochrome oxidase I for 385 individuals from 20 locations throughout the Rocky Mountains, ranging from southern Colorado to northern Montana. Analyses revealed at lease two centers of diversity in the northern and southern Rocky Mountains and strong population structure. Nested clade analysis suggested that the species experienced repeated cycles of population expansion and fragmentation. The estimated ages of these events, assuming a molecular clock, corresponded with paleoclimatic data on habitat expansion and contraction over the past 400,000 years. We propose that alpine butterflies persisted in an archipelago of isolated sky islands during interglacials and that populations expanded and became more connected during cold glacial periods. An archipelago model implies that the effects of genetic drift and selection varied among populations, depending on their latitude, area, and local environment. Alpine organisms are sensitive indicators of climate change and their history can be used to predict how high-elevation ecosystems might respond to further climate warming. [source] Dendritic cell activation by danger and antigen-specific T-cell signallingEXPERIMENTAL DERMATOLOGY, Issue 5 2000A. D. McLellan Abstract: Recent transplantation, animal and in vitro studies suggest a dependence of some immune reactions on tissue damage. Although many factors involved in enhancing immune responses through tissue damage have yet to be identified, recent data suggests that one of the targets of these cellular stress factors is the bone marrow derived dendritic cell ( DC). DC are potent initiators of primary immune responses and hold the key to immune reactions through their ability to sense changes in their local environment and respond appropriately to induce T-cell immunity, or possibly tolerance. In the lymph node, DC are also influenced by antigen-specific signalling from T cells, which may extend and amplify DC antigen presenting capabilities, especially for the stimulation of cytotoxic responses. It now appears that both tissue damage and antigen-specific T-cell derived signals act together on the DC to promote the appropriate immune reaction to antigen. Thus DC antigen presenting behaviour is not only dependent on the context of antigen encounter in the periphery, but also on the availability of antigen-specific T cells and their T-cell receptor specificities. [source] Functional biodiversity of macroinvertebrate assemblages along major ecological gradients of boreal headwater streamsFRESHWATER BIOLOGY, Issue 9 2005JANI HEINOArticle first published online: 3 AUG 200 Summary 1. Biodiversity,environment relationships are increasingly well-understood in the context of species richness and species composition, whereas other aspects of biodiversity, including variability in functional diversity (FD), have received rather little rigorous attention. For streams, most studies to date have examined either taxonomic assemblage patterns or have experimentally addressed the importance of species richness for ecosystem functioning. 2. I examined the relationships of the functional biodiversity of stream macroinvertebrates to major environmental and spatial gradients across 111 boreal headwater streams in Finland. Functional biodiversity encompassed functional richness (FR , the number of functional groups derived from a combination of functional feeding groups and habit trait groups), FD , the number of functional groups and division of individuals among these groups, and functional evenness (FE , the division of individuals among functional groups). Furthermore, functional structure (FS) comprised the composition and abundance of functional groups at each site. 3. FR increased with increasing pH, with additional variation related to moss cover, total nitrogen, water colour and substratum particle size. FD similarly increased with increasing pH and decreased with increasing canopy cover. FE decreased with increasing canopy cover and water colour. Significant variation in FS was attributable to pH, stream width, moss cover, substratum particle size, nitrogen, water colour with the dominant pattern in FS being related to the increase of shredder-sprawlers and the decrease of scraper-swimmers in acidic conditions. 4. In regression analysis and redundancy analysis, variation in functional biodiversity was not only related to local environmental factors, but a considerable proportion of variability was also attributable to spatial patterning of environmental variables and pure spatial gradients. For FR, 23.4% was related to pure environmental effects, 15.0% to shared environmental and spatial effects and 8.0% to spatial trends. For FD, 13.8% was attributable to environmental effects, 15.2% to shared environmental and spatial effects and 5% to spatial trends. For FE, 9.0% was related to environmental variables, 12.7% to shared effects of environmental and spatial variables and 4.5% to spatial variables. For FS, 13.5% was related to environmental effects, 16.9% to shared environmental and spatial effects and 15.4% to spatial trends. 5. Given that functional biodiversity should portray variability in ecosystem functioning, one might expect to find functionally rather differing ecosystems at the opposite ends of major environmental gradients (e.g. acidity, stream size). However, the degree to which variation in the functional biodiversity of stream macroinvertebrates truly portrays variability in ecosystem functioning is difficult to judge because species traits, such as feeding roles and habit traits, are themselves strongly affected by the habitat template. 6. If functional characteristics show strong responses to natural environmental gradients, they also are likely to do so to anthropogenic environmental changes, including changes in habitat structure, organic inputs and acidifying elements. However, given the considerable degree of spatial structure in functional biodiversity, one should not expect that only the local environment and anthropogenic changes therein are responsible for this variability. Rather, the spatial context, as well as natural variability along environmental gradients, should also be explicitly considered in applied research. [source] The influence of stream invertebrate composition at neighbouring sites on local assemblage compositionFRESHWATER BIOLOGY, Issue 2 2005R. A. SANDERSON Summary 1. The composition of freshwater invertebrate assemblages at a location is determined by a range of physico-chemical and biotic factors in the local environment, as well as larger-scale spatial factors such as sources of recruits. We assessed the relative importance of the species composition of local neighbourhoods and proximal environmental factors on the composition of invertebrate assemblages. 2. Macroinvertebrate assemblages were sampled at 188 running-water sites in the catchment of the River Rede, north-east England. A total of 176 species were recorded. 3. Environmental data, in the form of 13 biotic and abiotic measurements that described stream physical structure, aquatic vegetation and water characteristics, were recorded for each site. Detrended correspondence analysis was then used to simplify nine of these stream environmental variables to create an index of stream structure. 4. The species composition of the invertebrate assemblages was related to the environmental variables, using an information theoretic approach. The impact of the species composition of neighbouring sites on each site was determined using Moran's I and autoregressive modelling techniques. 5. Species composition was primarily associated with water pH and stream structure. The importance of the species composition of neighbouring sites in determining local species assemblages differed markedly between taxa. The autoregressive component was low for Coleoptera, intermediate for Trichoptera and Plecoptera, and high for Ephemeroptera. 6. We hypothesise that the observed differences in the autoregressive component amongst these orders reflects variation in their dispersal abilities from neighbouring sites. [source] Geographical variation in the size of body organs in seabirdsFUNCTIONAL ECOLOGY, Issue 3 2000G. M. Hilton Abstract 1.,The size of body organs shows adaptive temporal variation in many animal species. The variation in the size of body organs was examined to see if it is also a component of local adaptation to geographical variation in ecological conditions. 2.,Major body organs were measured in five species of Icelandic seabirds, sampled from two areas where birds experience slightly different ecological conditions. Between-area differences in ecological conditions were consistent among the study species, allowing tests of the generality of ecological effects on organ size. 3.,All major body organs showed geographical size variation. Livers and kidneys were larger in locations where daily energy expenditure was expected to be higher; small intestines were heavier where food was of lower energy density; stomachs were heavier where food was less digestible; heart and flight muscle were larger where flight costs were greater. 4.,It is concluded that adaptive variation in organ size may be an important means by which animals optimize exploitation of their local environment, and may be a proximate factor in intraspecific life-history and metabolic variations between geographically separate populations. [source] Speleothem preservation and diagenesis in South African hominin sites implications for paleoenvironments and geochronologyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2009Philip J. Hopley Plio-Pleistocene speleothems from australopithecine-bearing caves of South Africa have the potential to yield paleoenvironmental and geochronological information using isotope geochemistry. Prior to such studies it is important to assess the preservation of geochemical signals within the calcitic and aragonitic speleothems, given the tendency of aragonitic speleothems to recrystallize to calcite. This study documents the geochemical suitability of speleothems from the principal hominin-bearing deposits of South Africa. We use petrography, together with stable isotope and trace element analysis, to identify the occurrence of primary aragonite, primary calcite, and secondary calcite. This study highlights the presence of diagenetic alteration at many of the sites, often observed as interbedded primary and secondary fabrics. Trace element and stable isotopic values distinguish primary calcite from secondary calcite and offer insights into geochemical aspects of the past cave environment. ,13C values of the primary and secondary calcites range from +6 to ,9, and ,18O values range from ,4 to ,6,. The data are thus typical of meteoric calcites with highly variable ,13C and relatively invariant ,18O. High carbon isotope values in these deposits are associated with the effects of recrystallization and rapid outgassing of CO2 during precipitation. Mg/Ca and Sr/Ca ratios differ between primary and secondary calcite speleothems, aiding their identification. Carbon and oxygen isotope values in primary calcite reflect the proportion of C3 and C4 vegetation in the local environment and the oxygen isotope composition of rainfall. Primary calcite speleothems preserve the pristine geochemical signals vital for ongoing paleoenvironmental and geochronological research. © 2009 Wiley Periodicals, Inc. [source] Transfer or adapt business practices internationally?GLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 3 2010Some answers from Southeast Asia International organizations have long been torn between transferring their existing practices into new locations or adapting to local conditions. A major miscalculation can have extremely negative consequences for companies as they expand internationally. An examination of business practices in the Theravada Buddhist countries of Southeast Asia illustrates how breaking down business practices into their strategic, tactical, and operational levels may provide a useful guide for setting up initial operations in a foreign environment. It is proposed that strategic principles can be transferred but strategic practices should adapt to local conditions; tactical-level business practices will generally need to adapt to the local environment, while it is likely that best practices at the operational level can be transferred across international borders with little need to adapt to local conditions. © 2010 Wiley Periodicals, Inc. [source] Unravelling the effects of temperature, latitude and local environment on the reproduction of forest herbsGLOBAL ECOLOGY, Issue 6 2009P. De Frenne ABSTRACT Aim, To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location, Six regions along a latitudinal gradient from France to Sweden. Methods, Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number × seed mass, while germinable seed output (GSO) was expressed as seed number × germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results, Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions, We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made. [source] Toward a More Embedded Production System?GROWTH AND CHANGE, Issue 3 2009Automotive Supply Networks, Localized Capabilities in Poland ABSTRACT The article addresses the embeddedness of automotive production in Poland in terms of supply networks. A comprehensive analysis of more than 550 suppliers, supported by company interviews, shows that foreign-owned producers become embedded in Poland in the automotive supplier networks they have largely created themselves. Numerous local suppliers gain access to export markets and become integrated in a Europe-wide production system. This trend has been accompanied by significant upgrading of foreign affiliates and domestic firms in terms of product quality, cost efficiency, adaptability, and fast response, but far less in nonproduction competences such as R&D. It is argued that the competences of automotive suppliers in Poland are built upon the localized capabilities, which are a product of the dynamic interplay between the activity of foreign firms and the changing local environment comprising various stakeholders. The localized capabilities constitute elements of a company's sunk costs and are embedding automotive producers in Poland. At the same time, the dependence on decisions and innovations from abroad and the limited development of local design and brands may constrain the future role of suppliers from the semiperipheral economy of Poland. [source] Oligophenylenevinylenes in Spatially Confined Nanochannels: Monitoring Intermolecular Interactions by UV/Vis and Raman Spectroscopy,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2008Mariya Aloshyna Abstract Perhydrotriphenylene-based channel-forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)-type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host-guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials for opto-electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi-isolated entities of tightly packed, well-oriented objects with high PL quantum yields and the possibility of color tuning. [source] Apoptotic cells induce dendritic cell-mediated suppression via interferon-,-induced IDOIMMUNOLOGY, Issue 1 2008Charlotte A. Williams Summary Dendritic cells (DC) are sensitive to their local environment and are affected by proximal cell death. This study investigated the modulatory effect of cell death on DC function. Monocyte-derived DC exposed to apoptotic Jurkat or primary T cells failed to induce phenotypic maturation of the DC and were unable to support CD4+ allogeneic T-cell proliferation compared with DC exposed to lipopolysaccharide (LPS) or necrotic cells. Apoptotic cells coincubated with LPS- or necrotic cell-induced mature DC significantly suppressed CD80, CD86 and CD83 and attenuated LPS-induced CD4+ T-cell proliferation. Reduced levels of interleukin-12 (IL-12), IL-10, IL-6, tumour necrosis factor-, and interferon-, (IFN-,) were found to be concomitant with the suppressive activity of apoptotic cells upon DC. Furthermore, intracellular staining confirmed IFN-, expression by DC in association with apoptotic environments. The specific generation of IFN-, by DC within apoptotic environments is suggestive of an anti-inflammatory role by the induction of indoleamine 2,3-dioxygenase (IDO). Both neutralization of IFN-, and IDO blockade demonstrated a role for IFN-, and IDO in the suppression of CD4+ T cells. Moreover, we demonstrate that IDO expression within the DC was found to be IFN-,-dependent. Blocking transforming growth factor-, (TGF-,) also produced a partial release in T-cell proliferation. Our study strongly suggests that apoptosis-induced DC suppression is not an immunological null event and two prime mediators underpinning these functional effects are IFN-,-induced IDO and TGF-,. [source] Induction of an antitumour adaptive immune response elicited by tumour cells expressing de novo B7-1 mainly depends on the anatomical site of their delivery: the dose applied regulates the expansion of the responseIMMUNOLOGY, Issue 4 2003Silvia Sartoris Summary De novo expression of costimulatory molecules in tumours generally increases their immunogenicity, but does not always induce a protective response against the parental tumour. This issue was addressed in the mouse Sp6 hybridoma model, comparing different immunization routes (subcutaneous, intraperitoneal and intravenous) and doses (0·5 × 106 and 5 × 106 cells) of Sp6 cells expressing de novo B7-1 (Sp6/B7). The results can be summarized as follows. First, de novo expression of B7-1 rendered Sp6 immunogenic, as it significantly reduced the tumour incidence to ,15% with all delivery routes and doses tested, whereas wild-type Sp6 was invariably tumorigenic (100% tumour incidence). Second, long-lasting protection against wild-type Sp6 was mainly achieved when immunization with Sp6/B7 was subcutaneous: a dose of 0·5 × 106 Sp6/B7 cells elicited protection that was confined to sites in the same anatomical quarter as the immunizing injection. Repeated injections of the same dose extended protection against wild-type Sp6 to other anatomical districts, as well as a single injection of a 10-fold higher dose (5 × 106 cells). Finally, Sp6-specific cytotoxic T-lymphocyte activity was detected in draining lymph nodes, and the splenic expansion of Sp6-specific cytotoxic T-lymphocyte precursors quantitatively correlated with the dose of antigen. We conclude that activation of a protective immune response against Sp6 depends on the local environment where the immunogenic form of the ,whole tumour cell antigen' is delivered. The antigen dose regulates the anatomical extent of the protective response. [source] Ecometrics: The traits that bind the past and present togetherINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 2 2010Jussi T. ERONEN Abstract We outline here an approach for understanding the biology of climate change, one that integrates data at multiple spatial and temporal scales. Taxon-free trait analysis, or "ecometrics," is based on the idea that the distribution in a community of ecomorphological traits such as tooth structure, limb proportions, body mass, leaf shape, incubation temperature, claw shape, any aspect of anatomy or physiology can be measured across some subset of the organisms in a community. Regardless of temporal or spatial scale, traits are the means by which organisms interact with their environment, biotic and abiotic. Ecometrics measures these interactions by focusing on traits which are easily measurable, whose structure is closely related to their function, and whose function interacts directly with local environment. Ecometric trait distributions are thus a comparatively universal metric for exploring systems dynamics at all scales. The main challenge now is to move beyond investigating how future climate change will affect the distribution of organisms and how it will impact ecosystem services and to shift the perspective to ask how biotic systems interact with changing climate in general, and how climate change affects the interactions within and between the components of the whole biotic-physical system. We believe that it is possible to provide believable, quantitative answers to these questions. Because of this we have initiated an IUBS program iCCB (integrative Climate Change Biology). [source] Urban small vertebrate taphonomy: a case study from Anglo,Scandinavian YorkINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2001P.J. Piper Abstract Sampling of deposits at the Queens Hotel site, York, produced a substantial number of small terrestrial vertebrate remains from the Anglo,Scandinavian features. By studying bone surface modification, fragmentation and skeletal completeness as taphonomic indicators, it was possible to demonstrate that the assemblage had resulted from two very different modes of accumulation and deposition. Refuse pits situated within the boundaries of the tenements had acted as accumulators of the fragmented and abraded small mammal and amphibian bones that existed as a sub-surface death assemblage within the local environment. In contrast, the excellent preservation and skeletal completeness of numerous frogs recovered from the basal fill of a wooden well could be accounted for by their direct entry into the burial environment as a result of pit-fall trapping. This paper also discusses the implications that the temporal and spatial variation in deposition demonstrated by the micro-faunal remains has for the reconstruction of local ecological and environmental conditions within this site, and for other such sites. Copyright © 2001 John Wiley & Sons, Ltd. [source] Physical,statistical methods for determining state transition probabilities in mobile-satellite channel modelsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2001S. R. Saunders Abstract Signal propagation in land mobile satellite (LMS) communication systems has for the last decade become an essential consideration, especially when high-rate data services are involved. As far as urban or suburban built-up areas are concerned, the extent of the influence is mainly restricted to the roadside obstacles, since the satellite is positioned at relatively high elevation angles in most practical situations. Probably, the most common model currently used for representing the LMS channel is the Lutz model, which uses two states to represent line-of-sight and non-line-of-sight conditions. Transitions between these states are described by transition probabilities which are a function of the environment and the satellite elevation angles. Similarly, an extension to the model allows a four-state description to be used for the states associated with a pair of satellites used in a dual-diversity configuration. Calculation of the transition probabilities then requires knowledge of the correlation between the two channels, which in turn depends on the spatial characteristics of the local environment around the mobile. In both cases, the transition probabilities have been derived basically from measurements in the past. In the new approaches described in this paper, physical,statistical principles are applied to construct analytical formulas for the probabilities of shadowing and the correlation between states. These expressions apply particularly to systems operated in built-up environments, and have been checked against numerical experiments and against direct measurements. In both cases excellent agreement is obtained. Copyright © 2001 John Wiley & Sons, Ltd. [source] National-scale metacommunity dynamics of carabid beetles in UK farmlandJOURNAL OF ANIMAL ECOLOGY, Issue 2 2008David R. Brooks Summary 1Understanding the wide-scale processes controlling communities across multiple sites is a foremost challenge of modern ecology. Here, data from a nation-wide network of field sites are used to describe the metacommunity dynamics of arable carabid beetles. This is done by modelling how communities are structured at a local level, by changes in the environment of the sampled fields and, at a regional level, by fitting spatial parameters describing latitudinal and longitudinal gradients. 2Local and regional processes demonstrated independent and significant capacities for structuring communities. Within the local environment, crop type was found to be the primary determinant of carabid community composition. The regional component included a strong response to a longitudinal gradient, with significant increases in diversity in an east-to-west direction. 3Carabid metacommunities seem to be structured by a combination of species sorting dynamics, operating at two different, but equally important, spatial scales. At a local scale, species are sorted along a resource gradient determined by crop type. At a wider spatial scale species appear to be sorted along a longitudinal gradient. 4Nation-wide trends in communities coincided with known gradients of increased homogeneity of habitat mosaics and agricultural intensification. However, more work is required to understand fully how communities are controlled by the interaction of crops with changes in landscape structure at different spatial scales. 5We conclude that crop type is a powerful determinant of carabid biodiversity, but that it cannot be considered in isolation from other components of the landscape for optimal conservation policy. [source] Offshore renewable energy: ecological implications of generating electricity in the coastal zoneJOURNAL OF APPLIED ECOLOGY, Issue 4 2005ANDREW B. GILL Summary 1Global-scale environmental degradation and its links with non-renewable fossil fuels have led to an increasing interest in generating electricity from renewable energy resources. Much of this interest centres on offshore renewable energy developments (ORED). The large scale of proposed ORED will add to the existing human pressures on coastal ecosystems, therefore any ecological costs and benefits must be determined. 2The current pressures on coastal ecology set the context within which the potential impacts (both positive and negative) of offshore renewable energy generation are discussed. 3The number of published peer-review articles relating to renewable energy has increased dramatically since 1991. Significantly, only a small proportion of these articles relate to environmental impacts and none considers coastal ecology. 4Actual or potential environmental impact can occur during construction, operation and/or decommissioning of ORED. 5Construction and decommissioning are likely to cause significant physical disturbance to the local environment. There are both short- and long-term implications for the local biological communities. The significance of any effects is likely to depend on the natural disturbance regime and the stability and resilience of the communities. 6During day-to-day operation, underwater noise, emission of electromagnetic fields and collision or avoidance with the energy structures represent further potential impacts on coastal species, particularly large predators. The wider ecological implications of any direct and indirect effects are discussed. 7Synthesis and applications. This review demonstrates that offshore renewable energy developments will have direct and, potentially, indirect consequences for coastal ecology, with these effects occurring at different scales. Ecologists should be involved throughout all the phases of an ORED to ensure that appropriate assessments of the interaction of single and multiple developments with the coastal environment are undertaken. [source] Future eating and country keeping: what role has environmental history in the management of biodiversity?JOURNAL OF BIOGEOGRAPHY, Issue 5 2001D.M.J.S. Bowman In order to understand and moderate the effects of the accelerating rate of global environmental change land managers and ecologists must not only think beyond their local environment but also put their problems into a historical context. It is intuitively obvious that historians should be natural allies of ecologists and land managers as they struggle to maintain biodiversity and landscape health. Indeed, ,environmental history' is an emerging field where the previously disparate intellectual traditions of ecology and history intersect to create a new and fundamentally interdisciplinary field of inquiry. Environmental history is rapidly becoming an important field displacing many older environmentally focused academic disciplines as well as capturing the public imagination. By drawing on Australian experience I explore the role of ,environmental history' in managing biodiversity. First I consider some of the similarities and differences of the ecological and historical approaches to the history of the environment. Then I review two central questions in Australian environment history: landscape-scale changes in woody vegetation cover since European settlement and the extinction of the marsupials in both historical and pre-historical time. These case studies demonstrate that environmental historians can reach conflicting interpretations despite using essentially the same data. The popular success of some environmental histories hinges on the fact that they narrate a compelling story concerning human relationships and human value judgements about landscape change. Ecologists must learn to harness the power of environmental history narratives to bolster land management practices designed to conserve biological heritage. They can do this by using various currently popular environmental histories as a point of departure for future research, for instance by testing the veracity of competing interpretations of landscape-scale change in woody vegetation cover. They also need to learn how to write parables that communicate their research findings to land managers and the general public. However, no matter how sociologically or psychologically satisfying a particular environmental historical narrative might be, it must be willing to be superseded with new stories that incorporate the latest research discoveries and that reflects changing social values of nature. It is contrary to a rational and publicly acceptable approach to land management to read a particular story as revealing the absolute truth. [source] Role of D1 and E Cyclins in Cell Cycle Progression of Human Fibroblasts Adhering to Cementum Attachment Protein,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001Takayoshi Yokokoji Abstract Cementum attachment protein (CAP) is a collagenous protein present in the matrix of tooth cementum that mediates preferential attachment of some mesenchymal cell types, and CAP binding capacity is related to mineralizing tissue-forming capacity in culture. We have examined if adhesion to surfaces containing CAP as the only attachment protein permits human fibroblasts to escape G1 arrest and synthesize DNA, and if adhesion to CAP modulates the levels of cyclins D1 and E. Human gingival fibroblasts (HGFs) were serum-starved, trypsinized, and added to plates coated with CAP or bovine serum albumin (BSA). Cells were then exposed to either 10% fetal bovine serum (FBS) or to cementum-derived growth factor (CGF), an insulin-like growth factor I (IGF-I)-like molecule sequestered in tooth cementum, plus epidermal growth factor (EGF). DNA synthesis was measured as [3H]thymidine uptake, and cyclin D1 and E levels were determined by Western analysis. Cyclin E-dependent kinase (Cdk) activity was assessed in terms of H1 kinase activity in immunoprecipitates of cyclin E. Cells adhering to CAP synthesized DNA, whereas on BSA they remained unattached and did not synthesize DNA. Protein levels of cyclin D1 were higher in cells adhering to CAP in the absence and presence of growth factors. Cyclin E levels were not affected by adhesion alone, but they increased in the presence of growth factors. Cyclin E-associated kinase activity was higher in cells adherent on CAP, and it increased further in the presence of growth factors. Our results indicate that adhesion to CAP increases cyclin D1 levels and cyclin E-associated Cdk activity, and that these increases contribute to cell cycle progression. We previously observed that the signaling reactions induced during adhesion are characteristic of the CAP; together these observations indicate that specific matrix components present in the local environment can contribute to recruitment and differentiation of specific cell types for normal homeostasis and wound healing. [source] The influence of geographic and morphometric factors on the distribution of water bird species in small high altitude tropical man made reservoirs, Central Rift Valley, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Francis Mwaura Abstract Variability in waterfowl characteristics among eight high altitude (2040,2640 m) small shallow (0.065,0.249 km2; 0.9,3.1 m) reservoirs in the escarpment zone along the central rift valley in Kenya between Naivasha and Nakuru towns were studied between 1998 and 2000. The aim of the study was to establish whether the geographic status of small reservoirs in terms of altitude and surface gradient can affect the characteristics of their birdlife in terms of bird counts and species numbers. The study also aimed at establishing whether reservoir bird counts and species number can be predicted by reservoir morphometric factors especially water depth, surface area, length of shoreline and area-shoreline ratio. The other aim was to determine the influence of local environment especially distance from the nearest natural lakes, and house density on the birdlife. The findings showed that geographic location of the reservoirs in terms of altitude and landscape had a strong influence on birdlife whereby reservoirs in higher altitude and flat plateau landscape were found to support higher bird species and counts. Larger and deeper reservoirs were richer in water bird species but small and shallow reservoirs were superior in terms of both bird species and counts. Reservoirs with more coarse, irregular and highly erratic shorelines had higher species number than those with smooth and well-rounded shorelines. The reservoir birdlife was found to be influenced by the number of farm houses near the waterbodies and also the distance from the nearby rift valley lakes. The results showed that both geographic and morphometric considerations are necessary in the establishment of new reservoirs especially for utilization in birdlife conservation and ecotourism. Résumé Entre 1998 et 2000, nous avons étudié la variabilité des caractéristiques de l'avifaune aquatique de huit petits réservoirs peu profonds (0,065,0,249 km²; 0,9,3,1 m) de haute altitude (2040,2640 m) dans la région de l'escarpement de la Rift Valley située entre Naivasha et Nakuru, au Kenya. L'objectif de cette étude était d'établir si le statut géographique de réservoirs petits en termes d'altitude et de gradient de surface peut affecter les caractéristiques de leur avifaune en ce qui concerne le nombre d'oiseaux et d'espèces. L'étude visait aussi àétablir si l'on peut prédire la densité des oiseaux et le nombre d'espèces d'après les facteurs morphométriques du réservoir, et en particulier la profondeur de l'eau, la superficie de la surface, la longueur des berges et le rapport entre la superficie et la longueur de berges. L'autre objectif était de déterminer plus spécialement l'influence de la distance par rapport aux lacs naturels les plus proches et celle de la densité des habitations sur l'avifaune. Les résultats ont montré que la situation géographique des réservoirs en termes d'altitude et de paysage avait une forte influence sur l'avifaune, en ceci que les réservoirs de plus haute altitude et situés dans un paysage de plateau régulier accueillaient un plus grand nombre d'espèces et une plus forte densité d'oiseaux. Les réservoirs plus étendus et plus profonds étaient plus riches en espèces d'oiseaux d'eau, et les réservoirs plus petits et moins profonds étaient supérieurs en termes de nombre d'espèces d'oiseaux et de densité. Les réservoirs dont les berges étaient accidentées, instables et irrégulières avaient un nombre d'espèces plus élevé que ceux dont les berges étaient bien délimitées et planes. On a découvert que l'avifaune d'un réservoir était influencée par le nombre d'exploitations agricoles situées près du plan d'eau et aussi par la distance qui le séparait des lacs les plus proches de la Rift Valley. Les résultats ont montré qu'il faut tenir compte des données géographiques et morphométriques pour établir de nouveaux réservoirs, spécialement s'ils sont destinés à la conservation de l'avifaune et au tourisme. [source] Evaluation of extracts of Jatropha curcas and Moringa oleifera in culture media for selective inhibition of saprophytic fungal contaminantsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2009Grace Mebi Ayanbimpe Abstract Most fungi occur in nature and utilize simple sources of carbohydrates and nitrogen for growth. Sabouraud's dextrose agar has been an ideal medium for primary isolation of fungi from clinical specimens, but for specimens from nonsterile sites or heavily contaminated ones, it has been necessary to include inhibitory substances such as antibiotics like chloramphenicol (antibacterial) and cycloheximide (antifungal). The problems we have in the our laboratory owing to frequent contamination of cultures and the delays in the procurement of cycloheximide have stimulated a search for alternatives in our local environment to enhance effective laboratory diagnoses of fungal infections. Purified extracts of the leaves and bark of Jatropha curcas and Moringa oleifera (common plants in our locality) were tested against clinical isolates of fungi at various concentrations to determine the minimum inhibitory concentration at which common fungal contaminants are inhibited, without affecting the growth of the pathogenic fungi sought for. At a concentration of 0.75,mg,ml,1 contaminants were totally inhibited by the leaf extracts. The bark extracts did not inhibit any fungus even at higher concentrations. From the results it was evident that the leaf extracts of both plants have potentials for use as inhibitory substances in culture media against contaminant fungi including Aspergillus spp., Penicillium spp., etc. J. curcas and M. oleifera are very common plants in our locality. They can be obtained at almost no cost and at any time needed. The benefits of these findings to mycology laboratories in a developing country are enormous. J. Clin. Lab. Anal. 23:161,164, 2009. © 2009 Wiley-Liss, Inc. [source] Evaluation of semi-autonomous convoy drivingJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11-12 2008James Davis Autonomous mobility technologies may have applications to manned vehicle convoy operations,they have the ability to enhance both system performance and operator capability. This effort examines the potential impact of introducing semi-autonomous mobility [Convoy Active Safety Technologies (CAST)] into manned vehicles. Twelve civilians with experience driving military vehicles in convoy-type operations participated in this experiment. For the experiment, they were tasked with following a lead vehicle while completing a concurrent security task (scanning the local environment for targets). The control of the manned vehicle was varied between CAST and manual control at several different speed levels. Several objective speed and accuracy variables along with subjective operator assessment variables were examined for each task. The results support the potential benefits of incorporating semi-autonomous mobility technologies into manned vehicle convoy operations. The semi-autonomous mobility system was associated with significantly better performance in several aspects of operator situational awareness and convoy integrity, including enhanced target identification, improved maintenance of following distance, and improved performance for unanticipated stops. This experiment also highlighted a critical human factors issue associated with the incorporation of autonomy in real-world applications: participants felt that, overall, they outperformed the semi-autonomous system on the simulated convoy operation. The operator's perception of the system's performance could potentially affect his or her willingness to use the system in real-world applications. This experiment demonstrated that enhancements to overall system performance in real-world applications are achieved by considering both technological and human factors solutions. Published 2008 Wiley Periodicals, Inc., [source] | |||||||||||||||||||||||||||||||