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Selected AbstractsTransient concentration of a ,-tubulin-related protein with a pericentrin-related protein in the formation of basal bodies and flagella during the differentiation of Naegleria gruberiCYTOSKELETON, Issue 2 2002Mi Ra Suh Abstract The distribution of two proteins in Naegleria gruberi, N-,TRP (Naegleria ,-tubulin-related protein) and N-PRP (Naegleria pericentrin-related protein), was examined during the de novo formation of basal bodies and flagella that occurs during the differentiation of N. gruberi. After the initiation of differentiation, N-,TRP and N-PRP began to concentrate at the same site within cells. The percentage of cells with a concentrated region of N-,TRP and N-PRP was maximal (68%) at 40 min when the synthesis of tubulin had just started but no assembled microtubules were visible. When concentrated tubulin became visible (60 min), the region of concentrated N-,TRP and N-PRP was co-localized with the tubulin spot and then flagella began to elongate from the region of concentrated tubulin. When cells had elongated flagella, the concentrated N-,TRP and N-PRP were translocated to the opposite end of the flagellated cells and disappeared. The transient concentration of N-,TRP coincided with the transient formation of an F-actin spot at which N-,TRP and ,-tubulin mRNA were co-localized. The concentration of N-,TRP and formation of the F-actin spot occurred without the formation of microtubules but were inhibited by cytochalasin D. These observations suggest that the regional concentration of N-,TRP and N-PRP is mediated by actin filaments and might provide a site of microtubule nucleation for the assembly of newly synthesized tubulins into basal bodies and flagella. Cell Motil. Cytoskeleton 52:66,81, 2002. © 2002 Wiley-Liss, Inc. [source] A new approach to prioritizing marine fish and shellfish populations for conservationFISH AND FISHERIES, Issue 4 2001Einar Eg Nielsen Abstract There has been increasing awareness of the vulnerability of marine organisms to population extirpation and species extinction. While very few documented cases of species extinction exist in the marine environment, it is anticipated that managers will face the dilemma of prioritizing populations of marine fish and shellfish for protection in the near future. Current prioritization procedures have been developed from salmonid models with the intent of applying them to all marine organisms, and in some cases to freshwater and terrestrial taxa. In this review we provide evidence for the relevance of such a process for marine species and further suggest five broad categories of marine organisms that have distinctive traits influencing their genetic structure. The current prioritization models have been adapted to account for each of these species groups. Emphasis is placed on ,Classical Marine Species' which represent the opposite end of the continuum from the salmon model, displaying high within-population genetic variance. From this category, three cod (Gadus morhua) stocks were selected to evaluate a revised scheme developed specifically for ,Classical Marine Species' that includes performance measures such as (i) reduction in number of spawning populations; (ii) reduction of Ne : Nc (ratio of effective to census population size); (iii) changes in life-history traits; (iv) critical density for spawning success; and (v) patchy vs. continuous distribution pattern. When the salmonid scheme was applied, the cod examples were allocated low values, indicating that they were not under threat. However, when the revised scheme was applied, all three cod stocks were allocated high values, indicating that the revised scheme was more reflective of the particular life-history traits of this category of organisms. [source] Towards a predictive understanding of belowground process responses to climate change: have we moved any closer?FUNCTIONAL ECOLOGY, Issue 6 2008Elise Pendall Summary 1Belowground processes, including root production and exudation, microbial activity and community dynamics, and biogeochemical cycling interact to help regulate climate change. Feedbacks associated with these processes, such as warming-enhanced decomposition rates, give rise to major uncertainties in predictions of future climate. 2Uncertainties associated with these processes are more likely to be reduced if two key challenges can be met: increasing interdisciplinarity among researchers, and measuring belowground ecosystem structure and function at relevant spatial and temporal scales. For instance, recognizing the relationship between belowground primary production and soil respiration enhances modelling of global-scale C cycle temperature responses. At the opposite end of the spectrum, applying genomic techniques at the scale of microns improves mechanistic understanding of root,microbe interactions. 3Progress has been made in understanding interactions of belowground processes with climate change, although challenges remain. We highlight some of these advances and provide directions for key research needs in this Special Feature of Functional Ecology, which results from a symposium that was convened at the Soil Science Society of America National Meeting in November, 2006. [source] The Korean War and tourism: legacy of the war on the development of the tourism industry in South KoreaINTERNATIONAL JOURNAL OF TOURISM RESEARCH, Issue 3 2006Young-Sook Lee Abstract Although the development of tourism has been dominantly viewed and conceptualised in relation to the economic development of a region or a nation, some studies have argued that tourism fosters world peace. This argument, however, is not without some doubt for at the opposite end of the spectrum is that tourism might have a possible relationship with ,war'; the focus of this paper. This study, using qualitative research methods, traces the causes of the Korean War and its subsequent impacts upon the development of the tourism industry in South Korea. Findings indicate that the war had a significant impact upon the notion of tourism as a ,good' industry for society, which would bring benefits in the post-conflict era. Further, it created some ideas in society that purely consumptive travel is ,unpatriotic' and people should think about the interests of the nation when they travel. This paper concludes with a suggestion that future research should look into the ways in which tourism and tourists have developed where ,accumulation of capitalism' and changes in legislative moves, such as ,paid holidays' were not the initiating elements for a country's tourism development. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ecological biogeography of North American mammals: species density and ecological structure in relation to environmental gradientsJOURNAL OF BIOGEOGRAPHY, Issue 6 2000Catherine Badgley Abstract Aim, To evaluate the relationship of climate and physiography to species density and ecological diversity of North American mammals. Location, North America, including Mexico and Central America. Methods, Species density, size structure and trophic structure of mammalian faunas and nine environmental variables were documented for quadrats covering the entire continent. Spatial autocorrelation of species density and the environmental variables illustrated differences in their spatial structure at the continental scale. We used principal component analysis to reduce the dimensionality of the climatic variables, linear multiple regression to determine which environmental variables best predict species density for the continent and several regions of the continent, and canonical ordination to evaluate how well the environmental variables predict ecological structure of mammalian faunas over North America. Results, In the best regression model, five environmental variables, representing seasonal extremes of temperature, annual energy and moisture, and elevation, predicted 88% of the variation in species density for the whole continent. Among different regions of North America, the environmental variables that predicted species density vary. Changes in the size and trophic structure of mammalian faunas accompany changes in species density. Redundancy analysis demonstrated that environmental variables representing winter temperature, frostfree period, potential and actual evapotranspiration, and elevation account for 77% of the variation in ecological structure. Main conclusions, The latitudinal gradient in mammalian species density is strong, but most of it is explained by variation in the environmental variables. Each ecological category peaks in species richness under particular environmental conditions. The changes of greatest magnitude involve the smallest size categories (< 10 g, 11,100 g), aerial insectivores and frugivores. Species in these categories, mostly bats, increase along a gradient of decreasing winter temperature and increasing annual moisture and frostfree period, trends correlated with latitude. At the opposite end of this gradient, species in the largest size category (101,1000 kg) increase in frequency. Species in size categories 3 (101,1000 g), 5 (11,100 kg) and 6 (101,1000 kg), herbivores, and granivores increase along a longitudinal gradient of increasing annual potential evapotranspiration and elevation. Much of the spatial pattern is consistent with ecological sorting of species ranges along environmental gradients, but differential rates of speciation and extinction also may have shaped the ecological diversity of extant North American mammals. [source] Alpha-retinals as Rhodopsin Chromophores,Preference for the 9- Z Configuration and Partial Agonist Activity,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Yajie Wang The visual pigment rhodopsin, the photosensory element of the rod photoreceptor cell in the vertebrate retina, shows in combination with an endogenous ligand, 11- Z retinal, an astonishing photochemical performance. It exhibits an unprecedented quantum yield (0.67) in a highly defined and ultrafast photoisomerization process. This triggers the conformational changes leading to the active state Meta(rhodopsin) II. Retinal is covalently bound to Lys-296 of the protein opsin in a protonated Schiff base. The resulting positive charge delocalization over the terminal part of the polyene chain of retinal creates a conjugation defect that upon photoexcitation moves to the opposite end of the polyene. Shortening the polyene as in 4,5-dehydro,5,6-dihydro (alpha), 5,6-dihydro or 7,8-dihydro-analogs might facilitate photoisomerization of a 9- Z and a 11- Z bond. Here we describe pigment analogs generated with bovine opsin and 11- Z or 9- Z 4,5-dehydro,5,6-dihydro-retinal that were further characterized by UV,Vis and FTIR spectroscopy. The preference of opsin for native 11- Z retinal over the 9- Z isomer is reversed in 4,5-dehydro,5,6-dihydro-retinal. 9- Z 4,5-dehydro,5,6-dihydro-retinal readily generated a photosensitive pigment. This modification has no effect on the quantum yield, but affects the Batho,blueshifted intermediate (BSI) equilibrium and leads to a strong decrease in the G-protein activation rate because of a downshift of the pKa of the Meta I,Meta II equilibrium. [source] Ossification of the mouse metatarsal: Differentiation and proliferation in the presence/absence of a defined growth plateTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2006Philip L. Reno Abstract There is significant diversity in growth plate behavior among sites within an individual skeleton and between skeletons of different species. This variation within wild-type animals is an underutilized resource for studying skeletal development. One bone that potentially exhibits the most diverse behavior is the metatarsal. While one end forms a growth plate with an epiphyseal secondary center of ossification as in other long bones, the opposite end undergoes direct ossification in a manner more similar to short bones. Although descriptions of human metatarsal/metacarpal ossification are available, a detailed comparative analysis has yet to be conducted in an animal model amenable to biomolecular analysis. Here we report an analysis of proximal and distal ossification in an age series of mouse metatarsals. Safranin O staining was used for qualitative and quantitative histology, and chondrocyte differentiation and proliferation were analyzed using immunohistochemistry for type X collagen and proliferative cell nuclear antigen expression. We establish that, as in the human, both growth plate formation and direct ossification occur in the mouse metatarsal, with chondrocyte populations showing distinct differentiation patterns at opposite ends of the bone. In addition, growth plate formation is characterized by a peak of proliferation in reserve zone chondrocytes that distinguishes it from both established growth plates and direct ossification. Our analysis demonstrates that the mouse metatarsal is a productive model for investigating natural variation in ossification that can further understanding of vertebrate skeletal development and evolution. © 2005 Wiley-Liss, Inc. [source] Axonal secretion of reelin by cajal-retzius cells: Evidence from comparison of normal and RelnOrl mutant miceTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2001Paul Derer Abstract A novel secretory pathway has been identified in the study of mice homozygous for the RelnOrl mutation, a line characterised by the defective secretion of the large extracellular matrix glycoprotein Reelin. By using both light and electron microscopy, immunohistochemical studies for Reelin in these mutants identified morphological changes in their Cajal-Retzius cells (CR cells). The CR cells of the mutant displayed the characteristic features of bipolar, tangentially elongated neurons with a dendritic proximal pole and an axonal cone at the opposite end of the soma. At either pole, cisterns of prominent rough endoplasmic reticulum (RER) were found to be rich in Reelin. However, the Reelin-positive RER cisterns of the axonal cones were hugely dilated in homozygous RelnOrl mice as compared with their wild type counterparts. CR cell axons displayed beads throughout their length, each contained a smooth spheroidal cistern filled with Reelin-immunoreactive fibrillar material, and were increased in number and size in RelnOrl mice. RER phenotype was rescued in the RelnAlb2 mice, a mutation in which no Reelin protein is produced. We propose that the RER dilations viewed in the RelnOrl mutation are due to the accumulation of the defective Reelin protein, and the large axonal beads in RelnOrl mice reflect the accumulation of truncated Reelin as the result of defects in its secretion. These observations point to an original, hitherto unrecognised, mechanism of secretion by bulk transport in smooth cisterns from the axonal cone into the axon, followed by secretion in the cortical marginal zone from the axonal cisterns that we have named axonal reelin reservoirs. J. Comp. Neurol. 440:136,143, 2001. © 2001 Wiley-Liss, Inc. [source] Use of a branch wire to anchor stents for exact placement proximal to bifurcation stents: The reverse Szabo techniqueCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 6 2006Henry Lo MD Abstract This report describes a technique for correct positioning of a stent proximal to a bifurcation lesion treated with V-stents. A second wire passed through the first cell of a stent, the opposite end of the anchor wire technique as first described by Szabo et al, facilitated precise stent placement and eliminated erroneous positioning inside or outside the treated bifurcation lesion. © 2006 Wiley-Liss, Inc. [source] Non-atopic intrinsic asthma and the ,family tree' of chronic respiratory disease syndromesCLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2009P. G. Holt Summary We present a scheme below in which the most common forms of inflammatory diseases of the respiratory tract, notably atopic and non-atopic asthma and COPD, are depicted as separate offshoots from a common ,at-risk' pathway underpinned by genotypes related to aberrations in control of host defence and tissue repair mechanisms. We propose that entrance into this pathway is initially programmed by environmental experience during infancy and early childhood, in particular by severe lower respiratory tract infection, and that further progression towards expression of specific disease phenotype(s) is determined by the nature, timing and frequency of additional environmental insults subsequently encountered. At the one extreme, early sensitization of at-risk subjects to aeroallergens can potentially drive rapid progression towards expression of the atopic asthmatic phenotype under the dual onslaught of inflammatory responses to allergens/pathogens. At the opposite end of the spectrum the drip-feed effects of occasional infections on respiratory function(s) are amplified over a longer time frame by inflammation resulting from exposure to tobacco smoke and/or related chemical pollutants. Non-atopic asthma is envisaged to fit between these two extremes, being driven essentially by the downstream effects of respiratory infections alone in at-risk subjects. An important common factor in all three disease phenotypes is that acute exacerbations are typically driven by infections, the host responses to which display a characteristic T-helper type 2-like footprint, which in our view points to underlying genotype(s) which result in unbalanced host responses to respiratory pathogens. [source] Contactless Conductivity Detection in Capillary Electrophoresis: A ReviewELECTROANALYSIS, Issue 24 2004Pavel Kubá Abstract The popularity of contactless conductivity detection in capillary electrophoresis has been growing steadily over the last few years. Improvements have been made in the design of the detector in order to facilitate its handling, to allow easy incorporation into available instruments or to achieve higher sensitivity. The understanding of its fundamental working principles has been advanced and the detection approach has also been transferred to lab-on-chip devices. The range of applications has been extended greatly from the initial work on small inorganic ions to include organic species and biomolecules. Concurrent determination of cations and anions by dual injection from opposite ends has been demonstrated as well as sample introduction by using flow-injection systems for easy automation of the process. [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] Development and Evaluation of an Ultrasonic Ground Water Seepage MeterGROUND WATER, Issue 6 2001Ronald J. Paulsen Submarine ground water discharge can influence significantly the near-shore transport and flux of chemicals into the oceans. Quantification of the sources and rates of such discharge requires a ground water seepage meter that provides continuous measurements at high resolution over an extended period of time. An ultrasonic flowmeter has been adapted for such measurements in the submarine environment. Connected to a steel collection funnel, the meter houses two piezoelectric transducers mounted at opposite ends of a cylindrical flow tube. By monitoring the perturbations of fluid flow on the propagation of sound waves inside the flow tube, the ultrasonic meter can measure both forward and reverse fluid flows in real time. Laboratory and field calibrations show that the ultrasonic meter can resolve ground water discharges on the order of 0.1 ,m/sec, and it is sufficiently robust for deployment in the field for several days. Data from West Neck Bay, Shelter Island, New York, elucidate the temporal and spatial heterogeneity of submarine ground water discharge and its interplay with tidal loading. A negative correlation between the discharge and tidal elevation was generally observed. A methodology was also developed whereby data for the sound velocity as a function of temperature can be used to infer the salinity and source of the submarine discharge. Independent measurements of electrical conductance were performed to validate this methodology. [source] Temporal Elements in the Spatial Extension of Production NetworksGROWTH AND CHANGE, Issue 4 2006JOHAN WOXENIUS ABSTRACT The spatial extension of production networks presents a significant challenge to managers accustomed to reducing lead times by geographically contracting supply chains. This paper extends the theory on time in transportation by defining the elements of transport time, order time, timing, punctuality, and frequency and elaborating on their characteristics. Structured along these elements, it analyses the consequences of extending production networks from within a mature economic region, mainly the EU-15, U.S., and Japan, first to adjacent and then to nearby and finally distant low-cost regions. Distance obviously affects the transport quality in all time dimensions. Except for air parcel services that globally match what road transport offers within an economic region, the longer the distance, the lower the time-related performance. Distant, low-cost regions, meaning China and India, also imply a polarisation between air and sea transport at opposite ends of the time, cost, and capacity scales. This supply gap restricts the types of products traded. The conceptual framework is illustrated in the setting of a global vehicle manufacturer spatially extending its sourcing. It demands that sequenced sub-assemblies and small, cheap, and generic components are delivered from the vicinity of each assembly plant. Batched components can be sourced from adjacent regions, but deliveries from longer distances imply storage at pick-up points to fulfil their time requirements. Hence, the suppliers must offer the manufacturing firm deliveries as if they produce relatively close to the assembly plants. [source] Idiopathic Intracranial Hypertension and PostlumbarPuncture HeadacheHEADACHE, Issue 2 2004Yince Loh MD Idiopathic intracranial hypertension and low cerebrospinal pressure are 2 conditions that are thought to be on opposite ends of the cerebrospinal pressure spectrum. Headache is the prominent component of both conditions. We describe a patient whose evaluation for idiopathic intracranial hypertension resulted in a postlumbar puncture headache. Although not entirely intuitive, we suggest that the 2 conditions can be present in the same patient. [source] A comparison of HRM systems in the USA, Japan and Germany in their socio-economic contextHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 2 2006Markus Pudelko This article provides a comparative analysis of the HR practices of American, Japanese and German companies. The starting point is an investigation of the managerial, economic, socio-political and cultural contexts of the three HR systems. It will be demonstrated that the socio-economic contextual factors of the American and Japanese HR systems are in many ways at opposite ends of the spectrum, with the German factors in between. Subsequently, the three HR systems themselves are analysed. The data show that the same pattern, USA and Japan at the extremes and Germany taking a middle position, is valid also for the HR systems. This suggests that the relevant socio-economic context is highly pertinent for the establishment of an HR system. This outcome does not exclude either the integration of HR practices from a foreign HR model into the domestic one or standardisation efforts of HR practices of multinational companies, but confines the potential for cross-cultural learning and standardisation to what is within the ,fit' of the relevant socio-cultural context. [source] The relationship of total and per-gram rankings in competitive effect to the natural abundance of herbaceous perennialsJOURNAL OF ECOLOGY, Issue 1 2001Timothy G. Howard Summary 1,Using a field experiment and a garden experiment, I estimated the rankings in total and per-gram competitive effect of non-woody perennial old-field species. 2,Total competitive effects were defined as the relative reduction in growth of a target from no-neighbour to with-neighbour conditions. Per-gram competitive effects were defined as the per-unit relative reduction in target growth among increasing neighbour densities, and were determined from the shape of a nonlinear curve fit through a distribution of normalized target performance against neighbour mass. 3,In both experiments, mean total competitive effect differed significantly among species, indicating a strong competitive hierarchy. In the garden experiment only species at opposite ends of the ranking differed significantly in per-gram competitive effect, resulting in a weaker competitive hierarchy based on this measure. 4,Nonetheless, rankings of per-gram competitive effect were more strongly correlated with rank in abundance than were rankings of total competitive effect. 5,Per-gram competitive effect may be more predictive of natural abundance than total competitive effect for at least two reasons. The effects of neighbour abundance on targets are nonlinear, and unlike total effects, per-gram estimates of competitive effect may therefore indicate how competition changes over time with changing neighbour densities. Also, if higher per-gram competitive effect reflects higher per-unit nutrient uptake rates, it would probably be advantageous to a species throughout the individual's life span, rather than only when the individual is larger than its surrounding neighbours. [source] Conformational restrictions in the active site of unliganded human caspase-3JOURNAL OF MOLECULAR RECOGNITION, Issue 3 2003Chao-Zhou Ni Abstract Caspases are cysteine proteases that play a critical role in the initiation and regulation of apoptosis. These enzymes act in a cascade to promote cell death through proteolytic cleavage of intracellular proteins. Since activation of apoptosis is implicated in human diseases such as cancer and neurodegenerative disorders, caspases are targets for drugs designed to modulate their action. Active caspases are heterodimeric enzymes with two symmetrically arranged active sites at opposite ends of the molecule. A number of crystal structures of caspases with peptides or proteins bound at the active sites have defined the mechanism of action of these enzymes, but molecular information about the active sites before substrate engagement has been lacking. As part of a study of peptidyl inhibitors of caspase-3, we crystallized a complex where the inhibitor did not bind in the active site. Here we present the crystal structure of the unoccupied substrate-binding site of caspase-3. No large conformational differences were apparent when this site was compared with that in enzyme-inhibitor complexes. Instead, the 1.9,Ĺ structure reveals critical side chain movements in a hydrophobic pocket in the active site. Notably, the side chain of tyrosine204 is rotated by ,90° so that the phenol group occupies the S2 subsite in the active site. Thus, binding of substrate or inhibitors is impeded unless rotation of this side chain opens the area. The positions of these side chains may have important implications for the directed design of inhibitors of caspase-3 or caspase-7. Copyright © 2003 John Wiley & Sons, Ltd. [source] Live imaging of fluorescent proteins in chordate embryos: From ascidians to miceMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2006Yale J. Passamaneck Abstract Although we have advanced in our understanding of the molecular mechanisms intrinsic to the morphogenesis of chordate embryos, the question of how individual developmental events are integrated to generate the final morphological form is still unresolved. Microscopic observation is a pivotal tool in developmental biology, both for determining the normal course of events and for contrasting this with the results of experimental and pathological perturbations. Since embryonic development takes place in three dimensions over time, to fully understand the events required to build an embryo we must investigate embryo morphogenesis in multiple dimensions in situ. Recent advances in the isolation of naturally fluorescent proteins, and the refinement of techniques for in vivo microscopy offer unprecedented opportunities to study the cellular and molecular events within living, intact embryos using optical imaging. These technologies allow direct visual access to complex events as they happen in their native environment, and thus provide greater insights into cell behaviors operating during embryonic development. Since most fluorescent protein probes and modes of data acquisition are common across species, we have chosen the mouse and the ascidian, two model organisms at opposite ends of the chordate clade, to review the use of some of the current genetically-encoded fluorescent proteins and their visualization in vivo in living embryos for the generation of high-resolution imaging data. Microsc. Res. Tech. 69:160,167, 2006. © 2006 Wiley-Liss, Inc. [source] The Relationship between Cultural Values and Political Ideology, and the Role of Political KnowledgePOLITICAL PSYCHOLOGY, Issue 1 2009Kristy E. H. Michaud Cultural theory maintains that four worldviews,egalitarianism, individualism, hierarchicalism, and fatalism,can be used to describe people and societies. We examine survey measures of two of those worldviews,egalitarianism and individualism,to understand their relationship with belief systems. Contrary to what one might expect based on the cultural theory literature, we find that people with low levels of political knowledge seem not to have coherent worldviews regarding these issues. In contrast, people with high levels of political knowledge respond to egalitarianism and individualism questions as if they were opposite ends of a single, liberal-conservative continuum, rather than two of four distinct worldviews. We conclude that cultural theory researchers should take account of the influence of political knowledge whenever they investigate worldviews. [source] Analysis of leakage currents in photovoltaic modules under high-voltage bias in the field,PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2002J. A. del Cueto As photovoltaic modules become more widely disseminated in high-power or utility-power applications, their ability to withstand high voltage relative to ground becomes a reliability issue. Long-term effects of exposure to high-voltage stress in the field are investigated. Starting in early 1998, four commercially available PV modules inaugurated the high-voltage stress test at the Outdoor Test Facility at NREL. Modules representing both crystalline and amorphous silicon technologies were deployed on the high-voltage stress testbed located outdoors in order to simulate and assess operation in high-voltage array configurations. They were biased at positive and negative polarity 600 V at all times,except for 1 min at noon each day, when they were subjected to 2200 V bias,and their leakage currents to ground were monitored continuously. The ubiquitous effects of moisture on leakage conductance are analyzed. Module leakage conductance is found to be thermally activated with a characteristic energy that depends on relative humidity. Separate current paths likely responsible for leakage conductance are analyzed and identified at opposite ends of the relative humidity range. Leakage current data are integrated against time to arrive at accumulated charge due to long-term, high-voltage exposure. Published in 2002 by John Wiley & Sons, Ltd. [source] Ossification of the mouse metatarsal: Differentiation and proliferation in the presence/absence of a defined growth plateTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2006Philip L. Reno Abstract There is significant diversity in growth plate behavior among sites within an individual skeleton and between skeletons of different species. This variation within wild-type animals is an underutilized resource for studying skeletal development. One bone that potentially exhibits the most diverse behavior is the metatarsal. While one end forms a growth plate with an epiphyseal secondary center of ossification as in other long bones, the opposite end undergoes direct ossification in a manner more similar to short bones. Although descriptions of human metatarsal/metacarpal ossification are available, a detailed comparative analysis has yet to be conducted in an animal model amenable to biomolecular analysis. Here we report an analysis of proximal and distal ossification in an age series of mouse metatarsals. Safranin O staining was used for qualitative and quantitative histology, and chondrocyte differentiation and proliferation were analyzed using immunohistochemistry for type X collagen and proliferative cell nuclear antigen expression. We establish that, as in the human, both growth plate formation and direct ossification occur in the mouse metatarsal, with chondrocyte populations showing distinct differentiation patterns at opposite ends of the bone. In addition, growth plate formation is characterized by a peak of proliferation in reserve zone chondrocytes that distinguishes it from both established growth plates and direct ossification. Our analysis demonstrates that the mouse metatarsal is a productive model for investigating natural variation in ossification that can further understanding of vertebrate skeletal development and evolution. © 2005 Wiley-Liss, Inc. [source] Developmental changes in responsiveness to parents and unfamiliar adults in a monogamous monkey (Callicebus moloch)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2002D.J. Mayeaux Abstract Titi monkeys (Callicebus moloch) are monogamous New World primates that are characteristically found in family-type groups consisting of a mated adult pair and one or two young. The factors maintaining the small size of these groups are not known. Based on observations of free-ranging and captive families, parental aggression toward older offspring seems unlikely to play a significant role. Maturing individuals themselves, however, could undergo behavioral changes that weaken ties to their natal group. These might include waning of affiliative relations with parents, or subtle forms of aversion. Independent of such changes, increasing interest in unfamiliar conspecifics could be a factor. We examined these possibilities in the present study by assessing changes in social behavior and social preferences from initial ambulatory independence (6 months) through reproductive maturity (24 months) in a combined cross-sectional/longitudinal study of 21 captive titi monkeys living with their parents. Responses to both parents and to an unfamiliar adult heterosexual pair, a single unfamiliar adult male, and a single unfamiliar adult female were observed when subjects were given a choice between parents and strangers presented simultaneously or as the only social incentive. Social stimuli were at opposite ends of a 16.8-m-long test corridor. Subjects could move freely about the corridor for 5 min with each configuration of social stimuli. They stayed closer to parents than to strangers at all ages. Responsiveness to strangers increased with age and suggested growing ambivalence, particularly toward the male stranger. As they approached 24 months of age, male subjects showed a dramatic increase in the frequency and intensity of agonistic behaviors toward male strangers, behaviors that were rarely directed toward female strangers or parents. Waning of attraction to parents may be less important in dispersal from the natal group than changing reactions to strangers. Am. J. Primatol. 58:71,89, 2002. © 2002 Wiley-Liss, Inc. [source] Structure of a mutant T = 1 capsid of Sesbania mosaic virus: role of water molecules in capsid architecture and integrityACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2005V. Sangita Deletion of the N-terminal 31 amino acids from the coat protein (CP) of Sesbania mosaic virus (SeMV) results in the formation of T = 1 capsids. The X-ray crystal structure of CP-N,31 mutant capsids reveals that the CP adopts a conformation similar to those of other T = 1 mutants. The 40 N-terminal residues are disordered in CP-N,31. The intersubunit hydrogen bonds closely resemble those of the native capsid. The role of water molecules in the SeMV structure has been analyzed for the first time using the present structure. As many as 139 of the 173 waters per subunit make direct contacts with the protein atoms. The water molecules form a robust scaffold around the capsid, stabilize the loops and provide integrity to the subunit. These waters constitute a network connecting diametrically opposite ends of the subunit. Such waters might act as nodes for conveying signals for assembly or disassembly across a large conformational space. Many water-mediated interactions are observed at various interfaces. The twofold interface, which has the smallest number of protein,protein contacts, is primarily held by water-mediated interactions. The present structure illuminates the role of water molecules in the structure and stability of the capsid and points out their possible significance in assembly. [source] Highly selective single nucleotide polymorphism recogniton by a chiral (5S) PNA beacon,CHIRALITY, Issue 1 2009Filbert Totsingan Abstract A chiral peptide nucleic acid (PNA) beacon containing a C-5 modified monomer based on L-lysine was synthesized. The terminal amino group of the lysine side chain was linked to a spacer for future applications on surfaces. The PNA beacon bears a carboxyfluorescein fluorophore and a dabcyl quencher at opposite ends. The DNA binding properties were compared with those of a homologous PNA beacon containing only achiral monomers. Both beacons underwent a fluorescence increase in the presence of complementary DNA, with higher efficiency and higher selectivity (evaluated using single mismatched DNA sequences) observed for the chiral monomer containing PNA. Ion exchange (IE) HPLC with fluorimetric detection was used in combination with the beacon for the selective detection of complementary DNA. A fluorescent peak corresponding to the PNA beacon:DNA duplex was observed at a very low detection limit (1 nM). The discriminating capacity of the chiral PNA beacon for a single mismatch was found to be superior to those observed with the unmodified one, thus confirming the potency of chirality for increasing the affinity and specificity of DNA recognition. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||