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Surface Environment (surface + environment)
Selected AbstractsUse of episcopic differential interference contrast microscopy to identify bacterial biofilms on salad leaves and track colonization by Salmonella ThompsonENVIRONMENTAL MICROBIOLOGY, Issue 4 2008J. C. Warner Summary Zoonotic pathogens such as Salmonella can cause gastrointestinal illness if they are ingested with food. Foods such as salads pose a greater risk because they are consumed raw and have been the source of major outbreaks of disease from fresh produce. The novel light microscopy methods used in this study allow detailed, high resolution imaging of the leaf surface environment (the phyllosphere) and allow pathogen tracking. Episcopic differential interference contrast microscopy coupled with epifluorescence was used to view the natural microflora in situ on salad leaves and their topographical distribution. Fluorescent nucleic acid staining was used to differentiate between bacterial colonists and inorganic debris. Salmonella enterica serovar Thompson expressing green fluorescent protein was inoculated onto individual spinach leaves for 24 h at 22°C in order to observe spatial and temporal patterning of colonization on the two surfaces of each leaf under different osmotic conditions. The results obtained show that salad leaves are host to high numbers of bacteria, typically 105 per square millimetre. Cells are present in complex three-dimensional aggregations which often have a slimy appearance, suggesting the presence of biofilms. Washing of the leaves had little effect on the number of adherent pathogens, suggesting very strong attachment. Episcopic differential interference contrast microscopy is a rapid alternative to both scanning electron microscopy and confocal laser scanning microscopy for visualizing leaf topography and biofilm formation in the natural state. [source] Mapping the archaeological soil archive of sand and gravel mineral reserves in BritainGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2009Ingrid Ward Primary sand and gravel deposits in Britain play an important role in preserving our cultural heritage and are also a valuable aggregate resource. While an understanding of the extrinsic properties of the soil archive (such as pH, redox, groundwater) can provide a firstorder assessment of the potential risk to any archaeologically sensitive deposits, we have very poor definition of spatial variations in the extrinsic properties of soil that influence archaeological preservation at a regional and national scale. Developments in digital geological mapping, remote sensing, and geochemical survey data undertaken by the British Geological Survey (BGS) have, however, significantly extended capabilities in this respect and can potentially be used to provide a primary assessment of the sensitivity of the present soil archive and the potential risk from changes to the soil process on cultural material in areas earmarked for aggregate extraction. Two of the major factors affecting archaeological preservation,soil acidification and groundwater,can be mapped or predicted at scales of better than 1:50,000 across increasingly large parts of the country using a combination of regional hydrogeological, geophysical, and geochemical data. Additional data from site investigations may further refine preservation potential as a function of changes in redox potential and acidity. These data, maps and models can be used to (1) better establish a baseline for archaeological preservation at a regional and national scale and (2) improve our understanding of how the physical and chemical properties of the near surface environment can be managed to sustainably preserve archaeological materials in areas impacted by sand and gravel extraction. © 2009 Wiley Periodicals, Inc. [source] Mass-independent fractionation of sulfur isotopes in sulfides from the pre-3770 Ma Isua Supracrustal Belt, West GreenlandGEOBIOLOGY, Issue 4 2006D. PAPINEAU ABSTRACT Redox chemistry of the coupled atmosphere,hydrosphere system has coevolved with the biosphere, from global anoxia in the Archean to an oxygenated Proterozoic surface environment. However, to trace these changes to the very beginning of the rock record presents special challenges. All known Eoarchean (c. 3850,3600 Ma) volcanosedimentary successions (i.e. supracrustal rocks) are restricted to high-grade gneissic terranes that seldom preserve original sedimentary structures and lack primary organic biomarkers. Although complicated by metamorphic overprinting, sulfur isotopes from Archean supracrustal rocks have the potential to preserve signatures of both atmospheric chemistry and metabolic fractionation from the original sediments. We present a synthesis of multiple sulfur isotope measurements (32S, 33S and 34S) performed on sulfides from amphibolite facies banded iron-formations (BIFs) and ferruginous garnet-biotite (metapelitic) schists from the pre-3770 Ma Isua Supracrustal Belt (ISB) in West Greenland. Because these data come from some of the oldest rocks of interpretable marine sedimentary origin, they provide the opportunity to (i) explore for possible biosignatures of sulfur metabolisms in early life; (ii) assess changes in atmospheric redox chemistry from ,3.8 Ga; and (iii) lay the groundwork to elucidate sulfur biogeochemical cycles on the early Earth. We find that sulfur isotope results from Isua do not unambiguously indicate microbially induced sulfur isotopic fractionation at that time. A significantly expanded data set of ,33S analyses for Isua dictates that the atmosphere was devoid of free oxygen at time of deposition and also shows that the effects of post-depositional metamorphic remobilization and/or dilution can be traced in mass-independently fractionated sulfur isotopes. [source] Pressure gradient force, atmospheric circulation and climate in western Europe (1899,2002)INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2007Pierre P. Kastendeuch Abstract One mission of synoptic climatology is to quantify the link between atmospheric circulation and surface environment. The pressure gradient force (PGF) is used as a multiple index to summarize the monthly atmospheric circulation for a site in western Europe (5°E and 50°N). The study of the temporal evolution of the PGF components (direction, magnitude, X and Y components) was carried out for the period 1899,2002. The results reflect the variability in atmospheric circulation and reveal some trends. The magnitude of the PGF is particularly affected by several successive periods where the strength of the atmospheric flow was lower (negative trend) or higher (positive trend) than normal. During the last decades of the twentieth century the atmospheric flow appears stronger than before (positive trend), except in summer. As the direction of the PGF can be related to the trajectory of the flow via the Buys,Ballot law, its anomalies are directly related to anomalies in the advection of air masses. No definite trend can be detected for this variable. However, it seems that the northerly flow becomes rare in winter. The relevance of the PGF is also examined with regard to the evolution of monthly temperatures and precipitations via some series of multiple regressions. The best results are obtained for the precipitations, with an explained variance lying between 47 and 73% (respectively in May and February). For temperatures, the explained variance oscillates between 34 and 73% (in September and January). The fact that the meridional and zonal components of the PGF, and the absolute pressure at the site are explicitly taken into account, ensures a good quantification of the atmospheric circulation ,anomalies', that are largely responsible for the annual, seasonal or monthly singularities of temperature and precipitation over western Europe. Copyright © 2007 Royal Meteorological Society [source] Fossil testate amoebae in coastal deposits in the UK: implications for studies of sea-level changeJOURNAL OF QUATERNARY SCIENCE, Issue 5-6 2002Helen M. Roe Abstract Assemblages of testate amoebae in UK saltmarshes are strongly correlated with elevation and flooding duration, suggesting that if adequately preserved in sediments they may be used as accurate sea-level indicators. To examine the preservation of testate amoebae in the fossil record in coastal environments, subsamples were collected from a range of coastal sites around Britain, including saltmarsh, coastal reedswamp, isolation basin, back-barrier and coastal raised bog sites. The results showed that testate amoebae are present in the fossil record, although in variarble species diversities, concentrations and states of preservation. Testate amoebae were found to be well preserved in isolation basin infills and coastal raised bog deposits, where diverse assemblages (>20 taxa) were recorded. In the upper part of the isolation basin sequence from Loch nan Corr, northwest Scotland, the testate amoebae assemblages showed a greater degree of sensitivity to transitional salinity changes than existing foraminferal and larger testate amoebae data sets. This implies that testate amoebae, particularly small to medium-sized specimens (15,300 µm), may hold considerable potential for sea-level reconstruction in these environments. Preservation of testate amoebae in a freshly sampled core of saltmarsh sediment from South Wales was reasonable, although test distribution decreased significantly in abundance below 18 cm. The assemblage composition was similar to that found in the contemporary surface environment. The preservation of testate amoebae in saltmarsh and coastal reedswamp deposits of mid-Holocene age was variable and generally poor. Partial dehydration of the sediment samples may account for this. Further studies are required to examine the palaeoecology and distribution of testate amoebae in similar coastal settings, to strengthen these preliminary findings. Copyright © 2002 John Wiley & Sons, Ltd. [source] A petrological, mineralogical, and chemical analysis of the lunar mare basalt meteorite LaPaz Icefield 02205, 02224, and 02226METEORITICS & PLANETARY SCIENCE, Issue 7 2006Katherine H. Joy They consist mainly of zoned pyroxene and plagioclase grains, with minor ilmenite, spinel, and mesostasis regions. Large, possibly xenocrystic, forsteritic olivine grains (<3% by mode) contain small trapped multiphase melt inclusions. Accessory mineral and mesostasis composition shows that the samples have experienced residual melt crystallization with silica oversaturation and late-stage liquid immiscibility. Our section of LAP 02224 has a vesicular fusion crust, implying that it was at one time located sufficiently close to the lunar surface environment to have accumulated solar-wind-implanted gases. The stones have a comparable major element composition and petrography to low-Ti, low-Al basalts collected at the Apollos 12 and 15 landing sites. However, the LAP stones also have an enriched REE bulk composition and are more ferroan (Mg numbers in the range of 31 to 35) than similar Apollo samples, suggesting that they represent members of a previously unsampled fractionated mare basalt suite that crystallized from a relatively evolved lunar melt. [source] Proteomic analysis of conjucntival swab by mass spectrometryACTA OPHTHALMOLOGICA, Issue 2007V MCGILLIGAN Purpose: The purpose of this study was to identify proteins present in the tears and mucosal epithelium of the ocular surface. Methods: A cotton swab was rubbed across the anaesthetized inferior conjunctiva of a dry eye patient. Protein was extracted and subjected to 1D gel electrophoresis. After excision and trypsinisation, protein profiles from swab samples were identified using mass spectrometry carried out on a 3200 Q-TRAP Hybrid ESI Quadropole linear ion trap. Protein identification was performed using MASCOT software against a human database extracted from NCBI. Curation of the protein list was achieved using the bioinformatics tool PROVALT, which also calculated false-discovery rates. Results: In total 75 validated proteins were identified including the tear proteins, lactotransferrin, lysozyme, and proline rich proteins as well as a number of proteins not previously associated with the tear proteome. Proteins identified had a wide range of physio-chemical properties and included structural and functional proteins. Conclusions: Use of a simple swab combined with a GeLC-MS proteomic protocol led to unequivocal identification of a large range of proteins associated with the ocular surface proteome. This may allow a better characterisation of the ocular surface environment and discrimination between various eye conditions. Tear collection using capillaries can be tedious and may discourage clinicians from performing such a test. Use of a swab that can be frozen for analysis may encourage the use of this methodology. Analysis of this proteome offers huge clinical potential for investigation of ocular surface biomarkers for the development of novel diagnostic tools and monitoring of ocular disease. [source] Novel Brush Polymers with Phosphorylcholine Bristle Ends: Synthesis, Structure, Properties, and BiocompatibilityADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Gahee Kim Abstract New brush polymers with various numbers of bristle ends incorporating phosphorylcholine (PC) moieties are synthesized. The polymers are thermally stable up to 175,°C and form good-quality films with conventional spin-, roll-, and dip-coating, and subsequent drying processes. Interestingly, all these brush polymers, as a PC-containing polymer, demonstrate a stable molecular multi-bilayer structure in thin films that arise due to the efficient self-assembly of the bristles for temperatures <55,°C and PC-rich surfaces, and therefore successfully mimic natural cell-membrane surfaces. These brush-polymer films exhibit excellent water wettability and water sorption whilst retaining the remarkable molecular multi-bilayer structure, and thus have hydrophilic surfaces. These novel multi-bilayer structured films repel fibrinogen molecules and platelets from their surfaces but also have bactericidal effects on bacteria. Moreover, the brush-polymer films are found to provide comfortable surface environments for the successful anchoring and growth of HEp-2 cells, and to exhibit excellent biocompatibility in mice. These newly developed brush polymers are suitable for use in biomedical applications including medical devices and biosensors that require biocompatibility and the reduced possibility of post-operative infection. [source] | ||||||||||