2,811 research outputs found

    A unique assemblage of cosmopolitan freshwater bacteria and higher community diversity differentiate an urbanized estuary from oligotrophic Lake Michigan

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    Water quality is impacted significantly by urbanization. The delivery of increased nutrient loads to waterways is a primary characteristic of this land use change. Despite the recognized effects of nutrient loading on aquatic systems, the influence of urbanization on the bacterial community composition of these systems is not understood. We used massively-parallel sequencing of bacterial 16S rRNA genes to examine the bacterial assemblages in transect samples spanning the heavily urbanized estuary of Milwaukee, WI to the relatively un-impacted waters of Lake Michigan. With this approach, we found that genera and lineages common to freshwater lake epilimnia were common and abundant in both the high nutrient, urban-impacted waterways and the low nutrient Lake Michigan. Although the two environments harbored many taxa in common, we identified a significant change in the community assemblage across the urban-influence gradient, and three distinct community features drove this change. First, we found the urban-influenced waterways harbored significantly greater bacterial richness and diversity than Lake Michigan (i.e. taxa augmentation). Second, we identified a shift in the relative abundance among common freshwater lineages, where acI, acTH1, Algoriphagus and LD12, had decreased representation and Limnohabitans, Polynucleobacter, and Rhodobacter had increased representation in the urban estuary. Third, by oligotyping 18 common freshwater genera/lineages, we found that oligotypes (highly resolved sequence clusters) within many of these genera/lineages had opposite preferences for the two environments. With these data, we suggest many of the defined cosmopolitan freshwater genera/lineages contain both oligotroph and more copiotroph species or populations, promoting the idea that within-genus lifestyle specialization, in addition to shifts in the dominance among core taxa and taxa augmentation, drive bacterial community change in urbanized waters

    Induction of Colonic Aberrant Crypts in Mice by Feeding Apparent N-Nitroso Compounds Derived From Hot Dogs

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    Nitrite-preserved meats (e.g., hot dogs) may help cause colon cancer because they contain N-nitroso compounds. We tested whether purified hot-dog-derived total apparent N-nitroso compounds (ANC) could induce colonic aberrant crypts, which are putative precursors of colon cancer. We purified ANC precursors in hot dogs and nitrosated them to produce ANC. In preliminary tests, CF1 mice received 1 or 3 i.p. injections of 5mg azoxymethane (AOM)/kg. In Experiments 1 and 2, female A/J mice received ANC in diet. In Experiment 1, ANC dose initially dropped sharply because the ANC precursors had mostly decomposed but, later in Experiment 1 and throughout Experiment 2, ANC remained at 85 nmol/g diet. Mice were killed after 8 (AOM tests) or 17–34 (ANC tests) wk.Median numbers of aberrant crypts in the distal 2 cm of the colon for 1 and 3 AOMinjections, CF1 controls, ANC (Experiment 1), ANC (Experiment 2),and untreated A/J mice were 31, 74, 12, 20, 12, and 5–6, with P < 0.01 for both ANC tests. Experiment 2 showed somewhat increased numbers of colonic mucin-depleted foci in the ANC-treated group. We conclude that hot-dog-derived ANC induced significant numbers of aberrant crypts in the mouse colon

    Recruiting and retaining community researchers for a historical research project

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    This article explores how we recruited and retained a diverse group of community researchers from groups who faced barriers to engaging with research. All were mothers of preschool or primary age children, and fitted one or more of the following criteria: single parent, English as an additional language, first-generation migrant, inner-city resident. We explore the process of recruitment, and making the project accessible, as well as describing the factors that allowed researchers to remain engaged with the project over the course of a year. A dedicated community support worker played a crucial role in resolving barriers to participation, and supporting researchers’ well-being and personal development once they were in the group. The article identifies five key challenges encountered across the lifetime of the project, and the strategies we used to address them. We hope our reflections and practical suggestions will make a contribution to the understanding of how people with multiple accessibility challenges can be supported to take part in, and make an essential contribution to, community–university research projects

    The microbiome of urban waters

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    More than 50% of the world&rsquo;s population lives in urban centers. As collection basins for landscape activity, urban waters are an interface between human activity and the natural environment. The microbiome of urban waters could provide insight into the impacts of pollution, the presence of human health risks, or the potential for long-term consequences for these ecosystems and the people who depend upon them. An integral part of the urban water cycle is sewer infrastructure. Thousands of miles of pipes line cities as part of wastewater and stormwater systems. As stormwater and sewage are released into natural waterways, traces of human and animal microbiomes reflect the sources and magnitude of fecal pollution and indicate the presence of pollutants, such as nutrients, pathogens, and chemicals. Non-fecal organisms are also released as part of these systems. Runoff from impervious surfaces delivers microbes from soils, plants and the built environment to stormwater systems. Further, urban sewer infrastructure contains its own unique microbial community seemingly adapted to this relatively new artificial habitat. High microbial densities are conveyed via pipes to waterways, and these organisms can be found as an urban microbial signature imprinted on the natural community of rivers and urban coastal waters. The potential consequences of mass releases of non-indigenous microorganisms into natural waters include creation of reservoirs for emerging human pathogens, altered nutrient flows into aquatic food webs, and increased genetic exchange between two distinct gene pools. This review highlights the recent characterization of the microbiome of urban sewer and stormwater infrastructure and its connection to and potential impact upon freshwater systems. [Int Microbiol 18(3):141-149 (2015)]Keywords: urban freshwaters &middot; infrastructure and sanitation &middot; next generation sequencing &middot; human health &middot; aquatic food web

    Comparison of bacterial communities in sands and water at beaches with bacterial water quality violations

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    © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 9 (2014): e90815, doi:10.1371/journal.pone.0090815.Recreational water quality, as measured by culturable fecal indicator bacteria (FIB), may be influenced by persistent populations of these bacteria in local sands or wrack, in addition to varied fecal inputs from human and/or animal sources. In this study, pyrosequencing was used to generate short sequence tags of the 16S hypervariable region ribosomal DNA from shallow water samples and from sand samples collected at the high tide line and at the intertidal water line at sites with and without FIB exceedance events. These data were used to examine the sand and water bacterial communities to assess the similarity between samples, and to determine the impact of water quality exceedance events on the community composition. Sequences belonging to a group of bacteria previously identified as alternative fecal indicators were also analyzed in relationship to water quality violation events. We found that sand and water samples hosted distinctly different overall bacterial communities, and there was greater similarity in the community composition between coastal water samples from two distant sites. The dissimilarity between high tide and intertidal sand bacterial communities, although more similar to each other than to water, corresponded to greater tidal range between the samples. Within the group of alternative fecal indicators greater similarity was observed within sand and water from the same site, likely reflecting the anthropogenic contribution at each beach. This study supports the growing evidence that community-based molecular tools can be leveraged to identify the sources and potential impact of fecal pollution in the environment, and furthermore suggests that a more diverse bacterial community in beach sand and water may reflect a less contaminated site and better water quality.This work was supported by the National Science Foundation grant OCE-0430724, and the National Institute of Environmental Health Sciences grant P0ES012742 to the Woods Hole Center for Ocean and Human Health. E. Halliday was partially supported by WHOI Academic Programs and grants from the WHOI Ocean Ventures Fund and the WHOI Coastal Ocean Institute

    Stress corrosion in titanium alloys and other metallic materials

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    Multiple physical and chemical techniques including mass spectroscopy, atomic absorption spectroscopy, gas chromatography, electron microscopy, optical microscopy, electronic spectroscopy for chemical analysis (ESCA), infrared spectroscopy, nuclear magnetic resonance (NMR), X-ray analysis, conductivity, and isotopic labeling were used in investigating the atomic interactions between organic environments and titanium and titanium oxide surfaces. Key anhydrous environments studied included alcohols, which contain hydrogen; carbon tetrachloride, which does not contain hydrogen; and mixtures of alcohols and halocarbons. Effects of dissolved salts in alcohols were also studied. This program emphasized experiments designed to delineate the conditions necessary rather than sufficient for initiation processes and for propagation processes in Ti SCC

    A study to define meteorological uses and performance requirements for the Synchronous Earth Observatory Satellite

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    The potential meteorological uses of the Synchronous Earth Observatory Satellite (SEOS) were studied for detecting and predicting hazards to life, property, or the quality of the environment. Mesoscale meteorological phenonmena, and the observations requirements for SEOS are discussed along with the sensor parameters
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