1,879 research outputs found

    Notes and Comments: Federal Income Tax Aspects of Incorporating the Small Business

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    The corporate form is often superior to other business structures because of the financial flexibility available to the corporation under the corporate income tax provisions of the Internal Revenue Code. The author reviews these sections of the Code and discusses how they affect the decision of a small business to incorporate

    Notes and Comments: Federal Income Tax Aspects of Incorporating the Small Business

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    The corporate form is often superior to other business structures because of the financial flexibility available to the corporation under the corporate income tax provisions of the Internal Revenue Code. The author reviews these sections of the Code and discusses how they affect the decision of a small business to incorporate

    Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action

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    Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in response between plants treated with sarmentine and herbicidal soaps such as pelargonic acid (nonanoic acid). However, little was known about the mechanism of action leading to the rapid desiccation of foliage treated by sarmentine. In cucumber cotyledon disc-assays, sarmentine induced rapid light-independent loss of membrane integrity at 100 ”M or higher concentration, whereas 3 mM pelargonic acid was required for a similar effect. Sarmentine was between 10 and 30 times more active than pelargonic acid on wild mustard, velvetleaf, redroot pigweed and crabgrass. Additionally, the potency of 30 ”M sarmentine was greatly stimulated by light, suggesting that this natural product may also interfere with photosynthetic processes. This was confirmed by observing a complete inhibition of photosynthetic electron transport at that concentration. Sarmentine also acted as an inhibitor of photosystem II on isolated thylakoid membranes by competing for the binding site of plastoquinone. This can be attributed in part to structural similarities between herbicides like sarmentine and diuron. While this mechanism of action accounts for the light stimulation of the activity of sarmentine, it does not account for its ability to destabilize membranes in darkness. In this respect, sarmentine has some structural similarity to crotonoyl-CoA, the substrate of enoyl-ACP reductase, a key enzyme in the early steps of fatty acid synthesis. Inhibitors of this enzyme, such as triclosan, cause rapid loss of membrane integrity in the dark. Sarmentine inhibited the activity of enoyl-ACP reductase, with an I50app of 18.3 ”M. Therefore, the herbicidal activity of sarmentine appears to be a complex proces

    Phylogenies of Microcystin-Producing Cyanobacteria in the Lower Laurentian Great Lakes Suggest Extensive Genetic Connectivity

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    Lake St. Clair is the smallest lake in the Laurentian Great Lakes system. MODIS satellite imagery suggests that high algal biomass events have occurred annually along the southern shore during late summer. In this study, we evaluated these events and tested the hypothesis that summer bloom material derived from Lake St. Clair may enter Lake Erie via the Detroit River and represent an overlooked source of potentially toxic Microcystis biomass to the western basin of Lake Erie. We conducted a seasonally and spatially resolved study carried out in the summer of 2013. Our goals were to: 1) track the development of the 2013 summer south-east shore bloom 2) conduct a spatial survey to characterize the extent of toxicity, taxonomic diversity of the total phytoplankton population and the phylogenetic diversity of potential MC-producing cyanobacteria (Microcystis, Planktothrix and Anabaena) during a high biomass event, and 3) compare the strains of potential MC-producers in Lake St. Clair with strains from Lake Erie and Lake Ontario. Our results demonstrated a clear predominance of cyanobacteria during a late August bloom event, primarily dominated by Microcystis, which we traced along the Lake St. Clair coastline downstream to the Detroit River's outflow at Lake Erie. Microcystin levels exceeded the Province of Ontario Drinking Water Quality Standard (1.5 ”g L(-1)) for safe drinking water at most sites, reaching up to five times this level in some areas. Microcystis was the predominant microcystin producer, and all toxic Microcystis strains found in Lake St. Clair were genetically similar to toxic Microcystis strains found in lakes Erie and Ontario. These findings suggest extensive genetic connectivity among the three systems

    Spatio-temporal connectivity of the aquatic microbiome associated with cyanobacterial blooms along a Great Lake riverine-lacustrine continuum

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    Lake Erie is subject to recurring events of cyanobacterial harmful algal blooms (cHABs), but measures of nutrients and total phytoplankton biomass seem to be poor predictors of cHABs when taken individually. A more integrated approach at the watershed scale may improve our understanding of the conditions that lead to bloom formation, such as assessing the physico-chemical and biological factors that influence the lake microbial community, as well as identifying the linkages between Lake Erie and the surrounding watershed. Within the scope of the Government of Canada’s Genomics Research and Development Initiative (GRDI) Ecobiomics project, we used high-throughput sequencing of the 16S rRNA gene to characterize the spatio-temporal variability of the aquatic microbiome in the Thames River–Lake St. Clair-Detroit River–Lake Erie aquatic corridor. We found that the aquatic microbiome was structured along the flow path and influenced mainly by higher nutrient concentrations in the Thames River, and higher temperature and pH downstream in Lake St. Clair and Lake Erie. The same dominant bacterial phyla were detected along the water continuum, changing only in relative abundance. At finer taxonomical level, however, there was a clear shift in the cyanobacterial community, with Planktothrix dominating in the Thames River and Microcystis and Synechococcus in Lake St. Clair and Lake Erie. Mantel correlations highlighted the importance of geographic distance in shaping the microbial community structure. The fact that a high proportion of microbial sequences found in the Western Basin of Lake Erie were also identified in the Thames River, indicated a high degree of connectivity and dispersal within the system, where mass effect induced by passive transport play an important role in microbial community assembly. Nevertheless, some cyanobacterial amplicon sequence variants (ASVs) related to Microcystis, representing less than 0.1% of relative abundance in the upstream Thames River, became dominant in Lake St. Clair and Erie, suggesting selection of those ASVs based on the lake conditions. Their extremely low relative abundances in the Thames suggest additional sources are likely to contribute to the rapid development of summer and fall blooms in the Western Basin of Lake Erie. Collectively, these results, which can be applied to other watersheds, improve our understanding of the factors influencing aquatic microbial community assembly and provide new perspectives on how to better understand the occurrence of cHABs in Lake Erie and elsewhere

    Transitions in microbial communities along a 1600 km freshwater trophic gradient

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    This study examined vertically-resolved patterns in microbial community structure across a freshwater trophic gradient extending 1600 km from the oligotrophic waters of Lake Superior to the eutrophic waters of Lake Erie, the most anthropogenically influenced of the Laurentian Great Lakes system. Planktonic bacterial communities clustered by Principal Coordinates Analysis (PCoA) on UniFrac distance matrices into four groups representing the epilimnion and hypolimnion of the upper Great Lakes (Lakes Superior and Huron), Lake Superior\u27s northern bays (Nipigon and Black bays), and Lake Erie. The microbes within the upper Great Lakes hypolimnion were the most divergent of these groups with elevated abundance of Planctomycetes and Chloroflexi compared to the surface mixed layer. Statistical tests of the correlation between distance matrices identified temperature and sample depth as the most influential community structuring parameters, reflecting the strong UniFrac clustering separating mixed-layer and hypolimnetic samples. Analyzing mixed-layer samples alone showed clustering patterns were correlated with nutrient concentrations. Operational taxonomic units (OTU) which were differentially distributed among these conditions often accounted for a large portion of the reads returned. While limited in coverage of temporal variability, this study contributes a detailed description of community variability that can be related to other large freshwater systems characterized by changing trophic state

    Variation in particulate C : N : P stoichiometry across the Lake Erie watershed from tributaries to its outflow

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    © 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography Human activities can cause large alterations in biogeochemical cycles of key nutrients such as carbon (C), nitrogen (N), and phosphorus (P). However, relatively little is known about how these changes alter the proportional fluxes of these elements across ecosystem boundaries from rivers to lakes. Here, we examined environmental factors influencing spatial and temporal variation in particulate C : N : P ratios across the Lake Erie watershed from its tributaries to its outflow. Throughout the study, particulate nutrient ratios ranged widely (C : N 2.0–25.8, C : P 32–530, N : P 3.7–122.9), but mean values were generally lower than previous estimates from different aquatic environments. Particulate C : N ratios varied the least across all environments, but C : P and N : P ratios increased between tributaries and coastal areas and throughout the growing season in coastal environments. These ratios also differed temporally in offshore waters as particulate C : P and N : P were higher in the spring and summer and lower in the fall and winter. Particulate C : P ratios also increased between the western/central and eastern basins indicating differential nutrient processing across the lake. These stoichiometric changes were associated with unique environmental factors among ecosystems as tributary stoichiometry was related to terrestrial land use and land cover, coastal ratios were a product of mixing between riverine and offshore waters, and offshore patterns were influenced by differences in temperature and particulate nutrient loading among basins. Overall, by studying changes in particulate C : N : P ratios across the Lake Erie watershed, our study demonstrates the power of using mass balance principles to study nutrient transformations along the aquatic continuum

    Relationship between age at menopause, obesity, and incident heart failure: The Atherosclerosis Risk in Communities Study

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    Background The mechanisms linking menopausal age and heart failure (HF) incidence are controversial. We investigated for heterogeneity by obesity on the relationship between menopausal age and HF incidence. Methods and Results Using postmenopausal women who attended the Atherosclerosis Risk in Communities Study Visit 4, we estimated hazard ratios of incident HF associated with menopausal age using Cox proportional hazards models, testing for effect modification by obesity and adjusting for HF risk factors. Women were categorized by menopausal age: \u3c45 years, 45 to 49 years, 50 to 54 years, and ≄55 years. Among 4441 postmenopausal women, aged 63.5±5.5 years, there were 903 incident HF events over a mean follow-up of 16.5 years. The attributable risk of generalized and central obesity for HF incidence was greatest among women who experienced menopause at age ≄55 years: 11.09/1000 person-years and 7.38/1000 person-years, respectively. There were significant interactions of menopausal age with body mass index and waist circumference for HF incidence
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