The Effect of Nitrogen Loading on an Estuarine Faunal Community: A Stable Isotope Approach

Coastal ecosystems worldwide face increased nutrient enrichment from shoreline and watershed development and atmospheric pollution. To gain an understanding of the effects of nitrogen loading on the natural faunal community of Ruppia maritima beds in Northeast Creek estuary (Acadia National Park, Maine, USA), we (1) assessed the response of the faunal community to increased nitrogen loading using an in situ enrichment experiment during the summer growing season of 2001 (Chapter I), and (2) completed a description of the natural macroinvertebrate community in the estuary in 2001 with qualitative (May-July) and quantitative (August-October) monthly sample collections (Chapter 2). This study formed part of a larger study by the U.S. Geological Survey of the relationship between increased nutrient enrichment and ecosystem integrity in the estuary. Faunal community response to increased nitrogen loading was characterized by (1) assessing quantitative shifts in macroinvertebrate community composition and (2) identifying changes in food web structure using stable C and N isotope ratios of producers and consumers. Salinity in the estuary indicated that the system was dominated by freshwater inputs in the spring and became increasingly more marine throughout the summer (reaching 30% in the fall). Euryhaline freshwater fauna dominated Northeast Creek estuary throughout 2001. The most common invertebrates were non-biting midge larvae (Chironomidae: Dicrotendipes, Cricotopus and Chironomus), damselfly larvae (Coenagrionidae: Enallagma), gastropods and ostracods. Less common invertebrates included oligochaetes, water boatmen (Corixidae: Trichocorixa), water mites (Acari), and amphipods (Gammaridae: Gammarus). Brackish water fish, Fundulus heteroclitus, were also common in the estuary. Total macroinvertebrate densities were 31100 m-2 in August, 23200 m-2 in September and 27700 m-2 in October. Freshwater insects composed between 50 and 80% of the macroinvertebrate community in the estuary during this time period. The estuary was characterized by low taxa richness, diversity and evenness. Experimental nutrient additions resulted in significantly lower densities of herbivorous chironomids and predatory damselflies and higher densities of deposit feeding oligochaetes. Both R. maritima and epiphytic algae were more enriched in 15N under higher N conditions possibly due to increased denitrification. R. maritima was more depleted in 13C with loading while epiphytic material showed the opposite trend, indicating shifts in metabolic activity with increased loading. Mixing models showed a dependence of grazing chironomids on epiphytic algae under both natural and enriched conditions. Chironomus was dependent on allochthonous sources of detritus under natural conditions but under enriched conditions exhibited a shift to autochthonous sources of detritus. Predatory Enallagma was found to be largely dependent on grazing chironomids for prey although under the highest loading conditions this link may be broken. Experimental nutrient loading altered the composition and structure of the natural community in this estuary. This study \u27provides a baseline on faunal community composition and community response to nitrogen loading in NEC estuary for use in developing predictive tools for watershed-based planning and monitoring

Meteorological influences on coastal sea levels west of Port Phillip and their engineering significance

This report presents the results of an analysis of three years of tide and meteorological data aimed at delineating the influences of atmospheric pressure, waves, onshore winds and longshore winds on coastal sea levels West of Port Phillip Bay, Victoria« The data was used to develop predictive and hindcasting techniques for meteorological tides on the Otway Coast, using statistical methods, an empirical method and a mathematical model. The nature and magnitude of contributions of the various components of the meteorological tide, and the general variability of monthly and seasonal variations were also studied. It was found that meteorological tides on the Otway Coast can account for significant sea level changes, with the main factors being wind and atmospheric pressure. The wind component of the meteorological tide was found to be approximately twice the pressure component, and longshore winds were found to be more significant than onshore winds for wind setup on the Otway Coast. The meteorological tide models developed enable estimates of wind setup and atmospheric pressure setup on the Otway Coast to be readily computed using data from synoptic charts. The wave setup component could not be separated from the meteorological tide and is included in the wind setup component. The results of the investigation are relevant to the design and maintenance of coastal engineering works, and point to the need for the establishment and operation of coastal management schemes on the Otway Coast

Vascular stem cells in diabetic complications: evidence for a role in the pathogenesis and the therapeutic promise

Long standing diabetes leads to structural and functional alterations in both the micro- and the macro-vasculature. Vascular endothelial cells (ECs) are the primary target of the hyperglycemia-induced adverse effects. Vascular stem cells that give rise to endothelial progenitor cells (EPCs) and mesenchymal progenitor cells (MPCs) represent an attractive target for cell therapy for diabetic patients. A number of studies have reported EPC dysfunction as a novel participant in the culmination of the diabetic complications. The controversy behind the identity of EPCs and the similarity between these progenitor cells to hematopoietic cells has led to conflicting results. MPCs, on the other hand, have not been examined for a potential role in the pathogenesis of the complications. These multipotent cells, however, do show a therapeutic role. In this article, we summarize the vascular changes that occur in diabetic complications highlighting some of the common features, the key findings that illustrate an important role of vascular stem cells (VSCs) in the pathogenesis of chronic diabetic complications, and provide mechanisms by which these cells can be used for therapy. © 2012 Keats and Khan; licensee BioMed Central Ltd

Genome-Wide ENU Mutagenesis to Reveal Immune Regulators

AbstractA complete list of molecular components for immune system function is now available with the completion of the human and mouse genome sequences. However, identification and functional annotation of genes involved in immunological processes require a discovery methodology that can efficiently and broadly analyze the complex interplay of these components in vivo. Our recent experience indicates that genome-wide chemical mutagenesis in the mouse is an extremely powerful methodology for the identification of genes required for complex immunological processes

Vascular stem cells in diabetic complications: evidence for a role in the pathogenesis and the therapeutic promise

Long standing diabetes leads to structural and functional alterations in both the micro- and the macro-vasculature. Vascular endothelial cells (ECs) are the primary target of the hyperglycemia-induced adverse effects. Vascular stem cells that give rise to endothelial progenitor cells (EPCs) and mesenchymal progenitor cells (MPCs) represent an attractive target for cell therapy for diabetic patients. A number of studies have reported EPC dysfunction as a novel participant in the culmination of the diabetic complications. The controversy behind the identity of EPCs and the similarity between these progenitor cells to hematopoietic cells has led to conflicting results. MPCs, on the other hand, have not been examined for a potential role in the pathogenesis of the complications. These multipotent cells, however, do show a therapeutic role. In this article, we summarize the vascular changes that occur in diabetic complications highlighting some of the common features, the key findings that illustrate an important role of vascular stem cells (VSCs) in the pathogenesis of chronic diabetic complications, and provide mechanisms by which these cells can be used for therapy. © 2012 Keats and Khan; licensee BioMed Central Ltd

Proceedings of the workshop "Standard Model at the LHC" University College London 30 March - 1 April 2009

Proceedings from a 3-day discussion on Standard Model discoveries with the first LHC dataComment: 9 contributions to the proceedings of the LHC Standard Model worksho

Switch from canonical to noncanonical Wnt signaling mediates high glucose-induced adipogenesis

Human bone marrow mesenchymal progenitor cells (MPCs) are multipotent cells that play an essential role in endogenous repair and the maintenance of the stem cell niche. We have recently shown that high levels of glucose, conditions mimicking diabetes, cause impairment of MPCs, resulting in enhanced adipogenesis and suppression of osteogenesis. This implies that diabetes may lead to reduced endogenous repair mechanisms through altering the differentiation potential of MPCs and, consequently, disrupting the stem cell niche. Phenotypic alterations in the bone marrow of long-term diabetic patients closely resemble this observation. Here, we show that high levels of glucose selectively enhance autogenous Wnt11 expression in MPCs to stimulate adipogenesis through the Wnt/protein kinase C noncanonical pathway. This novel mechanism may account for increased bone marrow adipogenesis, severe bone loss, and reduced vascular stem cells leading to chronic secondary complications of diabetes. Stem Cells 2014;32:1649-1660 © 2014 AlphaMed Press