Arcellacea (Testate Amoebae) as Bio-indicators of Road Salt Contamination in Lakes

Winter deicing operations occur extensively in mid- to high-latitude metropolitan regions around the world and result in a significant reduction in road accidents. Deicing salts can, however, pose a major threat to water quality and aquatic organisms. In this paper we examine the utility of Arcellacea (testate amoebae) for monitoring lakes that have become contaminated by winter deicing salts, particularly sodium chloride. We analysed 50 sediment samples and salt-related water-property variables (chloride concentrations; conductivity) from 15 lakes in the Greater Toronto Area and adjacent areas of southern Ontario, Canada. The sampled lakes included lakes in proximity to major highways and suburban roads, and control lakes in forested settings away from road influences. Samples from the most contaminated lakes, with chloride concentrations in excess of 400 mg/l and conductivities of >800 μS/cm, were dominated by species typically found in brackish and/or inhospitable lake environments and by lower faunal diversities (lowest Shannon Diversity Index values) than samples with lower readings. Q-R-mode cluster analysis and Detrended Correspondence Analysis (DCA) resulted in the recognition of four assemblage groupings. These reflect varying levels of salt contamination in the study lakes, along with other local influences, including nutrient loading. The response to nutrients can, however, be isolated if the planktic eutrophic indicator species Cucurbitella tricuspis is removed from the counts. The findings show that the group have considerable potential for biomonitoring in salt-contaminated lakes, and through application to lake sediment cores, may provide significant insights into long-term benthic community health, which is integral for remedial efforts.

Beacon; Horizon

Horizon is a narrative clock made out of images accessed in realtime from webcams found in every time zone around the world. The result is a constantly updating array of images that read like a series of movie storyboards, but also as an idiosynratic global electronic sundial. BEACON continuously relays live web searches as they are being made around the world presenting them back in series and at regular intervals as an endless concrete poetry.

Electrochemical oxidation of propanil and related N-substituted amides

The electrochemical behaviour of propanil and related N-substituted amides (acetanilide and N,N-diphenylacetamide) was studied by cyclic and square wave voltammetry using a glassy carbon electrode. Propanil has been found to have chemical stability under the established analytical conditions and showed an oxidation peak at +1.27V versus Ag/AgCl at pH 7.5. N,N-diphenylacetamide has a higher oxidation potential than the other compounds of +1.49V versus Ag/AgCl. Acetanilide oxidation occurred at a potential similar to that of propanil, +1.24V versus Ag/AgCl. These results are in agreement with the substitution pattern of the nitrogen atom of the amide. A degradation product of propanil, 3,4-dichloroaniline (DCA), was also studied, and showed an oxidation peak at +0.66V versus Ag/AgCl. A simple and specific quantitative electroanalytical method is described for the analysis of propanil in commercial products that contain propanil as the active ingredient, used in the treatment of rice crops in Portugal.

Linking entrepreneural orientation to export performance: the role of intangible resources and dynamic capabilities

Understanding the determinants of international performance, and in particular, export performance is key for the success of international companies. Research in this area focuses mainly on how resources and capabilities allow companies to gain competitive advantage and superior performance in external markets. Building on the Resource-Based View (RBV) and the Dynamic Capabilities Approach (DCA), this study aims at analysing the effect of intangible resources and capabilities on export performance. Specifically, this study focuses on the proposition that entrepreneurial orientation potentiates the attraction of intangible resources, namely relational and informational resources. Moreover, we propose that these resources impact export performance both directly and indirectly through dynamic capabilities.

Bioelectrochemically-assisted reductive dechlorination of 1,2-dichloroethane by a Dehalococcoides-enriched microbial culture

The aim of this study was to verify the possibility to use a polarized graphite electrode as an electron donor for the reductive dechlorination of 1,2-dichloroethane, an ubiquitous groundwater contaminant. The rate of 1,2-DCA dechlorination almost linearly increased by decreasing the set cathode potential over a broad range of set cathode potentials (i.e., from −300 mV to −900 mV vs. the standard hydrogen electrode). This process was primarily dependent on electrolytic H2 generation. On the other hand, reductive dechlorination proceeded (although quite slowly) with a very high Coulombic efficiency (near 70%) at a set cathode potential of −300 mV, where no H2 production occurred. Under this condition, reductive dechlorination was likely driven by direct electron uptake from the surface of the polarized electrode. Taken as a whole, this study further extends the range of chlorinated contaminants which can be treated with bioelectrochemical systems.

Asymmetric cell division intersects with cell geometry : a method to extrapolate and quantify geometrical parameters of sensory organ precursors

La division cellulaire asymétrique (DCA) consiste en une division pendant laquelle des déterminants cellulaires sont distribués préférentiellement dans une des deux cellules filles. Par l’action de ces déterminants, la DCA générera donc deux cellules filles différentes. Ainsi, la DCA est importante pour générer la diversité cellulaire et pour maintenir l’homéostasie de certaines cellules souches. Pour induire une répartition asymétrique des déterminants cellulaires, le positionnement du fuseau mitotique doit être très bien contrôlé. Fréquemment ceci génère deux cellules filles de tailles différentes, car le fuseau mitotique n’est pas centré pendant la mitose, ce qui induit un positionnement asymétrique du sillon de clivage. Bien qu’un complexe impliquant des GTPases hétérotrimériques et des protéines liant les microtubules au cortex ait été impliqué directement dans le positionnement du fuseau mitotique, le mécanisme exact induisant le positionnement asymétrique du fuseau durant la DCA n'est pas encore compris. Des études récentes suggèrent qu’une régulation asymétrique du cytosquelette d’actine pourrait être responsable de ce positionnement asymétrique du faisceau mitotique. Donc, nous émettons l'hypothèse que des contractions asymétriques d’actine pendant la division cellulaire pourraient déplacer le fuseau mitotique et le sillon de clivage pour créer une asymétrie cellulaire. Nos résultats préliminaires ont démontré que le blebbing cortical, qui est une indication de tension corticale et de contraction, se produit préférentiellement dans la moitié antérieure de cellule précurseur d’organes sensoriels (SOP) pendant le stage de télophase. Nos données soutiennent l'idée que les petites GTPases de la famille Rho pourraient être impliqués dans la régulation du fuseau mitotique et ainsi contrôler la DCA des SOP. Les paramètres expérimentaux développés pour cette thèse, pour étudier la régulation de l’orientation et le positionnement du fuseau mitotique, ouvrirons de nouvelles avenues pour contrôler ce processus, ce qui pourrait être utile pour freiner la progression de cellules cancéreuses. Les résultats préliminaires de ce projet proposeront une manière dont les petites GTPases de la famille Rho peuvent être impliqués dans le contrôle de la division cellulaire asymétrique in vivo dans les SOP. Les modèles théoriques qui sont expliqués dans cette étude pourront servir à améliorer les méthodes quantitatives de biologie cellulaire de la DCA.

Increased brain lactate is central to the development of brain edema in rats with chronic liver disease

The pathogenesis of brain edema in patients with chronic liver disease (CLD) and minimal hepatic encephalopathy (HE) remains undefined. This study evaluated the role of brain lactate, glutamine and organic osmolytes, including myo-inositol and taurine, in the development of brain edema in a rat model of cirrhosis.Six-week bile-duct ligated (BDL) rats were injected with (13)C-glucose and de novo synthesis of lactate, and glutamine in the brain was quantified using (13)C nuclear magnetic resonance spectroscopy (NMR). Total brain lactate, glutamine, and osmolytes were measured using (1)H NMR or high performance liquid chromatography. To further define the interplay between lactate, glutamine and brain edema, BDL rats were treated with AST-120 (engineered activated carbon microspheres) and dichloroacetate (DCA: lactate synthesis inhibitor).Significant increases in de novo synthesis of lactate (1.6-fold, p<0.001) and glutamine (2.2-fold, p<0.01) were demonstrated in the brains of BDL rats vs. SHAM-operated controls. Moreover, a decrease in cerebral myo-inositol (p<0.001), with no change in taurine, was found in the presence of brain edema in BDL rats vs. controls. BDL rats treated with either AST-120 or DCA showed attenuation in brain edema and brain lactate. These two treatments did not lead to similar reductions in brain glutamine.Increased brain lactate, and not glutamine, is a primary player in the pathogenesis of brain edema in CLD. In addition, alterations in the osmoregulatory response may also be contributing factors. Our results suggest that inhibiting lactate synthesis is a new potential target for the treatment of HE.

Singlet Oxygen in Microporous Silica Xerogel:Quantum Yield and Oxidation at the Gas–Solid Interface

The quantum yields of singlet oxygen production and lifetimes at the gas–solid interface in silica gel material are determined. Different photosensitizers (PS) are encapsulated in parallelepipedic xerogel monoliths (PS-SG). PS were chosen according to their known photooxidation properties: 9,10-dicyanoanthracene (DCA), 9,10-anthraquinone (ANT), and a benzophenone derivative, 4-benzoyl benzoic acid (4BB). These experiments are mainly based on time-resolved 1O2 phosphorescence detection, and the obtained FD and tD values are compared with those of a reference sensitizer for production, 1H-phenalen-1- one (PN), included in the same xerogel. The trend between their ability to oxidize organic pollutants in the gas phase and their efficiency for production is investigated through photooxidation experiments of a test pollutant dimethylsulfide (DMS). The FD value is high for DCA-SG relative to the PN reference, whereas it is slightly lower for 4BB-SG and for ANT-SG. FD is related to the production of sulfoxide and sulfone as the main oxidation products for DMS photosensitized oxidation. Additional mechanisms, leading to C!S bond cleaveage, appear to mainly occur for the less efficient singlet oxygen sensitizers 4BB-SG and ANTSG.

Land degradation and vegetation distribution in Chott El Beida wetland, Algeria

The aim of this study is to explore the environmental factors that determine plant Community distribution in northeast Algeria. This paper provides a quantitative analysis of the vegetation-environment relationships for a study site in the Cholt El Beida wetland, a RAMSAR site in Setif, Algeria. Sixty vegetation plots were sampled and analysed using TWINSPAN and Detrended Correspondence Analysis (DCA) in order to identify the principal vegetation communities and determine the environmental gradients associated with these. 127 species belonging to 41 families and 114 genera were recorded. Six of the recorded species were endemic representing 4.7% of the total species. The richest families were Compositae, Gramineae, Cruciferae and Chenopodiaceae. Therophytes and hemicryptophytes were the most frequent life forms. the Mediterranean floristic element is dominant and is represented by 39 species. The samples were classified into four main community types. The principal DCA axes represent gradients of soil salinity, moisture and anthropogenic pressure. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in often critically endangered Mediterranean wetland areas. (C) 2008 Elsevier Ltd. All rights reserved.

Environmental factors and vegetation composition, Lefka Ori Massif, Crete, S. Aegean

Aim The aim of this study was to explore the environmental factors that determine the spatial distribution of oro-mediterranean and alti-mediterranean plant communities in Crete. Location The paper provides a quantitative analysis of vegetation-environment relationships for two study areas within the Lefka Ori massif Crete, a proposed Natura 2000 site. Methods Eleven environmental variables were recorded: altitude, slope, aspect, percentage of bare rock, percentage of unvegetated ground, soil depth, pH, organic matter content and percentages of sand, silt and clay content. Classification of the vegetation was based on twinspan, while detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to identify environmental gradients linked to community distribution. Results One hundred and twenty-five species were recorded from 120 plots located within the two study areas. Forty-seven of the recorded species are endemic, belonging to 35 families. Hemicryptophytes and chamaephytes were the most frequent, suggesting a typical oro-mediterranean life form spectrum. The samples were classified into five main community types and one transitional. The main gradients, identified by CCA, were altitude and surface cover type in the North-west site, while in the Central site the gradients were soil formation-development and surface cover type. Main conclusions The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in Mediterranean mountain zones.

Land degradation and vegetation distribution in Chott El Beida wetland, Algeria

The aim of this study is to explore the environmental factors that determine plant Community distribution in northeast Algeria. This paper provides a quantitative analysis of the vegetation-environment relationships for a study site in the Cholt El Beida wetland, a RAMSAR site in Setif, Algeria. Sixty vegetation plots were sampled and analysed using TWINSPAN and Detrended Correspondence Analysis (DCA) in order to identify the principal vegetation communities and determine the environmental gradients associated with these. 127 species belonging to 41 families and 114 genera were recorded. Six of the recorded species were endemic representing 4.7% of the total species. The richest families were Compositae, Gramineae, Cruciferae and Chenopodiaceae. Therophytes and hemicryptophytes were the most frequent life forms. the Mediterranean floristic element is dominant and is represented by 39 species. The samples were classified into four main community types. The principal DCA axes represent gradients of soil salinity, moisture and anthropogenic pressure. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in often critically endangered Mediterranean wetland areas. (C) 2008 Elsevier Ltd. All rights reserved.

Macrophyte community structure and species occurrence in relation to environmental determinants in the ephemeral aquatic habitats of Gavdos, Greece

The aims of this study were to explore the environmental factors that determine the distribution of plant communities in temporary rock pools and provide a quantitative analysis of vegetation-environment relationships for five study sites on the island of Gavdos, southwest of Crete, Greece. Data from 99 rock pools were collected and analysed using Two-Way Indicator Species Analysis (TWINSPAN), Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) to identify the principal communities and environmental gradients that are linked to community distribution. A total of 46 species belonging to 21 families were recorded within the study area. The dominant families were Labiatae, Gramineae and Compositae while therophytes and chamaephytes were the most frequent life forms. The samples were classified into six community types using TWINSPAN, which were also corroborated by CCA analysis. The principal gradients for vegetation distribution, identified by CCA, were associated with water storage and water retention ability, as expressed by pool perimeter and water depth. Generalised Additive Models (GAMs) were employed to identify responses of four dominant rock pool species to water depth. The resulting species response curves showed niche differentiation in the cases of Callitriche pulchra and Tillaea vaillantii and revealed competition between Zannichellia pedunculata and Chara vulgaris. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities. Generalised Additive Models are a powerful tool in investigating species response curves to environmental gradients. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in Mediterranean ephemeral pools.

Syntheses and crystal structures of two new coordination polymers of Cd(II) using organic spacer and inorganic-bridging ligands

Two new cadmium (II) complexes [Cd(hmt)(dca)(2)] (n) (1) and [Cd-3(hmt)(2)(SeCN)(6)(H2O)(2)] (n) (2) (hmt=hexamethylenetetramine, dca=dicyanamide) have been synthesized and characterized by X-ray single-crystal analysis. The complex 1 is a 2D rectangular grid of octahedral cadmium (II) with CdN6 chromophore where cadmium centers are doubly bridged by dicyanamide and hmt along a-axis, which are interlinked by dicyanamide running along c-axis. Whereas, complex 2 is a 1D chain of octahedral cadmium (II) with a three-leg ladder topology running along a-axis. The Cd(II) centers are doubly bridged through SeCN (infinite rail) along a-axis and singly bridged by hmt (two-step rung) along c-axis, having cadmium centers with CdSe2N3O and CdSe2N4 chromophores. The adjacent chains through H-bonding between coordinated water and hmt, and (SeSe)-Se-... interaction are extended to 2D supramolecular architecture.

Two new Ni-II complexes with mu(1.5)-dicyanamide as bridging ligand

One 3D and one 2D mu(1,5)-dicyanamide bridged Ni-II complexes having molecular formula [Ni(L1)(dca)(2)] (1) and [Ni-2(L-2)(2)(dca)(4)] (.) 0.5H(2)O (2) (L1 = 4-(2-aminoethyl)-morpholine, L2 = 1-(2-aminoethyl)-piperidine and dca = dicyanamide dianion) have been synthesized. X-ray single crystal analyses and low temperature magnetic measurements were used to characterize the complexes. Complex 1 represents a 3D structure where each metal ion is chelated by morpholine ligand (L1) and connected by four mu(1,5)-dca. Whereas complex 2 shows an undulated 2D structure with grid of (4,4) topology having two crystallographically independent Ni-II centers in similar octahedral environment where each metal center is chelated by one piperidine ligand (L2) and coordinated by four mu(1,5)-dca. Magnetic measurements of both the complexes indicate weak antiferromagnetic interactions through the mu-(1,5)-dca bridging ligands. (c) 2004 Elsevier B.V. All rights reserved.

Effect of colonic bacterial metabolites on Caco-2 cell paracellular permeability in vitro

One common effect of tumor promoters is increased tight junction (TJ) permeability. TJs are responsible for paracellular permeability and integrity of the barrier function. Occludin is one of the main proteins responsible for TJ structure. This study tested the effects of physiological levels of phenol, ammonia, primary bile acids (cholic acid, CA, and chenodeoxycholic acid, CDCA), and secondary bile acids (lithocholic acid, LCA, and deoxycholic acid, DCA) on paracellular permeability using a Caco-2 cell model. Paracellular permeability of Caco-2 monolayers was assessed by transepithelial electrical resistance (TER) and the apical to basolateral flux of [C-14]-mannitol. Secondary, but not primary, bile acids increased permeability as reflected by significantly decreased TER and increased mannitol flux. Both phenol and ammonia also increased permeability. The primary bile acid CA significantly increased occludin expression (P < 0.05), whereas CDCA had no significant effect on occludin expression as compared to the negative control. The secondary bile acids DCA and LCA significantly increased occludin expression (P < 0.05), whereas phenol had no significant effect on the protein expression as compared to the negative control. This suggests that the increased permeability observed with LCA, DCA, phenol, and ammonia was not related to an effect on occludin expression. In conclusion, phenol, ammonia, and secondary bile acids were shown to increase paracellular permeability and reduce epithelial barrier function at doses typical of levels found in fecal samples. The results contribute to the evidence these gut microflora-generated products have tumor-promoting activity.