bluuebunny/crossref_metadata_2025 huggingface dataset:
There are High Levels of Functional and Genetic Diversity in Oxyrrhis marina
Authors: LOWE CHRIS D. , DAY ADAM , KEMP STEPHEN J. , MONTAGNES DAVID J. S.
Published: September 2010

Abstract. Oxyrrhis marina, a widely distributed marine protist, is used to model heterotrophic flagellate responses in microbial food webs. Although clonal variability occurs in protists, assessments of intraspecific diversity are rare; such assessments are critical, particularly where species are used as models in ecological studies. To address the extent of intraspecific variation within O. marina, we assessed diversity among 11 strains using 5.8S rDNA and ITS sequences. The 5.8S rDNA and ITS regions revealed high divergence between strains: 63.1% between the most diverse. To compare O. marina diversity relative to other alveolates, 18S rDNA sequences for five strains were analysed with sequences from representatives of the major alveolate groups. 18S rDNA also revealed high divergence in O. marina. Additionally, consistent with phylogenies based on protein coding genes, maximum likelihood analysis indicated that O. marina was monophyletic and ancestral to the dinoflagellates. To assess ecophysiological differences, growth rates of seven O. marina strains were measured at 10 salinities (10–55‰). Two salinity responses occurred: one group achieved highest growth rates at high salinities; the other grew best at low salinities. There was no clear correlation between molecular, ecophysiological, or geographical differences. However, salinity tolerance was associated with habitat type: intertidal strains grew best at high salinities; open‐water strains grew best at low salinities. These data indicate the need to examine many strains of a species in both phylogenetic and ecological studies, especially where key‐species are used to model ecological processes.
Molecular, Morphological, and Experimental Evidence Support the Synonymy of Perkinsus chesapeaki and Perkinsus andrewsi
Authors: BURRESON EUGENE M. , REECE KIMBERLY S. , DUNGAN CHRISTOPHER F.
Published: September 2010

Abstract. Diverse analytical and experimental results confirm that two protistan parasites, Perkinsus chesapeaki and Perkinsus andrewsi, described separately as parasites of Mya arenaria and Macoma balthica clams sympatric in Chesapeake Bay, USA, represent a single species. Ribosomal RNA (rRNA) internal transcribed spacer (ITS) regions, rRNA large subunit (LSU) gene, and actin gene sequences were obtained from clonal Perkinsus spp. cultured in vitro. Although multiple polymorphic sequences were found in DNA from clonal cultures at each locus, identical ITS region and actin gene sequences were found in the P. andrewsi holotype culture and in Perkinsus sp. clonal cultures from M. arenaria and Tagelus plebius. All sequences determined from cultures of P. chesapeaki and P. andrewsi at each locus grouped together in monophyletic clades with high support values in phylogenetic analyses. In vitro isolates of Perkinsus spp. from M. arenaria and M. balthica were reciprocally infective for each other's cognate host. Lesions and histozoic parasite cell morphologies were consistent with those described for the original host/parasite interactions. In vitro isolate cell cycles and cell types of both parasites were indistinguishable. In accordance with the International Code of Zoological Nomenclature rules of priority, P. andrewsi is declared a junior synonym of P. chesapeaki.
Microsporidian Mitochondrial Proteins: Expression in Antonospora locustae Spores and Identification of Genes Coding for Two Further Proteins
Authors: WILLIAMS BRYONY A. P. , KEELING PATRICK J.
Published: September 2010

Abstract. Microsporidia are obligate intracellular parasites, phylogenetically allied to the fungi. Once considered amitochondriate, now a number of mitochondrion‐derived genes have been described from various species, and the relict organelle was recently identified in Trachipleistophora hominis. We have investigated the expression of potential mitochondrial targeted proteins in the spore stage to determine whether the organelle is likely to have a role in the spore or early infection stage. To investigate whether the Antonospora locustae genome codes for a different complement of mitochondrial proteins than Encephalitozoon cuniculi an EST library was searched for putative mitochondrial genes that have not been identified in the E. cuniculi genome project. The spore is the infectious stage of microsporidia, but is generally considered to be metabolically dormant. Fourteen genes for putatively mitochondrion‐targeted proteins were shown to be present in purified spore mRNA by 3′‐rapid amplification of cDNA ends and EST sequencing. Pyruvate dehydrogenase E1α and mitochondrial glycerol‐3‐phosphate dehydrogenase proteins were also shown to be present in A. locustae and E. cuniculi spores, respectively, suggesting a role for these proteins in the early stages of infection, or within the spore itself. EST sequencing also revealed two mitochondrial protein‐encoding genes in A. locustae that are not found in the genome of E. cuniculi. One encodes a possible pyruvate transporter, the other a subunit of the mitochondrial inner membrane peptidase. In yeast mitochondria, this protein is part of a trimeric complex that processes proteins targeted to the inner membrane and the intermembrane space, and its substrate in A. locustae is presently unknown.
In Vitro Evaluation of Screws and Suture Anchors in Metaphyseal Bone of the Canine Tibia
Authors: Robb Julie L. , Cook James L. , Carson William
Published: September 2010

Objective— To compare ease of insertion, load to failure, and mode of failure of cortical and cancellous screws, BoneBiter™, IMEX™, and TwinFix™ suture anchors in canine metaphyseal tibial bone.

Study Design— Experimental biomechanical study.

Animals— Canine cadaveric tibias.

Methods— One investigator inserted all anchors and subjectively evaluated ease of placement. Anchor systems were loaded to failure along axis of insertion with audio–video recording to determine failure mode.

Results— BoneBiter™ was the most difficult anchor to insert successfully. Mean±SD loads to failure were cancellous screw (711±193 N), IMEX™ 4.7 mm 18 g wire (661±163 N), IMEX™ 4.0 mm 18 g wire (661±165 N), cortical screw (635±184 N), BoneBiter™#5 Kevlar suture (393± 109 N), and TwinFix™ 5.0 mm #2 polyester (267±73 N). No significant differences were noted among the cortical screw, cancellous screw, IMEX™ 4.7 and 4.0 mm, all of which were significantly (P<.001) greater than BoneBiter™ and TwinFix™. Failure modes were pullout of bone, suture–wire breakage, eyelet breakage, or no failure to 1000 N: screws (18,0,0,2), IMEX™ (18,1,1,0), BoneBiter™ (2,8,0,0), and TwinFix™ (0,10,0,0).

Conclusions— Fixation devices were user friendly, with the exception of BoneBiter™. Mode of failure is dependent on suture material and anchor design. Cortical and cancellous screws, and IMEX™ anchors with 18 g wire have significantly greater load to failure compared with BoneBiter™ and TwinFix™ suture anchors.

Clinical Relevance— Based on load to failure, ease of use, design characteristics, and cost, IMEX™ anchors may have advantages over other comparable soft tissue fixation devices.
La répartition des salaires dans les pays de l'OCDE
Authors: ATKINSON Anthony B.
Published: September 2010

Il est généralement admis que les inégalités salariales se sont fortement accentuées dans les pays de l'OCDE depuis 1980. L'explication habituelle est la hausse constante de la demande de travail qualifié, due au progrès technique favorisant les qualifications, et l'exposition de la main‐d'æuvre non qualifiée à la concurrence internationale du fait de la mondialisation. Mais l'évolution de la répartition des salaires diffère d'un pays à l'autre et c'est dans la partie supérieure de l'échelle des revenus que leur dispersion augmente le plus. L'auteur se livre à un réexamen minutieux des données pour proposer d'ajouter d'autres explications à celle de la course entre technologie et éducation.
Externalisation, délocalisations et mesure de la productivité dans l'industrie aux Etats‐Unis
Authors: HOUSEMAN Susan
Published: September 2010

Les gains de productivité sont à la source des augmentations de salaires dans un secteur d'activité ou dans l'ensemble d'une économie. Dans les pays développés, la multiplication des externalisations, intérieures ou à l'étranger, complique gravement le calcul et l'interprétation de cet indicateur essentiel, en induisant une surestimation trompeuse des gains de productivité. S'agissant de l'industrie aux Etats‐Unis, l'auteur met en évidence plusieurs éléments indiquant que les effets de l'externalisation et des délocalisations sur la mesure de la productivité seraient significatifs. Ce qui expliquerait la modeste hausse des salaires aux Etats‐Unis malgré une forte augmentation de la productivité, telle qu'elle est mesurée.
Economie informelle, insécurité et cohésion sociale en Amérique latine
Authors: TOKMAN Victor E.
Published: September 2010

La plupart des pays d'Amérique latine se sont inspirés du modèle de l'Etat‐providence, l'ont appliquéà des degrés divers et de manière souvent impar‐faite en raison des différences structurelles qui les séparent des pays développés. La protection sociale y reste défaillante et le sentiment d'insécurité sociale répandu, surtout du fait de l'emploi précaire et informel. L'auteur explore la structure du travail en Amérique latine et décrit les initiatives en faveur de la cohésion sociale, com‐parées à celles de pays d'Europe, notamment. Il analyse les stratégies visant à incorporer le secteur informel à l'économie moderne, à lutter contre l'exclusion sociale et à concilier flexibilité pour les entreprises, sécurité pour les travailleurs et universalité de la protection sociale.
L'évolution du droit du travail: évaluation et comparaison des régimes réglementaires
Authors: DEAKIN Simon , LELE Priya , SIEMS Mathias
Published: September 2010

Nous présentons ici des données sur l'évolution de la législation du travail dans cinq pays (Allemagne, Etats‐Unis, France, Inde et Royaume‐Uni) en utilisant de nouvelles bases de données qui permettent de mesurer les évolutions juridiques dans le temps. Ces résultats jettent un éclairage sur l'affirmation voulant que la source juridique ou les styles réglementaires de common law ou de droit civil influent sur le contenu des régimes de droit du travail. Nous avons pu constater certaines divergences au niveau global entre les pays de common law et de droit civil, mais le tableau est beaucoup plus complexe lorsqu'on procède à une analyse plus fine des données pour identifier les évolutions dans certains domaines précis du droit du travail. Nous commentons l'importance potentielle de cette approche relativement nouvelle d'évaluation du droit, afin de comprendre les forces qui sous‐tendent l'évolution de la législation du travail.
Les modèles européens de l'emploi soumis à des pressions vers le changement
Authors: BOSCH Gerhard , RUBERY Jill , LEHNDORFF Steffen
Published: September 2010

Les ≪modèles nationaux de l'emploi≫ comprennent toutes les institutions qui, dans un pays, déterminent l'offre, la demande et l'utilisation de la main‐d'æuvre. Partant d'une étude des typologies de ces modèles, les auteurs examinent leur fonctionnement et leur capacité de résister aux pressions visant à les faire changer. La comparaison porte sur le maintien de conditions de travail décentes face à la déréglementation des marchés des produits et à l'augmentation du taux d'activité des femmes et des travailleurs âgés. Ils concluent sur la difficulté pour les Etats‐nations européens de réformer de l'intérieur leurs modèles nationaux de l'emploi et plaident pour une intégration des politiques à l'échelle européenne.
Informalité, Etat et contrat social en Amérique latine: étude préliminaire
Authors: SAAVEDRA Jaime , TOMMASI Mariano
Published: September 2010

Selon les auteurs, l'informalité en Amérique latine reflète le dysfonction‐nement des interactions entre les individus et l'Etat, ainsi que les lacunes de celuici en matière de redistribution et de biens et services collectifs. Il s'ensuit de faibles taux de contribution et de couverture pour la sécurité sociale; un non‐respect des réglementations fiscales, sociales et économiques; de faibles niveaux de recouvrement fiscal, d'application de la loi et de confiance dans l'Etat. Pour ces pays, tout le défi est de forger des contrats sociaux intégrateurs, fondés sur des consensus réalistes, compte tenu du cadre institutionnel et des normes sociales de chacun.
Aplicación del derecho laboral más allá del contrato de trabajo
Authors: FREEDLAND Mark
Published: September 2010

El ámbito personal del derecho del trabajo es un tema muy debatido y, en opinión del autor, sería insuficiente hacer un análisis exclusivamente contractual al respecto. Así, presenta una tipología amplia—basada en los países euro‐peos—en la que, junto con el «trabajo asalariado clásico», distingue las relaciones de trabajo individuales propias de los funcionarios públicos, «las profesiones libe‐rales», los emprendedores individuales, los trabajadores «marginales» y los recién llegados al mercado laboral. Después analiza dinámicamente estas categorías y sus relaciones desde el ángulo del «nexo de trabajo personal», concepto cuajado de ramificaciones jurídicas complejas que desbordan el marco contractual. En la con‐clusión, Mark Freedland pone de relieve el valor que reviste este planteamiento analítico para la labor que han emprendido la OIT y la Unión Europea con el afán de «modernizar» el derecho del trabajo.
Informalidad, inseguridad y cohesión social en América Latina
Authors: TOKMAN Víctor E.
Published: September 2010

El Estado de bienestar ha servido de modelo a la mayoría de los países latinoamericanos, aunque su implantación es muy variable y, en muchos casos, imperfecta, dadas las diferencias estructurales que los separan de las naciones desarrolladas. La protección social sigue siendo escasa, están sin cobertura muchos trabajadores de la economía informal y existe una percepción de inseguridad muy extendida. El autor estudia la compleja situación estructural y laboral de los países de América Latina, así como las últimas ideas aplicadas por los mismos y por la Unión Europea para fortalecer la cohesión social. Analiza estrategias con el fin de incorporar el sector informal a la modernidad, enfrentar la exclusión social y conciliar la flexibilidad para las empresas con la seguridad de los trabajadores y con una protección social lo más universal posible.
Derecho al trabajo. Conjugar derechos humanos y política de empleo
Authors: MUNDLAK Guy
Published: September 2010

En este artículo se explica la singularidad del derecho al trabajo dentro de los derechos humanos y los problemas y dudas con los que tropieza en la esfera de la normativa laboral. El autor compara dos planteamientos que encaran el asunto desde las perspectivas propias de los derechos humanos y de la política eco‐nómica: una ≪observación general≫ del Comité de Derechos Económicos, Sociales y Culturales, y la Estrategia Europea de Empleo. Aunque no sea fácil, las dos líneas de actuación pueden compaginarse para construir un sistema institucional en el que el derecho al trabajo sea una norma rectora, superior.
≪Informalidad≫, Estado y contrato social en América Latina. Estudio preliminar
Authors: SAAVEDRA Jaime , TOMMASI Mariano
Published: September 2010

Los autores estiman que la economía informal latinoamericana es un reflejo de unas relaciones disfuncionales entre los individuos y el Estado y de la incapacidad de éste de actuar eficazmente en las esferas de la redistribución y la provisión de bienes y servicios públicos. Ello se traduce en unos índices modestos de cotizaciones y de cobertura de la seguridad social; en una elusión general de las leyes tributarias, laborales y mercantiles, y en unos niveles bajos de recaudación tri‐butaria, de imperio del derecho y de confianza en el Estado. El reto que encara cada uno de los países latinoamericanos es forjar un contrato social más incluyente, asentado en un consenso nacional realista y que se amolde a las características institucionales propias y a las reglas sociales vigentes.
Evaluation of the use of coconut to treat chronic diarrhea in rhesus macaques (Macaca mulatta)
Authors: Wilk J.L. , Maginnis G.M. , Coleman K. , Lewis A. , Ogden B.
Published: September 2010

Background  Chronic diarrhea can be challenging to manage in captive rhesus macaques (Macaca mulatta) leading to ongoing diagnostics, medications, monitoring, and potential euthanasia. Coconut has been used as a dietary supplement for people with inflammatory bowel disease, with anecdotal reports of decreased diarrhea following the dietary addition. A dietary trial in rhesus macaques was initiated to evaluate the hypothesis that dietary coconut decreases symptoms of chronic diarrhea in rhesus macaques.

Methods  Ten rhesus macaques with chronic diarrhea were selected for the trial. Five of the subjects were fed coconut macaroons and five of the subjects were fed a sham cookie. Stool consistency was monitored daily for both groups.

Results and conclusions  Data of chi‐squared analysis obtained from eight rhesus macaques with chronic diarrhea showed that the use of coconut macaroons as a dietary supplement did not have a statistically significant effect on their diarrhea.
Testing a key assumption of host‐pathogen theory: density and disease transmission
Authors: Greer Amy L. , Briggs Cheryl J. , Collins James P.
Published: September 2010

Conventional disease theory suggests that extinction with density‐dependent transmission is unlikely as the threshold host density (KT) is greater than zero. Extinction may result if transmission is frequency dependent or the pathogen has an environmental reservoir. Given the importance of understanding how pathogens affect species richness and diversity there are few empirical tests of these conclusions. We used anAmbystoma tigrinum–Ambystoma tigrinumvirus (ATV) model system in the laboratory to examine disease transmission dynamics. SusceptibleA. tigrinumlarvae were exposed to three different densities and proportions of infected larvae for 24 h. We then housed susceptible hosts individually for 28 days and monitored them for infection. The density of infected hosts to which susceptible hosts were exposed was the best predictor of infection (p=0.037). There was no effect of host clutch on the probability of becoming infected (p=0.67). Larvae in the highest density treatments died sooner than larvae in lower density treatments (p<0.001). Asymptomatic but infected hosts shed sufficient virus into the water in a 24‐h period to infect susceptible hosts without any direct contact between individuals. ATV transmission was best described by a power function, leading to the prediction that extinction ofA. tigrinumas a result of this pathogen is unlikely. Indeed, field observations show that larval salamander populations that experience ATV‐driven epidemics may decrease, but not to extinction, and then recover. Disease is proposed as a possible explanation for the global decline of amphibians. Ranaviruses infect many amphibian populations, but based on our results may not be a general cause of declines to extinction. In contrast, frequency dependent transmission, environmental reservoirs and alternative hosts may be the most likely explanation for the enigmatic decline, at times to extinction, of some amphibian populations as a result of emerging infectious diseases, like the chytrid fungusBatrachochytrium dendrobatidis.
Oak seedling survival and growth along resource gradients in Mediterranean forests: implications for regeneration in current and future environmental scenarios
Authors: Gómez‐Aparicio L. , Pérez‐Ramos I. M. , Mendoza I. , Matías L. , Quero J. L. , Castro J. , Zamora R. , Marañón T.
Published: September 2010

Understanding seedling performance across resource gradients is crucial for defining the regeneration niche of plant species under current environmental conditions and for predicting potential changes under a global change scenario. A 2‐year field experiment was conducted to determine how seedling survival and growth of two evergreen and two deciduousQuercusspecies vary along gradients of light and soil properties in two Mediterranean forests with contrasting soils and climatic conditions. Half the seedlings were subjected to an irrigation treatment during the first year to quantify the effects on performance of an alteration in the summer drought intensity. Linear and non‐linear models were parameterized and compared to identify major resources controlling seedling performance. We found both site‐specific and general patterns of regeneration. Strong site‐specificity was found in the identity of the best predictors of seedling survival: survival decreased linearly with increasing light (i.e. increasing desiccation risk) in the drier site, whereas it decreased logistically with increasing spring soil water content (i.e. increasing waterlogging risk) in the wetter site. We found strong empirical support for multiple resource limitation at the drier site, the response to light being modulated by the availability of soil resources (water and P). Evidence for regeneration niche partitioning amongQuercusspecies was only found at the wetter site. However, at both sitesQuercusspecies shared the same response to summer drought alleviation through water addition: increased first‐year survival but not final survival (i.e. after two years). This suggests that extremely dry summers (i.e. the second summer in the experiment) can cancel out the positive effects of previous wetter summers. Therefore, an increase in the intensity and frequency of summer drought with climate change might cause a double negative impact onQuercusregeneration, due to a general reduction in survival probability and the annulment of the positive effects of (infrequent) ‘wet’ years. Overall, results presented in this study are a major step towards the development of a mechanistic model of Mediterranean forest dynamics that incorporates the idiosyncrasies and generalities of tree regeneration in these systems, and that allow simulation and prediction of the ecological consequences of resource level alterations due to global change.
Evidence for top predator control of a grazing ecosystem
Authors: Frank Douglas A.
Published: September 2010

The importance of top predators in controlling ecological processes in large, intact ecosystems is unclear. In grasslands that support abundant ungulates, top–down control by predators may be particularly important, because of the tight biogeochemical linkages of ungulate prey with plants and soil microbes. Here, I examined the effects of the recent reintroduction of the gray wolfCanis lupuson ecosystem processes in Yellowstone National Park, where herds of grazing ungulates previously have been shown to stimulate several processes, including soil net nitrogen (N) mineralization. Rates of ungulate grazing intensity and soil net N mineralization were compared before and after wolf reintroduction in grasslands ranging five‐fold in aboveground production. Grazing intensity and grassland net N mineralization declined after wolf reintroduction, a likely partial function of fewer ungulates; wolf predation has been one of several factors implicated in causing the decline in Yellowstone ungulates. In addition, the spatial pattern of grazing and net N mineralization changed after reintroduction. A shift in the spatial patterns of grazer‐associated processes is consistent with a growing body of work indicating that wolves have changed habitat use patterns of ungulates in Yellowstone National Park. These findings suggest widespread wolf effects on ungulate prey, plants, and microbial activity that have spatially reorganized grassland energy and nutrient dynamics in Yellowstone Park.
Habitat fragmentation and the functional efficiency of temperate dung beetles
Authors: Rosenlew Helena , Roslin Tomas
Published: September 2010

To understand how current patterns of habitat loss and fragmentation will ultimately affect ecosystem functioning, we need to match experimental manipulations of community structure with real changes occurring in the landscapes of today. In this study, we examine the consequences of habitat fragmentation on a key function: the decomposition of dung by invertebrates. In a microcosm experiment, we use previous observations of dung beetle assemblage structure in fragmented and intact landscapes to create realistic differences in assemblages of small, dung‐dwelling species in the genusAphodius. We ask whether such differences will affect ecosystem functioning, and how their effects compare to those of removing full functional groups: dung‐dwellingAphodius, tunnellingGeotrupes stercorarius, and/or earthworms. As measured by changes in dung fresh weight, we observe an overriding impact of removingG. stercorarius, with the amount of dung remaining at any one time doubling if the species is excluded. Compared to this major effect, there seem to be less effects of removingAphodius, ambiguous effects of excluding earthworms, and no detectable effects of relatively minor changes inAphodiusassemblages as induced by current levels of fragmentation. Overall, our results support the general notion that different species contribute highly unevenly to overall ecosystem functioning. Most importantly though, our findings suggest that the functional consequences of habitat loss will depend on taxon‐specific responses to landscape modification. Only by addressing these responses may we predict the actual consequences of habitat loss.
The role of migration for spatial turnover of arctic bird species in a circumpolar perspective
Authors: Henningsson Sara , Alerstam Thomas
Published: September 2010

Several different factors may determine where species range limits are located within regions of otherwise continuously available habitat and suitable climate. Within the Arctic tundra biome many bird species are migratory and their breeding distributions are affected by migration routes that are in turn limited by factors such as suitable winter habitat, migratory stopover sites, geographical barriers and historical routes of colonization.

We identified longitudinal zones in the circumpolar Arctic of pronounced changes in the avian species composition (high species spatial turnover; ‘species divides’). We tested for the association between migratory status and the geographical location and numbers of such species divides for species with non‐breeding habitats mainly within terrestrial, pelagic and coastal ecosystems.

Our results demonstrate that migration is of profound importance for both the number and locations of species divides in the Arctic. Long‐distance migration is associated with a large number of divides among terrestrial and coastal arctic birds but with a reduced number of divides among pelagic birds. We suggest that long‐distance migration permits pelagic but not terrestrial and coastal birds to colonize large winter ranges, which in turn causes expansion of breeding ranges, with more homogenous communities and reduction of species divides as consequences, among the long‐distance migrants of pelagic but not of terrestrial and coastal birds. Furthermore, the divides among long‐distance migrants are situated in two main regions, the Beringia and Greenland zones, while divides among short‐distance migrants are more evenly spaced throughout the circumpolar Arctic. The Beringia and Greenland divides result largely from inter‐continental colonization of new breeding ranges but retainment of original winter quarters in a process of evolution through extension of migration routes, leading to aggregated divides in the meeting zones of major global flyways.
Displaced Majority: Robertson Davies and the Euro‐Canadian Diaspora
Authors: Varsava Nina
Published: September 2010

This essay discusses constructions of Canadian identity. Throughout the nation's history, many Canadians of European descent have defined themselves in relation to Europe (and the United States), rather than developing a sense of independent national identity. In his writing – both fiction and nonfiction – Robertson Davies, a preeminent late twentieth‐century Canadian writer, evocatively portrays this Euro‐Canadian ‘‘diasporic consciousness.’’

Through an exploration of his Deptford Trilogy, in particular the first and most celebrated novel of the series –Fifth Business (1970) – I analyze Davies's depiction of Euro‐Canadian sensibilities. I also relate Davies's trilogy to the perspectives of other Canadian writers – past and contemporary – which demonstrate similar Eurocentric sentiments. I question why European‐descended Canadians, even those many generations removed from Europe, still cling to their European heritage: why they resist a definition of Canada that is grounded in history and culture native to Canadian soil.

In the essay, I evaluate the nostalgia of Euro‐Canadians for a European past. While acknowledging that this nostalgia is in many ways understandable and even inescapable, I also argue that, in order to develop the inclusive and unifying identity that Canada lacks, Canadians of all backgrounds must take more interest in the historical narratives and nuances that make Canadian society complex, unique, and worthy of deep exploration.
L’éloge de l'ellipse
Authors: Small Andrew
Published: September 2010

Oiseaux de Saint‐John Perse, un poème en 13 suites, est une œuvre de poïétique comparée. Par le moyen d'une rhétorique subtile, Saint‐John Perse montre dans ce poème que le processus de création chez Georges Braque est une métamorphose qui aboutit à l’équivalence entre le peintre et sa création. Il en va de même pour Saint‐John Perse et sa poésie, laquelle met en valeur cette « coincidence » entre le langage et le réel. Par le moyen de l'ellipse (un emploi rhétorique rendu célèbre par Longin pour réaliser le sublime dans les discours), le poète parachève cette équivalence. Le trait laconique de Braque fonctionne pareillement dans ses tableaux et ses lithographies. Ainsi la peinture de Braque tout aussi bien que la poésie de Saint‐John Perse deviennent plus que de simples œuvres d'art : ce sont autant de recherches spirituelles qui dépassent l'immanent pour atteindre le transcendant, ne serait‐ce que momentanément.
Melatonin acts as a growth‐stimulating compound in some monocot species
Authors: Hernández‐Ruiz Josefa , Cano Antonio , Arnao Marino B.
Published: September 2010

Abstract:  In a recent study melatonin (N‐acetyl‐5‐methoxytryptamine), a well‐investigated animal molecule but minimally studied in plants, was seen to have a physiological role as growth‐promoting molecule in lupin hypocotyls. In the present study, the role of melatonin as a growth promoter is extended to coleoptiles of canary grass, wheat, barley and oat, in which it shows a relative auxinic activity [with respect to indole‐3‐acetic acid (IAA), the main auxin in plants] of between 10 and 55%. In addition, melatonin is seen to have an important inhibitory growth effect on roots similar to that played by auxin. The quantitation by liquid chromatography with electrochemical detection and identification by tandem mass spectrometry of melatonin and IAA in etiolated coleoptiles of the monocots assayed showed that both compounds are present in similar levels in these tissues. These results point to the co‐existence of auxin and melatonin in tissues and raises the possibility of their co‐participation in some physiological actions as auxinic hormones in plants.
Melatonin prevents experimental liver cirrhosis induced by thioacetamide in rats
Authors: Cruz Adolfo , Padillo Francisco J. , Torres Eva , Navarrete Carmen M. , Muñoz‐Castañeda Juan R. , Caballero Francisco J. , Briceño Javier , Marchal Trinidad , Túnez Isaac , Montilla Pedro , Pera Carlos , Muntané Jordi
Published: September 2010

Abstract:  Liver cirrhosis is a critical stage of chronic liver diseases that can produce liver failure, portal hypertension and hepatocarcinoma. Sustained oxidative stress plays a key role in cell damage and fibrosis induced during liver cirrhosis. We evaluated the effect of oxidative stress regulation by melatonin on the development of parenchymal destruction and stellate cell activation in experimental liver cirrhosis. Melatonin was administered to rats with liver cirrhosis induced by thioacetamide (TAA) for 1 or 3 months. Liver injury was assessed by serological analysis, as well as hematoxylin‐eosin staining and the in situ apoptosis detection assay in liver sections. Oxidative stress was evaluated by lipoperoxide and reduced glutathione levels, and by the measurement of catalase and superoxide dismutase activities in liver and serum respectively. The activation of stellate cells was evaluated by α‐smooth muscle actin expression in liver sections. Our results showed that TAA induced oxidative stress with extensive tissue damage and enhanced α‐smooth muscle actin expression in liver. Melatonin prevented the oxidative stress‐related changes associated with TAA toxicity. In conclusion, the study showed that melatonin prevents the tissue damage and fibrosis associated with TAA‐induced liver cirrhosis in rats.
Tissue‐plasminogen activator‐induced ischemic brain injury is reversed by melatonin: role of iNOS and Akt
Authors: Kilic Ertugrul , Kilic Ülkan , Reiter Russel J. , Bassetti Claudio L. , Hermann Dirk M.
Published: September 2010

Abstract:  In vivo studies showed that tissue‐plasminogen activator (t‐PA) may aggravate neuronal injury after focal cerebral ischemia. We hypothesized that t‐PA impairs survival‐promoting cell signaling in the ischemic brain, which may be reversed by a neuroprotectant, i.e. melatonin. We examined the effects of t‐PA (10 mg/kg, i.v.), administered alone or in combination with melatonin (4 mg/kg, i.p.), on ischemic injury, inducible nitric oxide synthase (iNOS) expression as well as Akt, Bcl‐XL and caspase‐3 signaling following 90 min of intraluminal middle cerebral artery (MCA) occlusion in mice. t‐PA, delivered immediately after reperfusion onset, increased infarct volume at 24 hr after MCA occlusion, in accordance with previous findings. Melatonin reduced infarct size when administered alone and reversed the t‐PA‐induced brain injury. Immunohistochemical studies showed that t‐PA treatment was associated with an accumulation of iNOS positive cells in ischemic brain areas, which was abolished after co‐delivery of melatonin. Western blots revealed that t‐PA decreased phosphorylated Akt levels, but did not influence Bcl‐XL expression and caspase‐3 activity in ischemic brain lysates. Co‐treatment with melatonin restored phosphorylated Akt levels, increased Bcl‐XL expression and reduced caspase‐3 activity. We provide evidence that t‐PA‐induced brain injury is accompanied by an activation of iNOS and inhibition of phosphatidylinositol‐3 kinase/Akt. That melatonin reversed these signaling changes and the t‐PA‐induced brain injury makes this indole attractive as an add‐on treatment with thrombolytics.
Melatonin limits lung injury in bleomycin treated mice
Authors: Genovese Tiziana , Paola Rosanna Di , Mazzon Emanuela , Muià Carmelo , Caputi Achille P. , Cuzzocrea Salvatore
Published: September 2010

Abstract:  Melatonin is the principal secretory product of the pineal gland and its role as an immuno‐modulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and exerts protective effects in septic shock, hemorrhagic shock and inflammation. The aim of this study was to investigate the effect of melatonin on the lung injury caused by bleomycin (BLM) administration. Mice subjected to intratracheal administration of BLM developed significant lung injury characterized by a marked neutrophil infiltration [assessed by myeloperoxidase (MPO) activity] and by tissue edema. In addition, an increase of immunoreactivity to nitrotyrosine, poly‐ADP‐ribose (PAR) was also observed in the lung of BLM‐treated mice. Also, lung injury induced by BLM administration was correlated with a significant loss of body weight and with a significant mortality. Administration of melatonin (10 mg/kg i.p.) daily significantly reduced the (i) loss of body weight, (ii) mortality rate, (iii) infiltration of the lung with polymorphonuclear neutrophils (MPO activity), (iv) edema formation and (v) histological evidence of lung injury. Administration of melatonin also markedly reduced the nitrotyrosine and PAR formation. Taken together, our results demonstrate that treatment with melatonin significantly reduces lung injury induced by BLM in the mice.
Effect of MT1 melatonin receptor deletion on melatonin‐mediated phase shift of circadian rhythms in the C57BL/6 mouse
Authors: Dubocovich M. L. , Hudson R. L. , Sumaya I. C. , Masana M. I. , Manna E.
Published: September 2010

Abstract:  In the mouse suprachiasmatic nucleus (SCN), melatonin activates MT1 and MT2 G‐protein coupled receptors, which are involved primarily in inhibition of neuronal firing and phase shift of circadian rhythms. This study investigated the ability of melatonin to phase shift circadian rhythms in wild type (WT) and MT1 melatonin receptor knockout (KO) C57BL/6 mice. In WT mice, melatonin (90 μg/mouse, s.c.) administered at circadian time 10 (CT10; CT12 onset of activity) significantly phase advanced the onset of the circadian activity rhythm (0.60 ± 0.09 hr, n = 41) when compared with vehicle treated controls (−0.02 ± 0.07 hr, n = 28) (P < 0.001). In contrast, C57 MT1KO mice treated with melatonin did not phase shift circadian activity rhythms (−0.10 ± 0.12 hr, n = 42) when compared with vehicle treated mice (−0.12 ± 0.07 hr, n = 43). Similarly, in the C57 MT1KO mouse melatonin did not accelerate re‐entrainment to a new dark onset after an abrupt advance of the dark cycle. In contrast, melatonin (3 and 10 pm) significantly phase advanced circadian rhythm of neuronal firing in SCN brain slices independent of genotype with an identical maximal shift at 10 pm (C57 WT: 3.61 ± 0.38 hr, n = 3; C57 MT1KO: 3.45 ± 0.11 hr, n = 4). Taken together, these results suggest that melatonin‐mediated phase advances of circadian rhythms of neuronal firing in the SCN in vitro may involve activation of the MT2 receptor while in vivo activation of the MT1 and possibly the MT2 receptor may be necessary for the expression of melatonin‐mediated phase shifts of overt circadian activity rhythms.
The antidepressant‐like effect of the melatonin receptor ligand luzindole in mice during forced swimming requires expression of MT2 but not MT1 melatonin receptors
Authors: Sumaya I. C. , Masana M. I. , Dubocovich M. L.
Published: September 2010

Abstract:  We previously reported an antidepressant‐like effect in C3H/HeN mice during the forced swimming test (FST) following treatment with the MT1/MT2 melatonin receptor ligand, luzindole. This study investigated the role melatonin receptors (MT1 and/or MT2) may play in the effect of luzindole in the FST using C3H/HeN mice with a genetic deletion of either MT1 (MT1KO) or MT2 (MT2KO) melatonin receptors. In the light phase (ZT 9–11), luzindole (30 mg/kg, i.p.) significantly decreased immobility during swimming in both wild type (WT) (135.6 ± 25.3 s, n = 7) and MT1KO (132.6 ± 13.3 s, n = 8) as compared with vehicle‐treated mice (WT: 207.1 ± 6.0 s, n = 7; MT1KO: 209.5 ± 6.2 s, n = 8) (P < 0.001). In the dark phase (ZT 20–22), luzindole also decreased time of immobility in both WT (89.5 ± 13.9 s, n = 8) and MT1KO (66.5 ± 6.4 s, n = 8) mice as compared with the vehicle treated (WT: 193.8 ± 3.5, n = 6; MT1KO: 176.6 ± 6.2 s, n = 8) (P < 0.001). Genetic disruption of the MT1 gene did not alter the diurnal rhythm of serum melatonin in MT1KO mice (ZT 9–11: 1.3 ± 0.6 pg/mL, n = 7; ZT 20–22: 10.3 ± 1.1 pg/mL, n = 8) as compared with WT (ZT 9–11: 1.4 ± 0.7 pg/mL; ZT 20–22: 10.6 pg/mL). Swimming did not alter the serum melatonin diurnal rhythm in WT and MT1KO mice. Decreases in immobility of WT and MT1KO mice by luzindole treatment were not affected by gender or age (3 months versus 8 months). In contrast, luzindole did not decrease immobility during the FST in MT2KO mice. We conclude that the antidepressant‐like effect of luzindole may be mediated through blockade of MT2 rather than MT1 melatonin receptors.
Circadian phase determined from melatonin profiles is reproducible after 1 wk in subjects who sleep later on weekends
Authors: Revell Victoria L. , Kim Hyungsoo , Tseng Christine Y. , Crowley Stephanie J. , Eastman Charmane I.
Published: September 2010

Abstract:  The aim of this study was to determine whether circadian phase from salivary melatonin profiles is the same when measured in phase assessments 1 wk apart. Eleven healthy young men and women maintained a fixed, home sleep–wake schedule, in bed, in the dark 23:00–07:00 hr on weekdays. On Friday and Saturday nights they were permitted to wake up and go to bed up to 1 hr later, and on Saturdays and Sundays they could nap between 13:30 and 16:30 hr. The study was run in the summer. Subjects wore sunglasses when outside during the day, and went outside for at least 15 min between 08:00 and 09:00 hr each morning. They maintained this schedule for 15 days before the first assessment and the 6 days in between the two assessments. During the assessments subjects remained awake overnight in <5 lux and gave saliva samples every 30 min. A recovery nap (13:00–17:00 hr) followed the first session. The dim light melatonin onset (DLMO), offset (DLMOff) and midpoint were used as phase markers. There was minimal change in their timing between the two phase assessments. The average absolute change in midpoint (the change in phase regardless of direction) was 20 min. There was a small, 30 min delay in the DLMO. Thus, circadian phase can be measured a week in advance of any phase shifting intervention and, as long as the prescribed sleep and morning light schedule is maintained, the phase at the start of treatment can be confidently estimated.
Reduced lipolysis and increased lipogenesis in adipose tissue from pinealectomized rats adapted to training
Authors: Borges‐Silva Cristina N. , Fonseca‐Alaniz Miriam H. , Alonso‐Vale Maria I. C. , Takada Julie , Andreotti Sandra , Peres Sidney B. , Cipolla‐Neto José , Pithon‐Curi Tânia C. , Lima Fabio B.
Published: September 2010

Abstract: The current study investigated the effects of chronic training and pinealectomy on the lipogenic and lipolytic activity of adipose tissue. Pinealectomized and sham‐operated adult male Wistar rats were distributed in to four subgroups: pinealectomized untrained, pinealectomized trained, control untrained and control trained. At the end of the training period (8 wk) the rats were killed. Blood samples were collected for glucose, insulin and leptin determinations. Peri‐epididymal adipocytes were isolated for measurement of in vitro rates of lipolysis and incorporation of substrates (d‐[U‐14C]‐glucose,l‐[U‐14C]‐lactate, [2‐14C]‐acetate and [1‐14C]‐palmitate) into lipids, and samples of epididymal adipose tissue were homogenized for evaluation of glucose‐6‐phosphate dehydrogenase maximal activity. Pinealectomy resulted in a significantly increased lipolytic capacity in response to isoproterenol and a decrease in circulating leptin levels without affecting the rates of incorporation of different substrates into lipids. However, only in the intact control group did training promote a higher basal and isoproterenol‐stimulated lipolysis, increase the incorporation of palmitate (esterification), decrease the incorporation of acetate (lipogenesis) into lipids and diminish circulating leptin levels. These effects of exercise training were not seen in pinealectomized rats. However, pinealectomized trained animals showed a marked reduction in lipolysis and an increased rate of acetate incorporation. In conclusion, we demonstrated for the first time that the pineal gland plays an important role in the regulation of lipid metabolism in such a way that its absence caused a severe alteration in the balance between lipogenesis and lipolysis, which becomes evident with the adaptation to exercise training.
A proposed mechanism to explain the stimulatory effect of melatonin on antioxidative enzymes
Authors: Tomás‐Zapico Cristina , Coto‐Montes Ana
Published: September 2010

Abstract:  Melatonin, the main secretory product of the pineal gland, is known to collaborate against oxidative stress within cells, but its mechanism of action in terms of stimulating antioxidant enzymes remains unclear. Herein, we propose that melatonin modulates antioxidant enzyme activities via its interaction with calmodulin, which in turn inhibits downstream processes that lead to the inactivation of nuclear RORα melatonin receptor. Eventually, this nuclear transcription factor downregulates NF‐κB‐induced antioxidant enzyme expression. Therefore, the increment in antioxidant enzyme activities induced by melatonin involves the inhibition of the RORα pathway. Thus, in addition to its direct free radical scavenging activities, melatonin has important actions in oxidative defense by stimulating enzymes which metabolize free radicals and radical products to innocuous metabolites.
The heme oxygenase system and oral diseases
Authors: Fan W , Huang F , Zhu X , Li D , Fu S , He H
Published: September 2010

Oral Diseases (2011) 17, 252–257

Heme oxygenase (HO) system catabolizes heme into three products: carbon monoxide (CO), biliverdin/bilirubin and free iron, which consists of three forms identified to date: the oxidative stress‐inducible protein HO‐1 and the constitutive isozymes HO‐2 and HO‐3. HO has been involved in many physiological and pathophysiological processes, ranging from Alzheimer’s disease to cancer. The interest in HO system by scientists and clinicians involved with the oral and maxillofacial region is fairly recent, and few papers currently cited on HO relate to diseases in this anatomical area. This review will focus on the current understanding of the physiological significance of HO‐1 induction and its possible roles in the oral diseases studied to date. The implications for possible therapeutic manipulation of HO are also discussed.
Coronary heart disease and chronic periodontitis: is polymorphism of interleukin‐6 gene the common risk factor in a Chinese population?
Authors: Fan WH , Liu DL , Xiao LM , Xie CJ , Sun SY , Zhang JC
Published: September 2010

Oral Diseases (2011) 17, 270–276

Objectives:  Coronary heart disease (CHD) and chronic periodontitis (CP) both are multifactorial chronic diseases and related to inflammation. Interleukin‐6 (IL‐6) plays an important role in the pathogenesis of inflammatory diseases. The purpose of the study was to investigate the association among IL‐6 gene polymorphisms, CP and CHD susceptibility in a Chinese population.

Material and methods:  The investigation was conducted as a case‐control study involving 505 individuals: 113 patients with CHD and CP, 84 patients with CHD, 178 patients with CP and 130 control individuals. The polymorphisms of IL‐6 gene were analyzed by polymerase chain reaction‐restriction fragment length polymorphism. Relationships between the distributions of the genotypes and risk factors were also assessed.

Results:  Mutations at the loci ‐174 G/C, ‐597 G/A of IL‐6 were rare in a Chinese population. No significant difference for IL‐6‐572C/G polymorphism was detected among moderate CP group, severe CP group and control (P = 0.312 and 0.481), significant differences were found between CHD groups and non‐CHD groups (P ≤ 0.001). After adjustment for CHD risk factors, the G allele resulted in an increased risk (OR = 1.676‐1.856), the GG/CG genotype was nearly two times higher risk compared to CC genotype (OR = 2.010‐2.136).

Conclusions:  IL‐6‐572C/G polymorphism did not correlate with CP susceptibility, but might be a potential risk factor for CHD in a Chinese population.