Suchergebnisse

Thyroid hormones are involved in many developmental and physiological processes, including osmoregulation. The regulation of the thyroid system by environmental salinity in the euryhaline gilthead seabream (Sparus aurata) is still poorly characterized. To this end seabreams were exposed to four different environmental salinities (5, 15, 40 and 55 ppt) for 14 days, and plasma free thyroid hormones (fT3, fT4), outer ring deiodination and Na+/K+-ATPase activities in gills and kidney, as well as other osmoregulatory and metabolic parameters were measured. Low salinity conditions (5 ppt) elicited a significant increase in fT3 (29%) and fT4 (184%) plasma concentrations compared to control animals (acclimated to 40 ppt, natural salinity conditions in the Bay of Cádiz, Spain), while the amount of pituitary thyroid stimulating hormone subunit β (tshb) transcript abundance remained unchanged. In addition, plasma fT4 levels were positively correlated to renal and branchial deiodinase type 2 (dio2) mRNA expression. Gill and kidney T4-outer ring deiodination activities correlated positively with dio2 mRNA expression and the highest values were observed in fish acclimated to low salinities (5 and 15 ppt). The high salinity (55 ppt) exposure caused a significant increase in tshb expression (65%), but deiodinase gene expression (dio1 and dio2) and activity did not change and were similar to controls (40 ppt). In conclusion, acclimation to different salinities led to changes in the peripheral regulation of thyroid hormone metabolism in seabream. Therefore, thyroid hormones are involved in the regulation of ion transport and osmoregulatory physiology in this species. The conclusions derived from this study may also allow aquaculturists to modulate thyroid metabolism in seabream by adjusting culture salinity. ; This work was partially supported by a Socrates/Erasmus Grant from the European Union and a Ph.D. scholarship from the University of Cadiz (UCA 2009-074-FPI) to I. R-J. It has been also supported by grants AGL2007-61211/ACU (Ministerio de Educación y Ciencia and FEDER, Spain) and Proyecto de Excelencia PO7-RNM-02843 (Junta de Andalucía) to J.M.M. BL (SFRH/BPD/89889/2012) and PISP (SFRH/BPD/84033/2012) were supported by the Science Foundation (FCT) of Portugal. ; Peer reviewed

Thyroid hormones are involved in many developmental and physiological processes, including osmoregulation. The regulation of the thyroid system by environmental salinity in the euryhaline gilthead seabream (Sparus aurata) is still poorly characterized. To this end seabreams were exposed to four different environmental salinities (5, 15, 40 and 55 ppt) for 14 days, and plasma free thyroid hormones (fT3, ff4), outer ring deiodination and Na+/K+ -ATPase activities in gills and kidney, as well as other osmoregulatory and metabolic parameters were measured. Low salinity conditions (5 ppt) elicited a significant increase in fT3 (29%) and ff4 (184%) plasma concentrations compared to control animals (acclimated to 40 ppt, natural salinity conditions in the Bay of Cadiz, Spain), while the amount of pituitary thyroid stimulating hormone subunit 13 (tshb) transcript abundance remained unchanged. In addition, plasma fT4 levels were positively correlated to renal and branchial deiodinase type 2 (dio2) mRNA expression. Gill and kidney T4-outer ring deiodination activities correlated positively with dio2 mRNA expression and the highest values were observed in fish acclimated to low salinities (5 and 15 ppt). The high salinity (55 ppt) exposure caused a significant increase in tshb expression (65%), but deiodinase gene expression (diol and dio2) and activity did not change and were similar to controls (40 ppt). In conclusion, acclimation to different salinities led to changes in the peripheral regulation of thyroid hormone metabolism in seabream. Therefore, thyroid hormones are involved in the regulation of ion transport and osmoregulatory physiology in this species. The conclusions derived from this study may also allow aquaculturists to modulate thyroid metabolism in seabream by adjusting culture salinity. (C) 2016 Elsevier Inc. All rights reserved. ; Socrates/Erasmus Grant from the European Union ; University of Cadiz [UCA 2009-074-FPI] ; Ministerio de Education y Ciencia, Spain [AGL2007-61211/ACU] ; FEDER, Spain ...

AbstractThis article is a reaction to the rapid changes many urban areas are undertaking in attempts to counter the contemporary terrorist threat since the devastating events of September 11th. The response of central London authorities both pre‐ and post‐ September 11th is used as the lens through which to view attempts to reduce the real and perceived threat of terrorist attack through the adoption of territorial approaches to security, both physical and technological, which are increasingly being utilized at ever‐expanding spatial scales. It argues that this situation all too often produces a scenario of 'splintered urbanism' as security rings are thrown up around carefully selected sections of cities deemed most at risk. It further argues for a balance to be struck between competing concerns for freedom of access, mobility and other democratic freedoms, and the need for cities to adopt increasingly militarized security perspectives in their counter‐terrorism efforts.Cet article présente une réaction aux rapides changements que de nombreuses zones urbaines entreprennent afin de contrer la menace terroriste actuelle depuis les ravages du 11 septembre. La réponse des autorités du centre de Londres, à la fois avant et après cette date, sert ainsi de loupe permettant d'observer les efforts de minimisation de cette menace d'agression, tant subjective que réelle. Il s'agit de démarches territoriales à l'égard de la sécurité (matérielle et technologique) appliquées de plus en plus souvent à des échelles spatiales sans cesse élargies. De cette situation, naît trop souvent un scénario 'd'urbanisme fragmenté', les anneaux de sécuritéétant jetés autour de portions soigneusement sélectionnées de villes jugées le plus en danger. L'article défend la nécessité de trouver un équilibre entre les préoccupations opposées que sont les liberté d'accès, mobilité ou autres libertés démocratiques et le besoin des villes d'adopter des perspectives sécuritaires de plus en plus militarisées dans leurs tentatives contre le terrorisme.

The present study examines inner and outer suburban ring attainment outcomes among racial and ethnic groups that reside in the nation's metropolitan areas. The main objective is to evaluate the extent to which the relationship between racial and ethnic group's socioeconomic status characteristics and residence between inner and outer suburban rings conforms to the tenets of the spatial assimilation model. Using micro-level data from the five-year 2012–2016 American Community Survey, the author calculates binomial logistic regression models to determine the effects of socioeconomic status (SES) and other relevant predictors on residence within the nation's metropolitan area's suburban inner and outer rings. The results both confirm and contradict the main tenets of the spatial assimilation model. To the extent that income, education, and homeownership are positively related to residence in both suburban rings, the findings also suggest that access to inner and outer rings is hierarchically stratified by race and ethnicity.