Área mitocondrial relativa nos epitélios branquial e renal do baiacu estuarino tropical Sphoeroides testudineus após aclimatação a água do mar isosmótica

The gills of teleost fishes are responsible both for gas exchange in respiration and salt transport in osmoregulation (JOBLING,  1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; EVANS et al., 1999; EVANS et al., 2005). In marine teleosts the gill epithelium secretes salt mainly through chloride cells (JOBLING, 1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are typically located between secondary lamellae at their insertion in the gill filament (inter-lamellar region) or in the gill filament itself (LAURENT & DUNEL, 1980; PERRY, 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are rounded, display abundant mitochondria, a tubular system of endomembranes, sub-apical vesicles, and extensive intercellular junctional complexes (LAURENT & DUNEL, 1980; JOBLING, 1995; ZADUNAISKY, 1996; PERRy, 1997; EVANS et al., 2005).The gills of teleost fishes are responsible both for gas exchangein respiration and salt transport in osmoregulation (JOBLING,  1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; EVANS et al., 1999; EVANS et al., 2005). In marine teleosts the gill epithelium secretes salt mainly through chloride cells (JOBLING, 1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are typically located between secondary lamellae at their insertion in the gill filament (inter-lamellar region) or in the gill filament itself (LAURENT & DUNEL, 1980; PERRY, 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are rounded, display abundant mitochondria, a tubular system of endomembranes, sub-apical vesicles, and extensive intercellular junctional complexes (LAURENT & DUNEL, 1980; JOBLING, 1995; ZADUNAISKY, 1996; PERRy, 1997; EVANS et al., 2005)

Estabilidade osmótica dos fluídos celômicos de um pepino do mar (Holothuria grisea) e de uma estrela-do-mar (Asterina stellifera) (Echinodermata) expostos ao ar durante a maré baixa: um estudo de campo

Animais de entre-marés podem ser expostos ao ar durante a maré baixa, por pelo menos 1-2 horas. Os animais expostos ao ar são susceptíveis a perda de sal e/ou entrada de água durante chuva intensa, ou perda de água pela ação de dessecação do sol. A osmolalidade de amostras de fluido celômico obtidas do pepino-do-mar Holothuria grisea e da estrela-do-mar Asterina stellifera expostas ao ar, ou de animais controles imersos na água do mar adjacente foi determinada. As amostras foram obtidas imediatamente após a exposição ao ar, e novamente após uma hora de exposição ao ar, durante a maré baixa no campo, em tempo nublado, chuvoso, ou ensolarado, na Praia rochosa do Quilombo, Penha, Sul do Brasil. Uma hora de exposição a qualquer das condições climáticas indicadas não alterou a osmolalidade dos fluidos celômicos. Houve pequena redução nas osmolalidades dos fluidos celômicos durante a exposição ao ar com precipitação de chuva. Sugere-se que estes equinodermas possam imediatamente detectar sua exposição ao ar, e possam então reduzir a permeabilidade osmótica de sua parede do corpo, para evitar perda de água para o ar ou entrada de água/saída de sal durante a chuva. ABSTRACT Intertidal animals can be exposed to the air during low tide, for at least 1-2 hours. Animals exposed to the air are subject to salt loss (or water gain) from heavy rains or volume loss from the desiccating action of the sun. Coelomic fluid samples obtained from the sea-cucumber Holothuria grisea and the starfish Asterina stellifera exposed to the air or from control animals submerged in surrounding sea water have been assayed for osmolality. Samples were obtained right after air exposure and again after 1 hour of exposure to the air during low tide in the field, either under cloudy, rainy or sunny weather conditions, in the rocky beach of Quilombo, Penha, Southern Brazil. One hour of exposure to any of the conditions did not change coelomic fluid osmolalities. There was a slight reduction in coelomic fluid osmolalities upon air exposure during rainfall. It is suggested that these echinoderms can somehow immediately detect air exposure and reduce their body wall permeability to avoid water loss or water influx/salt loss during rainfall. RÉSUMÉ Animaux dentre-marées peuvent êtres exposés a lair libre pendant le reflux de la marée, pour environ une ou deux heures seulement. Ces animaux, quand exposés a lair libre, sont susceptibles de perdre du sel et dabsorber de leau pendant une période de pluie intense. Par contre, ils peuvent perdre de leau si soumis a laction de dessèchement due a une éxposition au soleil. On a réussi a determiner losmolalité déchantillons du fluide celomique obtenus du Pépin-de-mer Holothuria grisea et de lÉtoile-de-mer Asterina stellifera exposés a lair libre, e danimaux-controles immergés dans leau de mer voisin. Les échantillons ont été obtenus tout de suite après lexposition à lair et, une seconde fois, après une heure dexposition à lair libre, pendant la durée de la marée basse, soit sous la pluie, soit au soleil ou soit sous un ciel ombrageux, à la plage rocailleuse de Quilombo, Penha, au sud du Brésil. Une heure déxposition à nimporte quelles conditions climatiques indiquées, nont pas pu altérer losmolalité des fluides celomiques, ce que sugère la conclusion que ces échinodermes peuvent détecter immédiatement sa exposition à lair libre et peuvent tout de suite réduire la permeabilité osmotique de la membrane que recouvre son corps pour éviter perdre deau et, de la même façon, reduire labsortion de leau pendant la pluie. On a observé une petite réduction de fluides celomiques pendant lexposition a lair, avec ocurrence de pluie

Unidirectional Na\u3csup\u3e+\u3c/sup\u3e and Ca\u3csup\u3e2+\u3c/sup\u3e fluxes in two euryhaline teleost fishes, Fundulus heteroclitus and Oncorhynchus mykiss, acutely submitted to a progressive salinity increase

Na+ and Ca2+ regulation were compared in two euryhaline species, killifish (normally estuarine-resident) and rainbow trout (normally freshwater-resident) during an incremental salinity increase. Whole-body unidirectional fluxes of Na+ and Ca2+, whole body Na+ and Ca2+, and plasma concentrations (trout only), were measured over 1-h periods throughout a total 6-h protocol of increasing salinity meant to simulate a natural tidal flow. Killifish exhibited significant increases in both Na+ influx and efflux rates, with efflux slightly lagging behind efflux up to 60% SW, but net Na+ balance was restored by the time killifish reached 100% SW. Whole body Na+ did not change, in agreement with the capacity of this species to tolerate daily salinity fluctuations in its natural habitat. In contrast, rainbow trout experienced a dramatic increase in Na+ influx (50-fold relative to FW values), but not Na+ efflux between 40 and 60% SW, resulting in a large net loading of Na+ at higher salinities (60-100% SW), and increases in plasma Na+ and whole body Na+ at 100% SW. Killifish were in negative Ca2+ balance at all salinities, whereas trout were in positive Ca2+ balance throughout. Ca2+ influx rate increased two- to threefold in killifish at 80 and 100% SW, but there were no concomitant changes in Ca2+ efflux. Ca2+ flux rates were affected to a larger degree in trout, with twofold increases in Ca2+ influx at 40% SW and sevenfold increases at 100% SW. Again, there was no change in Ca2+ efflux with salinity, so plasma Ca2+ concentration increased in 100% SW. As the killifish is regularly submitted to increased salinity in its natural environment, it is able to rapidly activate changes in unidirectional fluxes in order to ensure ionic homeostasis, in contrast to the trout. © 2007 Springer-Verlag

MOOCs- Tendencias de diseño visual y organización de contenidos

info:eu-repo/semantics/publishedVersio

Domain-wall structure in thin films with perpendicular anisotropy: Magnetic force microscopy and polarized neutron reflectometry study

Ferromagnetic domain patterns and three-dimensional domain-wall configurations in thin CoCrPt films with perpendicular magnetic anisotropy were studied in detail by combining magnetic force microscopy and polarized neutron reflectometry with micromagnetic simulations. With the first method, lateral dimension of domains with alternative magnetization directions normal to the surface and separated by domain walls in 20-nm-thick CoCrPt films were determined in good agreement with micromagnetic simulations. Quantitative analysis of data on reflectometry shows that domain walls consist of a Bloch wall in the center of the thin film, which is gradually transformed into a pair of Néel caps at the surfaces. The width and in-depth thickness of the Bloch wall element, transition region, and Néel caps are found consistent with micromagnetic calculations. A complex structure of domain walls serves to compromise a competition between exchange interactions, keeping spins parallel, magnetic anisotropy orienting magnetization normal to the surface, and demagnetizing fields, promoting in-plane magnetization. It is shown that the result of such competition strongly depends on the film thickness, and in the thinner CoCrPt film (10 nm thick), simple Bloch walls separate domains. Their lateral dimensions estimated from neutron scattering experiments agree with micromagnetic simulations.Microelectronics Advanced Research Corporation (MARCO)United States. Defense Advanced Research Projects Agenc

Phylodynamics of vampire bat-transmitted rabies in Argentina

Common vampire bat populations distributed from Mexico to Argentina are important rabies reservoir hosts in Latin America. The aim of this work was to analyse the population structure of the rabies virus (RABV) variants associated with vampire bats in the Americas and to study their phylodynamic pattern within Argentina. The phylogenetic analysis based on all available vampire bat-related N gene sequences showed both a geographical and a temporal structure. The two largest groups of RABV variants from Argentina were isolated from northwestern Argentina and from the central western zone of northeastern Argentina, corresponding to livestock areas with different climatic, topographic and biogeographical conditions, which determined their dissemination and evolutionary patterns. In addition, multiple introductions of the infection into Argentina, possibly from Brazil, were detected. The phylodynamic analysis suggests that RABV transmission dynamics is characterized by initial epizootic waves followed by local enzootic cycles with variable persistence. Anthropogenic interventions in the ecosystem should be assessed taking into account not only the environmental impact but also the potential risk of disease spreading through dissemination of current RABV lineages or the emergence of novel ones associated with vampire bats.Fil: Torres, Carolina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lema, C.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud; ArgentinaFil: Gury Dohmen, F.. Instituto de Zoonosis “Dr. Luis Pasteur”; ArgentinaFil: Beltran, F.. Instituto de Zoonosis “Dr. Luis Pasteur”; ArgentinaFil: Novaro, L.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; ArgentinaFil: Russo, S.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; ArgentinaFil: Freire, M. C.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud; ArgentinaFil: Velasco Villa, A.. Centers for Disease Control and Prevention; Estados UnidosFil: Mbayed, Viviana Andrea. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cisterna , D. M.. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; Argentin

Mineralocorticoid Receptor Modulation by Dietary Sodium Influences NAFLD Development in Mice

Introduction and Objectives Nonalcoholic-fatty-liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome (MetS). Mineralocorticoid receptor (MR) activation is associated with increased risk of MetS but few studies have assessed the role of liver MR on NAFLD. We aimed to evaluate the effect of MR modulation by sodium intake in liver injury in experimental models of NAFLD. Materials and Methods C57BL/6J mice were fed either a high-fat-diet (HFD) or a choline/methionine deficient (MCD) diet with different sodium concentrations. Hepatic concentration of lipid species, serum aldosterone levels, expression of MR, proinflammatory and profibrotic markers and liver histology were assessed. Results Mice fed with High-Na+/HFD showed a lower MR expression in liver (p = 0.01) and less steatosis on histology (p = 0.04). Consistently, animals from this group exhibited lower levels of serum aldosterone (p = 0.028) and lower hepatic triglyceride content (p = 0.008). This associated to a reduced expression of lipogenic genes, significant changes in lipid subspecies, lower HOMA-IR (p < 0.05), and lower expression of pro-inflammatory and profibrotic markers compared to those mice fed a Low-Na+/HFD. Additionally, mice fed a High-Na+/HFD showed higher expression of salt-inducible kinase (SIK)-1 and lower expression of serum-and-glucocorticoid-inducible kinase (SGK)-1. Similar results were observed with the MCD diet model. Conclusion We identified in two experimental models of NAFLD that High-Na+ diet content is associated to lower serum aldosterone levels and hepatic MR downregulation, associated to decreased steatosis and reduced de novo hepatic lipogenesis, proinflammatory and profibrotic markers. Decreased activation of hepatic MR seems to generate beneficial downstream inhibition of lipogenesis in experimental NAFLD.This work was funded, in part, by grants from the Chilean Government [FONDECYT #1150327 and #1191145 to M.A.; #1200227 to JPA; #1190419 to R.B and #1191183 to F.B.; #1211879 to D.C.) and the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, AFB170005, CARE Chile UC)]. MA is part of the European- Latin American ESCALON consortium funded by the European Union’s Horizon 2020 Research and Innovation Program under grant agreement no. 825510. Funding from Ayudas para apoyar grupos de investigación del sistema Universitario Vasco (IT971-16 to P.A.), MCIU/AEI/FEDER, UE (RTI2018-095134-B-100 to P.A) is also acknowledged

We are more than EFL teachers-we are Educators: Emancipating EFL student-teachers through photovoice

The prevailing pedagogical orientations of English as a foreign language (EFL) education in Spain oppress learners intellectually in ways that are counterproductive to their learning. As a reaction to this, 129 EFL student-teachers (STs) took part during the 2013/14, 2014/15, and 2015/16 academic years in a workshop which drew on the methodology of participatory action research and on photovoice as a data-creating strategy, in order to emancipate these STs intellectually, boost their EFL development, and offer an alternative critical model for their future EFL teaching. The research was assessed collectively through a variety of qualitative strategies. Results showed that the photovoice workshop created a rich and meaningful context for EFL learning, one which enabled the STs to fully actualize their intellectual potential by producing knowledge collectively, thereby setting a memorable educational example for their own future teaching