Mountain Pastures Structure and Its Relationship with Grazing

The present work aims toward an approach to mountain pastures as a system of relationships in which it is needed to point out those environmental factors that reflect more clearly their structure and potential productivity. This initial step of pasture tipification is important as a previous activity before the planning and management of protected areas because these areas support an intensive pastoral activity. In order to achieve this objective a field study was conducted in two areas in the Gorbeia Natural Park (Bizkaia): Arraba and Aldamiñape, located at 900-1100 masl. In each pasture four plots were selected according to orientation (north/south) and slope (\u3c 10%/\u3e 10%), and botanical composition and potential yield determined, as well as the pasture rejected by the livestock at three different times (June-August-November). Besides the herbage biomass yield data were related to grass height. It is observed that the topographical factors studied do not have a clear effect on potential yield at the different areas; however, there is a clear seasonality, being august the period with the highest herbage biomass production. Analyzing the data of herbage rejected by the livestock it is noted a differential livestock distribution on the pasture through the grazing time, being the area of Aldamiñape facing north and with \u3e 10% slope the area with the highest grazing pressure, which in turn is the area with a highest cover degree by Agrostis curtisii, an species of low nutritional value

Quaternary structure of a G-protein coupled receptor heterotetramer in complex with Gi and Gs

Background: G-protein-coupled receptors (GPCRs), in the form of monomers or homodimers that bind heterotrimeric G proteins, are fundamental in the transfer of extracellular stimuli to intracellular signaling pathways. Different GPCRs may also interact to form heteromers that are novel signaling units. Despite the exponential growth in the number of solved GPCR crystal structures, the structural properties of heteromers remain unknown. Results: We used single-particle tracking experiments in cells expressing functional adenosine A1-A2A receptors fused to fluorescent proteins to show the loss of Brownian movement of the A1 receptor in the presence of the A2A receptor, and a preponderance of cell surface 2:2 receptor heteromers (dimer of dimers). Using computer modeling, aided by bioluminescence resonance energy transfer assays to monitor receptor homomerization and heteromerization and G-protein coupling, we predict the interacting interfaces and propose a quaternary structure of the GPCR tetramer in complex with two G proteins. Conclusions: The combination of results points to a molecular architecture formed by a rhombus-shaped heterotetramer, which is bound to two different interacting heterotrimeric G proteins (Gi and Gs). These novel results constitute an important advance in understanding the molecular intricacies involved in GPCR function

Managing and resisting ‘degeneration’ in employee-owned businesses: a comparative study of two large retailers in Spain and the UK

Employee-owned businesses have recently enjoyed a resurgence of interest as possible ‘alternatives’ to the somewhat tarnished image of conventional investor-owned capitalist firms. Within the context of global economic crisis, such alternatives seem newly attractive. This is somewhat ironic because, for more than a century, academic literature on employee-owned businesses has been dominated by the ‘degeneration thesis’. This suggested that these businesses tend towards failure – they either fail commercially, or they relinquish their democratic characters. Bucking this trend and offering a beacon - especially in the UK - has been the commercially successful, co-owned enterprise of the John Lewis Partnership (JLP) whose virtues have seemingly been rewarded with favourable and sustainable outcomes. This paper makes comparisons between JLP and its Spanish equivalent Eroski – the supermarket group which is part of the Mondragon cooperatives. The contribution of this paper is to examine in a comparative way how the managers in JLP and Eroski have constructed and accomplished their alternative scenarios. Using longitudinal data and detailed interviews with senior managers in both enterprises it explores the ways in which two large, employee-owned, enterprises reconcile apparently conflicting principles and objectives. The paper thus puts some new flesh on the ‘regeneration thesis’

Improved methodical approach for quantitative BRET analysis of G protein coupled receptor dimerization

G Protein Coupled Receptors (GPCR) can form dimers or higher ordered oligomers, the process of which can remarkably influence the physiological and pharmacological function of these receptors. Quantitative Bioluminescence Resonance Energy Transfer (qBRET) measurements are the gold standards to prove the direct physical interaction between the protomers of presumed GPCR dimers. For the correct interpretation of these experiments, the expression of the energy donor Renilla luciferase labeled receptor has to be maintained constant, which is hard to achieve in expression systems. To analyze the effects of non-constant donor expression on qBRET curves, we performed Monte Carlo simulations. Our results show that the decrease of donor expression can lead to saturation qBRET curves even if the interaction between donor and acceptor labeled receptors is non-specific leading to false interpretation of the dimerization state. We suggest here a new approach to the analysis of qBRET data, when the BRET ratio is plotted as a function of the acceptor labeled receptor expression at various donor receptor expression levels. With this method, we were able to distinguish between dimerization and non-specific interaction when the results of classical qBRET experiments were ambiguous. The simulation results were confirmed experimentally using rapamycin inducible heterodimerization system. We used this new method to investigate the dimerization of various GPCRs, and our data have confirmed the homodimerization of V2 vasopressin and CaSR calcium sensing receptors, whereas our data argue against the heterodimerization of these receptors with other studied GPCRs, including type I and II angiotensin, β2 adrenergic and CB1 cannabinoid receptors

Desafíos políticos de los países de inmigración

13 págs.-- Publicado en "Confluencia XXI. Revista de Pensamiento Político" (México), nº 3 (Oct-Dic 2008) bajo el título monográfico "Migrantes: ¿Por qué se van? ¿Por qué se quedan?".Las migraciones, una práctica tan antigua como la propia condición humana, se han convertido en un factor estructural de primer orden, en uno de los macrofenómenos más definitorios de nuestra época y en un complejo reto para las sociedades contemporáneas. En prácticamente todos los países del mundo, todo lo que concierne a este complejo fenómeno ocupa un lugar destacado en la agenda política. La gestión, el control y la integración de los movimientos internacionales de personas se presentan como un policy field de creciente y prioritaria relevancia. No se trata, sin embargo, de una cuestión de mera moda: el número de países implicados de manera significativa en las migraciones internacionales ha aumentado considerablemente, hasta el punto de que resulta realmente difícil encontrar algún Estado que no sea bien un país de inmigración, bien un país de emigración o bien ambas cosas a la vez, cuando no al menos un país de tránsito. No ha de extrañar entonces que la mayoría de los gobiernos haya tomado conciencia de la necesidad de ofrecer una respuesta en términos legales e institucionales a un fenómeno de carácter permanente que puede llegar a alterar la estructura demográfica, social, cultural, económica y laboral de un país. Dada la complejidad de la cuestión, y por cuestiones de economía argumentativa, aquí se abordará de manera fundamental desde la perspectiva de los países receptores, que, por lo demás, es también la adoptada en forma habitual por los países europeos que registran mayor inmigración. Sin embargo, el fenómeno migratorio es fundamentalmente transnacional y tiene fehacientes repercusiones en los países de emigración.Peer reviewe

Nanomolar oxytocin synergizes with weak electrical afferent stimulation to activate the locomotor CPG of the rat spinal cord in vitro.

Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM-1 \u3bcM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other protocols, and delineate the use of oxytocin to strengthen the efficiency of electrical stimulation to activate locomotor circuits

Estructura de los pastizales implantados en la zona del Gorbeia

La crisis del sector ganadero en los últimos años y la disminución de la carga ganadera en los pastizales de montaña provocó el abandono de estas áreas y la reinvasión de especies arbustivas. No obstante, hoy en día, ha aparecido una fuerte demanda por parte de los ganaderos para realizar transformaciones de áreas de matorral. Los pastizales objeto de este estudio, Altunoste y Arkaola, fueron implantados en los años 1984 y 1992 respectivamente, con laboreo y establecimiento de especies de interés forrajero (raigrás inglés, trébol blanco y dactilo). Entre los factores determinantes en la correcta implantación de un pastizal en suelos ácidos de monte están el encalado y la fertilización que se aplica. La metodología que se utiliza para estudiar el comportamiento de una especie con respecto a estos factores es la de los perfiles ecológicos. Entre los resultados obtenidos destacar que el factor pH es el principal responsable del mantenimiento de las especies sembradas, así como la plasticidad ecológica que presenta el dactilo frente al raigrás inglés y el trébol blanco más estrictos.Azken urteotan abeltzaintzak jasandako krisiak eta mendi-larreetako abere-zamaren gutxipenak area horien utziera sortarazi zuen eta honekin espezie zuhaixkaren birsatzea. Gaur egun berriz, abeltzainak sastraka-areak eraldatzeko eskari sendoa burutzen ari dira. Aztertutako zelaiak, Altunoste eta Arkaola, 1984 eta 1992. urtean ezarri ziren, hurrenez hurren. Horretarako lurra landu eta bazka bezala interesa duten espezie berriak erein ziren (erraigras ingelesa, hirusta zuria eta alka-belarra). Mendiko lur azidoetan larre baten ezarpen egokian karea eta ongarria botatzea faktore mugatzaileak dira. Faktore hauekiko espezieek duten portaera ikasteko erabiltzen den metodologia perfil ekologikoena da. Emaitzen arabera ereindako espezien mantenuan, pH-a da erantzule printzipala, eta baita alka-belarrak duen plastikotasun ekologikoa hertsiagoak diren erraigras ingelesa eta hirusta zuriaren aurrean.Dans les dernières années la cris de secteur d'élevage et la disminution de la charge éleveuse dans le pâturage de montagne ont provoquaient l'abondonement de ces terrains et la reinvasion des espèces arbustives. Cependant, actuellement, a apparu une forte demande des éleveurs pour réaliser des transformations des terrains de buisson. Les pâturages objet de cette étude, Altunoste et Arkaola, ont été plantés les années 1984 et 1992 respectivement, avec labourage et établissement des espèces d'interet fourregères (ray-gras anglais, trèfle blanc et le dactyle). Entre les facteurs déterminant la correcte implantation d'un pâturage dans les soles acides de montagne sont le badigeonnage et la fertilisation qui s'applique. La méthodologie qui s'utilise pour étudier le comportement d'une espèce en ce qui concerne ces facteurs c'est celle des perfiles écologiques. Entre les résultats obtenu vient le facteur pH c'est le principale responsable de subsistance des espèces cultivées, ainssi que la plasticité écologique qui représente le dactyle en face le ray-gras anglais et le trèfle blanc les plus stricts.The crisis that is undergoing the livestock sector and the decrease in the grazing pressure on mountain grasslands have lead to the abandonment of those areas and the reinvasion by shrubs. Nevertheless, nowadays there is an increasing demand of farmers to made transformations in the shruy areas: Arkaola and Altunoste. These meadows were sown in 1984 and 1992, respectively, with tillage and establishment of species of foraging interest (ryegrass, white clover and cocksfoot). Among the determinant factors for the correct establishment of the meadows on montain acid soils are liming and the fertilize rapplied. The methodology used to study the behaviour of the species according to those factors are Ecological Profiles. The results show that the pH is the main responsable for the maintenance of the sown species and that the cocksfoot has a higher ecological plasticity, than the ryegrass and white clover