Chromophore structural changes in rhodopsin from nanoseconds to microseconds following pigment photolysis

Rhodopsin is a prototypical G protein-coupled receptor that is activated by photoisomerization of its 11-cis-retinal chromophore. Mutant forms of rhodopsin were prepared in which the carboxylic acid counterion was moved relative to the positively charged chromophore Schiff base. Nanosecond time-resolved laser photolysis measurements of wild-type recombinant rhodopsin and two mutant pigments then were used to determine reaction schemes and spectra of their early photolysis intermediates. These results, together with linear dichroism data, yielded detailed structural information concerning chromophore movements during the first microsecond after photolysis. These chromophore structural changes provide a basis for understanding the relative movement of rhodopsin’s transmembrane helices 3 and 6 required for activation of rhodopsin. Thus, early structural changes following isomerization of retinal are linked to the activation of this G protein-coupled receptor. Such rapid structural changes lie at the heart of the pharmacologically important signal transduction mechanisms in a large variety of receptors, which use extrinsic activators, but are impossible to study in receptors using diffusible agonist ligands.

Increased in vivo apoptosis in cells lacking mitochondrial DNA gene expression

We have attempted to determine whether loss of mtDNA and respiratory chain function result in apoptosis in vivo. Apoptosis was studied in embryos with homozygous disruption of the mitochondrial transcription factor A gene (Tfam) and tissue-specific Tfam knockout animals with severe respiratory chain deficiency in the heart. We found massive apoptosis in Tfam knockout embryos at embryonic day (E) 9.5 and increased apoptosis in the heart of the tissue-specific Tfam knockouts. Furthermore, mtDNA-less (ρ0) cell lines were susceptible to apoptosis induced by different stimuli in vitro. The data presented here provide in vivo evidence that respiratory chain deficiency predisposes cells to apoptosis, contrary to previous assumptions based on in vitro studies of cultured cells. These results suggest that increased apoptosis is a pathogenic event in human mtDNA mutation disorders. The finding that respiratory chain deficiency is associated with increased in vivo apoptosis may have important therapeutic implications for human disease. Respiratory chain deficiency and cell loss and/or apoptosis have been associated with neurodegeneration, heart failure, diabetes mellitus, and aging. Furthermore, chemotherapy and radiation treatment of cancer are intended to induce apoptosis in tumor cells. It would therefore be of interest to determine whether manipulation of respiratory chain function can be used to inhibit or enhance apoptosis in these conditions.

The H+-Sucrose Cotransporter NtSUT1 Is Essential for Sugar Export from Tobacco Leaves1

In many species translocation of sucrose from the mesophyll to the phloem is carrier mediated. A sucrose/H+-symporter cDNA, NtSUT1, was isolated from tobacco (Nicotiana tabacum) and shown to be highly expressed in mature leaves and at low levels in other tissues, including floral organs. To study the in vivo function of NtSUT1, tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter. Upon maturation, leaves of transformants expressing reduced amounts of SUT1 mRNA curled downward, and strongly affected plants developed chloroses and necroses that led to death. The leaves exhibited impaired ability to export recently fixed 14CO2 and were unable to export transient starch during extended periods of darkness. As a consequence, soluble carbohydrates accumulated and photosynthesis was reduced. Autoradiographs of leaves show a heterogenous pattern of CO2 fixation even after a 24-h chase. The 14C pattern does not change with time, suggesting that movement of photosynthate between mesophyll cells may also be impaired. The affected lines show a reduction in the development of the root system and delayed or impaired flowering. Taken together, the effects observed in a seed plant (tobacco) demonstrate the importance of SUT1 for sucrose loading into the phloem via an apoplastic route and possibly for intermesophyll transport as well.

Photosystem II Cyclic Heterogeneity and Photoactivation in the Diazotrophic, Unicellular Cyanobacterium Cyanothece Species ATCC 511421

The unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 demonstrated important modifications to photosystem II (PSII) centers when grown under light/dark N2-fixing conditions. The properties of PSII were studied throughout the diurnal cycle using O2-flash-yield and pulse-amplitude-modulated fluorescence techniques. Nonphotochemical quenching (qN) of PSII increased during N2 fixation and persisted after treatments known to induce transitions to state 1. The qN was high in cells grown in the dark, and then disappeared progressively during the first 4 h of light growth. The photoactivation probability, ε, demonstrated interesting oscillations, with peaks near 3 h of darkness and 4 and 10 h of light. Experiments and calculations of the S-state distribution indicated that PSII displays a high level of heterogeneity, especially as the cells prepare for N2 fixation. We conclude that the oxidizing side of PSII is strongly affected during the period before and after the peak of nitrogenase activity; changes include a lowered capacity for O2 evolution, altered dark stability of PSII centers, and substantial changes in qN.

Excited-state dynamics in photosystem II: Insights from the x-ray crystal structure

The heart of oxygenic photosynthesis is photosystem II (PSII), a multisubunit protein complex that uses solar energy to drive the splitting of water and production of molecular oxygen. The effectiveness of the photochemical reaction center of PSII depends on the efficient transfer of excitation energy from the surrounding antenna chlorophylls. A kinetic model for PSII, based on the x-ray crystal structure coordinates of 37 antenna and reaction center pigment molecules, allows us to map the major energy transfer routes from the antenna chlorophylls to the reaction center chromophores. The model shows that energy transfer to the reaction center is slow compared with the rate of primary electron transport and depends on a few bridging chlorophyll molecules. This unexpected energetic isolation of the reaction center in PSII is similar to that found in the bacterial photosystem, conflicts with the established view of the photophysics of PSII, and may be a functional requirement for primary photochemistry in photosynthesis. In addition, the model predicts a value for the intrinsic photochemical rate constant that is 4 times that found in bacterial reaction centers.

Magnetic activity and differential rotation in the young Sun-like stars KIC 7985370 and KIC 7765135

Aims. We present a detailed study of the two Sun-like stars KIC 7985370 and KIC 7765135, to determine their activity level, spot distribution, and differential rotation. Both stars were previously discovered by us to be young stars and were observed by the NASA Kepler mission. Methods. The fundamental stellar parameters (vsini, spectral type, T_eff, log g, and [Fe/H]) were derived from optical spectroscopy by comparison with both standard-star and synthetic spectra. The spectra of the targets allowed us to study the chromospheric activity based on the emission in the core of hydrogen Hα and Ca ii infrared triplet (IRT) lines, which was revealed by the subtraction of inactive templates. The high-precision Kepler photometric data spanning over 229 days were then fitted with a robust spot model. Model selection and parameter estimation were performed in a Bayesian manner, using a Markov chain Monte Carlo method. Results. We find that both stars are Sun-like (of G1.5 V spectral type) and have an age of about 100–200 Myr, based on their lithium content and kinematics. Their youth is confirmed by their high level of chromospheric activity, which is comparable to that displayed by the early G-type stars in the Pleiades cluster. The Balmer decrement and flux ratio of their Ca ii-IRT lines suggest that the formation of the core of these lines occurs mainly in optically thick regions that are analogous to solar plages. The spot model applied to the Kepler photometry requires at least seven persistent spots in the case of KIC 7985370 and nine spots in the case of KIC 7765135 to provide a satisfactory fit to the data. The assumption of the longevity of the star spots, whose area is allowed to evolve with time, is at the heart of our spot-modelling approach. On both stars, the surface differential rotation is Sun-like, with the high-latitude spots rotating slower than the low-latitude ones. We found, for both stars, a rather high value of the equator-to-pole differential rotation (dΩ ≈ 0.18 rad d^-1), which disagrees with the predictions of some mean-field models of differential rotation for rapidly rotating stars. Our results agree instead with previous works on solar-type stars and other models that predict a higher latitudinal shear, increasing with equatorial angular velocity, that can vary during the magnetic cycle.

La ruralidad del 15-M. Iniciativas desde el movimiento agroecológico alicantino

La principal imagen del movimiento 15-M viene simbolizada por las acampadas en las plazas de numerosas ciudades españolas, es decir, su apariencia urbana. No obstante, el derecho a la alimentación sana, el consumo responsable, el acceso a la tierra, la conservación de ecosistemas agrarios y la despoblación del medio rural han sido algunas de las temáticas debatidas en el seno del movimiento. Ello demuestra una sustancial preocupación por la cuestión tanto ambiental como agraria, para las cuales se reclaman alternativas desde una perspectiva propiamente rural. Como se pretende hacer ver en este artículo, en el seno del movimiento 15-M las cuestiones urbanas y rurales son indisociables. Entre ellas destaca la reivindicación de la soberanía alimentaria y de la agroecología como horizontes de una transformación en la organización del territorio. En este artículo se sintetizan los aspectos de ruralidad del movimiento 15-M y sus reivindicaciones de carácter social, ambiental y territorial. De manera particular, se consideran las características propias de iniciativas incipientes que se están llevando a cabo en la provincia de Alicante, en el sureste del Estado español, así como de sus interrelaciones con movimientos rurales en el ámbito regional, nacional e internacional.

El lenguaje gráfico de Eduardo Chillida como aportación conceptual para la identidad tipográfica de la Universidad del País Vasco —UPV/EHU—

Este proyecto de investigación financiado por la Universidad del País Vasco/Euskal Herriko Unibertsitatea —UPV/EHU-PES 11/31—, a través de su programa de investigación estratégica, tiene como objetivo la creación de la tipografía de identidad visual corporativa de la Universidad del País Vasco —UPV/EHU—, cuyo inicio conceptual para dotar de unas características de identidad visual corporativa a la UPV/EHU, ha sido planteado desde las especulaciones estéticas sobre la forma, materializadas por Eduardo Chillida. En la producción gráfica de este artista encontramos una sutil coincidencia con principios vitales para la creación tipográfica, en cuanto al planteamiento de formas dinámicas y constructivas, en las que el rigor geométrico es vencido por una suerte de organicidad que parte del núcleo mismo de la estructura —«cursus»—, por: la fuerza vital que imprime la acción modulada del gesto —«ductus»—; por la dialéctica entre lo lleno y lo vacío —forma/contraforma—, por el impulso y la espontaneidad — carácter—, o por la afirmación de un lenguaje plástico en la cultura diferenciada del medio en el que se vive —identidad—.

International financial regulation: A role for the Eurozone? EU Diplomacy Paper 08/2012, October 2012

The deepest financial crisis to strike the global economy since the Great Depression has unceremoniously called into question the very foundations of the Western economic model. The liberalisation of capital flows and the growing internationalisation of financial markets outpaced global regulatory and supervisory efforts. The repercussions of the financial crisis have given new dynamism to the reform of financial regulation both globally and within the European Union (EU). The Eurozone, by way of its own failings, has emerged as a stronger conceptual and legitimate entity since the onset of the crisis, but to what extent does this equate to a greater external role, in particular in the reform of international financial regulation? This paper argues that the Eurozone is currently not in a position to play an important role in the reform of international financial regulation, as it is a weak actor in the context of the EU financial architecture, which is still largely characterised by differing national regimes, a prevailing influence from the UK and fragmented external representation. The key finding from this study is that internal tensions in the EU are at the very heart of the Eurozone’s difficulties in playing a role in the reform of international financial regulation. Surmounting these tensions is a pre-requisite for the Eurozone if it is to overcome its structural weakness in international financial politics. However, the implications of such evolutions to the Eurozone, as an entity, and to European integration are far-reaching.

Drogas recreativas : o coração do prazer

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Selfmapping : o mapa colaborativo como medium de visualização espácio-temporal

THE MAP AS A COLLABORATIVE MEDIUM FOR SPATIO-TEMPORAL VISUALIZATION This dissertation focuses on the relationship between maps and spatio-temporal data visualization. It is divided into two components: theoretical framework and practical approach. The study begins by questioning the role of the map in today’s digital society and particularly its role in visualization, and finishes with the conceptualization and development of an interactive dot map that visualizes data from Instagram and Twitter. Nowadays, geographic information is no longer produced just by experts, but also by ordinary people that are able to participate in data creation and exchange. The Web 2.0 lies in the heart of this change, where social media represent a significant tool for producing geotagged content, allowing its users to share their location and to spatially reference their publications. Furthermore, amateur mapmaking and neogeography have benefited from the emergence of several new devices that enable the creation of digital maps that are interactive, adaptable and easily shared on the Web. This study adopts a descriptive approach calling upon the diverse aspects of the map and its evolution as a medium for visualizing geotagged data, highlighting collaborative mapping as an emerging subject area that is of mandatory future research. Relevant projects are also analyzed in order to identify trends and different approaches for visualizing social media data in its spatial context, intended to support the project’s conceptualization, development and evaluation. The created map demonstrates how spatial knowledge and perception of place are now redefined by the contributions of individuals; it also shows how that activity produces new sources of geographic information, forcing the development of new techniques and approaches that allow an adequate exploration of content and visualization methods of the contemporary map

Can the eurozone survive? Jean Monnet/Robert Schuman Paper Series Vol. 12, No. 4, May 2012

From the Introduction. As financial and economic turmoil continues to rock the Eurozone nations and even threatens to undermine the political stability in the region, it may be helpful to recall the circumstances that helped bring about the formation of the European Union and the common currency of the Eurozone. While issues of trade, finance, and economics were at the heart of many of the agreements upon which the European Union was founded, there were larger issues about a shared future for Europeans that went beyond fiscal concerns. As the economic conditions in Europe and the rest of the world appear to have brought the Eurozone to the brink of collapse, the question at hand is whether the strength of the euro and the economies of the Eurozone nations will be able to withstand the forces that threaten not just the economic ties among the nations of the Eurozone and the EU, but that also strain the historical, cultural, and political foundations on which those economic ties were forged.

Exploitative Abuses: Which Competition Policy, Which Public Policy? Research Papers in Law, 2/2007

As the final session of the day, my aim in this paper is to briefly outline the nature of exploitative abuses before turning to the question of the relationship between competition law and intellectual property law in the context of what Teubner calls the regulatory trilemma and from that draw a two-fold conclusion. First, the demands on law from the social phenomenon of markets are more acute when those demands raise issues across the different law domains of IP and competition. Second, where IP law and competition meet, the aim should be for both domains to internalise the values of the other. This however can only happen to the extent but only to the extent that there can be what Collins1 calls productive disintegration. Finally, in the specific context of exploitative abuses the overlap between IP law and competition law arises primarily in relation to claims of excessive pricing in licensing arrangements. Such claims could form the basis of a private action2 or can be made in the context of compulsory dealing decisions such as Microsoft.3 The involvement of competition agencies in pricing decisions goes to the heart of concerns about the nature of competition law and the role of competition agencies and highlights the need for the law to indirectly control rather than inappropriately attempt to directly control markets.

Logements insalubres en contexte pluriethnique : étude de cas et pistes d'intervention pour le quartier Norgate dans l'arrondissement Saint-Laurent à Montréal

Ce mémoire explore le rôle du logement dans l'expérience migratoire des nouveaux et nouvelles arrivantes à Montréal et l'impact de celui-ci sur les premières années d'installation, en fonction des caractéristiques socioculturelles des individus. Pour ce faire, une étude collaborative a été menée sur le cas spécifique du quartier de Norgate, situé en plein cœur de l'arrondissement Saint-Laurent. Norgate est un quartier où se produit un renouvellement constant de locataires d'origine immigrante en provenance des quatre coins du monde, et où subsistent d'importants problèmes de pauvreté. En se penchant sur ce milieu de vie et sur les conditions d'habitat de ses résident-e-s, nous avons constaté à quel point un nombre important de locataires vivaient dans des logements en mauvais état, et parfois même dans de graves conditions d'insalubrité. Nous avons cherché à comprendre comment un tel espace urbain pouvait en venir à être aussi dégradé et quels étaient les rôles et responsabilités des différents paliers étatiques face à une telle situation. À travers ce processus, nous avons exploré l'ensemble des possibilités d'action proposées par les différents acteurs (institutionnels, communautaires, résidentiels) ayant un potentiel pouvoir d'agir dans le quartier. Ce mémoire montre comment la problématique des logements dans l'espace urbain est liée à une multitude de facteurs interreliés et qui s'influencent mutuellement, d'où la nécessité d'une approche systémique dans l'analyse du champ de l'anthropologie urbaine. Il cherche également à montrer en quoi un mouvement urbain efficient nécessite un partenariat rigoureux entre les différents acteurs agissant sur le territoire, dans une logique de compréhension et de respect de la diversité des tactiques.

Étude de l’orientation cardinale sud dans les sépultures mayas de la Période Classique

Ce mémoire porte sur l’étude de l’orientation des sépultures mayas de la Période Classique (250 - 900/1000 de notre ère). Il s’agit d’une recherche visant à comprendre le choix d’une orientation sud des défunts dans la vallée du Belize et ses environs. L’intérêt porté à cette région vient du fait que l’orientation sud des défunts est un phénomène que l’on retrouve rarement sur le territoire maya, sauf à cet endroit. Alors que la présence de la cardinalité en lien avec la cosmovision maya est attestée dans l’architecture, le plan des sites, la forme et la fonction des divinités, dans l’agriculture, etc., il est plutôt rare qu’elle soit analysée dans les études du traitement funéraire. Ainsi, le but de cette recherche est de saisir l’ampleur de la pratique de l’orientation sud des défunts sur le territoire maya, de comprendre son origine et sa ou ses possible(s) signification(s). Les données des sépultures de la Période Classique de cinq sites de la vallée du Belize (Baking Pot, Barton Ramie, Blackman Eddy, Cahal Pech et Xunantunich), de quatre sites du Plateau Vaca (Minanha, Pacbitun, Mountain Cow et Caracol) et de trois sites situés à l’ouest (Holmul) et au nord (San José et Altun Ha) de ces deux régions sont compilées. Les résultats révèlent que le coeur de cette pratique se trouve dans la vallée du Belize, bien qu’une orientation sud des défunts ait été retrouvée partout. Cette pratique semble apparaitre à la fin de la Période Préclassique et les analyses ne révèlent pas de lien entre l’orientation sud et certaines variables (âge, sexe, position du défunt). Finalement, on arrive à la conclusion qu’il est possible que cette orientation sud des défunts soit en lien avec le passage des défunts dans l’inframonde et que cela forme un choix culturel local en lien avec le statut et l’identité du défunt.