Quantification of magmatic and hydrothermal processes in a peralkaline syenite-alkali granite complex based on textures, phase equilibria, and stable and radiogenic isotopes

The Puklen complex of the Mid-Proterozoic Gardar Province, South Greenland, consists of various silica-saturated to quartz-bearing syenites, which are intruded by a peralkaline granite. The primary mafic minerals in the syenites are augite +/- olivine + Fe-Ti oxide + amphibole. Ternary feldspar thermometry and phase equilibria among mafic silicates yield T = 950-750degreesC, a(SiO2) = 0.7-1 and an f(O2) of 1-3 log units below the fayalite-magnetite-quartz (FMQ) buffer at 1 kbar. In the granites, the primary mafic minerals are ilmenite and Li-bearing arfvedsonite, which crystallized at temperatures below 750degreesC and at f(O2) values around the FMQ buffer. In both rock types, a secondary post-magmatic assemblage overprints the primary magmatic phases. In syenites, primary Ca-bearing minerals are replaced by Na-rich minerals such as aegirine-augite and albite, resulting in the release of Ca. Accordingly, secondary minerals include ferro-actinolite, (calcite-siderite)(ss), titanite and andradite in equilibrium with the Na-rich minerals. Phase equilibria indicate that formation of these minerals took place over a long temperature interval from near-magmatic temperatures down to similar to300degreesC. In the course of this cooling, oxygen fugacity rose in most samples. For example, late-stage aegirine in granites formed at the expense of arfvedsonite at temperatures below 300degreesC and at an oxygen fugacity above the haematite-magnetite (HM) buffer. The calculated delta(18)O(melt) value for the syenites (+5.9 to +6.3parts per thousand) implies a mantle origin, whereas the inferred delta(18)O(melt) value of <+5.1parts per thousand for the granitic melts is significantly lower. Thus, the granites require an additional low-delta(18)O contaminant, which was not involved in the genesis of the syenites. Rb/Sr data for minerals of both rock types indicate open-system behaviour for Rb and Sr during post-magmatic metasomatism. Neodymium isotope compositions (epsilonNd(1170 Ma) = -3.8 to -6.4) of primary minerals in syenites are highly variable, and suggest that assimilation of crustal rocks occurred to variable extents. Homogeneous epsilon(Nd) values of -5.9 and -6.0 for magmatic amphibole in the granites lie within the range of the syenites. Because of the very similar neodymium isotopic compositions of magmatic and late- to post-magmatic minerals from the same syenite samples a principally closed-system behaviour during cooling is implied. In contrast, for the granites an externally derived fluid phase is required to explain the extremely low epsilon(Nd) values of about -10 and low delta(18)O between +2.0 and +0.5parts per thousand for late-stage aegirine, indicating an open system in the late-stage history. In this study we show that the combination of phase equilibria constraints with stable and radiogenic isotope data on mineral separates can provide much better constraints on magma evolution during emplacement and crystallization than conventional whole-rock studies.

Role of CLOCK and circadian rhythms in calcium homeostasis

Le maintien d'une concentration sanguine constante de calcium est d'une importance cruciale et trois organes participent à la balance calcique normale : les reins, les intestins et les os. La concentration plasmatique de calcium est strictement régulée par l'hormone parathyroïdienne (PTH) et par la vitamine D. Des variations circadiennes de la PTH, de la vitamine D ainsi que du calcium plasmatique ont été décrites précédemment chez l'humain ainsi que chez le rat. Ces rythmes de PTH dans le sérum sont importants pour la régulation du remodelage de l'os. En effet, il a été montré chez les souris C57BL/6J que des injections de PTH une fois par jour mènent à une augmentation de la densité minérale de l'os alors que l'infusion en continu de PTH est associée à une diminution de cette densité. La vitamine D joue également un rôle fondamental dans la physiologie osseuse, car un déficit en vitamine D peut conduire à une ostéomalacie. Cependant la fonction des oscillations de vitamine D au niveau de l'homéostasie osseuse reste inconnue. L'horloge circadienne est un système interne de contrôle biologique du temps générant des rythmes de 24 heures dans l'expression des gènes, ainsi que dans la physiologie et le comportement. Ce contrôle s'opère par des boucles rétroactives positives et négatives de l'expression de gènes circadiens tels que CLOCK, BMAL1, CRY1 et 2 ou PERI et 2. Dans ce travail, nous avons émis l'hypothèse que l'homéostasie calcique est sous le contrôle de l'horloge circadienne. Dans un premier temps, nous avons montré chez les souris C57BL/6J des variations journalières des concentrations de calcium, de PTH et de vitamine D dans le sang, ainsi que de calcium dans les urines. Nous avons également démontré des changements au niveau de l'expression rénale des gènes importants dans l'homéostasie du calcium, tant au niveau de l'ARN messager que des protéines. Ensuite, pour analyser le rôle du système de l'horloge circadienne dans l'homéostasie du calcium, nous avons étudié des souris dans lesquelles a été supprimé le gène CLOCK crucial pour la fonction de l'horloge et nous avons comparé ces souris à des souris de type sauvage de même portée. Les souris CLOCK-I- étaient hypercalciuriques à chaque moment de la journée. Cependant le rythme circadien de l'excrétion de calcium était préservé. Le taux de calcium plasmatique ne différait pas entre les génotypes, mais les souris CLOCK -/- ne montraient pas de variations journalières de ce paramètre. Une perte du rythme journalier était également observée pour les niveaux de vitamine D, perte qui pourrait être une cause de l'altération de la micro-architecture osseuse révélée chez les souris CLOCK-/-. En effet, ces souris montrent une diminution du nombre de trabécules, de leur volume ainsi que de leur surface, ce qui suggère la présence d'ostéoporose. Nous avons également trouvé que le rythme de l'expression de l'ARN messager de CYP27B1 était aboli dans les reins des souris CLOCK -/-, ce qui peut expliquer l'altération du rythme de la vitamine D. Les taux sanguins de PTH étaient comparables entre les souris CLOCK -/- et de type sauvage. Dans les reins, une augmentation de l'expression de l'ARN messager de TRPV5 et NCX1 a été constatée, ce qui suggérerait une augmentation de la réabsorption de calcium dans le tubule convoluté distal et dans le tubule connecteur. Dans les intestins, la réabsorption calcique était diminuée, chez les souris CLOCK-I-, fait confirmé par une diminution des niveaux d'ARN messager de TRPV6 et PMCAL. En résumé, la suppression du gène CLOCK chez les souris a conduit à une hypercalciurie, une altération du rythme des taux plasmatiques de calcium et de vitamine D et à une détérioration de l'architecture osseuse. Pour conclure, ces résultats montrent que l'horloge circadienne est essentielle à l'homéostasie calcique ainsi qu'à la physiologie des os. - L'ostéoporose affecte environ 22 millions de femmes et 5.5 millions d'hommes en Europe, réduisant significativement leur qualité de vie et a causé 3.5 millions de nouvelles fractures en 2010. Les dépenses totales liées à ces fractures ont atteint 37 milliards d'euro et ce coût devrait augmenter de 25% d'ici à 2025. Le nombre de nouvelles fractures dues à l'ostéoporose à travers le monde est estimé à environ 1000 par heure. Parmi les causes de l'ostéoporose, le déficit én calcium et/ou en vitamine D joue un rôle important, mais il existe également des causes génétiques ou liées à des facteurs comme les hormones sexuelles (estrogènes, testostérone), l'âge, le tabac, le poids corporel, certains médicaments,... La vie est rythmique : ceci est dû à l'alternance naturelle du jour et de la nuit et de ses effets sur le corps. La prise alimentaire, par exemple, est un processus qui a lieu pendant la phase active, qui est prévisible (il se produit toujours au même moment) et qui peut être anticipé par le corps. Pour cela, une horloge interne est présente dans chaque cellule du corps et est synchronisée par la lumière du jour, entre autres stimuli. Cette horloge indique la phase du jour et régule l'expression de gènes impliqués dans les différents processus qui nécessitent une anticipation. Pendant mon travail de thèse, je me suis demandé si des îythmes circadiens (c'est-à-dire d'une durée d'environ 24 heures et indépendants des stimuli externes) étaient observables'pour les gènes régulant les flux de calcium dans le corps et si l'interruption de ces rythmes pouvait mener à des altérations de la qualité de l'os. J'ai d'abord travaillé avec des souris normales et j'ai pu montrer la présence de rythmes au niveau du calcium sanguin et urinaire, mais également au niveau des hormones et gènes qui contrôlent le métabolisme du calcium dans le corps, comme la vitamine D et l'hormone parathyroidienne. De manière intéressante, j'ai observé que la plupart de ces gènes ont un rythme synchronisé. J'ai ensuite utilisé un modèle de souris dans lequel l'horloge interne a été génétiquement invalidée et j'ai montré que ces souris présentent une augmentation de leur excrétion urinaire de calcium et un rythme circadien altéré de la vitamine D dans le sang. Ces souris absorbent aussi moins bien le calcium intestinal et présentent une ostéoporose marquée. Ce travail montre donc que l'horloge interne est nécessaire pour établir un rythme circadiens de certains facteurs influant les flux de calcium dans l'organisme, comme la vitamine D, et que la perturbation de ces rythmes mène à une dérégulation du métabolisme osseux. Ainsi, la perturbation de l'horloge interne peut causer une ostéoporose et une hypercalciurie qui pourraient aboutir à la formation de fractures et de calculs rénaux. L'extrapolation de ces observations chez l'homme ou à des changements plus subtiles des rythmes circadiens, comme le décalage horaire, restent à montrer. Cette recherche a démontré que les rythmes circadiens des mécanismes de régulation des flux de calcium dans l'organisme sont essentiels au maintien d'un squelette normal et suggère que les perturbations des rythmes circadiens pourraient être une nouvelle cause de l'ostéoporose. - Maintaining constant calcium concentration in the plasma is of a crucial importance and three organs participate in normal calcium balance - kidney, gut and bone. Plasma calcium concentration is strictly regulated by parathyroid hormone (PTH) and vitamin D. Circadian variations of PTH, vitamin D and plasma calcium were previously described in humans, as well as in rats. Rhythms in serum PTH are important for balanced bone remodelling. Indeed in C57BL/6J mice, PTH injection once per day leads to an increase in bone mineral density (BMD), whilst continuous infusion is associated with decreased BMD. Vitamin D also plays a crucial role in bone physiology, since the deficiency in vitamin D can lead to rickets/osteomalacia. However, the role of vitamin D rhythms in bone homeostasis remains unknown. The circadian clock is an. internal time-keeping system generating rhythms in gene expression with 24h periodicity, in physiology and in behaviour. It is operated by positive- and negative-feedback loops of circadian genes, such as CLOCK, BMAL1, CRY1 and 2 or PERI and 2. In this work, we hypothesized, that calcium homeostasis is under the control of the circadian clock. First, we showed daily variations in urinary calcium and serum calcium, PTH and l,25(OH)2 vitamin D, together with renal mRNA and protein levels of genes involved in calcium homeostasis in C57BL/6J mice. Second, and to investigate the role of the circadian clock system in calcium handling, we studied mice lacking the gene CLOCK crucial for fonction of the clock system and compared them to the WT littermates. CLOCK-/- mice were hypercalciuric at all timepoints of the day. However, the circadian rhythm of calcium excretion was preserved. Serum calcium levels did not differ between the genotypes, but CLOCK-/- mice did not exhibit daily variation for this parameter. Loss of rhythm was observed also for serum l,25(OH)2 vitamin D levels, which may be one of the causes of altered bone microarchitecture that was revealed in CLOCK-/- mice. They displayed increased trabecular separation and decreased trabecular number, trabecular bone volume and trabecular bone surface, suggestive of osteoporosis. We found that the rhythm of the mRNA expression of CYP27B1 was abolished in the kidney of CLOCK-/- mice, which could induce the altered rhythm of l,25(OH)2 vitamin. Serum PTH levels were comparable between CLOCK-/- and WT mice. In the kidney, increased mRNA expression of TRPV5 and NCX1 suggests increased calcium reabsorption in the distal convoluted and connecting tubule. In the gut, intestinal calcium absorption was decreased in CLOCK¬/- mice, confirmed by decreased mRNA levels of TRPV6 and PMCA1. In summary, deletion of the CLOCK gene in mice conducts to hypercalciuria, alteration of the rhythm in serum calcium and l,25(OH)2D levels, and impainnent of their bone microarchitecture. In conclusion, these data show that the circadian clock system is essential in calcium homeostasis and bone physiology.

Testing the influence of topography and material properties on catchment-scale soil moisture patterns using remotely sensed vegetation patterns in a humid temperate catchment, northern Britain

In order to evaluate the relationship between the apparent complexity of hillslope soil moisture and the emergent patterns of catchment hydrological behaviour and water quality, we need fine-resolution catchment-wide data on soil moisture characteristics. This study proposes a methodology whereby vegetation patterns obtained from high-resolution orthorectified aerial photographs are used as an indicator of soil moisture characteristics. This enables us to examine a set of hypotheses regarding what drives the spatial patterns of soil moisture at the catchment scale (material properties or topography). We find that the pattern of Juncus effusus vegetation is controlled largely by topography and mediated by the catchment's material properties. Characterizing topography using the topographic index adds value to the soil moisture predictions relative to slope or upslope contributing area (UCA). However, these predictions depart from the observed soil moisture patterns at very steep slopes or low UCAs. Copyright (c) 2012 John Wiley & Sons, Ltd.

Signalling value of maternal and paternal melanism in the barn owl : implication for the resolution of the lek paradox

Secondary sexual characters often signal qualities such as physiological processes associated with resistance to various sources of stress. When the expression of an ornament is not sex-limited, we can identify the costs and benefits of displaying a trait that is typical of its own sex or of the other sex. Indeed, the magnitude and sign of the covariation between physiology and the extent to which an ornament is expressed could differ between males and females if, for instance, the regulation of physiological processes is sensitive to sex hormones. Using data collected over 14 years in the nocturnal barn owl Tyto alba, we investigated how nestling body mass covaries with a heritable melanin-based sex-trait, females displaying on average larger black feather spots than males. Independently of nestling sex, year and time of the day large-spotted nestlings were heavier than small-spotted nestlings. In contrast, the magnitude and sign of the covariation between nestling body mass and the size of parental spots varied along the day in a way that depended on the year and parental gender. In poor years, offspring of smaller-spotted mothers were heavier throughout the resting period; in the morning, offspring sired by larger-spotted fathers were heavier than offspring of smaller-spotted fathers, while in the evening the opposite pattern was found. Thus, maternal and paternal coloration is differentially associated with behaviour or physiology, processes that are sensitive to time of the day and environmental factors. Interestingly, the covariation between offspring body mass and paternal coloration is more sensitive to these environmental factors than the covariation with maternal coloration. This indicates that the benefit of pairing with differently spotted males may depend on environmental conditions, which could help maintain genetic variation in the face of intense directional (sexual) selection.

The interplay of spatial and climatic landscapes in the genetic distribution of a South American parrot

AimOur aim was to understand the interplay of heterogeneous climatic and spatial landscapes in shaping the distribution of nuclear microsatellite variation in burrowing parrots, Cyanoliseus patagonus. Given the marked phenotypic differences between populations of burrowing parrots we hypothesized an important role of geographical as well climatic heterogeneity in the population structure of this species. LocationSouthern South America. MethodsWe applied a landscape genetics approach to investigate the explicit patterns of genetic spatial autocorrelation based on both geography and climate using spatial principal component analysis (sPCA). This necessitated a novel statistical estimation of the species climatic landscape, considering temperature- and precipitation-based variables separately to evaluate their weight in shaping the distribution of genetic variation in our model system. ResultsGeographical and climatic heterogeneity successfully explained molecular variance in burrowing parrots. sPCA divided the species distribution into two main areas, Patagonia and the pre-Andes, which were connected by an area of geographical and climatic transition. Moreover, sPCA revealed cryptic and conservation-relevant genetic structure: the pre-Andean populations and the transition localities were each divided into two groups, each management units for conservation. Main conclusionssPCA, a method originally developed for spatial genetics, allowed us to unravel the genetic structure related to spatial and climatic landscapes and to visualize these patterns in landscape space. These novel climatic inferences underscore the importance of our modified sPCA approach in revealing how climatic variables can drive cryptic patterns of genetic structure, making the approach potentially useful in the study of any species distributed over a climatically heterogeneous landscape.

Automobile Corporate Networks in Europe : Sectoral Specialization of Central and Eastern European Cities

The global automobile industry is made up of very large corporations and their various subsidiaries containing different functions that create complex locational structures. The networks formed by the 19 largest automobile transnational corporations constitute an automobile "oligopoly" representing more than 90% (OICA, 2012) of the world's production. Since the mid-1990s, Central and Eastern European cities have become attractive for transnational corporations and particularly for the production functions in the automobile sector. This leads to a crucial question. Are strategic functions (such as R&D) within these networks also located in Central and Eastern Europe, or is the region still manufacturing-oriented in the automobile industry? This paper focuses on the patterns and the main factors influencing the role of some of these new central and Eastern European cities that have become integrated in the global value chain of the automobile industry. By analysing the various locations of the specialized functions within the corporations, this study aims to extend the research on global value chains (Gereffi and Korzeniewicz; 1994, Sturgeon, 2000; Krätke, 2014). The spatial patterns of the various functions and the ownerships networks of the automobile industry are constructed in order to identify the cities supporting it. In particular, the way that national metropolises bring their national territories into the globalization of the automobile industry is addressed. For example, are there some specific advantages of capital cities compared to cities that have less integration in globalization terms?