Tectonomagmatic evolution of Western Amazonia: Geochemical characterization and zircon U-Pb geochronologic constraints from the Peruvian Eastern Cordilleran granitoids

The results of a coupled, in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb study on zircon and geochemical characterization of the Eastern Cordilleran intrusives of Peru reveal 1.15 Ga of intermittent magmatism along central Western Amazonia, the Earth's oldest active open continental margin. The eastern Peruvian batholiths are volumetrically dominated by plutonism related to the assembly and breakup of Pangea during the Paleozoic-Mesozoic transition. A Carboniferous-Permian (340-285 Ma) continental arc is identified along the regional orogenic strike from the Ecuadorian border (6 degrees S) to the inferred inboard extension of the Arequipa-Antofalla terrane in southern Peru (14 degrees S). Widespread crustal extension and thinning, which affected western Gondwana throughout the Permian and Triassic resulted in the intrusion of the late- to post-tectonic La Merced-San Ramon-type anatectites dated between 275 and 220 Ma, while the emplacement of the southern Cordillera de Carabaya peraluminous granitoids in the Late Triassic to Early Jurassic (220-190 Ma) represents, temporally and regionally, a separate tectonomagmatic event likely related to resuturing of the Arequipa-Antofalla block. Volcano-plutonic complexes and stocks associated with the onset of the present Andean cycle define a compositionally bimodal alkaline suite and cluster between 180 and 170 Ma. A volumetrically minor intrusive pulse of Oligocene age (ca. 30 Ma) is detected near the southwestern Cordilleran border with the Altiplano. Both post-Gondwanide (30-170 Ma), and Precambrian plutonism (691-1123 Ma) are restricted to isolated occurrences spatially comprising less than 15% of the Eastern Cordillera intrusives. Only one remnant of a Late Ordovician intrusive belt is recognized in the Cuzco batholith (446.5 +/- 9.7 Ma) indicating that the Famatinian arc system previously identified in Peru along the north-central Eastern Cordillera and the coastal Arequipa-Antofalla terrane also existed inboard of this parautochthonous crustal fragment. Hitherto unknown occurrences of late Mesoproterozoic and middle Neoproterozoic granitoids from the south-central cordilleran segment define magmatic events at 691 +/- 13 Ma, 751 +/- 8 Ma, 985 +/- 14 Ma, and 1071-1123 +/- 23 Ma that are broadly coeval with the Braziliano and Grenville-Sunsas orogenies, respectively. Our data suggest the existence of a continuous orogenic belt in excess of 3500 km along Western Amazonia during the formation of Rodinia, its ``early'' fragmentation prior to 690 Ma, and support a model of reaccretion of the Paracas-Arequipa-Antofalla terrane to western Gondwana in the Early Ordovician with subsequent detachment of the Paracas segment in form of the Mexican Oaxaquia microcontinent in Middle Ordovician. A tectonomagmatic model involving slab detachment, followed by underplating of cratonic margin by asthenospheric mantle is proposed for the genesis of the volumetrically dominant Late Paleozoic to early Mesozoic Peruvian Cordilleran batholiths.

Mephedrone pharmacokinetics after intravenous and oral administration in rats: relation to pharmacodynamics

Rationale Mephedrone (4-methylmethcathinone) is a still poorly known drug of abuse, alternative to ecstasy or cocaine. Objective The major aims were to investigate the pharmacokineticsa and locomotor activity of mephedrone in rats and provide a pharmacokinetic/pharmacodynamic model. Methods Mephedrone was administered to male SpragueDawley rats intravenously (10 mg/kg) and orally (30 and 60 mg/kg). Plasma concentrations and metabolites were characterized using LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180240 min. Results Mephedrone plasma concentrations after i.v. administration fit a two-compartment model (α=10.23 h−1, β=1.86 h−1). After oral administration, peak mephedrone concentrations were achieved between 0.5 and 1 h and declined to undetectable levels at 9 h. The absolute bioavailability of mephedrone was about 10 % and the percentage of mephedrone protein binding was 21.59±3.67%. We have identified five phase I metabolites in rat blood after oral administration. The relationship between brain levels and free plasma concentration was 1.85±0.08. Mephedrone induced a dose-dependent increase in locomotor activity, which lasted up to 2 h. The pharmacokineticpharmacodynamic model successfully describes the relationship between mephedrone plasma concentrations and its psychostimulant effect. Conclusions We suggest a very important first-pass effect for mephedrone after oral administration and an easy access to the central nervous system. The model described might be useful in the estimation and prediction of the onset, magnitude,and time course of mephedrone pharmacodynamics as well as to design new animal models of mephedrone addiction and toxicity.

Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death.

Ischemia/reperfusion (I/R) is a pivotal mechanism of liver damage after liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol (CBD), the nonpsychotropic constituent of marijuana, in a mouse model of hepatic I/R injury. I/R triggered time-dependent increases/changes in markers of liver injury (serum transaminases), hepatic oxidative/nitrative stress (4-hydroxy-2-nonenal, nitrotyrosine content/staining, and gp91phox and inducible nitric oxide synthase mRNA), mitochondrial dysfunction (decreased complex I activity), inflammation (tumor necrosis factor α (TNF-α), cyclooxygenase 2, macrophage inflammatory protein-1α/2, intercellular adhesion molecule 1 mRNA levels; tissue neutrophil infiltration; nuclear factor κB (NF-κB) activation), stress signaling (p38MAPK and JNK), and cell death (DNA fragmentation, PARP activity, and TUNEL). CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress, and cell death and also attenuated the bacterial endotoxin-triggered NF-κB activation and TNF-α production in isolated Kupffer cells, likewise the adhesion molecule expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α and attachment of human neutrophils to the activated endothelium. These protective effects were preserved in CB(2) knockout mice and were not prevented by CB(1/2) antagonists in vitro. Thus, CBD may represent a novel, protective strategy against I/R injury by attenuating key inflammatory pathways and oxidative/nitrative tissue injury, independent of classical CB(1/2) receptors.

High-precision dating and origin of synsedimentary volcanism in the Late Carboniferous Salvan-Dorenaz basin (Aiguilles-Rouges Massif, Western Alps)

Late Variscan volcanic activity is documented in the Late Carboniferous Salvan-Dorenaz sedimentary basin and in the neighboring basement units of the Aiguilles-Rouges and Mont-Blanc crystalline massifs (Western Alps). Precise U/Pb isotopic dating, zircon morphology and geochemical analyses indicate that volcanism occurred during short-lived pulses and that coexisting crustal and mantle sources were involved in the production of melts. Volcanic and subvolcanic products were emplaced along major N-S to NNE-SSW transtensional fracture zones, similar to the ones that governed intense basement exhumation and that favored the formation and filling of the Late Carboniferous Salvan-Dorenaz continental basin. In the Aiguilles-Rouges massif, dacitic flows outcropping at the base of the Salvan-Dorenaz basin erupted at 308 +/- 3 Ma; they represent the surface equivalent of the nearby Vallorcine peraluminous granite and associated rhyolitic dykes (311 +/- 17 Ma). In the Mont Blanc massif, calc-alkaline rhyolitic dykes were emplaced simultaneously (307 +/- 2 Ma) at shallow crustal levels, but they derive from deeper magma sources denoting enhanced mantellic activity. Recently identified tuffs and volcaniclastic layers embedded at different levels of the Salvan-Dorenaz stratigraphic record testify a 295 +3/-4 Ma old episode of highly explosive volcanism from distant volcanic centers, possibly located in the Aar-Gotthard massifs (Central Alps). Their zircon typology is highly heterogeneous. documenting wall-rock contamination of the melts and/or admixture of crustal sediments, whereas consistent subpopulations point to high-temperature magmas of deep-seated origin and alkaline affinity. The dated volcanic layers from the Salvan-Dorenaz basin set the beginning of the detrital sedimentation at 308 +/- 3 Ma and constrain the deposition of 1.5-1.7 km thick of elastic sediments within a time span of 10-15 Ma. These results infer minimum, long-term subsidence rates during basin evolution in the order of >0.1 mm/a, while in the surrounding basement units estimated exhumation rates are in the range of 1 mm/a. All dated rocks contain inherited zircon populations about 350, 450 or 600 Ma old.

Epidote in hydrous mafic magmas : near solidus phase relations in the lower crust

Crystallisation of hydrous mafic magmas at high pressure is a subject of numerous petrologic and experimental studies since the last century and is mainly related to the process of continental crust formation and the possible link between mantle derived melts and low pressure granitoids. Albeit the sequence of crystallization is well constrained by experimental studies, the origin of exposed lower crustal rocks exposed on the earth surface is controversial. Ones line of argument is favouring high pressure crystallization of dry or wet mafic magmas, whereas others invoke partial melting of pre-existing crust. Therefore studies involving field, textural and chemical observations of exposed lower crust such as in Kohistan (Pakistan) or Talkeetna (Alaska) are crucial to understand the continental crust formation processes via arc magmatism. Epidote-bearing gabbros are very sparse and always associated with the deep part of continental crust (>30 km) as in the Kohistan Arc Complex (Pakistan) or in the Chelan Complex (western U.S.). Magmatic epidote is restricted to a small temperature interval above the water-saturated solidus of MORB and represent the last crystallizing liquids in lower crustal regions. However, epidote and melt stability at lower crustal pressures are not clearly established.¦The Chelan complex (western U.S.) at the base of the Cascadian Arc is composed mainly by peraluminous tonalité associated with gabbroic and ultramafic rocks and was traditionally interpreted as a migmatitic terrain. However field, chemical and mineralogical observations rather suggest a magmatic origin and point to a protracted crystallization at intermediate to high pressure ~ 1.0 GPa dominated by amphibole fractionation and followed by isobaric cooling down to 650°C. Crystal fractionation modelling using whole rock composition and field constraints is able to generate peraluminous tonalité. The modelled crystallisation sequence and the volume proportions are in agreement with experimental studies performed at these pressures. The Chelan complex was thus not formed during a partial melting event, but represent the sequence of crystallisation occurring at the base of the crust. Massive fractionation of hornblende is able to generate peraluminous tonalité without significant assimilation of crustal rock.¦Similarly to the Chelan complex, the base of the Kohistan arc is composed of cumulates derived by high pressure crystallization of hydrous magma. In garnet gabbros, epidote occurs as magmatic phase, crystallising from hydrous interstitial melt trapped between grain boundaries at lower crustal pressures (Ρ ~ 1.2 GPa) for temperature of (650-700 °C). Trace and REE signature in epidote indicate that epidote was formed through peritectic reaction involving garnet, clinopyroxene and plagioclase. At the beginning of the crystallisation epidote signature is dominated by REE content in the melt, whereas at the end the signature is dominated by reacting phases. Melt in equilibrium with epidote inferred from the partition coefficients available is similar to intrusive tonalité up the section indicating that hydrous melt was extracted from the garnet gabbros. In some gabbros epidote shows single homogeneous compositions, while in others coexisting epidote have different compositions indicating the presence of solvi along the Al-Fe3+ join. The overgowths are only observed in presence of paragonite in the assemblage, suggesting high water content. At high water content, the hydrous solidus is shift to lower temperature and probably intersects the solvi observed along the Al-Fe3+ join. Therefore, several compositions of epidote is stable at high water content.¦-¦La composition chimique de la croûte continentale est considérée comme similaire à celle du magmatisme calco-alcalin de marge continentale active (enrichissement en éléments mobiles dans les fluides, anomalies négatives en Nb, Ta et éléments à haut potentiel électronique, etc...). Cependant la nature andésitique de la croûte continentale (Si02 > 60 wt%), résultant des nombreuses intrusions de granitoïdes dans la croûte supérieure, est sujette à polémique et le lien entre les magmas dérivés du manteau et les roches évoluées de faible profondeur n'est pas clairement établi (fusion partielle de croûte basaltique, cristallisation fractionnée à haute pression, etc...).¦Les affleurements de croûte profonde sont rares mais précieux, car ils permettent d'observer les phénomènes se passant à grande profondeur. Le complexe de Chelan (Washington Cascades) en est un exemple. Formé à environ 30 km de profondeur, il est composé de roches gabbroïques et ultramafiques, ainsi que de tonalités, qui furent souvent interprétés comme le produit de la fusion partielle de la croûte. Cependant, les relations de terrain, la chimie des éléments majeurs et des éléments traces sont cohérentes avec l'évolution d'un complexe magmatique mafique dans la croûte profonde ou moyenne ( 1.0 GPa), dominée par le fractionnement de l'amphibole. Après son emplacement, le complexe a subi un refroidissement isobare jusqu'à des températures de l'ordre de 650 °C, déduit de la composition chimique des minéraux. Un bilan de masse contraint pax les observations de terrain permet de calculer la séquence et les volumes de fractionnement. Les faciès évolués légèrement hyperalumineux observés sur le terrain peuvent être générés par la cristallisation de 3 % de websterite à olivine, 12 % d'hornblendite à pyroxène 33 % d'hornblendite, 19 % de gabbros, 15 % de diorite et 2 % de tonalité. Nous montrons ainsi qu'une série de fractionnement contrôlée par l'amphibole permet de générer des tonalités sans assimilation de matériel crustal et l'exemple de Chelan illustre la viabilité de ce processus dans la formation de croûte continentale.¦Les réactions proches du solidus saturé en H20 dans les systèmes basaltiques à des pressions élevées restent énigmatiques. Diverses expériences tendent à montrer que l'épidote est stable dans ces conditions, mais rarement observée (décrite ?) comme phase primaire dans les systèmes naturels. Les épidotes trouvées dans les gabbros de Jijal (nord-Pakistan) montrent des textures de type .magmatique telles qu'observées dans les roches évoluées. Le contenu en terres rares de ces épidotes est très variable allant de signatures enrichies en terres rares légères impliquant la présence de liquide interstitiel à des signatures complètement déprimées en ces mêmes éléments, évoquant une cristallisation en coexistence avec du grenat. Ces diverses signatures reflètent un chemin de cristallisation en présence de liquide interstitiel et enregistrent des réactions péritectiques impliquant grenat, clinopyroxene et plagioclase à des pressions de ~ 1.2 GPa pour des températures de 650-700 °C. Cependant dans quelques échantillons deux ou trois compositions d'épidotes coexistent démontrant la présence de lacunes d'immiscibilité le long de la solution solide épidote-clinozoïsite. La forte teneur en H20 du liquide magmatique est certainement à l'origine de la coexistence de deux compositions distinctes.

Effect of spatial processes on the evolution of ecological niches and dispersal in metacommunity systems

RésuméLa coexistence de nombreuses espèces différentes a de tout temps intrigué les biologistes. La diversité et la composition des communautés sont influencées par les perturbations et l'hétérogénéité des conditions environnementales. Bien que dans la nature la distribution spatiale des conditions environnementales soit généralement autocorrélée, cet aspect est rarement pris en compte dans les modèles étudiant la coexistence des espèces. Dans ce travail, nous avons donc abordé, à l'aide de simulations numériques, la coexistence des espèces ainsi que leurs caractéristiques au sein d'un environnement autocorrélé.Afin de prendre en compte cet élément spatial, nous avons développé un modèle de métacommunauté (un ensemble de communautés reliées par la dispersion des espèces) spatialement explicite. Dans ce modèle, les espèces sont en compétition les unes avec les autres pour s'établir dans un nombre de places limité, dans un environnement hétérogène. Les espèces sont caractérisées par six traits: optimum de niche, largeur de niche, capacité de dispersion, compétitivité, investissement dans la reproduction et taux de survie. Nous nous sommes particulièrement intéressés à l'influence de l'autocorrélation spatiale et des perturbations sur la diversité des espèces et sur les traits favorisés dans la métacommunauté. Nous avons montré que l'autocorrélation spatiale peut avoir des effets antagonistes sur la diversité, en fonction du taux de perturbations considéré. L'influence de l'autocorrélation spatiale sur la capacité de dispersion moyenne dans la métacommunauté dépend également des taux de perturbations et survie. Nos résultats ont aussi révélé que de nombreuses espèces avec différents degrés de spécialisation (i.e. différentes largeurs de niche) peuvent coexister. Toutefois, les espèces spécialistes sont favorisées en absence de perturbations et quand la dispersion est illimitée. A l'opposé, un taux élevé de perturbations sélectionne des espèces plus généralistes, associées avec une faible compétitivité.L'autocorrélation spatiale de l'environnement, en interaction avec l'intensité des perturbations, influence donc de manière considérable la coexistence ainsi que les caractéristiques des espèces. Ces caractéristiques sont à leur tour souvent impliquées dans d'importants processus, comme le fonctionnement des écosystèmes, la capacité des espèces à réagir aux invasions, à la fragmentation de l'habitat ou aux changements climatiques. Ce travail a permis une meilleure compréhension des mécanismes responsables de la coexistence et des caractéristiques des espèces, ce qui est crucial afin de prédire le devenir des communautés naturelles dans un environnement changeant.AbstractUnderstanding how so many different species can coexist in nature is a fundamental and long-standing question in ecology. Community diversity and composition are known to be influenced by heterogeneity in environmental conditions and disturbance. Though in nature the spatial distribution of environmental conditions is frequently autocorrelated, this aspect is seldom considered in models investigating species coexistence. In this work, we thus addressed several questions pertaining to species coexistence and composition in spatially autocorrelated environments, with a numerical simulations approach.To take into account this spatial aspect, we developed a spatially explicit model of metacommunity (a set of communities linked by dispersal of species). In this model, species are trophically equivalent, and compete for space in a heterogeneous environment. Species are characterized by six life-history traits: niche optimum, niche breadth, dispersal, competitiveness, reproductive investment and survival rate. We were particularly interested in the influence of environmental spatial autocorrelation and disturbance on species diversity and on the traits of the species favoured in the metacommunity. We showed that spatial autocorrelation can have antagonistic effects on diversity depending on disturbance rate. Similarly, spatial autocorrelation interacted with disturbance rate and survival rate to shape the mean dispersal ability observed in the metacommunity. Our results also revealed that many species with various degrees of specialization (i.e. different niche breadths) can coexist together. However specialist species were favoured in the absence of disturbance, and when dispersal was unlimited. In contrast, high disturbance rate selected for more generalist species, associated with low competitive ability.The spatial structure of the environment, together with disturbance and species traits, thus strongly impacts species diversity and, more importantly, species composition. Species composition is known to affect several important metacommunity properties such as ecosystem functioning, resistance and reaction to invasion, to habitat fragmentation and to climate changes. This work allowed a better understanding of the mechanisms responsible for species composition, which is of crucial importance to predict the fate of natural metacommunities in changing environments

Polymorphisms in candidate genes and their association with carcass traits and meat quality in Nellore cattle

The objective of this work was to estimate the allele polymorphism frequencies of genes in Nellore cattle and associate them with meat quality and carcass traits. Six hundred males were genotyped for the following polymorphisms: DGAT1 (VNTR with 18 nucleotides at the promoter region); ANK1, a new polymorphism, identified and mapped here at the gene regulatory region NW_001494427.3; TCAP (AY428575.1:g.346G>A); and MYOG (NW_001501985:g.511G>C). In the association study, phenotype data of hot carcass weight, ribeye area, backfat thickness, percentage of intramuscular fat, shear force, myofibrillar fragmentation index, meat color (L*, a*, b*), and cooking losses were used. Allele B from the ANK1 gene was associated with greater redness (a*). Alleles 5R, 6R, and 7R from the DGAT1 VNTR gene were associated with increased intramuscular fat, reduced cooking losses and increased ribeye area, respectively. The single nucleotide polymorphism (SNP) of the TCAP gene was not polymorphic, and MYOG alleles were not associated with any of the evaluated characteristics. These results indicate that ANK1 and DGAT1 genes can be used in the selection of Nellore cattle for carcass and meat quality.

Demogenetics in metapopulations

SUMMARY : Human-induced habitat fragmentation constitutes a major threat to biodiversity. Small and isolated populations suffer from increased stochasticity and from limited rescue effects. These two factors may be sufficient to cause local extinctions but fragmentation induces some genetic consequences that can also contribute significantly to extinction risks. Increased genetic drift reduces the effectiveness of selection against deleterious mutations, leading to their progressive accumulation. Drift also decreases both the standing genetic variation and the rate of fixation of beneficial mutations, limiting the evolutionary potential of isolated populations. Demography and genetics further interact and feed back on each other, progressively driving fragmented populations into "extinction vortices". The aim of the thesis was to better understand the processes occurring in fragmented populations. For this, I combined simulation studies and empirical data from three species that live in structured habitats. Chapter 1 and 2 investigate the demography of two shrew species in fragmented habitats. I showed that connectivity and habitat quality strongly affect the demography of the greater white-tooted shrew, although demographic stochasticity was extremely high. I also demonstrated that habitat fragmentation is one of the leading factors allowing the local coexistence of two competing shrew species. Chapter 3 and 4 focus on measuring connectivity in fragmented populations based on genetic data. In particular, I showed that genetic data can be used to detect the landscape elements impeding dispersal. In Chapter 5 that deals with the accumulation of deleterious mutations in fragmented populations, I demonstrated that mutation accumulation, as well a time to extinction, can be predicted from simple demographic and genetic measures. In the last two chapters, I monitored individual reproductive success in an isolated tree frogs population. These data allowed quantifying the effective population size, a measure closely linked to population evolutionary potential. To conclude, this thesis brings some new insights into the processes occurring in fragmented populations, and I hope it will contribute to the improvement of the management and conservation of fragmented populations.

Within- and among-population impact of genetic erosion on adult fitness-related traits in the European tree frog Hyla arborea.

Assessing in wild populations how fitness is impacted by inbreeding and genetic drift is a major goal for conservation biology. An approach to measure the detrimental effects of inbreeding on fitness is to estimate correlations between molecular variation and phenotypic performances within and among populations. Our study investigated the effect of individual multilocus heterozygosity on body size, body condition and reproductive investment of males (that is, chorus attendance) and females (that is, clutch mass and egg size) in both small fragmented and large non-fragmented populations of European tree frog (Hyla arborea). Because adult size and/or condition and reproductive investment are usually related, genetic erosion may have detrimental effects directly on reproductive investment, and also on individual body size and condition that in turn may affect reproductive investment. We confirmed that the reproductive investment was highly size-dependent for both sexes. Larger females invested more in offspring production, and larger males attended the chorus in the pond more often. Our results did not provide evidence for a decline in body size, condition and reproductive effort with decreased multilocus heterozygosity both within and among populations. We showed that the lack of heterozygosity-fitness correlations within populations probably resulted from low inbreeding levels (inferior to ca. 20% full-sib mating rate), even in the small fragmented populations. The detrimental effects of fixation load were either low in adults or hidden by environmental variation among populations. These findings will be useful to design specific management actions to improve population persistence.

Growth mechanisms and timing of emplacement of a vertically layered mafic intrusion in the feeder zone of an ocean island volcano (Fuerteventura, Canary islands)

Résumé pour le grand public L'île de Fuerteventura (Canaries) offre l'occasion rare d'observer les racines d'un volcan océanique édifié il y a 25 à 30 millions d'années et complètement érodé. On y voit de nombreux petits plutons de forme et composition variées, témoignant d'autant d'épisodes de l'activité magmatique. L'un de ces plutons, appelé PX1, présente une structure inhabituelle formée d'une alternance de bandes verticales d'épaisseur métrique à hectométrique de roches sombres de composition pyroxénilique ou gabbroïque. Les pyroxénites résultent clairement de l'accumulation de cristaux de pyroxènes et non de la simple solidification d'un magma? Se pose dès lors la question de la nature du processus qui a conduit à l'accumulation verticale de niveaux concentrés en pyroxènes. En effet, les litages pyroxénitiques classiques sont subhorizontaux, car ils résultent de l'accumulation gravitaire des cristaux séparés du magma dont ils cristalli¬sent par sédimentation. Cette étude vise à identifier et comprendre les mécanismes qui ont engendré ce Iitage minéralogique vertical et l'im¬portant volume de ces faciès cumulatifs. Nous nous sommes également intéressés aux conditions de pression et de température régnant au moment de la mise en place du pluton, ainsi qu'à sa durée de vie et à sa vitesse de refroidis¬sement. Enfin une approche géochimique nous a permis de préciser la nature de la source mantellique des magmas liés à cette activité magmatique. PX1 est en réalité un complexe filonien formé à des conditions de pression et de température de 1-2 kbar et 1050- 1100°C; sa construction a nécessité au moins 150 km3 de magma. L'alternance d'horizons gabbroïques et pyroxéniti¬ques représente des injections successives de magma sous la forme de filons verticaux, mis en place dans un contexte régional en extension. L'étude des orientations des minéraux dans ces faciès révèle que les horizons gabbroïques enregistrent l'extension régionale, alors que les pyroxénites sont générées par une compaction au sein du pluton. Ceci suggère que le régime des contraintes, qui était extensif lors de l'initiation de la mise en place de PX1, est pério¬diquement devenu compressif au sein même du pluton. Cette compression serait liée à des cycles de mise en place où la vitesse de croissance du pluton dépassait celle de l'extension régionale. La différenciation observée au sein de chaque horizon, depuis des pyroxénites riches en olivine jusqu'à des pyroxé¬nites à plagioclase interstitiel et des gabbros, ainsi que la composition géochimique des minéraux qui les constituent suggèrent que chaque filon vertical s'est mis en place à partir d'un magma de composition identique, puis a évolué indépendamment des autres en fonction du régime thermique et du régime des contraintes local. Lorsque le magma en train de cristalliser s'est trouvé en compression, le liquide résiduel a été séparé des cristaux déjà formés et extrait du système, laissant derrière lui une accumulation de cristaux dont la nature et les proportions dépendaient du stade de cristallisation atteint par le magma au moment de l'extraction. Ainsi, les niveaux de pyroxénites à olivine (premier minéral à cristalliser) ont été formés lorsque le magma correspondant était encore peu cristallisé; à l'inverse, les py¬roxénites riches en plagioclase (minéral plus tardif dans la séquence de cristallisation) et certains gabbros à caractère cumulatif résultent d'une compression tardive dans le processus de cristallisation du filon concerné. Les liquides résiduels extraits des niveaux pyroxénitiques sont rarement observés dans PX1, certaines poches et filonets de com¬position anorthositique pourraient en être les témoins. L'essentiel de ces liquides a probablement gagné des niveaux supérieurs du pluton, voire la surface du volcan. L'origine du régime compressif périodique affectant les filons en voie de cristallisation est attribuée aux injections suivantes de magma au sein du pluton, qui se sont succédées à un rythme plus rapide que la vitesse de consolidation des filons. Des datations U/Pb de haute précision sur des cristaux de zircon et de baddeleyite ainsi que40Ar/39Ar sur des cris¬taux d'amphibole révèlent une initiation de la mise en place de PX1 il y a 22.1 ± 0,7 Ma; celle-ci a duré quelque 0,48 ± 0,22 à 0,52 ± 0,29 Ma. Ce laps de temps est compatible avec celui nécessaire à la cristallisation des filons individuels, qui va de moins d'une année lors de l'initiation du magmatisme à 5 ans lors du maximum d'activité de PX1. La présence de cristaux résorbés enregistrant une cristallisation complexe suggère l'existence d'une chambre mag¬matique convective sous-jacente à PX1 et périodiquement rechargée. Les compositions isotopiques des roches étu¬diées révèlent une source mantellique profonde de type point chaud avec une contribution du manteau lithosphéri- que métasomatisé présent sous les îles Canaries. Résumé L'intrusion mafique Miocène PX1 fait partie du soubassement superficiel (0.15-0.2 GPa, 1100 °Q d'un volcan d'île océanique. La particularité de ce pluton est l'existence d'alternances d'unités de gabbros et de pyroxénites qui met¬tent en évidence un litage magmatique vertical (NNE-SSW). Les horizons gabbroiques et pyroxénitiques sont constitués d'unités de différenciation métriques qui suggèrent tine mise en place par injections périodiques de filons verticaux de magma formant un complexe filonien. Chaque filon vertical a subi une différenciation parallèle à un front de solidification sub-vertical parallèle aux bords du filon. Les pyroxénites résultent du fractionnement et de l'accumulation d'olivine ± clinopyroxene ± plagioclase à partir d'un magma basaltique faiblement alcalin et sont interprétées comme étant des imités de différenciation tronquées dont le liquide interstitiel a été extrait par compaction. L'orientation préférentielle des clinopyroxènes dans ces pyroxe- nites (obtenues par analyse EBSD et micro-tomographique) révèle une composante de cisaillement simple dans la genèse de ces roches, ce qui confirme cette interprétation. La compaction des pyroxénites est probablement causée par a mise en place de filons de magma suivants. Le liquide interstitiel expulsé est probablement par ces derniers. Les clinopyroxènes des gabbros, montrent une composante de cisaillement pure suggérant qu'ils sont affectés par une déformation syn-magmatique parallèle aux zones de cisaillement NNE-SSW observées autour de PX1 et liées au contexte tectonique Miocène d'extension régionale. Ceci suggère que les gabbros sont liés à des taux de mise en place faibles à la fin de cycles d'activité magmatique et sont peu ou pas affectés par la compaction. L'initiation et la géométrie de PX1 sont donc contrôlées par le contexte tectonique régional d'extension alors que les taux et les volumes de magma dépendent de facteurs liés à la source. Des taux d'injection élevés résultent probable¬ment en une croissance du pluton supérieure à la place crée par cette extension. Dans ce cas de figure, la propagation des nouveaux dykes et l'inaptitude du magma à circuler à travers les anciens dykes cristallisés pourrait causer une augmentation de la pression non-lithostatique sur ces derniers, exprimée par un cisaillement simple et l'expulsion du liquide interstitiel qu'ils contiennent (documenté par les zones de collecte anorthositiques). Les compositions en éléments majeurs et traces des gabbros et pyroxenites de PX1 sont globalement homogènes et dépendent de la nature cumulative des échantillons. Cependant, de petites variations des concentrations en éléments traces ainsi que les teneurs en éléments traces des bordures de clinopyroxenes suggèrent que ces derniers ont subi un processus de rééquilibrage et de cristallisation in situ. L'homogénéité des compositions chimiques des échantillons, ainsi que la présence de grains de clinopyroxene résorbés suggère que le complexe filonien PX1 s'est mis en place au dessus d'une chambre magmatique périodiquement rechargée dans laquelle la convection est efficace. Chaque filon est donc issu d'un même magma, mais a subi une différenciation par cristallisation in situ (jusqu'à 70% de fraction¬nement) indépendamment des autres. Dans ces filons cristallisés, les minéraux cumulatifs subissent un rééquilibrage partiel avec les liquide interstitiel avant que ce dernier ne soit expulsé lors de la compaction (mettant ainsi un terme à la différenciation). Ce modèle de mise en place signifie qu'un minimum de 150Km3 de magma est nécessaire à la genèse de PX1, une partie de ce volume ayant été émis par le 'Central Volcanic Complex' de Fuerteventura. Les rapports isotopiques radiogéniques mesurés révèlent la contribution de trois pôles mantelliques dans la genèse du magma formant PX1. Le mélange de ces pôles HIMU, DMM et EM1 refléterai l'interaction du point chaud Cana¬rien avec un manteau lithosphérique hétérogène métasomatisé. Les petites variations de ces rapports et des teneurs en éléments traces au sein des faciès pourrait refléter des taux de fusion partielle variable de la source, résultant en un échantillonnage variable du manteau lithosphérique métasomatisé lors de son interaction avec le point chaud. Des datations U/Pb de haute précision (TIMS) sur des cristaux de zircon et de baddeleyite extraits de gabbros de PX1 révèlent que l'initiation de la cristallisation du magma a eu lieu il y a 22.10±0.07 Ma et que l'activité magmatique a duré un minimum de 0.48 à 0.52 Ma. Des âges 40Ar/39Ar obtenus sur amphibole sont de 21.9 ± 0.6 à 21.8 ± 0.3 Ma, identiques aux âges U/Pb. La combinaison de ces méthodes de datations, suggère que le temps maximum nécessaire à PX1 pour se refroidir en dessous de la température de fermeture de l'amphibole est de 0.8Ma. Ceci signifie que la durée de vie de PX1 est de 520 000 à 800 000 ans. La coexistence de cristaux de baddeleyite et de zircon dans un gabbro est attribuée à son interaction avec un fluide riche en C02 relâché par les carbonatites encaissantes lors du métamorphisme de contact généré par la mise en place de PX1 environ 160 000 ans après le début de sa mise en place. Les durées de vie obtenue sont en accord avec le modèle de mise en place suggérant une durée de cristallisation poux chaque filon allant de 1 an à 5 ans. Abstract The Miocene PX1 gabbro-pyroxenite intrusion (Fuerteventura, Canary Islands), is interpreted as the shallow-level feeder-zone (0.15-0.2 GPa and 1100-1120°C), to an ocean island volcano. The particularity of PX1 is that it displays a NNE-SSW trending vertical magmatic banding expressed by alternating gabbro and pyroxeriite sequences. The gabbro and pyroxenite sequences consist of metre-thick differentiation units, which suggest emplacement by pe¬riodic injection of magma pulses as vertical dykes that amalgamated, similarly to a sub-volcanic sheeted dyke com¬plex. Individual dykes underwent internal differentiation following a solidification front (favoured by a significant lateral/horizontal thermal gradient) parallel to the dyke edges. Pyroxenitic layers result from the fractionation and accumulation of clinopyroxene ± olivine ± plagioclase crystals from a mildly alkaline basaltic liquid and are interpre¬ted as truncated differentiation sequences, from which residual melts were extracted by compaction. Clinopyroxene mineral orientation in pyroxenites (evidenced by EBSD and micro X-ray tomography analysis) display a marked pure shear component, supporting this interpretation. Compaction and squeezing of the crystal mush is ascribed to the incoming and inflating magma pulses. The resulting expelled interstitial liquid was likely collected and erupted along with the magma flowing through the newly injected dykes. Gabbro sequences represent crystallised coalesced magma batches, emplaced at lower rates at the end of eruptive cycles, and underwent minor melt extraction as evi¬denced by clinopyroxene orientations that record a simple shear component suggesting syn-magmatic deformation parallel to observed NNF.-SSW trending shear-zones induced by the regional tensional Miocene stress-field. The initiation and geometry of PX1 is controlled by the regional extensional tectonic regime whereas rates and vo¬lumes of magma depend on source-related factors. High injection rates are likely to induce intrusion growth rates larger than could be accommodated by the regional extension. In this case, dyke tip geometry and the inability of magma to circulate through previously emplaced and crystallised dykes could result in an increase of non-lithostatic pressure on previously emplaced mushy dyke walls; generating strong pure-shear compaction and interstitial melt expulsion within the feeder-zone as recorded by the cumulitic pyroxenite bands and anorthositic collection zones. The whole-rock major and trace-element chemistry of PX1 gabbros and pyroxenites is globally homogeneous and controlled by the cumulate nature of the samples (i.e. on the modal proportions of olivine, pyroxene, plagioclase and oxides). However, small variations of whole-rock trace-element contents as well as trace-element contents of clinopyroxene rims suggest that in-situ re-equilibration and crystallisation has occurred. Additionally, the global homogeneity and presence of complex zoning of rare resorbed clinopyroxene crystals suggest that the PX1 feeder- zone overlies a periodically replenished and efficiently mixed magma chamber. Each individual dyke of magma thus originated from a compositionally constant mildly alkaline magma and differentiated independently from the others reaching up to 70% fractionation. Following dyke arrest these are affected by interaction with the trapped interstitial liquid prior to its compaction-linked expulsion (thus stopping the differentiation process). This emplacement model implies that minimum amount of approximately 150 km3 of magma is needed to generate PX1, part of it having been erupted through the overlying Central Volcanic Complex of Fuerteventura. The radiogenic isotope ratios of PX1 samples reveal the contribution on three end-members during magma genesis. This mixing of the H1MU, EMI and DMM end-members could reflect the interaction of the deep-seated Canarian mantle plume with a heterogeneous metasomatic and sepentininsed lithospheric mantle. Additionally, the observed trace-element and isotopic variations within the same fades groups could reflect varying degrees of partial melting of the source region, thus tapping more or less large areas of the metasomatised lithospheric mantle during interac¬tion with the plume. High precision ID-TIMS U/Pb zircon and baddeleyite ages from the PX1 gabbro samples, indicate initiation of magma crystallisation at 22.10 ± 0.07 Ma. The magmatic activity lasted a minimum of 0.48 to 0.52 Ma. 40Ar/39Ar amphibole ages are of 21.9 ± 0.6 to 21.8 ± 0.3, identical within errors to the U/Pb ages. The combination of the 40Ar/39Ar and U/Pb datasets imply that the maximum amount of time PX1 took to cool below amphibole Tc is 0.8 Ma, suggesting PX1 lifetime of 520 000 to 800 000 years. On top of this, the coexistence of baddeleyite and zircon in a single sample is ascribed to the interaction of PX1 with C02-rich carbonatite-derived fluids released from the host-rock carbonatites during contact metamorphism 160 000 years after PX1 initiation. These ages are in agreement with the emplacement model, implying a crystallisation time of less than 1 to 5 years for individual dykes.

Volcanic debris avalanche deposits of the upper Maronne valley (Cantal Volcano, France): evidence for contrasted formation and transport mechanisms

The deposits of two volcanic debris avalanches (VDA I and II) that occur in the upper Maronne valley, northwest sector of Cantal Volcano, France, were studied to establish their mechanisms of formation, transport and deposition. These two volcanic debris avalanches that clearly differ with regard to their structures, textures and extensions, exemplify the wide spectrum of events associated with large-scale sector collapse. VDA I is voluminous (similar to1 km(3) in the upper Maronne valley) and widespread. The deposits comprise two distinct facies: the block facies that forms the intermediate and upper part of the unit and the mixed facies that crops out essentially at the base of the unit. The block facies consists of more or less brecciated lava, block-and-ash-flow breccia and pumice-flow tuff megablocks set in breccias resulting from block disaggregation. Mixing and differential movements are almost absent in this part of the VDA. The mixed facies consists of breccias rich in fine particles that originate from block disagregation, as well as being picked up from the substratum during movement. Mixing and differential movements are predominant in this zone. Analysis of fractures on lava megablocks suggests that shear stress during the initial sliding is the principal cause of fracture. These data strongly indicate that VDA I is purely gravitational and argue for a model in which the initial sliding mass transforms into a flow due to differential in situ fragmentation caused by the shear stress. VDA II is restricted to low-topography areas. Its volume, in the studied area, is about 0.3 km(3). The deposits consist of brecciated, rounded blocks and megablocks set in a fine-grained matrix composed essentially of volcanic glass. This unit is stratified, with a massive layer that contains all the megablocks at the base and in the intermediate part, and in the upper part a normally graded layer that contains only blocks <1 m in size. The different lithologies present are totally mixed. These observations suggest that VDA II may be of the Bezymianny-type and that it underwent a flow transformation from a turbulent to a stratified flow consisting of a basal hyperconcentrated laminar body overlain by a dilute layer. (C) 2000 Elsevier Science B.V. All rights reserved.

Insights into the biogeographical history of the Lower Guinea Forest Domain: evidence for the role of refugia in the intraspecific differentiation of Aucoumea klaineana.

Determining the biogeographical histories of rainforests is central to our understanding of the present distribution of tropical biodiversity. Ice age fragmentation of central African rainforests strongly influenced species distributions. Elevated areas characterized by higher species richness and endemism have been postulated to be Pleistocene forest refugia. However, it is often difficult to separate the effects of history and of present-day ecological conditions on diversity patterns at the interspecific level. Intraspecific genetic variation could yield new insights into history, because refugia hypotheses predict patterns not expected on the basis of contemporary environmental dynamics. Here, we test geographically explicit hypotheses of vicariance associated with the presence of putative refugia and provide clues about their location. We intensively sampled populations of Aucoumea klaineana, a forest tree sensitive to forest fragmentation, throughout its geographical range. Characterizing variation at 10 nuclear microsatellite loci, we were able to obtain phylogeographic data of unprecedented detail for this region. Using Bayesian clustering approaches, we demonstrated the presence of four differentiated genetic units. Their distribution matched that of forest refugia postulated from patterns of species richness and endemism. Our data also show differences in diversity dynamics at leading and trailing edges of the species' shifting distribution. Our results confirm predictions based on refugia hypotheses and cannot be explained on the basis of present-day ecological conditions.

Frequencies of candidate genes and associations with carcass and meat traits in Nellore and crossbred cattle

Abstract: The objective of this work was to estimate allelic frequencies of the polymorphisms IGF2/MboII (G > T) of the insulin-like growth factor 2 (IGF2) gene, DQ499531.1:g.134A > T of the pro-melanin-concentrating hormone (PMCH) gene, and DQ667048.1:g.3290G > T of the RARrelated orphan receptor C (RORC) gene in beef cattle of different genetic groups, and to evaluate the associations between these polymorphisms and traits related to carcass composition and meat quality. Data on carcass and meat quality of 499 animals was used: of 313 Nellore (Bos indicus) and of 186 Nellore crossed with different taurine (Bos taurus) breeds. For the IGF2/MboII polymorphism, the frequencies found for the G allele were 0.231 and 0.631 for Nellore and crossed breeds, respectively. For the DQ499531.1:g.134A > T polymorphism, the allelic frequencies of A were 0.850 for Nellore and 0.905 for crossed breeds. For the DQ667048.1:g.3290G > T polymorphism, the allelic frequencies of G were 0.797 and 0.460 for Nellore and crossed breeds, respectively. The evaluated single nucleotide polymorphisms (SNPs) are not significantly associated with carcass and meat traits (rib eye area, back fat thickness, shear force, total lipids, and myofibrillar fragmentation index), suggesting little utility of the analyzed polymorphisms of the IGF2, PMHC, and RORC genes as selection markers in the studied cattle populations.

GPS-paikkatiedonliittäminen matkapuhelinpalveluihin

2000-luvun vaihteessa paikkatietoa hyödyntävistä matkapuhelinpalveluista odotettiin muodostuvan eräs merkittävimmistä kilpailuvalteista eri matkapuhelinoperaattoreiden välillä. Kiinnostusta paikkatietoa hyödyntäviin palveluihin lisäsi kaupallisten sovellusten lisäksi Yhdysvaltojen liittovaltioiden liikenneministeriön säätämä laki, joka velvoittaa paikantamaan yleiseen hätänumeroon soitetut puhelut. Erityisesti laite- ja verkkotoimittajat odottivat tämänluovan heille uusia markkinoita. Markkinoille tuli useita kilpailevia menetelmiä, joilla matkapuhelimia voitiin paikantaa. Suurin osa näistä menetelmistä hyödynsi GSM-verkon signalointia paikannuksen tekemiseen. Samaan aikaan kohonnut matkapuhelinten suorituskyky mahdollisti GPS-vastaanottimien integroinnin matkapuhelimiin ja ensimmäiset tällaiset matkapuhelimet ilmestyivät markkinoille. Matkapuhelinten paikantamiseen liittyvä standardointi on melko hajanaista. ETSI on standardoinut joukon erilaisia menetelmiä, joilla matkapuhelin paikkatieto voidaan selvittää. Nämä standardit eivät kuitenkaan määrittele sitä, kuinka paikkatieto siirretään sitä hyödyntävien palveluiden käyttöön. Paikkatiedonsiirtämiseen ja esittämiseen liittyvässä standardoinnissa eri laite- ja ohjelmistovalmistajat ovat tehneet liittoutumia keskenään ja esitelleet keskenään kilpailevia standardeja ja suosituksia. Tälläkään osa-alueella mikään liittoutuma ei ole saavuttanut määräävää markkina-asemaa. Tässä työssä suunniteltiin ja toteutettiin järjestelmä, jonka avulla voidaan paikantaa sellaisia GSM-päätelaitteita, joihin on integroitu GPS-vastaanotin. Toteutettu järjestelmä liitettiin uudeksi paikannusmenetelmäksi solupaikannuksen rinnalle Sonera Pointer paikannusjärjestelmään. Työn aikana testattiin joukko markkinoilla olleita GSM-puhelimia, joihin oli integroitu GPS-vastaanotin. Matkapuhelinten testauksessa erityinen huomio kiinnittyi siihen, kuinka GPS-paikkatieto saadaan siirrettyä matkapuhelimesta verkossa sijaitsevien sovellusten käyttöön. Toteutetun järjestelmän suunnittelussa täkein lähtökohta oli järjestelmän joustavuus. Standardien hajanaisuus ja osittainen puuttuminen aiheuttivat sen, että järjestelmästä oli tehtävä mahdollisimman helposti laajennettava. Toinen merkittävä suunnitteluun vaikuttanut tekijä oli operaattoririippumattomuus, koska Sonera Pointer järjestelmää oli tarkoitus myydä myös muille matkapuhelinoperaattoreille.

Morbillivirus glycoprotein expression induces ER stress, alters Ca2+ homeostasis and results in the release of vasostatin.

Although the pathology of Morbillivirus in the central nervous system (CNS) is well described, the molecular basis of neurodegenerative events still remains poorly understood. As a model to explore Morbillivirus-mediated CNS dysfunctions, we used canine distemper virus (CDV) that we inoculated into two different cell systems: a monkey cell line (Vero) and rat primary hippocampal neurons. Importantly, the recombinant CDV used in these studies not only efficiently infects both cell types but recapitulates the uncommon, non-cytolytic cell-to-cell spread mediated by virulent CDVs in brain of dogs. Here, we demonstrated that both CDV surface glycoproteins (F and H) markedly accumulated in the endoplasmic reticulum (ER). This accumulation triggered an ER stress, characterized by increased expression of the ER resident chaperon calnexin and the proapoptotic transcription factor CHOP/GADD 153. The expression of calreticulin (CRT), another ER resident chaperon critically involved in the response to misfolded proteins and in Ca(2+) homeostasis, was also upregulated. Transient expression of recombinant CDV F and H surface glycoproteins in Vero cells and primary hippocampal neurons further confirmed a correlation between their accumulation in the ER, CRT upregulation, ER stress and disruption of ER Ca(2+) homeostasis. Furthermore, CDV infection induced CRT fragmentation with re-localisation of a CRT amino-terminal fragment, also known as vasostatin, on the surface of infected and neighbouring non-infected cells. Altogether, these results suggest that ER stress, CRT fragmentation and re-localization on the cell surface may contribute to cytotoxic effects and ensuing cell dysfunctions triggered by Morbillivirus, a mechanism that might potentially be relevant for other neurotropic viruses.