The extent of the collateral circulation influences the postprandial increase in portal pressure in patients with cirrhosis.

Background: In cirrhosis, repeated flares of portal pressure and collateral blood flow provoked by postprandial hyperaemia may contribute to variceal dilation and rupture. Aim: To examine the effect of the extent of the collateral circulation on the postprandial increase in portal pressure observed in cirrhosis. Patients and methods: The hepatic venous pressure gradient (HVPG), hepatic blood flow and azygos blood flow were measured in 64 patients with cirrhosis before and after a standard liquid meal. Results: Peak increases in HVPG (median+14.9%), hepatic blood flow (median+25.4%), and azygos blood flow (median+32.2%) occurred at 30 min after the meal. Compared with patients with marked postprandial increase in HVPG (above the median, n¿=¿32), those showing mild (<15%, n¿=¿32) increase in HVPG had a higher baseline azygos flow (p<0.01) and underwent a greater postprandial increase in azygos flow (p<0.02). Hepatic blood flow increased similarly in both groups. Postprandial increases in HVPG were inversely correlated (p<0.001) with both baseline azygos flow (r¿=¿¿0.69) and its postprandial increase (r¿=¿¿0.72). Food intake increased nitric oxide products in the azygos (p<0.01), but not in the hepatic vein. Large varices (p<0.01) and previous variceal bleeding (p<0.001) were more frequent in patients with mild increase in HVPG. Conclusions: Postprandial hyperaemia simultaneously increases HVPG and collateral flow. The extent of the collateral circulation determines the HVPG response to food intake. Patients with extensive collateralisation show less pronounced postprandial increases in HVPG, but associated with marked flares in collateral flow. Collateral vessels preserve their ability to dilate in response to increased blood flow.

Genetic isolation of insular populations of the Maghrebian bat, Myotis punicus, in the Mediterranean Basin

We investigate the population genetic structure of the Maghrebian bat, Myotis punicus, between the mainland and islands to assess the island colonization pattern and current gene flow between nearby islands and within the mainland. Location North Africa and the Mediterranean islands of Corsica and Sardinia. Methods We sequenced part of the control region (HVII) of 79 bats across 11 colonies. The phylogeographical pattern was assessed by analysing molecular diversity indices, examining differentiation among populations and estimating divergence time. In addition, we genotyped 182 bats across 10 colonies at seven microsatellite loci. We used analysis of molecular variance and a Bayesian approach to infer nuclear population structure. Finally, we estimated sex-specific dispersal between Corsica and Sardinia. Results Mitochondrial analyses indicated that colonies between Corsica, Sardinia and North Africa are highly differentiated. Within islands there was no difference between colonies, while at the continental level Moroccan and Tunisian populations were highly differentiated. Analyses with seven microsatellite loci showed a similar pattern. The sole difference was the lack of nuclear differentiation between populations in North Africa, suggesting a male-biased dispersal over the continental area. The divergence time of Sardinian and Corsican populations was estimated to date back to the early and mid-Pleistocene. Main conclusions Island colonization by the Maghrebian bats seems to have occurred in a stepping-stone manner and certainly pre-dated human colonization. Currently, open water seems to prevent exchange of bats between the two islands, despite their ability to fly and the narrowness of the strait of Bonifacio. Corsican and Sardinian populations are thus currently isolated from any continental gene pool and must therefore be considered as different evolutionarily significant units (ESU).

Structure and spatial variability of Pinus uncinata Ram. growth forms at two contrasting treeline ecotones in the Spanish Pyrenees.

Describimos la distribución espacial de individuos de Pinus uncinata clasificados según su forma de crecimiento y tamaño en dos ecotonos poco perturbados del límite altitudinal del árbol situados en los Pirineos Centrales españoles (Ordesa, O; Tessó, T). En cada sitio situamos una parcela rectangular (30 140 m), que incluía los límites del árbol y del bosque, y cuyo lado mayor seguía el gradiente altitudinal. En ambos sitios, los individuos vivos eran más grandes y tenían un mayor número de cohortes de acículas pendiente abajo. La distribución de las clases de individuos según su forma de crecimiento y tamaño en el sitio O seguía una secuencia de mayor tamaño pendiente abajo, desde abundantes individuos policórmicos arbustivos (krummholz) con pocas cohortes de acículas (1-3) hasta individuos arbóreos mayores unicórmicos con varias cohortes de acículas (4-12). Por el contrario, los cambios estructurales en el ecotono del sitio T fueron graduales y no siguieron de forma tan clara dicha secuencia

The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications

Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas.

Surface-dependent strategies and energy flux in benthic marine communities or, why corals do not exist in the Mediterranean

Most structure-building organisms in rocky benthic communities are surface-dependent because their energy inputs depend mainly on the surface they expose to water. Two photosynthetic strategies, divided into calcareous and non calcareous algae, strict suspension-feeders and photosynthetic suspension feeders (e.g. hermatypic corals) are the four main strategies evolutively acquired by benthic organisms. Competition between those strategies occur in relation to productivity of the different species, in such a way that, for given environmental conditions, species with a higher growth (P/B ratio) would dominate. At a worldwide scale, littoral marine benthos can he considered to fit into the four fields defined by two main axes: the first, relates to productivity and relies atrophic and oligotrophic waters and the second is defined by the degree of environmental variability or seasonality (from high to low). Coral reefs (marine ecosystems dominated by photosynthetic suspension feeders) develop in the space of oligotrophic areas with low variability, while kelp beds (marine ecosystem dominated by large, non calcareous algae) are to be found only in eutrophic places with a high variability. The space of eutrophic waters with a low variability do not has specially adapted, high structured, benthic marine ecosystems, and in these conditions opportunistic algae and animals predominate. Finally, photophilic mediterranean benthos -devoid of kelps and without hermatypic corals- typifies the field of oligotrophic areas with high variability; in its more genuine aspect, Mediterranean benthos is represented by small algae with a high percentage of calcareous thallii. In all cases strict suspension-feeders compete successfully with photosynthetic organisms only in situations of low irradiances or very high inputs of POM. In its turn, Mediterranean rocky benthos, in spite of its relative uniformity, is geographically organized along the same axes. The Gulf of Lions and the insular bottoms (Balearic Islands, for example) would correspond to the extremes of eutrophic-high variability areas and oligotrophic-low variability areas, respectively. Irradiance, nutrient and POM concentration, and hydrodynamism are the three variables which mainly affect the distribution of the different surface-dependent strategies, and thus, these parameters are of paramount interest for understanding the trophic structure of Mediterranean benthic communities. In environments non limited by light, nutrient availability, defined as the product between nutrient -POM concentration and hydrodynamism, states the dominance of calcareous versus non calcareous algae. Calcareous algae dominate in oligotrophic waters while non-calcareous algae dominate in moderately eutrophic waters. In light-limited environments, passive suspension feeders (octocorallaria, gorgonians) become dominant species if POM availability is enhanced by a high hydrodynamism (strong currents); in waters with a low charge of POM organisms of other groups, mainly active suspension feeders, predominate (sponges, bryozoans, scleractiniarians). In any case, there always exists a very variable bathymetric zone, depending on light attenuation and nutrient-POM availability, where encrusting calcareous algae strongly compete with suspension feeders (coralligenous).

Spatial distribution and biomass of aquatic rooted macrophytes and their relevance in the metabolism of a Mediterranean coastal lagoon

This work aims to characterise the current autotrophic compartment of the Albufera des Grau coastal lagoon (Menorca, Balearic Islands) and to assess the relationship between the submerged macrophytes and the limnological parameters of the lagoon. During the study period the submerged vegetation was dominated by the macrophyte Ruppia cirrhosa, which formed dense extensive meadows covering 79% of the surface. Another macrophyte species, Potamogeton pectinatus, was also observed but only forming small stands near the rushing streams. Macroalgae were only occasionally observed. Macrophyte biomass showed a clear seasonal trend, with maximum values in July. The biomass of R. cirrhosa achieved 1760 g DW m-2, the highest biomass ever reported for this species in the literature. The seasonal production-decomposition cycle of the macrophyte meadows appears to drive the nutrient dynamics and carbon fluxes in the lagoon. Despite the significant biomass accumulation and the absence of a washout of nutrients and organic matter to the sea, the lagoon did not experience a dystrophic collapse. These results indicate that internal metabolism is more important than exchange processes in the lagoon.

Structure and kinematics of the Jungfrau syncline, Faflertal (Valais, Alps), and its regional significance

The formation and structural evolution of the jungrau syncline is described, based on excellent outcrops occurring in the lotschental, in the central alps of switzerland. the quality of the outcrops allows us to demonstrate that the external massifs of the swiss alps have developed due to internal folding. The jungfrau suncline, which separates the autochtonous gastern dome from the aar massif basement gneiss folds, is composed of slivers of basement rocks with their mesozoic sedimentary cover. in the inner faflertal, a side valley of the lotschental, the 200 m thick syncline cp, roses fpir imots, the gastern massif with a reduced mesozoic sedimentary cover in a normal stratigraphic succession, two units of overturned basement rocks with their mesozoic sedimentary cover, and the overturned lower limn of the tschingelhorn gneiss fold of the aar massif with lenses of its sedimentary cover. stratigraphy shows that the lower units, related to the gastern massis, are condensed and that the upper units, deposited farther away from a gastern paleo-high, form a more complete sequence, linked to the doldenhorn meso-cneozoic basin fill. the integration of these local observations with published regional data leads to the following model. on the northern margin of the doldenhorn hbasin, at the northern fringe of the alpine tethuys, the pre-triassic crystalline basement and its mesozoic sedimentary cover were folded by ductile deformation at temperatures above 300 degrees C and in the presence of high fluid pressures, as the helveti c and penninic nappes were overthrusted towards the northwest during the main alpine deformation phase, the visosity contrast between the basement gneisses and the sediments caused the formation of large basement anticlines and tight sedimentary sunclines (mullion-type structures). The edges of basement blocks bounded buy pre-cursor se-dipping normal faults at the northwestern border of the doldenhorn basin were deformed bu simple shear, creating overturned slices of crystalline rocks with their sedimentary cover in what now forms the hungfrau syncline. the localisation of ductile deformation in the vicinity of pre-existing se-dipping faults is thought to have been helped by the circulation of fluids along the faults; these fluids would have been released from the mesozoic sediments by metamorphic dehydration reactions accompanied by creep and dynamic recrystallisation of quartz at temperatures above 300 degrees C. Quantification of the deformation suggests an strain ellipsoid with a ratio (1 + e(1)/+ e(3)) of approximately 1000. The jungfrau suncline was deformed bu more brittle nw-directed shear creating well-developed shear band cleavages at a late stage, after cooling by uplift and erosion. It is suggested that the external massifs of the apls are basement gneiss folds created at temperatures of 300 degrees C by detachment through ductile deformation of the upper crust of the european plate as it was underthrusted below the adriatic plate.

Overfishing of small pelagic fishes increases trophic overlap between immature and mature striped dolphins in the Mediterranean Sea

The interactions among diet, ecology, physiology, and biochemistry affect N and C stable isotope signatures in animal tissues. Here, we examined if ecological segregation among animals in relation to sex and age existed by analyzing the signatures of delta15N and delta13C in the muscle of Western Mediterranean striped dolphins. Moreover, we used a Bayesian mixing model to study diet composition and investigated potential dietary changes over the last two decades in this population. For this, we compared isotope signatures in samples of stranded dolphins obtained during two epizootic events occurring in 1990 and 2007-2008. Mean delta13C values for females and males were not significantly different, but age-related variation indicated delta13C enrichment in both sexes, suggesting that females and males most likely fed in the same general areas, increasing their consumption of benthic prey with age. Enrichment of delta15N was only observed in females, suggesting a preference for larger or higher trophic level prey than males, which could reflect different nutritional requirements. delta13C values showed no temporal variation, although the mean delta15N signature decreased from 1990 to 2007-2008, which could indicate a dietary shift in the striped dolphin over the last two decades. The results of SIAR indicated that in 1990, hake and sardine together contributed to 60% on the diet of immature striped dolphins, and close to 90% for mature striped dolphins. Conversely, the diet of both groups in 2007-2008 was more diverse, as hake and sardine contributed to less than 40% of the entire diet. These results suggest a dietary change that was possibly related to changes in food availability, which is consistent with the depletion of sardine stocks by fishing.

Stable C and N isotope concentration in several tissues of the loggerhead sea turtle Caretta caretta from the western Mediterranean and dietary implications

The isotopic concentrations of carapace scutes, skin, muscle and blood of loggerhead sea turtles (Caretta caretta) from the Balearic Archipelago were analysed to investigate the pattern of variation between tissues and to assess the position of this species in the trophic webs of the Algerian Basin. Skin showed higher δ13C values than muscle or carapace scutes and these showed higher values than blood. Conversely, muscle showed higher δ15N values than skin, skin showed higher values than blood and blood showed higher values than carapace scutes. Dead and live sea turtles from the same habitat did not differ in the concentration of stable isotopes. However, some of the tissues of the turtles caught in drifting longlines in the oceanic realm showed higher δ13C values than those from the turtles caught by hand or in trammel nets over the continental shelf, although they did not differ in the δ15N. Comparison of the concentration of stable isotopes in the turtles with that of other species from several areas of the Algerian Basin revealed that they consumed planktonic prey and that the trophic level of the sea turtles was higher than that of carnivorous cnidarians but lower than that of zooplanktophagous fish and crustaceans.

The data treatment dependent variability of U-Pb zircon ages obtained using mono-collector, sector field, laser ablation ICP-MS

U-Pb dating of zircons by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is a widely used analytical technique in Earth Sciences. For U-Pb ages below 1 billion years (1 Ga), Pb-206/U-238 dates are usually used, showing the least bias by external parameters such as the presence of initial lead and its isotopic composition in the analysed mineral. Precision and accuracy of the Pb/U ratio are thus of highest importance in LA-ICPMS geochronology. We consider the evaluation of the statistical distribution of the sweep intensities based on goodness-of-fit tests in order to find a model probability distribution fitting the data to apply an appropriate formulation for the standard deviation. We then discuss three main methods to calculate the Pb/U intensity ratio and its uncertainty in the LA-ICPMS: (1) ratio-of-the-mean intensities method, (2) mean-of-the-intensity-ratios method and (3) intercept method. These methods apply different functions to the same raw intensity vs. time data to calculate the mean Pb/U intensity ratio. Thus, the calculated intensity ratio and its uncertainty depend on the method applied. We demonstrate that the accuracy and, conditionally, the precision of the ratio-of-the-mean intensities method are invariant to the intensity fluctuations and averaging related to the dwell time selection and off-line data transformation (averaging of several sweeps); we present a statistical approach how to calculate the uncertainty of this method for transient signals. We also show that the accuracy of methods (2) and (3) is influenced by the intensity fluctuations and averaging, and the extent of this influence can amount to tens of percentage points; we show that the uncertainty of these methods also depends on how the signal is averaged. Each of the above methods imposes requirements to the instrumentation. The ratio-of-the-mean intensities method is sufficiently accurate provided the laser induced fractionation between the beginning and the end of the signal is kept low and linear. We show, based on a comprehensive series of analyses with different ablation pit sizes, energy densities and repetition rates for a 193 nm ns-ablation system that such a fractionation behaviour requires using a low ablation speed (low energy density and low repetition rate). Overall, we conclude that the ratio-of-the-mean intensities method combined with low sampling rates is the most mathematically accurate among the existing data treatment methods for U-Pb zircon dating by sensitive sector field ICPMS.