The Relationship Between Microbial Community Structures and Environmental Parameters Revealed by Metagenomic Analysis of Hot Spring Water in the Kirishima Area, Japan

Diverse microorganisms specifically inhabit extreme environments, such as hot springs and deep-sea hydrothermal vents. To test the hypothesis that the microbial community structure is predictable based on environmental factors characteristic of such extreme environments, we conducted correlation analyses of microbial taxa/functions and environmental factors using metagenomic and 61 types of physicochemical data of water samples from nine hot springs in the Kirishima area (Kyusyu, Japan), where hot springs with diverse chemical properties are distributed in a relatively narrow area. Our metagenomic analysis revealed that the samples can be classified into two major types dominated by either phylum Crenarchaeota or phylum Aquificae. The correlation analysis showed that Crenarchaeota dominated in nutrient-rich environments with high concentrations of ions and total carbons, whereas Aquificae dominated in nutrient-poor environments with low ion concentrations. These environmental factors were also important explanatory variables in the generalized linear models constructed to predict the abundances of Crenarchaeota or Aquificae. Functional enrichment analysis of genes also revealed that the separation of the two major types is primarily attributable to genes involved in autotrophic carbon fixation, sulfate metabolism and nitrate reduction. Our results suggested that Aquificae and Crenarchaeota play a vital role in the Kirishima hot spring water ecosystem through their metabolic pathways adapted to each environment. Our findings provide a basis to predict microbial community structures in hot springs from environmental parameters, and also provide clues for the exploration of biological resources in extreme environments

Morphology of the Intraslab Seismic Zone and Devolatilization Phase Equilibria of the Subducting Slab Peridotite

The dehydration-induced earthquake hypothesis for intermediate-depth earthquakes in a subduction zone was examined semi-quantitatively in the light of multi-component phase equilibria of the mantle. Based on the expected dehydration equilibria in subducting peridotite, we found a further organized structure in the hypocentral distribution observed in northeast Japan to the double seismic zone (DSZ). The structure of the seismic zone is possibly controlled by a chemical rather than a mechanical process. We first constructed a phase diagram in the model system MgO-Al2O3-SiO2-H2O (MASH) using thermodynamic calculations. Then possible hypocenter distributions in subducting mantle were semi-quantitatively predicted on the assumption that: 1) any dehydration induces earthquakes; 2) a subducting slab is more or less hydrated; 3) hydrated mantle is approximated by the MASH model system; and, 4) dehydration proceeds near equilibrium. The predicted topology of dehydrationinduced seismic zones reproduces the double seismic zone (DSZ); also predicted are multiple seismic zones, multiple convergences of the seismic planes, and thermal structure dependence of the convergence depth of the DSZ. These predictions are compared to seismic observations in NE Japan and the world's subduction zones. In NE Japan, the geometry of the double seismic zone and the hypocenter clusters between the double seismic planes compare well to the predicted dehydrationinduced multiple seismic zones and multiple convergences, assuming a simple prograde P-T path for the coldest thermal center of the slab. The correlation of the age of the subducting plate and the depth of the convergence of the world's DSZ is also consistent with the prediction. The assumption of a hydrated mantle is examined by seismic tomography beneath the Kanto area. The Poisson's ratio calculated between the two seismic planes at a depth ca. 50-80 km suggests the existence of serpentinized peridotite in the subducting mantle at those depths, even though the degree of hydration is not so strong (ca. 50-30%) and is heterogeneous. Transform faults, oceanic fracture zones, and faults at the trench are all considered to be possible hydration sites of the oceanic mantle. Using the dehydration induced-earthquake model, the link between the dehydration and the seismic zone provides us with the thermal structure in the subducting slab. The estimated thermal structure exhibits a higher temperature than previous numerical simulations, particularly within the slab. Our estimate suggests viscous heating has been underestimated in previous numerical simulations and heat transfer by a fluid produced by the dehydration of the slab mantle must be included in the model. The dehydration model is also applicable to deep seismicity in the mantle transition zone

P-T evolution of Glenelg eclogites, NW Scotland: Did they experience ultrahigh-pressure metamorphism?

Eclogites and their retrogressed equivalents from the eastern unit of the Glenelg-Attadale Inlier in NW Scotland preserve much microstructural evidence that indicates that very high-pressure/temperature eclogite facies conditions were reached, and followed by decompression and hydration during exhumation. Rutile exsolution in garnet and quartz exsolution in omphacite and titanite formed through mineral reactions during high P-T peak metamorphism. Isochemical phase diagrams modeled for samples from three different locations indicate that the outer part of the eastern unit preserves a peak metamorphic condition of c. 850-1000 degrees C at 18-25 kbar, whereas the central part has a similar pressure (c. 23 kbar), but a lower temperature (c. 670 degrees C). Due to the limitations in the phase diagram calculations the estimated P-T conditions represent the minimum conditions attained by the peak metamorphic assemblage, and the pre-exsoived peak assemblage probably stabilized at a higher pressure. This observation is strongly supported by the presence of exsolution microstructures. The present results demonstrate that the eastern unit experienced very high P-T conditions during peak metamorphism and a tight clockwise P-T trajectory and provide the first indication of possible ultrahigh-pressure metamorphism in the Glenelg eclogites. (C) 2009 Elsevier B.V. All rights reserved

Majoritic garnet: A new approach to pressure estimation of shock events in meteorites and the encapsulation of sub-lithospheric inclusions in diamond

A means for estimating pressures in natural samples based on both the coupled substitution (Na+) (Ti+Si)=(M) (Al+Cr), and the classic pyroxene-stoichiometry majorite-substitution into garnet at high-pressure, is derived for garnets with majoritic chemistry. The technique is based on a compilation of experimental data for different bulk compositions. It is compositionally and thermally robust and can be used to estimate pressures experienced by natural materials during formation of majoritic garnet. In addition, it can be used either retrospectively, or in new experimental studies to establish the pressures of crystallization of reaction products, and determine if disequilibrium is recorded by the chemistries of majoritic garnets. Pressures are calculated based on majoritic chemistries in chondritic meteorites and diamond inclusions. Majoritic garnets associated with Mg perovskite in shocked L chondrites (n=4) yield uniform pressures of 23.8±0.2GPa that are slightly higher than pressures recorded by majoritic garnet in shock-derived melt veins in L chondrites (22.4±0.6GPa; n=5). Similar pressures are also exhibited by shock-derived majoritic garnets in H chondrites (22.2±1.1GPa; n=3). Diamond inclusions with eclogitic and peridotitic majoritic garnet chemistries exhibit mean pressures of 10.7±2.7GPa (n=30) and 8.3±1.6GPa (n=15) respectively, consistent with a sub-lithospheric origin. However, pressures defined by majoritic diamond inclusions from Jagersfontein (22.3±0.8GPa and 16.9±1GPa), Monastery (15.7±7GPa) and Kankan (15.5±0.2GPa) show that these inclusions originated from the mantle transition zone. Thus, this new single-phase method for pressure estimation has unmatched potential to map the depth of formation of garnets with majoritic chemistries that occur as diamond inclusions in all parageneses except those that include Ca silicate perovskite. The derived pressures confirm the sub-lithospheric origin of eclogitic majoritic diamond inclusions, and thus provide a more comprehensive picture of the important role of storage of oceanic lithosphere in the transition zone

Multicenter study on hemorrhagic risk of heparin bridging therapy for periendoscopic thromboprophylaxis

Background: For endoscopic interventions, heparin bridging therapy is recommended in patients who are at high risk from interruption of antithrombotic therapy. Although heparin bridging has been reported to be effective in preventing thrombosis, several reports have raised concerns about increased risk of bleeding. The aim of this study was to clarify complications of hepari bridging therapy in therapeutic endoscopy. Methods: A nationwide multicenter survey using questionnaire was performed about patients undergoing therapeutic endoscopy with heparin bridging. Patients who underwent therapeutic endoscopy without heparin bridging therapy were considered as controls. Compliance scores of heparin bridging therapy guideline were employed, and association was analyzed between the score and occurrence of post-procedural bleeding. Results: The incidence of post-procedural bleeding was significantly higher (13.5 %, 33/245) in the heparin group compared with the control group (2.7 %, 299/11102)(p < 0.001). Thrombosis occurred in 1 patient each in the two groups. In the heparin group, post-procedural bleeding was more likely to be delayed bleeding. Dose adjustment of heparin was a significant factor contributing to bleeding. The compliance score of heparin bridging therapy guideline was significantly higher in those who suffered bleeding. Conclusions: Heparin bridging therapy significantly increased the risk of post-procedural bleeding compared with the control. The bleeding risk was associated with greater adherence with guidelines for heparin bridging therapy