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Obligate acidophilic members of the thaumarchaeotal genus Candidatus Nitrosotalea play an important role in nitrification in acidic soils, but their evolutionary and physiological adaptations to acidic environments are still poorly understood, with only a single member of this genus (Ca. N. devanaterra) having its genome sequenced. In this study, we sequenced the genomes of two additional cultured Ca. Nitrosotalea strains, extracted an almost complete Ca. Nitrosotalea metagenome-assembled genome from an acidic fen, and performed comparative genomics of the four Ca. Nitrosotalea genomes with 19 other archaeal ammonia oxidiser genomes. Average nucleotide and amino acid identities revealed that the four Ca. Nitrosotalea strains represent separate species within the genus. The four Ca. Nitrosotalea genomes contained a core set of 103 orthologous gene families absent from all other ammonia-oxidizing archaea and, for most of these gene families, expression could be demonstrated in laboratory culture or the environment via proteomic or metatranscriptomic analyses respectively. Phylogenetic analyses indicated that four of these core gene families were acquired by the Ca. Nitrosotalea common ancestor via horizontal gene transfer from acidophilic representatives of Euryarchaeota. We hypothesize that gene exchange with these acidophiles contributed to the competitive success of the Ca. Nitrosotalea lineage in acidic environments.

© 2016 Sinclair et al.Understanding the distribution of taxa and associated traits across different environments is one of the central questions in microbial ecology. High-throughput sequencing (HTS) studies are presently generating huge volumes of data to address this biogeographical topic. However, these studies are often focused on specific environment types or processes leading to the production of individual, unconnected datasets. The large amounts of legacy sequence data with associated metadata that exist can be harnessed to better place the genetic information found in these surveys into a wider environmental context. Here we introduce a software program, seqenv, to carry out precisely such a task. It automatically performs similarity searches of short sequences against the ``nt'' nucleotide database provided by NCBI and, out of every hit, extracts-if it is available-the textual metadata field. After collecting all the isolation sources from all the search results, we run a text mining algorithm to identify and parse words that are associated with the Environmental Ontology (EnvO) controlled vocabulary. This, in turn, enables us to determine both in which environments individual sequences or taxa have previously been observed and, by weighted summation of those results, to summarize complete samples. We present two demonstrative applications of seqenv to a survey of ammonia oxidizing archaea as well as to a plankton paleome dataset from the Black Sea. These demonstrate the ability of the tool to reveal novel patterns in HTS and its utility in the fields of environmental source tracking, paleontology, and studies of microbial biogeography. To install seqenv, go to: https://github.com/xapple/seqenv.

In this study, we investigated the impact of soil pH on the diversity and abundance of archaeal ammonia oxidizers in 27 different forest soils across Germany. DNA was extracted from topsoil samples, the amoA gene, encoding ammonia monooxygenase, was amplified; and the amplicons were sequenced using a 454-based pyrosequencing approach. As expected, the ratio of archaeal (AOA) to bacterial (AOB) ammonia oxidizers’ amoA genes increased sharply with decreasing soil pH. The diversity of AOA differed significantly between sites with ultra-acidic soil pH (<3.5) and sites with higher pH values. The major OTUs from soil samples with low pH could be detected at each site with a soil pH <3.5 but not at sites with pH >4.5, regardless of geographic position and vegetation. These OTUs could be related to the Nitrosotalea group 1.1 and the Nitrososphaera subcluster 7.2, respectively, and showed significant similarities to OTUs described from other acidic environments. Conversely, none of the major OTUs typical of sites with a soil pH >4.6 could be found in the ultra- and extreme acidic soils. Based on a comparison with the amoA gene sequence data from a previous study performed on agricultural soils, we could clearly show that the development of AOA communities in soils with ultra-acidic pH (<3.5) is mainly triggered by soil pH and is not influenced significantly by the type of land use, the soil type, or the geographic position of the site, which was observed for sites with acido-neutral soil pH.

We reply to the comments of J. Philip regarding the structure of La Nerthe range (southern Provence, France) and the timing of the deformation. We first agree with J. Philip on the structural independence of La Nerthe and L’Etoile ranges. We then discuss the allochthonous and autochthonous models. The allochthonous model mainly relies on a reactivation of a N-verging thrust during the Oligocene. There are no evidences for a Middle Rupelian thrusting event and the interpretation of the Oligocene series in southern Provence area was entirely revised. J. Philip’s Argumentation is solely based on the existence of steep dipping Rupelian limestones. However we demonstrate that they could be tilted along normal faults as it is the case in the Marseille basin. Recent works clearly show that the Oligocene Marseille and Saint-Pierre basins have a similar tectonic history resulting from two main extensional events. The last point debated by J. Philip is the age of the strike-slip faults. As it is pointed in our contribution the strike-slip fault planes cut folded strata and were reactivated during an extensional event. This strike-slip faulting event occurred between the latest stages of the main Bartonian compressional event and the beginning of the Early Rupelian extensional tectonics. As pointed by J. Philip the E-trending faults of Saint-Pierre basin acted as normal faults during the Oligocene. We however suggest that these faults were inherited from the Late Eocene strike-slip tectonics and reactivated during the Oligocene.

We present results from multibeam bathymetric data acquired during 2005 and 2006, in the region of maximum slip of the 26 Dec. 2004 earthquake (Mw 9.2). These data provide high-resolution images of seafloor morphology of the entire NW Sumatra forearc from the Sunda trench to the submarine volcanic arc just north of Sumatra. A slope gradient analysis of the combined dataset accurately highlights those portions of the seafloor shaped by active tectonic, depositional and/or erosional processes. The greatest slope gradients are located in the frontal 30 km of the forearc, at the toe of the accretionary wedge. This suggests that long-term deformation rates are highest here and that probably only minor amounts of slip are accommodated by other thrust faults further landward. Obvious N-S oriented lineaments observed on the incoming oceanic plate are aligned sub-parallel to the fracture zones associated with the Wharton fossil spreading center. Active strike-slip motion is suggested by recent deformation with up to 20-30 m of vertical offset. The intersection of these N-S elongated bathymetric scarps with the accretionary wedge partly controls the geometry of thrust anticlines and the location of erosional features (e.g. slide scars, canyons) at the wedge toe. Our interpretation suggests that these N-S lineaments have a significant impact on the oceanic plate, the toe of the wedge and further landward in the wedge. Finally, the bathymetric data indicate that folding at the front of the accretionary wedge occurs primarily along landward-vergent (seaward-dipping) thrusts, all unusual style in accretionary wedges worldwide. The N-S elongated lineaments locally act as boundaries between zones with predominant seaward versus landward vergence.

Trench-parallel thrust faults verging both landward and seaward were mapped in the portion of wedge located between northern Sumatra and the Indian-Indonesian boundary. The spatial aftershocks distribution of the 26th December 2004 earthquake shows that the post-seismic motion is partitioned along two thrust faults, the Lower and Median Thrust Faults, the latter being right-laterally offset by a N-S lower plate fracture zone located along the 93.6 degrees N meridian. Between February 2005 and August 2005, the upper plate aftershock activity shifted from southeast of this fracture zone to northwest of it, suggesting that the lower plate left-lateral motion along the fracture zone may have induced a shift of the upper plate post-seismic activity along the Median Thrust Fault. Based on swath bathymetric and 3.5 kHz data, co-seismic deformations were weak close to the trench. Joint seismic-geodetic determination of slip distribution and time arrivals and heights of tsunami waves suggest that the co-seismic slip was maximum along a portion of the Upper Thrust Fault located north of the Tuba Ridge, suggesting that the Upper Thrust Fault might be a splay fault originated at the interplate fault plane. As the Upper Thrust Fault is steeper than the slab, the vertical motion of the adjacent Outer Arc and overlying water is much larger compared to the one resulting from slip on the megathrust alone, increasing tsunamogenic effects.

Using a regional GPS data set including ?190 stations in Asia, from Nepal to eastern Indonesia and spanning 11 years, we update the present?day relative motion between the Indian and Sundaland plates and discuss the deformation taking place between them in Myanmar. Revisiting measurements acquired on the Main Boundary Thrust in Nepal, it appears that points in southern Nepal exhibit negligible deformation with respect to mainland India. Including these points, using a longer time span than previous studies, and making an accurate geodetic mapping in the newest reference frame allows us to refine the present?day Indian motion. Our results confirm that the current motion of India is slower than predicted by the NUVEL?1A model, and in addition our India?Eurasia motion is significantly (?5 mm/yr) slower than previous geodetic determinations. This new Indian motion, combined with a refined determination of the Sundaland motion, gives way to a relative India?Sunda angular velocity of 20.2°N, 26.1°E, 0.370°/Myr in ITRF2000, predicting a relative motion of 35 mm/yr oriented N10° at the latitude of Myanmar. There, the Sagaing Fault accommodates only 18 mm/yr of right?lateral strike slip, only half of the shear component of motion. We present two models addressing how and where the remaining deformation may occur. A first model of distributed deformation implies convergence on the Arakan subduction (the northern continuation of the now famous Sumatra?Andaman Trench) and wrench faulting in the Arakan wedge. The second model uses localized deformation, where deformation observed west of the Sagaing Fault is entirely due to elastic loading on a faster and oblique Arakan subduction (23 mm/yr). This latter model predicts that a major earthquake of Mw 8.5 may occur every century on this segment of the subduction., Space Engineering, Aerospace Engineering

This paper presents some of the implications of oceanic asperities in subduction zones, based on examples gathered during the world circumnavigation of R/V Jean Charcot . The study of these examples provides a new overview of active margin modelling in response to asperity subduction. It is concluded that both erosion and accretion may be governed by the oceanic plate even though frontal tectonic erosion is better documented because it is accessible to conventional surveys. Most of the time, erosion is due to the relaxation of the arc slope in the wake of asperity/subduction.