Identification of the Rem-responsive element of mouse mammary tumor virus

Mouse mammary tumor virus (MMTV) has previously been shown to encode a functional homolog of the human immunodeficiency virus-1 (HIV-1) nuclear export protein Rev, termed Rem. Here, we show that deletion of the rem gene from a MMTV molecular clone interfered with the nucleo-cytoplasmic transport of genomic length viral mRNA and resulted in a loss of viral capsid (Gag) protein production. Interestingly, nuclear export of single-spliced env mRNA was only moderately affected, suggesting that this transcript is, at least to some extent, transported via a distinct, Rem-independent export mechanism. To identify and characterize a cis-acting RNA element required for Rem responsiveness (RmRE), extensive computational and functional analyses were performed. By these means a region of 490 nt corresponding to positions nt 8517–nt 9006 in the MMTV reference strain was identified as RmRE. Deletion of this fragment, which spans the env-U3 junction region, abolished Gag expression. Furthermore, insertion of this sequence into a heterologous HIV-1-based reporter construct restored, in the presence of Rem, HIV-1 Gag expression to levels determined for the Rev/RRE export system. These results clearly demonstrate that the identified region, whose geometry resembles that of other retroviral-responsive elements, is capable to functionally substitute, in the presence of Rem, for Rev/RRE and thus provide unequivocal evidence that MMTV is a complex retrovirus

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODP Expedition 340

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor-sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of pre-existing low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or micro-faulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor-sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits comprised of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution dataset to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes. This article is protected by copyright. All rights reserved

The Evolution of the Silver Hills Volcanic Center, and Revised 40Ar/39Ar Geochronology of Montserrat, Lesser Antilles, With Implications for Island Arc Volcanism

Studying the older volcanic centers on Montserrat, Centre Hills and Silver Hills, may reveal how volcanic activity can change over long time periods (≥1 Myr), and whether the recent activity at the Soufrière Hills is typical of volcanism throughout Montserrat's history. Here, we present the first detailed mapping of the Silver Hills, the oldest and arguably least studied volcanic center on Montserrat. Volcanism at the Silver Hills was dominated by episodic andesite lava dome growth and collapse, produced Vulcanian style eruptions, and experienced periodic sector collapse events, similar to the style of volcanic activity that has been documented for the Centre Hills and Soufrière Hills. We also present an updated geochronology of volcanism on Montserrat, by revising existing ages and obtaining new 40Ar/39Ar dates and palaeomagnetic ages from marine tephra layers. We show that the centers of the Silver, Centre, and Soufrière Hills were active during at least ∼2.17–1.03 Ma, ∼1.14–0.38 Ma, and ∼0.45 Ma–present, respectively. Combined with timings of volcanism on Basse-Terre, Guadeloupe these ages suggest that ∼0.5–1 Ma is a common lifespan for volcanic centers in the Lesser Antilles. These new dates identify a previously unrecognized overlap in activity between the different volcanic centers, which appears to be a common phenomenon in island arcs. We also identify an older stage of Soufrière Hills activity ∼450–290 ka characterized by the eruption of hornblende-orthopyroxene-phyric lavas, demonstrating that the petrology of the Soufrière Hills eruptive products has changed at least twice throughout the volcano's development

Surfing the spectrum - what is on the horizon?

Diagnostic imaging techniques have evolved with technological advancements - but how far? The objective of this article was to explore the electromagnetic spectrum to find imaging techniques which may deliver diagnostic information of equal, or improved, standing to conventional radiographs and to explore any developments within radiography which may yield improved diagnostic data. A comprehensive literature search was performed using Medline, Web of Knowledge, Science Direct and PubMed Databases. Boolean Operators were used and key-terms included (not exclusively): terahertz, X-ray, ultraviolet, visible, infra-red, magnetic resonance, dental, diagnostic, caries and periodontal. Radiographic techniques are primarily used for diagnostic imaging in dentistry, and continued developments in X-ray imaging include: phase contrast, darkfield and spectral imaging. Other modalities have potential application, for example, terahertz, laser doppler and optical techniques, but require further development. In particular, infra-red imaging has regenerated interest with caries detection in vitro, due to improved quality and accessibility of cameras. Non-ionising imaging techniques, for example, infra-red, are becoming more commensurate with traditional radiographic techniques for caries detection. Nevertheless, X-rays continue to be the leading diagnostic image for dentists, with improved diagnostic potential for lower radiation dose becoming a reality

Geochemical insights into the internal dynamics of debris avalanches. A case study: The Socompa avalanche, Chile

International audienceOne way to infer the internal dynamics of debris avalanches is to characterize the heterogeneity of their deposits. Here we present high-precision Sr-Nd isotope compositions, plus major and trace element concentrations, of matrix samples and rock fragments from the Socompa debris-avalanche deposit (Chile). The Socompa blocks are easily identifiable in the field, but distinguishing substrate debris from disaggregated material formed at the volcano is difficult to do with only field criteria. Combining isotope data with field observations can help with this. Measured Sr and Nd isotope ratios show significant variations, defining a binary mixing array where matrix and rock deposits overlap. This testifies to the mixing of crushed rocks during collapse and/or movement. Assimilation of Socompa basement appears to be variable; overall, it is far lower than was previously proposed. Comparison between matrix and block samples in contact, over the whole surface area of the deposit, shows that the isotopic heterogeneity increases from source to front. Close to the Socompa, matrices are resulting from simple crushing of adjacent rocks. At the front, rock samples with distinct compositions are found in a close relationship with matrices that result either from mixing of these (or some of these) rocks or from crushing of basement material. Between the source and the front, the efficient mixing of Socompa rocks (and basement rocks) generates matrices with isotopic compositions distinct from those of the blocks they are in contact with. We interpret these results as being due to more efficient vertical mixing during the avalanche emplacement

Submarine landslides around volcanic islands: A review of what can be learned from the Lesser Antilles Arc

International audienc

Consensus statements regarding the multidisciplinary care of limb amputation patients in disasters or humanitarian emergencies: Report of the 2011 humanitarian action summit surgical working group on amputations following disasters or conflict

Limb amputations are frequently performed as a result of trauma inflicted during conflict or disasters. As demonstrated during the 2010 earthquake in Haiti, coordinating care of these patients in austere settings is complex. During the 2011 Humanitarian Action Summit, consensus statements were developed for international organizations providing care to limb amputation patients during disasters or humanitarian emergencies. Expanded planning is needed for a multidisciplinary surgical care team, inclusive of surgeons, anesthesiologists, rehabilitation specialists and mental health professionals. Surgical providers should approach amputation using an operative technique that optimizes limb length and prosthetic fitting. Appropriate anesthesia care involves both peri-operative and long-term pain control. Rehabilitation specialists must be involved early in treatment, ideally before amputation, and should educate the surgical team in prosthetic considerations. Mental health specialists must be included to help the patient with community reintegration. A key step in developing local health systemsis the establishment of surgical outcomes monitoring. Such monitoring can optimizepatient follow-up and foster professional accountability for the treatment of amputation patients in disaster settings and humanitarian emergencies. © Copyright Knowlton © World Association for Disaster and Emergency Medicine 2012