Ecological and Biological Response of Benthic Foraminifera Under Oxygen-Depleted Conditions: Evidence from Laboratory Approaches

Laboratory experiments are a valuable way to elucidate physiological and ecological processes of benthic foraminifera under oxygen-depleted conditions. Experimentally tested survival rates and other experiments show high tolerance of many species under low oxic to anoxic conditions. Laboratory observations raised different assumptions to explain the physiological adaptations to this tolerance. Denitrification processes seem to be one important mechanism. Nevertheless, foraminifera try to colonize sediment horizons with optimal species-specific oxygen concentrations. Experimental settings demonstrated the importance of oxygen gradients for the orientation in sediments. At the same time, foraminifera change the oxygen concentration in their microenvironment by respiration. Despite high bioturbation, they do not appear to influence the flux of oxygen into the sediment. Experimental working in oxygen-depleted environments needs a reliable determination of living foraminifera during the experiment, e.g., different biochemical techniques. Additionally, electrochemical or optical oxygen sensors that measure the oxygen concentration are necessary

Three-dimensional MRI assessment of regional wall stress after acute myocardial infarction predicts postdischarge cardiac events

PURPOSE: To determine the prognostic significance of systolic wall stress (SWS) after reperfused acute myocardial infarction (AMI) using MRI. MATERIALS AND METHODS: A total of 105 patients underwent MRI 7.8 +/- 4.2 days after AMI reperfusion. SWS was calculated by using a three-dimensional (3D) MRI approach to left ventricular (LV) wall thickness and to the radius of curvature. Between hospital discharge and the end of follow-up, an average of 4.1 +/- 1.7 years after AMI, 19 patients experienced a major cardiac event, including cardiac death, nonfatal reinfarction or heart failure (18.3%). RESULTS: The results were mainly driven by heart failure outcome. In univariate analysis the following factors were predictive of postdischarge major adverse cardiac events: 1) at the time of AMI: higher heart rate, previous calcium antagonist treatment, in-hospital congestive heart failure, proximal left anterior descending artery (LAD) occlusion, a lower ejection fraction, higher maximal ST segment elevation before reperfusion, and ST segment reduction lower than 50% after reperfusion; 2) MRI parameters: higher LV end-systolic volume, lower ejection fraction, higher global SWS, higher SWS in the infarcted area (SWS MI) and higher SWS in the remote myocardium (SWS remote). In the final multivariate model, only SWS MI (odds ratio [OR]: 1.62; 95% confidence interval [CI]: 1.01-2.60; P = 0.046) and SWS remote (OR: 2.17; 95% CI: 1.02-4.65; P = 0.046) were independent predictors. CONCLUSION: Regional SWS assessed by means of MRI a few days after AMI appears to be strong predictor of postdischarge cardiac events, identifying a subset of at risk patients who could qualify for more aggressive management

Vertical distribution and respiration rates of benthic foraminifera: Contribution to aerobic remineralization in intertidal mudflats covered by Zostera noltei meadows

The present study investigates the influence of seagrass root systems on benthic hard-shelled meiofauna (foraminifera). In February and July 2011, sediment cores were collected at low tide at two sites in Arcachon lagoon, a vegetated site with Zostera noltei and a second site with bare sediments. We used the highly discriminative CellTracker™ Green fluorogenic probe technique to recognize living foraminifera and to describe foraminiferal density and diversity. Three dominant species of foraminifera were observed: Ammonia tepida, Haynesina germanica and Eggerella scabra. The two calcareous species, A. tepida and H. germanica, were preferentially found in the upper half to 1 cm of the sediment. At the vegetated site, these two species had a slightly deeper microhabitat. In the literature, both species have been described alive in much deeper sediment layers, possibly due to false positives from the Rose Bengal staining method. These two species also showed 1) higher densities at the site with Z. noltei, 2) a higher density in February when conditions were supposed optimal due to a microphytobenthos bloom, and 3) dissolved calcitic shells in July, probably resulting from a lower pH. The agglutinated species E. scabra was present alive down to at least 7 cm depth. E. scabra showed high densities in the anoxic part of the sediment at both the vegetated and bare sites, with a substantially higher density in summer at the site with bare sediments. Its presence at depth may be related to its trophic requirements; this species could be less dependent on labile organic matter than A. tepida and H. germanica. On this intertidal mudflat, the foraminiferal contribution to aerobic carbon remineralization, based on respiration rate measurements, can account for up to 7% of the diffusive oxygen uptake, almost five times more than the maximum contribution recorded in open marine environments (300 m depth) in the Bay of Biscay

Experimental fossilisation of viruses from extremophilic Archaea

The role of viruses at different stages of the origin of life has recently been reconsidered. It appears that viruses may have accompanied the earliest forms of life, allowing the transition from an RNA to a DNA world and possibly being involved in the shaping of tree of life in the three domains that we know presently. In addition, a large variety of viruses has been recently identified in extreme environments, hosted by extremophilic microorganisms, in ecosystems considered as analogues to those of the early Earth. Traces of life on the early Earth were preserved by the precipitation of silica on the organic structures. We present the results of the first experimental fossilisation by silica of viruses from extremophilic Archaea (SIRV2 – <i>Sulfolobus islandicus</i> rod-shaped virus 2, TPV1 – <i>Thermococcus prieurii</i> virus 1, and PAV1 – <i>Pyrococcus abyssi</i> virus 1). Our results confirm that viruses can be fossilised, with silica precipitating on the different viral structures (proteins, envelope) over several months in a manner similar to that of other experimentally and naturally fossilised microorganisms. This study thus suggests that viral remains or traces could be preserved in the rock record although their identification may be challenging due to the small size of the viral particles

La baisse du permis de conduire chez les jeunes adultes: simple report ou désamour de la voiture?

À l’instar de plusieurs pays occidentaux, la proportion de jeunes adultes titulaires d’un permis de conduire a diminué en Suisse (de plus de 70 % en 2000 à moins de 60 % en 2010). Cet article aborde ce phénomène en conceptualisant tout d’abord le permis de conduire comme un ensemble de règles, un droit de participer au système automobile et un rite de passage. La propension à obtenir le permis de conduire et son évolution sont ensuite analysées sur la base des Microrecensements mobilité et transports 2000 et 2010. Les résultats montrent que cette baisse s’explique en majeure partie par un report de l’âge d’obtention du permis et non par un renoncement définitif. Ce report semble moins dû à une complexification des règles ou à une augmentation des coûts mais davantage à un rapport plus fonctionnel et utilitaire à la voiture

Pneumococcal septicemiae (Streptococcus pneumoniae) in the calves

Les auteurs décrivent un foyer de septicémie à pneumocoques ( Strepto coccus pneumoniae) chez des veaux en France. L’affection sévit chez des animaux très jeunes de 0 à 8 semaines jusqu’à 3 mois et est d’évolution très rapide (quelques heures) accompagnée d’entérite subaiguë, et de lésions pulmonaires diffuses. Cette maladie peut être confondue avec de la colibacillose ou de la salmonellose ; seuls les examens bactériologiques permettent le diagnostic. C’est une affection bien connue en Allemagne, Danemark, Suisse, présente aussi en Italie et en Angleterre. En France, la maladie existe mais l’évolution est telle que les différentes phases de son diagnostic sont difficiles. Le sérotype de Streptococcus pneumoniae trouvé dans cette étude est un 18, sérotype assez fréquent en médecine humaine.The authors describe an outbreak of pneumococcal septicemiae ( Strep tococcus pneumoniae ) in the calves in France. The disease take its course in very young animals of 0 to 8 weeks old up to 3 months. The evolution is very speedy (a few hours) with clinical signs of sub acute enteritis and diffuse pulmonary lesions ; this disease can be confused with collibacillosis and salmonellosis ; and the diagnosis can be made only by bacteriological examination. This affection is well known in Germany, Denmark and Switzerland, and exists in Italy and Great Britain. In France the disease exists but the evolution is such that the different phases of the different phases of the diagnosis are difficult. The serotye of Streptococcus pneumoniae isolated in this study is serotype 18 wich is rather frequent in human medicine

Benthic foraminifera as bio-indicators of environmental quality ; Development of foraminiferal indices

Date du colloque : 06/2011International audienc

Anomalously low modulus of the interpenetrating-phase composite of Fe and Mg obtained by liquid metal dealloying

A bulk interpenetrating-phase composite consisting of immiscible Fe and Mg metals is fabricated by liquid metal dealloying. The composite exhibits an anomalously low value of the Young's modulus of 20 ± 3 GPa, when probed in compression. The Young's modulus values obtained from nanoindentation and ultrasonic measurements are, however, significantly higher than that in compression, but still remain lower than theoretical values obtained from the Hashin-Shtrikman bounds and a micromechanics model. Such a deviation is explained by the weak interfaces between Fe and Mg phases that promote phase boundary sliding upon mechanical loading, leading to a low effective modulus. © 201

Double-J ureteral stent under local anesthesia for women

INTRODUCTION: Ureteral stent placement is a key urologic procedure used to manage ureteral obstructions. It is usually performed under general anesthesia (GA) with its inherent risks. The objective was to evaluate safety, feasibility and tolerance of ureteral stent placement under local anesthesia (LA) in women. MATERIALS AND METHODS: From January 2010 to January 2013, we prospectively and consecutively reviewed all female patients who had an urgent retrograde ureteral stent placement under LA. Only primary stent placements were included in the study. Pain was assessed after surgery by Visual Analog Scale (VAS) and pain and comfort assessment during stent placement were reported. We compared outcomes and tolerance with patients under general anesthesia (GA) matched by age and operatives indications during the same period. RESULTS: We included 36 patients (18 under LA and 18 under GA) with a mean age of 59.4 +/- 22.4 years. The mean operative time was 24.4 +/- 12.9 min and 18.8 +/- 6.5 min in LA group and GA group (p = 0.110), respectively. One patient needed GA due to a poor tolerance. The mean perioperative VAS scores under LA and GA were 5.89 +/-2.95 and 2.06 +/- 2.67 (p < 0.0001), respectively. There were no intraoperative complications in either group. The procedure was painful for 16 (88.8%) patients from the LA group and 9 (50%) patients would not accept to undergo this intervention under LA again. CONCLUSION: Ureteral stent placement under LA in women can be performed safely and effectively. However, this procedure is painful and should be proposed only to selected cases