Antifouling bastadin congeners target blue mussel phenoloxidase and complex copper(II) ions

Synthetically prepared congeners of spongederived bastadin derivatives such as 5,5'-dibromohemibastadin- 1 (DBHB) that suppress the settling of barnacle larvae were identified in this study as strong inhibitors of blue mussel phenoloxidase that is involved in the firm attachment of mussels to a given substrate. The IC50 value of DBHB as the most active enzyme inhibitor encountered in this study amounts to 0.84 mu M. Inhibition of phenoloxidase by DBHB is likely due to complexation of copper(II) ions from the catalytic centre of the enzyme by the a-oxo-oxime moiety of the compound as shown here for the first time by structure activity studies and by X-ray structure determination of a copper(II) complex of DBHB.Biotechnology & Applied MicrobiologyMarine & Freshwater BiologySCI(E)EI0ARTICLE61148-11581

Resonant demagnetization of a dipolar BEC in a 3D optical lattice

We study dipolar relaxation of a chromium BEC loaded into a 3D optical lattice. We observe dipolar relaxation resonances when the magnetic energy released during the inelastic collision matches an excitation towards higher energy bands. A spectroscopy of these resonances for two orientations of the magnetic field provides a 3D band spectroscopy of the lattice. The narrowest resonance is registered for the lowest excitation energy. Its line-shape is sensitive to the on-site interaction energy. We use such sensitivity to probe number squeezing in a Mott insulator, and we reveal the production of three-body states with entangled spin and orbital degrees of freedom.Comment: 5 pages, 3 Figures, Supplemental Materia

Time in the Alexandria Quartet

Any study of The Alexandria Quartet would be incomplete without a discussion of Durrell's concept of time. His spacetime relativity proposition is central to the work and, therefore, must be fully understood if The Alexandria quartet is to be appreciated. This investigation proposes to examine Durrell's relativity proposition as it is presented in The Alexandria Quartet. The study will begin with a general discussion of time from both a scientific and philosophical point of view. This introduction will focus on the modern cyclic view of time, or mind-time, as opposed to the more traditional linear concept of time. After the introductory presentation, the study will deal with the view of time as presented by Durrell in The Alexandria Quartet and will concentrate on time and setting, on time and modern love, on time and reality as seen from the varying points of view of the many characters, and finally on time and the artist

Toward a Common Framework and Database of Materials for Soft Robotics

To advance the field of soft robotics, a unified database of material constitutive models and experimental characterizations is of paramount importance. This will facilitate the use of finite element analysis to simulate their behavior and optimize the design of soft-bodied robots. Samples from seventeen elastomers, namely Body Double™ SILK, Dragon Skin™ 10 MEDIUM, Dragon Skin 20, Dragon Skin 30, Dragon Skin FX-Pro, Dragon Skin FX-Pro + Slacker, Ecoflex™ 00–10, Ecoflex 00–30, Ecoflex 00–50, Rebound™ 25, Mold Star™ 16 FAST, Mold Star 20T, SORTA-Clear™ 40, RTV615, PlatSil® Gel-10, Psycho Paint®, and SOLOPLAST 150318, were subjected to uniaxial tensile tests according to the ASTM D412 standard. Sample preparation and tensile test parameters are described in detail. The tensile test data are used to derive parameters for hyperelastic material models using nonlinear least-squares methods, which are provided to the reader. This article presents the mechanical characterization and the resulting material properties for a wide set of commercially available hyperelastic materials, many of which are recognized and commonly applied in the field of soft robotics, together with some that have never been characterized. The experimental raw data and the algorithms used to determine material parameters are shared on the Soft Robotics Materials Database GitHub repository to enable accessibility, as well as future contributions from the soft robotics community. The presented database is aimed at aiding soft roboticists in designing and modeling soft robots while providing a starting point for future material characterizations related to soft robotics research

Proton-transfer pathways in the mitochondrial S. cerevisiae cytochrome c oxidase

In cytochrome c oxidase (CytcO) reduction of O2 to water is linked to uptake of eight protons from the negative side of the membrane: four are substrate protons used to form water and four are pumped across the membrane. In bacterial oxidases, the substrate protons are taken up through the K and the D proton pathways, while the pumped protons are transferred through the D pathway. On the basis of studies with CytcO isolated from bovine heart mitochondria, it was suggested that in mitochondrial CytcOs the pumped protons are transferred though a third proton pathway, the H pathway, rather than through the D pathway. Here, we studied these reactions in S. cerevisiae CytcO, which serves as a model of the mammalian counterpart. We analyzed the effect of mutations in the D (Asn99Asp and Ile67Asn) and H pathways (Ser382Ala and Ser458Ala) and investigated the kinetics of electron and proton transfer during the reaction of the reduced CytcO with O2. No effects were observed with the H pathway variants while in the D pathway variants the functional effects were similar to those observed with the R. sphaeroides CytcO. The data indicate that the S. cerevisiae CytcO uses the D pathway for proton uptake and presumably also for proton pumping

A common coupling mechanism for A-type heme-copper oxidases from bacteria to mitochondria

Mitochondria metabolise almost all of the oxygen that we consume, reducing it to water by cytochrome c oxidase (CcO). CcO maximises energy capture into the protonmotive force by pumping protons across the mitochondrial inner membrane. Forty years after the H+/e- stoichiometry was established, a consensus has yet to be reached on the route taken by pumped protons to traverse CcO’s hydrophobic core and on whether bacterial and mitochondrial CcOs operate via the same coupling mechanism. To resolve this, we exploited the unique amenability to mitochondrial DNA mutagenesis of the yeast S. cerevisiae to introduce single point mutations in the hydrophilic pathways of CcO to test function. From ADP/O ratio measurements on preparations of intact mitochondria, we definitely established that the D-channel, and not the H-channel, is the proton pump of the yeast mitochondrial enzyme, supporting an identical coupling mechanism in all forms of the enzyme

Ecological monitoring of coral reefs in IFRECOR survey sites in Martinique between 2001 and 2006

Monitoring of coral reefs in Martinique started in 2001, after the first permanent IFRECOR survey site was created in the island. Four permanent transects of 60 m long are sampled twice a year during the dry and the wet season in the area. Benthic community cover and fish assemblages are assessed using scuba diving techniques. The benthic communities composition remained stable, while already degraded, until end 2005 with average coral cover values of 38.7 % over the Southern reef sites and 22.9 % on the Atlantic coast. The major bleaching event during the second semester of the year 2005 killed about 14 % of the coral colonies in Martinique. Beginning 2006, a disease outbreak also killed another 15 % of the corals, with signifi cant differences between species. Globally, although coral reef decline had started before these events, an average of 30 % of the coral reefs of Martinique disappeared during the past 2 years. Thereby, there was a decrease in the average coral cover down to 32.9 % (South Caribbean) and 14.8 % (Atlantic). No effect has been recorded yet on coral reef fi sh assemblages in terms of total biodiversity, individuals and biomass. Global climate change and anthropogenic pressures are principally involved in the coral reef ecological status in Martinique. Regional MPAs projects are under review and could be an environmental issue for coral reef protection and preservation in the futureLes récifs coralliens de Martinique font l'objet d'un suivi scientifique depuis 2001, date de création de la première station de référence IFRECOR dans le département. Progressivement 4 stations ont été mises en place sous la forme de transects permanents d'une longueur de 60 m et sont échantillonnées chaque année au cours des saisons sèche et humide. Le recouvrement par les communautés benthiques ainsi que la structure des peuplements ichtyologiques sont évalués à partir d'un protocole d'observation en plongée. Les communautés, bien que déjà dégradées, présentaient une stabilité relative jusque fin 2005, avec un taux de couverture moyen de 38,7 % du fond pour les sites coralliens du sud Caraïbe à 22,9 % sur la côte atlantique. L'épisode de blanchissement qui a touché l'ensemble de la Caraïbe au second semestre 2005 a entraîné une mortalité des colonies coralliennes évaluée à 14 %. Début 2006, le développement de maladies spécifiques des coraux a fait à nouveau chuter le taux de corail vivant de 15 %, avec des différences significatives selon les espèces. Globalement, bien que le déclin des récifs ait été amorcé bien avant ces événements majeurs, la perte en corail vivant sur les récifs de Martinique est évaluée à 30 % en moyenne au cours des deux dernières années. Ainsi les taux de couverture moyens en corail évalués au cours des deux suivis de l'année 2006 n'étaient plus que de 32,9 % à 14,8 % sur les mêmes sites respectifs. Aucun changement significatif dans la structure des peuplements de poissons (biodiversité totale, effectifs et biomasse) pris dans leur ensemble n'a été mis en évidence suite à ces changements écologiques. Le réchauffement climatique et les nombreuses pressions anthropiques qui s'exercent sur les côtes de l'île sont majoritairement responsables de cet état écologique. Des projets de réserves marines régionales sont en cours d'étude et devraient permettre de prendre des mesures efficaces de préservation des écosystèmes coralliens de la Martinique dans les années à venir