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

Differently Shaped Hard Body Colloids in Confinement: From passive to active particles

We review recent progress in the theoretical description of anisotropic hard colloidal particles. The shapes considered range from rods and dumbbells to rounded cubes, polyhedra and to biaxial particles with arbitrary shape. Our focus is on both static and dynamical density functional theory and on computer simulations. We describe recent results for the structure, dynamics and phase behaviour in the bulk and in various confining geometries, e.g. established by two parallel walls which reduce the dimensionality of the system to two dimensions. We also include recent theoretical modelling for active particles, which are autonomously driven by some intrinsic motor, and highlight their fascinating nonequilibrium dynamics and collective behaviour.Comment: 15 pages, 6 figures, EPJ ST (accepted

Techno-economic evaluation of biomass-to-fuels with solid-oxide electrolyzer

Thermochemical biomass-to-fuel conversion requires an increased hydrogen concentration in the syngas derived from gasification, which is currently achieved by water–gas-shift reaction and CO2 removal. State-of-the-art biomass-to-fuels convert less than half of the biomass carbon with the remaining emitted as CO2. Full conversion of biomass carbon can be achieved by integrating solid-oxide electrolyzer with different concepts: (1) steam electrolysis with the hydrogen produced injected into syngas, and (2) co-electrolysis of CO2 and H2O to convert the CO2 captured from the syngas. This paper investigates techno-economically steam- or co-electrolysis-based biomass-to-fuel processes for producing synthetic natural gas, methanol, dimethyl ether and jet fuel, considering system-level heat integration and optimal placement of steam cycles for heat recovery. The results show that state-of-the-art biomass-to-fuels achieve similar energy efficiencies of 48–51% (based on a lower heating value) for the four different fuels. The integrated concept with steam electrolysis achieves the highest energy efficiency: 68% for synthetic natural gas, 64% for methanol, 63% for dimethyl ether, and 56% for jet fuel. The integrated concept with co-electrolysis can enhance the state-of-the-art energy efficiency to 66% for synthetic natural gas, 61% for methanol, and 54% for jet fuel. The biomass-to-dimethyl ether with co-electrolysis only reaches an efficiency of 49%, due to additional heat demand. The levelized cost of the product of the integrated concepts highly depends on the price and availability of renewable electricity. The concept with co-electrolysis allows for additional operation flexibility without renewable electricity, resulting in high annual production. Thus, with limited annual available hours of renewable electricity, biomass-to-fuel with co-electrolysis is more economically convenient than that with steam electrolysis. For a plant scale of 60 MWth biomass input with the renewable electricity available for 1800 h annually, the levelized cost of product of biomass-to-synthesis-natural-gas with co-electrolysis is 35 $/GJ, 20% lower than that with steam-electrolysis

The role of surface free energy in the early in vivo formation of dental plaque on human enamel and polymeric substrata

Strips of teflon and cellulose acetate were glued to the upper lateral incisors of human volunteers in a split mouth, double blind study on the influence of the substratum surface free energy (s.f.e.) on supragingival dental plaque accumulation during a three day period of no oral hygiene. Plaque accumulation, microbial composition of the plaque and s.f.e. of the microorganisms were determined and compared to plaque developed on natural enamel surfaces. Significantly less microorganisms colonised the polymer surfaces (p &lt; 0.002). Streptococcus sanguis I was the predominant microorganism found in enamel samples, comprising about one-third of the total microflora, whereas it was recovered infrequently and in lower numbers from the polymeric surfaces, which predominantly contained Streptococcus sanguis II. Only on cellulose acetate sometimes high numbers of Streptococcus mitis and Streptococcus morbillorum were detected. The mean s.f.e. of the total plaque flora was lowest on teflon (84.5 mJ m-2) followed by cellulose acetate (86.0 mJm-2), whereas enamel harboured a microflora with a significantly higher mean s.f.e. (930 mJ m-2; p &lt; 0.05). Also within the same bacterial species lower s.f.e. strains were isolated from the polymer surfaces compared to enamel. The results conform to a previously postulated model in which the interfacial free energy is the driving force for adhesion of microorganisms to solid surfaces.</p

An adaptive inelastic magnetic mirror for Bose-Einstein condensates

We report the reflection and focussing of a Bose-Einstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beam-expander, producing an ultra-cold collimated fountain of matter wavesComment: 4 pages, 4 figure

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

Transcript profiling in Candida albicans reveals new cellular functions for the transcriptional repressors CaTup1, CaMig1 and CaNrg1.

The pathogenic fungus, Candida albicans contains homologues of the transcriptional repressors ScTup1, ScMig1 and ScNrg1 found in budding yeast. In Saccharomyces cerevisiae, ScMig1 targets the ScTup1/ScSsn6 complex to the promoters of glucose repressed genes to repress their transcription. ScNrg1 is thought to act in a similar manner at other promoters. We have examined the roles of their homologues in C. albicans by transcript profiling with an array containing 2002 genes, representing about one quarter of the predicted number of open reading frames (ORFs) in C. albicans. The data revealed that CaNrg1 and CaTup1 regulate a different set of C. albicans genes from CaMig1 and CaTup1. This is consistent with the idea that CaMig1 and CaNrg1 target the CaTup1 repressor to specific subsets of C. albicans genes. However, CaMig1 and CaNrg1 repress other C. albicans genes in a CaTup1-independent fashion. The targets of CaMig1 and CaNrg1 repression, and phenotypic analyses of nrg1/nrg1 and mig1/mig1 mutants, indicate that these factors play differential roles in the regulation of metabolism, cellular morphogenesis and stress responses. Hence, the data provide important information both about the modes of action of these transcriptional regulators and their cellular roles. The transcript profiling data are available at http://www.pasteur.fr/recherche/unites/RIF/transcriptdata/