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Although marine picophytoplankton are at the base of the global food chain, accounting for half of the planetary primary production, they are outnumbered 10 to 1 and are largely controlled by hugely diverse populations of viruses. Eukaryotic microalgae form a ubiquitous and particularly dynamic fraction of such plankton, with environmental clone libraries from coastal regions sometimes being dominated by one or more of the three genera Bathycoccus , Micromonas , and Ostreococcus (class Prasinophyceae). The complete sequences of two double-stranded (dsDNA) Bathycoccus , one dsDNA Micromonas , and one new dsDNA Ostreococcus virus genomes are described. Genome comparison of these giant viruses revealed a high degree of conservation, both for orthologous genes and for synteny, except for one 36-kb inversion in the Ostreococcus lucimarinus virus and two very large predicted proteins in Bathycoccus prasinos viruses. These viruses encode a gene repertoire of certain amino acid biosynthesis pathways never previously observed in viruses that are likely to have been acquired from lateral gene transfer from their host or from bacteria. Pairwise comparisons of whole genomes using all coding sequences with homologous counterparts, either between viruses or between their corresponding hosts, revealed that the evolutionary divergences between viruses are lower than those between their hosts, suggesting either multiple recent host transfers or lower viral evolution rates.

The cell cycle of the chlorophyll b -possessing marine cyanobacterium Prochlorococcus is highly synchronized under natural conditions. To understand the underlying molecular mechanisms we cloned and sequenced dnaA and ftsZ , two key cell cycle-associated genes, and studied their expression. An axenic culture of Prochlorococcus sp. strain PCC 9511 was grown in a turbidostat with a 12 h–12 h light-dark cycle for 2 weeks. During the light periods, a dynamic light regimen was used in order to simulate the natural conditions found in the upper layers of the world's oceans. This treatment resulted in strong cell cycle synchronization that was monitored by flow cytometry. The steady-state mRNA levels of dnaA and ftsZ were monitored at 4-h intervals during four consecutive division cycles. Both genes exhibited clear diel expression patterns with mRNA maxima during the replication (S) phase. Western blot experiments indicated that the peak of FtsZ concentration occurred at night, i.e., at the time of cell division. Thus, the transcript accumulation of genes involved in replication and division is coordinated in Prochlorococcus sp. strain PCC 9511 and might be crucial for determining the timing of DNA replication and cell division.

Eric Karsenti et al.-- 5 pages, 2 figures, With biology becoming quantitative, systems-level studies can now be performed at spatial scales ranging from molecules to ecosystems. Biological data generated consistently across scales can be integrated with physico-chemical contextual data for a truly holistic approach, with a profound impact on our understanding of life [1]–[5]. Marine ecosystems are crucial in the regulation of Earth's biogeochemical cycles and climate [6],[7]. Yet their organization, evolution, and dynamics remain poorly understood [8],[9]. The Tara Oceans project was launched in September 2009 for a 3-year study of the global ocean ecosystem aboard the ship Tara. A unique sampling programme encompassing optical and genomic methods to describe viruses, bacteria, archaea, protists, and metazoans in their physico-chemical environment has been implemented. Starting as a grassroots initiative of a few scientists, the project has grown into a global consortium of over 100 specialists from diverse disciplines, including oceanography, microbial ecology, genomics, molecular, cellular, and systems biology, taxonomy, bioinformatics, data management, and ecosystem modeling. This multidisciplinary community aims to generate systematic, open access datasets usable for probing the morphological and molecular makeup, diversity, evolution, ecology, and global impacts of plankton on the Earth system, We are keen to thank the commitment of the following people and sponsors who made this singular expedition possible: CNRS, EMBL, Genoscope/CEA, VIB, Stazione Zoologica Anton Dohrn, UNIMIB, ANR (projects POSEIDON, BIOMARKS, PROMETHEUS, and TARA-GIRUS), FWO, BIO5, Biosphere 2, agnès b., the Veolia Environment Foundation, Region Bretagne, World Courier, Illumina, Cap L'Orient, the EDF Foundation EDF Diversiterre, FRB, the Prince Albert II de Monaco Foundation, Etienne Bourgois, the Tara schooner and its captain and crew. Tara Oceans would not exist without the continuous support of the participating 23 institutes (see http://oceans.taraexpeditions.org). Special thanks also goes to Fabrice Not and Noan Le Bescot for creating the figures of this manuscript. This is contribution number 0001 of the Tara Oceans Expedition 2009–2012

International audience; The asymmetric total synthesis of the originally proposed structure of gymnangiamide, a cytotoxic pentapeptide isolated from the marine hydroid Gymnangium regae Jaderholm, has been achieved. Key to the synthesis was the use of asymmetric hydrogenation of alpha-substituted beta-ketoesters through dynamic kinetic resolution for the preparation of nonproteinogenic chiral amino acids. The disparity of the NMR spectra between the synthetic material containing the L-serine residue and the natural product required a revision of the proposed structure.

International audience; Lipid and fatty acid composition are considered to be key parameters that determine the nutritive quality of phytoplankton diets for zooplanktonic herbivores. The fitness, reproduction and physiology of the grazers are influenced by these factors. The trophic transfer of lipids and fatty acids from algal cells has been typically studied by using simple extraction and quantification approaches, which, as we argue here, do not reflect the actual situation in the plankton. We show that cell disruption, as it occurs during a predator's grazing on diatoms can drastically change the lipid and fatty acid content of the food. In some algae, a rapid depletion of polyunsaturated fatty acids (PUFAs) is observed within the first minutes after cell disruption. This fatty acid depletion is directly linked to the production of PUFA-derived polyunsaturated aldehydes (PUA); these are molecules that are thought to be involved in the chemical defence of the algae. PUA-releasing diatoms are even capable of transforming lipids from other sources if these are available in the vicinity of the wounded cells. Fluorescent staining reveals that the enzymes involved in lipid transformation are active in the foregut of copepods, and therefore link the depletion processes directly to food uptake. Incubation experiments with the calanoid copepod Temora longicornis showed that PUFA depletion in PUA-producing diatoms is correlated to reduced hatching success, and can be compensated for by externally added single fatty acids.

influence de la localisation et de la profondeur. Les evenements de blanchissement corallien sont parmi les perturbations les plus frequentes et les plus devastatrices que subissent les recifs coralliens. A Moorea (Polynesie francaise), entre mars et juillet 2002, une moyenne de 55 ± 14% des colonies a blanchi. L'intensite du blanchissement variait fortement en fonction des genres consideres, de la localisation et de la profondeur, atteignant 72% en certaines stations. Les coraux ont davantage blanchi au niveau des stations profondes qu'aux faibles profondeurs, et plus sur la cote nord que sur la cote ouest. Cette forte variabilite a petite echelle spatiale est probablement le resultat d'interactions entre des facteurs extrinseques, comme l'hydrodynamisme, et intrinseques, comme des adaptations differentielles des associations algues/corail a l'augmentation de la temperature.

International audience; Two main periods can be considered in the history of fish metabolism under pressure. The first period (roughly from 1870 to 1970) was mainly descriptive: survival times and behavior were studied and some authors described an increase in oxygen consumption under pressure; later, the counteracting effects of high temperature on pressure were mentioned. The second period (from 1970 onwards) was more integrative and two major ways were explored. The first was to use shallow-water fish, experimentally exposed to hydrostatic pressure, which can induce a metabolic state resembling histotoxic hypoxia. The second way was to use deep-living fish which have, when compared to surface fish, muscle enzymes with higher structural stability, lower activity (in relationship with habitat depth) and kinetics that are less sensitive to pressure increase. Using this approach, it was also shown that muscle composition and function were somewhat different at depth and that deep fish are well adapted to pressure partly by maintaining membrane fluidity (homeoviscous theory). Since about 1990, the two above-mentioned approaches have still been pursued but by fewer researchers. Studies on deep-living fish are mainly concerned with enzyme kinetics whereas shallow water fish are used mainly for cellular energetic studies. Regarding this topic, it has been shown that yellow freshwater eels are able to acclimate to high-pressure effects, by optimizing membrane fluidity and composition (as achieved by deep-living fish), by improving oxidative phosphorylation (increase of P/O ratio) and the glycolytic pathway.

The current status of the discipline of Marine Sciences, in Spain, is claimed to be bibliographically represented as complete according to the “repertoire” of actions, each reader has at his disposal when meeting the strategies and tools targeted to retrieve information after metadata. To keep abreast of the spanish thesaurus regarding the bibliographic databases publicly available within the Web, a benchmarking search has been conducted. The four universities with Ms.D. studies on marine sciences, the spanish council for scientific research (CSIC), the Spanishinstitute for the oceanography (IEO), and the spanish network for the R&D (Network IRIS) have been focused on. The assessment is performed with the vision that there is no fixed, universal technology transfer process common to all institutions. Financial metrics have been discarded as particular disadvantaged for interdisciplinary research fields. Instead of this, a helpful reference point have resulted from the thematic groups oriented framing production of externalities. The study indicates the advantages of being able to mount the results of the metadata work on the internet. It presents the thesaurus of Icman (Marine Sciences Institute of Andalusia), as a digital publication available to make sense of the web-based contents on the intranet of the library., Puede considerarse que la situación actual de la disciplina de las ciencias marinas, en España, es bibliograficamente completa de acuerdo con el "repertorio" de acciones, que cada lector tiene a su disposición cuando se recurre a las estrategias y herramientas pensadas para recuperar información por medio de metadatos. Para estar al día en cuanto a los tesauros españoles relevantes para las bases de datos bibliográficas disponibles publicamente dentro de Internet, se realizó una búsqueda de evaluación comparativa. Se ha centrado en las cuatro universidades con estudios de grado de master en ciencias marinas, el consejo superior de investigación científicas (CSIC), el instituto español de oceanografía (IEO), y la red española para la I+D (RedIRIS). La evaluación se realizó con la visión de que no hay un proceso de transferencia de tecnología universal y fijo que sea común para todas las instituciones. Se han decartado todas las medidas financieras, desafortunadas cuando se utilizan en ámbitos de investigación interdisciplinar. En lugar de esto, un útil punto de vista podría resultar de los marcos de producción de externalidades orientados por los grupos temáticos. En el estudio se señalan las ventajas de las posibilidades para montar en internet el trabajo con los metadatos. Presenta el tesauro del Icman (Instituto de ciencias marinas de Andalucía), como una publicación digital para comprender los contenidos basados en internet que están disponibles en la intranet de la biblioteca., L'état actuel de la discipline des sciences marines, en Espagne, peut-être dite bibliographiquement complète conformément au "répertoire" d'actions, que chaque lecteur a à sa disposition lorsqu'il accueille les stratégies et les instruments orientés pour récupérer l'information avec des métadonnées. Afin de se tenir au fait des thesaurus espagnols quant aux bases de données bibliographiques ouvertes au public sur des sites Web, une recherche comparative des performances a été entreprise. Elle a pris pour point de mire les quatre universités avec des Masters en Sciences Marines, le Conseil espagnol pour la recherche scientifique (CSIC), l'Institut espagnol d'océanographie (IEO), et le Réseau espagnol d'interconnexion des centres informatiques des universités et des centres de recherche (RedIRIS). Le test a été effectué en cohérence avec la conscience de l'absence d'un processus universal et fixe de transférence de technologie vers toutes les institutions. Les résultats financiers ont été écartés, comme particulièrement inconvénients pour les champs de recherche interdisciplinaires. Au lieu d'exprimer cela, une référence utile est survenue sur le cadre de la production des externalités des groupes orientés vers les thématiques. L'étude signale la possibilité de pouvoir monter sur internet les résultats du travail avec les métadonnées. Il caractérise le thesaurus du Icman (Institut des sciences marines de l'Andalousie), comme une publication en version numérique pour y retrouver les contenus d'Internet disponible dans l'intranet de la bibliothèque.