Together throughout the year: seasonal patterns of bacterial and eukaryotic microbial communities in a macrotidal estuary.

Background: Estuaries are complex ecosystems linking river and marine environments, where microorganisms play a key role in maintaining ecosystem functions. In the present study, we investigated monthly 8 sites at two depth layers and over a one-year period the bacterial and eukaryotic community dynamics along the Seine macrotidal estuary (Normandy, France). To date, the taxonomy of the microbial diversity present in this anthropized estuary remains elusive and the drivers of the microbial community structure are still unknown.

Diversity and evolution of tyrosinase enzymes involved in the adhesive systems of mussels and tubeworms.

Mussels and tubeworms have evolved similar adhesive systems to cope with the hydrodynamics of intertidal environments. Both secrete adhesive proteins rich in DOPA, a post-translationally modified amino acid playing essential roles in their permanent adhesion. DOPA is produced by the hydroxylation of tyrosine residues by tyrosinase enzymes, which can also oxidize it further into dopaquinone.

Temporal pesticide dynamics alter specific eukaryotic taxa in a coastal transition zone.

Land use change and anthropogenic forcing can drastically alter the rates and patterns of sediment transport and modify biodiversity and ecosystem functions in coastal transition zones, such as the coastal ecosystems. Molecular studies of sediment extracted DNAs provide information on currently living organisms within the upper layers or buried from various periods of time, but might also provide knowledge on species dynamics, replacement and turnover. In this study, we evaluated the eukaryotic communities of a marine core that present a shift in soil erosion that was linked to glyphosate usage and correlated to chlordecone resurgence since 2000.

Differentially Shapes the Microbiota Composition and Diversity at Coastal Tide Sites and Inland Storage Sites on Caribbean Islands.

Rafts of drifting pelagic that are circulating across the Atlantic Ocean are complex ecosystems composed of a large number of associated species. Upon massive stranding, they lead to various socio-environmental issues including the inflow of contaminants and human health concerns. In this study, we used metabarcoding approaches to examine the differences in both the eukaryotic- and prokaryotic-associated communities from present in two islands of the Lesser Antilles, namely Guadeloupe and Martinique.

Kakila database: Towards a FAIR community approved database of cetacean presence in the waters of the Guadeloupe Archipelago, based on citizen science.

Background: In the French West Indies, more than 20 species of cetaceans have been observed over the last decades. The recognition of this hotspot of biodiversity of marine mammals, observed in the French Exclusive Economic Zone of the West Indies, motivated the French government to create in 2010 a marine protected area (MPA) dedicated to the conservation of marine mammals: the Agoa Sanctuary. Threats that cetacean populations face are multiple, but well-documented.

Analysis of interdomain taxonomic patterns in urban street mats.

Streets are constantly crossed by billions of vehicles and pedestrians. Their gutters, which convey stormwater and contribute to waste management, and are important for human health and well-being, probably play a number of ecological roles. Street surfaces may also represent an important part of city surface areas.

Adhesive gland transcriptomics uncovers a diversity of genes involved in glue formation in marine tube-building polychaetes.

Unlabelled: Tube-building sabellariid polychaetes are hermatypic organisms capable of forming vast reefs in highly turbulent marine habitats. Sabellariid worms assemble their tube by gluing together siliceous and calcareous clastic particles using a polyelectrolytic biocement. Here, we performed transcriptomic analyses to investigate the genes that are differentially expressed in the parathorax region, which contains the adhesive gland and tissues, from the rest of the body.

Aquatic urban ecology at the scale of a capital: community structure and interactions in street gutters.

In most cities, streets are designed for collecting and transporting dirt, litter, debris, storm water and other wastes as a municipal sanitation system. Microbial mats can develop on street surfaces and form microbial communities that have never been described. Here, we performed the first molecular inventory of the street gutter-associated eukaryotes across the entire French capital of Paris and the non-potable waters sources.

First proteomic analyses of the dorsal and ventral parts of the Sepia officinalis cuttlebone.

Unlabelled: Protein compounds constituting mollusk shells are known for their major roles in the biomineralization processes. These last years, a great diversity of shell proteins have been described in bivalves and gastropods allowing a better understanding of the calcification control by organic compounds and given promising applications in biotechnology. Here, we analyzed for the first time the organic matrix of the aragonitic Sepia officinalis shell, with an emphasis on protein composition of two different structures: the dorsal shield and the chambered part.

Physiological adjustments and transcriptome reprogramming are involved in the acclimation to salinity gradients in diatoms.

Salinity regimes in estuaries and coastal areas vary with river discharge patterns, seawater evaporation, the morphology of the coastal waterways and the dynamics of marine water mixing. Therefore, microalgae have to respond to salinity variations at time scales ranging from daily to annual cycles. Microalgae may also have to adapt to physical alterations that induce the loss of connectivity between habitats and the enclosure of bodies of water.

Multiparametric analyses reveal the pH-dependence of silicon biomineralization in diatoms.

Diatoms, the major contributors of the global biogenic silica cycle in modern oceans, account for about 40% of global marine primary productivity. They are an important component of the biological pump in the ocean, and their assemblage can be used as useful climate proxies; it is therefore critical to better understand the changes induced by environmental pH on their physiology, silicification capability and morphology. Here, we show that external pH influences cell growth of the ubiquitous diatom Thalassiosira weissflogii, and modifies intracellular silicic acid and biogenic silica contents per cell.

Diatoms: self assembled silica nanostructures, and templates for bio/chemical sensors and biomimetic membranes.

In this review we highlight recent advances in the understanding of biosilica production, biomodification of diatom frustules and their subsequent applications in bio/chemical sensors, and as a model membrane for filtration and separation.

The Ectocarpus genome and the independent evolution of multicellularity in brown algae.

Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig.

Genome-wide transcriptome analyses of silicon metabolism in Phaeodactylum tricornutum reveal the multilevel regulation of silicic acid transporters.

Background: Diatoms are largely responsible for production of biogenic silica in the global ocean. However, in surface seawater, Si(OH)(4) can be a major limiting factor for diatom productivity. Analyzing at the global scale the genes networks involved in Si transport and metabolism is critical in order to elucidate Si biomineralization, and to understand diatoms contribution to biogeochemical cycles.

Plasticity and robustness of pattern formation in the model diatom Phaeodactylum tricornutum.

Understanding the morphogenesis of mineralized structures found in shells, bones, teeth, spicules and plant cell walls is difficult because of the complexities underlying biomineralization, and the requirement of accurate models for pattern formation. Here, we investigated the spatial and temporal development of siliceous structures found in a model diatom species, Phaeodactylum tricornutum, for which the entire genome has been sequenced and transformation is routine. Analyses of pattern formation revealed that the process of silicification starts from a 'pi-like' structure that controls the spatial organization of a sternum upon which regular instabilities are initiated and developed.

The Phaeodactylum genome reveals the evolutionary history of diatom genomes.

Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one-fifth of the primary productivity on Earth. The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology. Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T.

Whole-cell response of the pennate diatom Phaeodactylum tricornutum to iron starvation.

Marine primary productivity is iron (Fe)-limited in vast regions of the contemporary oceans, most notably the high nutrient low chlorophyll (HNLC) regions. Diatoms often form large blooms upon the relief of Fe limitation in HNLC regions despite their prebloom low cell density. Although Fe plays an important role in controlling diatom distribution, the mechanisms of Fe uptake and adaptation to low iron availability are largely unknown.

Biomimetic dual templating of silica by polysaccharide/protein assemblies.

The control of silica growth by living organisms such as diatoms is known to involve the templating effect of several biomolecules working concomitantly. However, until now, biomimetic studies involving model molecules have mainly been performed with single templates. We show here that the addition of two biopolymers, gelatin and alginic acid, to silicate solutions allows the formation of complex structures resulting from the combined templating effect of both components at different scales.

New tools for labeling silica in living diatoms.

Silicon biomineralization is a widespread mechanism found in several kingdoms that concerns both unicellular and multicellular organisms. As a result of genomic and molecular tools, diatoms have emerged as a good model for biomineralization studies and have provided most of the current knowledge on this process. However, the number of techniques available to study its dynamics at the cellular level is still rather limited.

Influence of poly-L-lysine on the biomimetic growth of silica tubes in confined media.

Pore channels of polycarbonate membranes were recently used as biomimetic models to study the effect of confinement on silicate condensation, leading to the formation of silica tubes exhibiting a core-shell structure. In this work, we preimmobilized poly-L-lysine on the membrane pores, leading to modification of the tube shell formation process and variation in core particle size. These data strengthen previous assumptions on the role of confinement on silica growth, i.

Sol-gel encapsulation extends diatom viability and reveals their silica dissolution capability.

Several strains of diatom exhibit a long-term viability in silica gels and demonstrate the ability to dissolve the silica in their surroundings.

Biomimetic growth of silica tubes in confined media.

Polymer membranes were used as biomimetic environments to study the effect of confinement on silica formation. Within membrane pores, silica tubes were formed, consisting of a dense silica shell incorporating nanoparticle aggregates. The shell structure does not depend on the membrane pore size, suggesting that its formation proceeds via interfacial interactions with the pore surface.