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Évry, France

Lorion M.,Japan Agency for Marine - Earth Science and Technology | Halary S.,University Pierre and Marie Curie | Do Nascimento J.,University Pierre and Marie Curie | Samadi S.,French Natural History Museum | And 2 more authors.
Cahiers de Biologie Marine | Year: 2012

Small mytilids of the genus Idas are related to the large mussels found worldwide at deep-sea hydrothermal vents and cold seeps. They are therefore keys to a better understanding of the colonization of vents and seeps by symbiont-bearing organisms, but still little is known about their biology. For this study, specimens of a mytilid referred to the genus Idas were collected from various substrates in a cold seep area near the Nile deep sea fan. Based on molecular and morphological data, all specimens are confirmed to belong to a single species of the genus Idas, which was previously shown to host six distinct bacterial symbionts. Its larval shell characteristics indicate a long planktonic phase, which could explain its close relationship to a mussel species that occurs in the Gulf of Mexico. 3-D FISH indicates the dominance of sulfur-oxidizing, methane-oxidizing and methylotrophic symbionts in all specimens analysed.

Lorion J.,French Natural History Museum | Buge B.,French Natural History Museum | Cruaud C.,Genoscope | Samadi S.,French Natural History Museum
Molecular Phylogenetics and Evolution | Year: 2010

Bathymodiolinae mussels have been used as a biological model to better understand the evolutionary origin of faunas associated with deep-sea hydrothermal vents and cold seeps. Most studies to date, however, have sampled with a strong bias towards vent and seep species, mainly because of a lack of knowledge of closely related species from organic falls. Here we reassess the species diversity of deep-sea mussels using two genes and a large taxon sample from the South-Western Pacific. This new taxonomic framework serves as a basis for a phylogenetic investigation of their evolutionary history. We first highlight an unexpected allopatric pattern and suggest that mussels usually reported from organic falls are in fact poorly specialized with regard to their environment. This challenges the adaptive scenarios proposed to explain the diversification of the group. Second, we confirm that deep-sea mussels arose from organic falls and then colonized hydrothermal vents and cold seeps in multiple events. Overall, this study constitutes a new basis for further phylogenetic investigations and a global systematic revision of deep-sea mussels. © 2010 Elsevier Inc.

Martin G.,CIRAD - Agricultural Research for Development | Baurens F.-C.,CIRAD - Agricultural Research for Development | Cardi C.,CIRAD - Agricultural Research for Development | D'Hont A.,CIRAD - Agricultural Research for Development | Aury J.-M.,Genoscope
PLoS ONE | Year: 2013

Background:Banana (genus Musa) is a crop of major economic importance worldwide. It is a monocotyledonous member of the Zingiberales, a sister group of the widely studied Poales. Most cultivated bananas are natural Musa inter-(sub-)specific triploid hybrids. A Musa acuminata reference nuclear genome sequence was recently produced based on sequencing of genomic DNA enriched in nucleus.Methodology/Principal Findings:The Musa acuminata chloroplast genome was assembled with chloroplast reads extracted from whole-genome-shotgun sequence data. The Musa chloroplast genome is a circular molecule of 169,972 bp with a quadripartite structure containing two single copy regions, a Large Single Copy region (LSC, 88,338 bp) and a Small Single Copy region (SSC, 10,768 bp) separated by Inverted Repeat regions (IRs, 35,433 bp). Two forms of the chloroplast genome relative to the orientation of SSC versus LSC were found. The Musa chloroplast genome shows an extreme IR expansion at the IR/SSC boundary relative to the most common structures found in angiosperms. This expansion consists of the integration of three additional complete genes (rps15, ndhH and ycf1) and part of the ndhA gene. No such expansion has been observed in monocots so far. Simple Sequence Repeats were identified in the Musa chloroplast genome and a new set of Musa chloroplastic markers was designed.Conclusion:The complete sequence of M. acuminata ssp malaccensis chloroplast we reported here is the first one for the Zingiberales order. As such it provides new insight in the evolution of the chloroplast of monocotyledons. In particular, it reinforces that IR/SSC expansion has occurred independently several times within monocotyledons. The discovery of new polymorphic markers within Musa chloroplast opens new perspectives to better understand the origin of cultivated triploid bananas. © 2013 Martin et al.

Thubaut J.,French Natural History Museum | Puillandre N.,French Natural History Museum | Faure B.,University Pierre and Marie Curie | Faure B.,British Petroleum | And 2 more authors.
Ecology and Evolution | Year: 2013

Bathymodiolinae are giant mussels that were discovered at hydrothermal vents and harboring chemosynthetic symbionts. Due to their close phylogenetic relationship with seep species and tiny mussels from organic substrates, it was hypothesized that they gradually evolved from shallow to deeper environments, and specialized in decaying organic remains, then in seeps, and finally colonized deep-sea vents. Here, we present a multigene phylogeny that reveals that most of the genera are polyphyletic and/or paraphyletic. The robustness of the phylogeny allows us to revise the genus-level classification. Organic remains are robustly supported as the ancestral habitat for Bathymodiolinae. However, rather than a single step toward colonization of vents and seeps, recurrent habitat shifts from organic substrates to vents and seeps occurred during evolution, and never the reverse. This new phylogenetic framework challenges the gradualist scenarios "from shallow to deep." Mussels from organic remains tolerate a large range of ecological conditions and display a spectacular species diversity contrary to vent mussels, although such habitats are yet underexplored compared to vents and seeps. Overall, our data suggest that for deep-sea mussels, the high specialization to vent habitats provides ecological success in this harsh habitat but also brings the lineage to a kind of evolutionary dead end. This new multigene phylogeny challenges previous gradualist evolutionary scenarios, such as the "shallow to deep" hypothesis. The evolutionary history of the Bathymodiolinae appears more complex than previously thought. Overall, our data suggest that for deep-sea mussels, the high specialization to vent habitats provides ecological success in this harsh habitat but also brings the lineage to a kind of evolutionary dead-end. © 2013 The Authors.

Gomez-Pereira P.R.,Max Planck Institute for Marine Microbiology | Gomez-Pereira P.R.,UK National Oceanography Center | Schuler M.,Max Planck Institute for Marine Microbiology | Schuler M.,Max Planck Institute of Biochemistry | And 9 more authors.
Environmental Microbiology | Year: 2012

Bacteroidetes are widespread in marine systems where they play a crucial role in organic matter degradation. Whole genome analysis of several strains has revealed a broad glycolytic and proteolytic potential. In this study, we used a targeted metagenomic approach to investigate the degradation capabilities of distinct Bacteroidetes clades from two contrasting regions of the North Atlantic Ocean, the Polar Biome (BPLR) and the North Atlantic Subtropical (NAST). We present here the analysis of 76 Bacteroidetes fosmids, of which 28 encode the 16S rRNA gene as phylogenetic marker, and their comparison to complete Bacteroidetes genomes. Almost all of the 16S rRNA harbouring fosmids belonged to clades that we previously identified in BPLR and NAST. The majority of sequenced fosmids could be assigned to Bacteroidetes affiliated with the class Flavobacteria. We also present novel genomic information on the classes Cytophagia and Sphingobacteria, suggesting a capability of the latter for attachment to algal surfaces. In our fosmid set we identified a larger potential for polysaccharide degradation and cell surface attachment in the phytoplankton-rich BPLR. Particularly, two flavobacterial fosmids, one affiliated with the genus Polaribacter, showed a whole armoury of enzymes that likely function in degradation of sulfated polysaccharides known to be major constituents of phytoplankton cell walls. Genes involved in protein and peptidoglycan degradation, although present in both fosmid sets, seemed to have a slight preponderance in NAST. This study provides support for the hypothesis of a distinct specialization among marine Bacteroidetes for the degradation of certain types of polymers. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

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