Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Digestive tubules of Strombidae are composed by three cell types: digestive cells, vacuolated cells, and crypt cells. The last one is characterized by the presence of intracellular granules identified as spherocrystals. Such structures are known to occur in basophilic cells of gastropod digestive gland, where they are supposed to be involved in the regulation of some minerals and in detoxification. In this study, energy-dispersive X-ray analysis (EDX) and energy filtered transmission electron microscopy (EFTEM) were used to determine the elemental content of spherocrystals in two Strombidae, Strombus gigas and Strombus pugilis. In freshly collected individuals of both species, the following elements were detected: Ca, Fe, Mg, P, and Zn. Aluminum and Mn were also detected in S. gigas. Their presence in spherocrystals indicates that, in Strombidae, spherocrystals are involved in the regulation of minerals and essential trace metals. In order to answer the question ''are spherocrystals involved in nonessential trace metals scavenging?,'' artificial cadmium and lead exposure by both waterborne and dietary pathways was applied to S. pugilis. No evidence of cadmium (Cd(NO3)2) or lead (Pb(NO3)2) provided by food was found in spherocrystals. Cadmium provided in water (Cd(NO3)2 and CdCl2) causes structural modifications of the digestive gland; however, this element was not trapped in spherocrystals. These results suggest that spherocrystals are not involved in detoxification of such nonessential trace metals.
ISSN: 1059-910X

hal-00743762
https://hal.univ-antilles.fr/hal-00743762
DOI : 10.1002/jemt.21073

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ctenophores are a phylum of non-bilaterian marine (mostly planktonic) animals, characterised by several unique synapomorphies (e.g., comb rows, apical organ). Relationships between and within the nine recognised ctenophore orders are far from understood, notably due to a paucity of phylogenetically informative anatomical characters. Previous attempts to address ctenophore phylogeny using molecular data (18S rRNA) led to poorly resolved trees but demonstrated the paraphyly of the order Cydippida. Here we compiled an updated 18S rRNA data set, notably including a few newly sequenced species representing previously unsampled families (Lampeidae, Euryhamphaeidae), and we constructed an additional more rapidly evolving ITS1 + 5.8S rRNA + ITS2 alignment. These data sets were analysed separately and in combination under a probabilistic framework, using different methods (maximum likelihood, Bayesian inference) and models (e.g., doublet model to accommodate secondary structure; data partitioning). An important lesson from our exploration of these datasets is that the fast-evolving internal transcribed spacer (ITS) regions are useful markers for reconstructing high-level relationships within ctenophores. Our results confirm the paraphyly of the order Cydippida (and thus a ``cydippid-like'' ctenophore common ancestor) and suggest that the family Mertensiidae could be the sister group of all other ctenophores. The family Lampeidae (also part of the former ``Cydippida'') is probably the sister group of the order Platyctenida (benthic ctenophores). The order Beroida might not be monophyletic, due to the position of Beroe abyssicola outside of a clade grouping the other Beroe species and members of the ``Cydippida'' family Haeckeliidae. Many relationships (e.g. between Pleurobrachiidae, Beroida, Cestida, Lobata, Thalassocalycida) remain unresolved. Future progress in understanding ctenophore phylogeny will come from the use of additional rapidly evolving markers and improvement of taxonomic sampling.
ISSN: 0944-2006

hal-01544475
https://hal.archives-ouvertes.fr/hal-01544475
DOI : 10.1016/j.zool.2014.06.004

Éditeur(s) : HAL CCSD
Résumé : International audience
Symbiosis is a widespread phenomenon in the biosphere. In marine benthic environments breakdown of symbiosis is responsible for coral bleaching and dramatically affects coral reef ecosystems functioning [1]. In the water column, planktonic organisms are key component of pelagic ecosystems and a number of species form mutualistic association with microalgae forming a photosymbiosis [2]. Here we intended to investigate the genetic basis of photosymbiosis, through a transcriptomic approach on marine plankton organisms. We focused more specifically on associations occurring between radiolarian host (protist, zooplankton) and dinoflagellates symbiont (protist, phytoplankton) living inside the host cell. It has recently been highlighted that these holobionts are widespread in oligotrophic open oceans and there are also evidences of their fundamental implication in biogeochemical carbon, silica and strontium cycles [3, 4, 5, 6]. RNA-seq technologies allow obtaining an unprecedented amount of data for unicellular organisms isolated from the environment [7]. The study of such non-model holobionts datasets requires de novo assembly, which implies considerable computational resources and the potential production of chimeric sequences [8, 9].We therefore developed an original strategy aiming at accelerating and improving de novo assembly for holobiont datasets. We chose SIMKA [10] a fast kmer-based method initially developed to estimate the similarity between numerous metagenomic datasets, and which has been recently adapted to extract their common sequences. As our symbionts are identified, we used SIMKA to compare our holobionts transcriptomes to publicly available dinoflagellates transcriptomes [11] generating two datasets, one composed of reads from the symbionts and another with reads from the host (for which no reference data are currently available). Independent assemblies were then performed in parallel, accelerating the study process, and minimizing the proportion of resulting chimeric sequences. Our strategy produced a unique and comprehensive genomic dataset for Radiolaria [12, 13], and offers a pragmatic, large scale, comparison strategy to assemble and study holobionts [9]. Our new sequences obtained from holobionts study will be used for phylogenomics investigation, as reference for environmental metagenomic studies and ultimately to understand and characterize the molecular basis of symbiotic relationships in the plankton.Bibliografic references :[1] Simon K. Davy, Denis Allemand, and Virginia M. Weis. “Cell Biology of Cnidarian-Dinoflagellate Symbiosis”. In: Microbiology and Molecular Biology Reviews 76.2 (June 1, 2012), pp. 229–261. issn: 1092-2172, 1098- 5557. doi: 10.1128/MMBR.05014-11.[2] Janouškovec, J. et al. “Major transitions in dinoflagellate evolution unveiled by phylotranscriptomics”. in: PNAS 201614842 (2016). doi:10.1073/pnas.1614842114[3] Tristan Biard et al. “In situ imaging reveals the biomass of giant protists in the global ocean”. In: Nature advance online publication (Apr. 20, 2016). issn: 0028-0836. doi: 10.1038/nature17652.[4] Lionel Guidi et al. “Plankton networks driving carbon export in the olig- otrophic ocean”. In: Nature 532.7600 (Apr. 28, 2016), pp. 465–470. issn: 0028-0836. doi: 10.1038/nature16942.[5] Diane K. Stoecker et al. “Acquired phototrophy in aquatic protists”. In: Aquatic Microbial Ecology 57.3 (Nov. 24, 2009), pp. 279–310. doi: 10.3354/ame01340.[6] Johan Decelle et al. “An original mode of symbiosis in open ocean plankton”. In: Proceedings of the National Academy of Sciences 109.44 (Oct. 30, 2012), pp. 18000–18005. issn: 0027-8424, 1091-6490. doi: 10. 1073/pnas.1212303109.[7] Sergio Balzano et al. “Transcriptome analyses to investigate symbiotic relationships between marine protists”. In: Frontiers in Microbiology 6 (Mar. 17, 2015). issn: 1664-302X. doi: 10.3389/fmicb.2015.00098.[8] Li, B. et al. “Evaluation of de novo transcriptome assemblies from RNA-Seq data”. In: Genome Biology 15, 553 (2014).[9] Sangwan, N., Xia, F. & Gilbert, J. A. “Recovering complete and draft population genomes from metagenome datasets”. In: Microbiome 4, 8 (2016).[10] Gaëtan Benoit et al. “Multiple comparative metagenomics using mul- tiset k -mer counting”. In: PeerJ Computer Science 2 (Nov. 14, 2016). doi: 10.7717/peerj-cs.94.[11] Patrick J. Keeling et al. “The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): Illuminating the Functional Diversity of Eukaryotic Life in the Oceans through Transcriptome Sequencing”. In: PLOS Biol 12.6 (June 2014), e1001889. issn: 1545-7885. doi: 10.1371/journal.pbio.1001889.[12] Burki, F. et al. “Evolution of Rhizaria: new insights from phylogenomic analysis of uncultured protists”. In BMC Evolutionary Biology 10, 377 (2010).
International Conference on Holobionts
Paris, France

hal-01575069
https://hal.inria.fr/hal-01575069

Éditeur(s) : HAL CCSD Federation of American Society of Experimental Biology
Résumé : International audience
Testes of most male mammals present the particularity of being externalized from the body and are consequently slightly cooler than core body temperature (4-8 degrees C below). Although, hypothermia of the testis is known to increase germ cells apoptosis, little is known about the underlying molecular mechanisms, including cold sensors, transduction pathways, and apoptosis triggers. In this study, using a functional knockout mouse model of the cold and menthol receptors, dubbed transient receptor potential melastatine 8 (TRPM8) channels, we found that TRPM8 initiated the cold-shock response by differentially modulating cold- and heat-shock proteins. Besides, apoptosis of germ cells increased in proportion to the cooling level in control mice but was independent of temperature in knockout mice. We also observed that the rate of germ cell death correlated positively with the reactive oxygen species level and negatively with the expression of the detoxifying enzymes. This result suggests that the TRPM8 sensor is a key determinant of germ cell fate under hypothermic stimulation.Borowiec, A.-S., Sion, B., Chalmel, F., Rolland, A. D., Lemonnier, L., De Clerck, T., Bokhobza, A., Derouiche, S., Dewailly, E., Slomianny, C., Mauduit, C., Benahmed, M., Roudbaraki, M., Jegou, B., Prevarskaya, N., Bidaux, G. Cold/menthol TRPM8 receptors initiate the cold-shock response and protect germ cells from cold-shock-induced oxidation.
ISSN: 0892-6638

hal-01390973
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01390973
DOI : 10.1096/fj.201600257R
PUBMED : 27317670

Éditeur(s) : HAL CCSD Groupe français de géomorphologie (GFG)
Résumé : International audience
La lagune de la Manche-à-Eau , écosystème d'eau saumâtre, est soumise non seulement quotidiennement à la marée et aux alizés, mais aussi régulièrement aux ouragans. On cherche à mettre en relation son évolution morphologique avec la fréque nce des cyclones. Sur la photographie aérienne de l'Institut Géographique National de 2004, on a superposé un quadrillage selon une maille de 90 m dans un Système d'Information Géographique. Les 37 points géoréfércncés ainsi obtenus ont été bornés sur le terrain avec un système de positionnement global. D'après les photographies aériennes, le dessin des contours rend possible le suivi morphologique depuis 1950. La profondeur est mesurée en 1 437 points avec une perche et une sonde bathymétrique. L'ôrientat ion des courants est établie au flot et au jusant avec des penons fixés aux 37 points et une boussole. On a mesuré le mamage moyen et calculé les volumes d 'eau renouvelés à chaque marée. Le suivi cartographique montre une stabi lisation des contours et de l'île de La Fourche due à l'effet de protection des palétuviers entre eux (effet" bouclier ") et au sol (tourbe racinaire) et une agrégation ou désagrégation des îlots selon le passage des ouragans. D'après la bathymétrie actuelle, le comblement de la lagune et le creusement des chenaux sont constatés. Les courants généraux sont gouvernés en surface par les alizés, vents de SSE-NNW, et par le va-et-vient de la marée. Les descentes et remontées d 'eau obligent les courants à emprunter en profondeur les passages situés le long des berges et autour des dépressions et des hauts-fonds. Le volume d'eau de la lagune renouvelé à chaque marée (14,8 %) combiné à l'hydrodynamisme actif et varié tend à vivifier cet écosystème.
ISSN: 1266-5304

hal-00761085
https://hal.univ-antilles.fr/hal-00761085
DOI : 10.4000/geomorphologie.7606

Éditeur(s) : HAL CCSD Presses polytechniques et universitaires romandes, Publisher of the EPFL Press
Résumé : Chacun peut observer dans le monde réel l’omniprésence de systèmes complexes constitués de nombreux éléments en interaction et dont les caractéristiques globales ne peuvent se réduire à celles de leurs composants : ce sont par exemple les cellules d’un organisme vivant, les colonies de fourmis, les écosystèmes, ou encore les systèmes économiques, l’Internet et les réseaux sociaux. Dans le futur, nos sociétés devront relever l’immense défi scientifique et technologique qui consiste à comprendre ces systèmes pour les adapter, les contrôler et les modéliser. Au travers d’exemples choisis sans complication inutile, les auteurs proposent une introduction par la pratique aux systèmes complexes. Leur méthode repose sur la conviction que toute compréhension suppose un acte d’expérience; l’ouvrage est composé d’ateliers où il s’agit de simuler une dynamique collective à partir de sa modélisation orientée-agent. Les étudiants, les enseignants, les créateurs et plus largement toute personne avide de développer sa culture et d’actualiser ses connaissances tireront parti de cet ouvrage pluridisciplinaire accessible à un large public.
https://hal.archives-ouvertes.fr/hal-01284628

ISBN : 978-2-88074-991-0
hal-01284628
https://hal.archives-ouvertes.fr/hal-01284628

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : 21st International Colloquium on Animal Cytogenetics and Gene Mapping (ICACGM), Naples, ITALY, JUN 07-10, 2014
International audience
o abstract
ISSN: 0967-3849

hal-01544759
https://hal.archives-ouvertes.fr/hal-01544759

Éditeur(s) : HAL CCSD Springer International Publishing
Résumé : International audience
This two-volume book set focuses on the Siberian sturgeon. Acipenser baerii Brandt 1869, one of the 27 “existing” sturgeon species, is a native species of the Siberian catchments, where – as in many other parts of the world – the sturgeon populations are now threatened. Sturgeon farming practices targeting caviar and meat production have been expanding worldwide since the 1990s, and have seen a further increase since the turn of the century. Among the handful of sturgeon species used for significant production, the most dominant is the Siberian sturgeon. Given its peculiar phylogenetic position as a chondrostei and its use as a biological model in e.g. France, the species has also attracted the attention of biologists.
The Siberian Sturgeon (Acipenser baerii, Brandt, 1869)

ISBN : 978-3-319-61925-5
hal-01563969
http://hal.upmc.fr/hal-01563969

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Grey (Halichoerus grypus) and harbour seals (Phoca vitulina) are sympatric seal species, but they display distinct strategies of habitat use and connectivity between haulout sites. The distribution patterns and variations in relative abundance of both species were investigated along the French coast of the English Channel, at the southern limit of their range where seal numbers are increasing. Regular censuses conducted at all main haulout sites in mainland France showed significant seasonal variations at most sites, with more harbour seals counted during summer (breeding and moulting seasons), and more grey seals during summer only in the eastern English Channel. Trends in maximum haulout numbers at haulout sites showed a significant increase over the last five years, ranging from 9.7 to 30.9% per year for harbour seals, and from 5.8% (in the western English Channel) to 49.2% (in the eastern English Channel) per year for grey seals. These rates of increase in grey seal numbers are not linked to local pup production and most probably result from seal movements from the southwest British Isles and the North Sea, respectively. Aerial surveys conducted across the English Channel showed that most seal observations at sea were concentrated in the north-eastern English Channel. Telemetry showed that the 28 harbour seals tracked remained highly coastal, within a radius of 100 km from their haulout sites, and did not move to other known colonies. Grey seals moved much greater distances, reaching up to 1200 km from their capture site. More than half of the 45 grey seals tracked crossed the English Channel, especially during the breeding season, moving to known colonies in the southwest British Isles and the North Sea. Combining individual tracks and long-term surveys of the seal populations allowed a better understanding of the dynamics of these populations and their connectivity at a larger regional scale. The findings provide direct information for the management of grey and harbour seals within the frame of the Marine Strategy Framework Directive, and highlight focus areas where potential interactions between the two species should be monitored.
ISSN: 0967-0645

hal-01509674
https://hal.archives-ouvertes.fr/hal-01509674
DOI : 10.1016/j.dsr2.2017.04.004

Éditeur(s) : HAL CCSD
Résumé : International audience
The presence of photosynthetic zooxanthellae (dinoflagellates) in the tissue of many cnidarians is the main reason for their ecological success (i.e. coral reefs). It could also be the main cause of their demise, as the worldwide bleaching of reef-building coral is nothing less than the breakdown of this symbiotic association. The stability of this relationship is the principal marker for the biomonitoring of cnidarian health. We have therefore developed a new, simple method to isolate zooxanthellae in a few steps using NaOH solution. The protocol was validated in three symbiotic cnidarian species: a sea anemone, a gorgonian and a coral. Our method allows the isolation of intact and viable zooxanthellae with better yields than classic methods, especially for species with a calcareous skeleton. Moreover, the isolated zooxanthellae were free of host nucleic contaminants, facilitating subsequent specific molecular analyses.
Journal of Experimental Biology

hal-01546180
https://hal.archives-ouvertes.fr/hal-01546180
DOI : 10.1242/jeb.074955

Éditeur(s) : HAL CCSD Landes Bioscience
Résumé : International audience
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
Autophagy

hal-00735751
https://hal.archives-ouvertes.fr/hal-00735751
PUBMED : 22966490

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Since its original description as a chordate, the Late Devonian Scaumenella mesacanthi has been interpreted alternately as a prochordate, a larval ostracoderm and an immature acanthodian. For the past 30 years, these minute specimens were generally considered as decayed acanthodians, most of them belonging to Triazeugacanthus affinis. Among the abundant material of `Scaumenella', we identified a size series of 188 specimens of Triazeugacanthus based on otolith characteristics. Despite taphonomic alteration, we describe proportional growth and progressive appearance of skeletal elements through size increase. Three ontogenetic stages are identified based on squamation extent, ossification completion and allometric growth. We demonstrate that what has been interpreted previously as various degrees of decomposition corresponds to ontogenetic changes.
ISSN: 1744-9561

hal-01545474
https://hal.archives-ouvertes.fr/hal-01545474
DOI : 10.1098/rsbl.2014.0950

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Dentin matrix acidic phosphoprotein 1 (DMP1) is an acidic, highly phosphorylated, noncollagenous protein secreted during dentin and bone formation. Previous functional studies of DMP1 have revealed various motifs playing a role in either mineralization or cell differentiation. We performed an evolutionary analysis of DMP1 to identify residues and motifs that were conserved during 220 millions years (Ma) of mammalian evolution, and hence have an important function. In silico search provided us with 41 sequences that were aligned and analyzed using the Hyphy program. We showed that DMP1 contains 55 positions that were kept unchanged for 220 Ma. We also defined in a more precise manner some motifs that were already known (i.e., cleavage sites, RGD motif, ASARM peptide, glycosaminoglycan chain attachment site, nuclear localization signal sites, and dentin sialophosphoprotein-binding site), and we found five, highly conserved, new functional motifs. In the near future, functional studies could be performed to understand the role played by them.
ISSN: 0022-2844

hal-01545482
https://hal.archives-ouvertes.fr/hal-01545482
DOI : 10.1007/s00239-013-9539-2

Éditeur(s) : HAL CCSD
Résumé : During the course of their life cycle organisms are exposed to natural environment variations capable of inducing physiological, morphological and behaviour changes, thus a phenotypic plasticity. Phenotypic plasticity is the ability of a genotype to generate a new phenotype following exogeneous or endogeneous stress. Here, we investigated the phenotypic plasticity of the non-calcifying symbiotic cnidarian Anemonia viridis at multiple levels of structural complexity, in vivo and in vitro. In vivo, we determined the mechanisms behind the phenotypic plasticity under expected future climate change (i.e. ocean acidification and ocean warming). Our results show physiological changes in the inorganic carbon use of the sea anemone A. viridis exposed to high pCO2 during a long-term stress in natura or a short-term stress in controlled conditions. We then observed an equivalent decrease in carbonic anhydrase activity, a key enzyme of cnidarian carbon concentrating mechanisms. Also, we demonstrated that an increase in seawater temperature modified the response observed during a high pCO2 scenario. In vitro, we established a viable primary cell culture from regenerating tentacles of A. viridis. We determined the gastrodermal tissue origin of the cultivated cells and validated the use of this new tool to the in vitro study of stress response at the cellular level. The set-up of this powerful in vitro tool will open a multitude of perspectives for the study of cellular responses to exogeneous stress (as global change perturbations) and to endogeneous stress (as the symbiosis constraints experienced by symbiotic cnidarians)
Durant leur cycle de vie, les organismes sont exposés à des variations environnementales capables d'induire des changements physiologiques, morphologiques et comportementaux, résultant d’une plasticité phénotypique. La plasticité phénotypique est la capacité d'un génotype à générer un nouveau phénotype suite à un stress. Ici, nous avons étudié la plasticité phénotypique d’un Cnidaire symbiotique et non-calcifiant, l’anémone de mer Anemonia viridis, à de multiples niveaux de complexité structurale, in vivo et in vitro. In vivo, nous avons identifié les mécanismes sous-jacents de la plasticité phénotypique potentiellement induits par les futurs changements climatiques (acidification et réchauffement des océans). Nos résultats montrent des modifications dans l'utilisation du carbone inorganique par A. viridis exposée à une forte pCO2 lors d’un stress chronique in natura ou lors d’un stress court en conditions contrôlées. Nous avons ainsi observé une diminution des activités anhydrase carbonique, une enzyme clé des mécanismes de concentration du carbone chez les Cnidaires. Nous avons aussi démontré que l'augmentation concomittante de la température modifie la réponse observée lors d'une élévation seule de la pCO2. In vitro, nous avons établi une culture de cellules primaires viables issue de tentacules d’A. viridis en régénération. Nous avons déterminé l'origine gastrodermale des cellules cultivées et validé l'utilisation de ce nouvel outil pour l'étude de la réponse au stress au niveau cellulaire. Ce nouvel outil ouvre une multitude de perspectives pour l'étude des réponses cellulaires aux stress exogènes (changement climatique) et endogènes (contraintes dues à la symbiose)
https://tel.archives-ouvertes.fr/tel-01674220

Droits : info:eu-repo/semantics/OpenAccess
NNT : 2016AZUR4136
tel-01674220
https://tel.archives-ouvertes.fr/tel-01674220
https://tel.archives-ouvertes.fr/tel-01674220/document
https://tel.archives-ouvertes.fr/tel-01674220/file/2016AZUR4136.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Despite the increasing dominance of turf algae in coral reefs, few studies have investigated their physiological and ecological responses to changes in abiotic factors. We tested the effects of depth and ultraviolet radiation on turf algae at different levels of successional stages using two experiments. Depth-related differences were found for all turf algal communities, characterized by a higher amount of the cyanobacteria taxon Dichothrix and the red filamentous genera Poly-/Herposiphonia in the shallow and the appearance of oscillating cyanobacteria in deeper waters. In the first experiment, cross-depth transplantation of 153 days old communities influenced percentage cover, biomass and taxa composition. Downward transplantation lowered overall biomass and abundance of the foraminifera Sorites, whereas the crustose green alga Pringsheimiella and filamentous cyanobacteria colonized the communities. A nearly reverse pattern was observed in upward transplanted communities. Overall we distinguished between sensitive taxa, like Oscillatoria, and taxa able to acclimate to alterations in their environment, like Pringsheimiella, Poly/Herposiphonia and Dichothrix. In the second experiment, algae grown for 285 days at 5 m were exposed together with a set of sterile settlement tiles to three UVR regimes at 2 m for 22 days. UVR had no effect on turf algal communities regardless of successional stage. This study highlights the presence of high light and UV tolerant species. The high UV tolerance of turf communities may confer a competitive advantage over other more sensitive coral reef biota, such as corals. This study demonstrates that turf algae are dynamic communities exhibiting species-specific resistance to environmental changes.
ISSN: 0022-0981

hal-01333486
https://hal-univ-perp.archives-ouvertes.fr/hal-01333486
DOI : 10.1016/j.jembe.2014.07.017

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Wood debris are an important component of mangrove marine environments. Current knowledge of the ecological role of wood falls is limited by the absence of information on metazoan colonization processes over time. The aim of this study was to provide insights to their temporal dynamics of wood eukaryotic colonization from a shallow water experiment in a mangrove swamp. Combined in situ chemical monitoring and biological surveys revealed that the succession of colonizers in the mangrove swamp relates with the rapid evolution of sulfide concentration on the wood surface. Sulfide-tolerant species are among the first colonizers and dominate over several weeks when the sulfide content is at its maximum, followed by less tolerant opportunistic species when sulfide decreases. This study supports the idea that woody debris can sustain chemosynthetic symbioses over short time-scale in tropical shallow waters.
ISSN: 0141-1136

hal-01545913
https://hal.archives-ouvertes.fr/hal-01545913
DOI : 10.1016/j.marenvres.2013.03.007

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Cold seeps have recently been discovered in the Nile deep-sea fan (Eastern Mediterranean), and data regarding associated fauna are still scarce. In this study, two bivalve species associated with carbonate crusts and reduced sediment are identified based on sequence analysis of their 18S and 28S rRNAencoding genes, and associated bacterial symbioses are investigated using 16S rRNA gene sequencing and microscopy-based approaches. The specimens are closely related to Myrtea spinifera and Thyasira flexuosa, two species previously documented at various depths from other regions but not yet reported from the Eastern Mediterranean. Both species harbour abundant gammaproteobacterial endosymbionts in specialized gill epithelial cells. The Myrtea-associated bacterium is closely related to lucinid symbionts from both deep-sea and coastal species, whereas the Thyasira-associated bacterium is closely related to the symbiont of a T. flexuosa from coastal waters off the U.K. An epsilonproteobacterial sequence has also been identified in Thyasira which could correspond to a helicoid-shaped morphotype observed by electron microscopy, but this was not confirmed using fluorescent in situ hybridization. Virus-like particles were observed within some symbionts in Thyasira, mostly in bacteriocytes localized close to the ciliated zone of the gill filament. Overall, results indicate that very close relatives of shallow species M. spinifera and T. flexuosa occur at cold seeps in the Eastern Mediterranean and harbour chemoautotrophic symbioses similar to those found in their coastal relatives.
ISSN: 0173-9565

hal-00743765
https://hal.univ-antilles.fr/hal-00743765
DOI : 10.1111/j.1439-0485.2010.00413.x

Éditeur(s) : HAL CCSD Information Science Reference
Evolving Application Domains of Data Warehousing and Mining: Trends and Solutions

hal-00468097
https://hal.archives-ouvertes.fr/hal-00468097

Éditeur(s) : HAL CCSD
Résumé : International audience
The 20th Caribbean Academy of Sciences Biennal Meeting was held in Guadeloupe, FWI, on November 24 th to 26 th, 2016. It has gathered over 130 participants from more than 14 countries within or outside the Caribbean. In this booklet, you may find all abstracts form the scientific sessions, and the desciption of two round tables and three symposiums. Sessions were as followed :- Poster session- Mathematics and Informatics- Science Education- Physics of the Athmosphere- Medical Sciences (1)- Interface and Material Physics- Radiochemistry and Nuclear Medicine and Biomolecules- Interdisciplinary Oral Session- Biology- Hydrology and Hydrodynamics- Material and Environmental Chemistry- Medical Sciences (2)
https://hal.univ-antilles.fr/hal-01413318
Dehaies, Guadeloupe

hal-01413318
https://hal.univ-antilles.fr/hal-01413318
https://hal.univ-antilles.fr/hal-01413318v2/document
https://hal.univ-antilles.fr/hal-01413318/file/CAS_2016_Booklet.pdf

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
PurposeMarine mangrove sediments in the Manche-à-Eau lagoon (Guadeloupe, Caribbean Sea) harbor locally extensive, white microbial mats. These mats cover the surface of reduced sediments near the roots of red mangrove trees, Rhizophora mangle, and are mainly composed of sulfur-oxidizing bacteria belonging to the Beggiatoaceae family, with some filamentous cyanobacteria. The goal of this study was to investigate the possible influence of sediment characteristics on the presence of these microbial mats.Materials and methodsFour push cores were collected in April 2013, two from zones with microbial mats and two from zones without mats. Sediment characteristics (grain-size distribution, mineralogy, total organic carbon (TOC) and total nitrogen (TN) contents, atomic TOC/TN ratios, and organic matter (OM) δ13C values) were compared for all four cores.Results and discussionSignificant differences were observed between sediments below microbial mats and those without mats. Sediments with microbial mats contained greater amounts of clay, and higher TOC, TN, and TOC/TN ratios, with lower total carbonate content and δ13C values. The higher clay content most likely results from lower fluid flow velocity near to mangrove roots, while higher TOC/TN ratios and lower δ13C values indicate higher inputs of OM from mangrove trees. These results are consistent with the fact that microbial mats were observed near the roots of mangrove trees, which trap OM from terrestrial vegetation and fine sediments.ConclusionsThe grain-size distribution of sediment particles, the total carbonate content, and the δ13C values are the main parameters discriminating between zones with microbial mats and those without mats. Variations in total carbonate content, which is mainly of biogenic origin, result from conditions that are more favorable for benthic organisms in zones without microbial mats. Variations of the TOC/TN ratios are controlled by the presence of a non-negligible amount of inorganic nitrogen bound to surface clay mineral particles and/or by microbial processes.
ISSN: 1439-0108

hal-01545903
https://hal.archives-ouvertes.fr/hal-01545903
DOI : 10.1007/s11368-016-1555-6