Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Numerous field studies highlighted the capacities of marine sponges to bioaccumulate trace elements and assessed their potential as biomonitors of the marine environment. Experimental works demonstrated that dissolved metals and radionuclides can be taken up directly by sponge tissues but, to the best of our knowledge, little is known on the contribution of the dietary pathway through the consumption of contaminated bacteria considered as one of the trophic source in sponge diet. Objectives of this work are to study trophic transfer of radiotracers 110mAg, 241Am, 109Cd, 57Co, 134Cs, 54Mn and 65Zn from the marine bacteria Pseudomonas stutzeri to the Mediterranean sponges Aplysina cavernicola and Ircinia oros. P. stutzeri efficiently bioaccumulated trace elements in our culture experimental conditions with CF comprised between 105 and 107 after 48 hours of growth in radiolabeled medium. When fed with these radiolabelled bacteria, A. cavernicola took up around 60% of radiotracers accumulated in trophic source except 134Cs for which only 8% has been transferred from bacteria to sponge. Contrasting to this, I. oros retained only 7% of 110mAg, 109Cd and 65Zn counted in bacteria, but retained 2-fold longer accumulated metals in its tissues. The sponge inter-specific differences of accumulation and depuration following a trophic exposure are discussed with respect to the structure and the clearance capacities of each species.
ISSN: 0045-6535

hal-01217273
https://hal.archives-ouvertes.fr/hal-01217273
https://hal.archives-ouvertes.fr/hal-01217273/document
https://hal.archives-ouvertes.fr/hal-01217273/file/Pub%20Bacteria%20CHEM_HAL.pdf
DOI : 10.1016/j.chemosphere.2015.10.046

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Symbioses with the dinoflagellate Symbiodinium are widespread among marine invertebrates and protists, especially in nutritionally demanding habitats, such as tropical coral reefs, where they play a major role in ecosystem survival. Moreover, apart from corals and sea anemones, many of the Symbiodinium species and clades involved in these partnerships remain to be characterized. This study provides new insights into nudibranch and sponge associations with Symbiodinium by sequencing regions of the Symbiodinium 28S rDNA and the host mitochondrial COI oxidase. Specimens were sampled between 2011 and 2013 from locations around the islands of Moorea and Tahiti, French Polynesia. Our results revealed that some of the sponges and nudibranchs harbored typical Symbiodinium from clade B or C while others harbored new, undescribed Symbiodinium-like dinoflagellates. A detailed analysis of the different life stages of the nudibranch Phestilla lugubris and of its specific coral prey, Porites rus, suggests a prey-predator horizontal transfer of the symbiont and its vertical inheritance from the parent to the eggs.
Les symbioses à zooxanthelles, dinoflagellés du genre Symbiodinium, sont largement répandues chez les invertébrés marins et les protozoaires, notamment dans les eaux oligotrophes, où ils jouent un rôle important dans la survie des récifs coralliens. De plus, excepté chez les coraux et les anémones, les différentes espèces et clades de Symbiodinium impliqués dans ces associations restent à être caractérisés. Notre étude, grâce à l’utilisation des marqueurs génétiques 28S ADNr des Symbiodinium et la sous-unité 1 de la cytochrome oxydase mitochondriale (COI) de l’hôte, procure de nouvelles données quant aux associations des éponges et des nudibranches avec les Symbiodinium. L’échantillonnage a eu lieu autour de Moorea et de Tahiti (Polynésie française), entre 2011 et 2013. Nos résultats révèlent que certaines espèces d’éponges et de nudibranches possèdent les clades B et C communément retrouvés, chez les coraux notamment, alors que d’autres présentent de nouveaux dinoflagellés « Symbiodinium-like ». Une analyses détaillée des Symbiodinium à différents stades du cycle de vie du nudibranche corallivore Phestilla lugubris et de son corail hôte Porites rus suggèrent l’existence d’un transfert horizontal de Symbiodinium proie–prédateur et un transfert vertical du parent P. lugubris à ses œufs.
ISSN: 1631-0691

hal-01145518
https://hal.archives-ouvertes.fr/hal-01145518
DOI : 10.1016/j.crvi.2015.01.005

Éditeur(s) : Springer
Résumé : Because of their characteristic living environments, marine organisms produce a variety of lipids. Fatty acids constitute the essential part of triglycerides and wax esters, which are the major components of fats and oils. Nevertheless, phospholipids and glycolipids have considerable importance and will be taken into account, especially the latter compounds that excite increasing interest regarding their promising biological activities. Thus, in addition to the major polyunsaturated fatty acids (PUFA) such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, a great number of various fatty acids occur in marine organisms, e.g. saturated, mono- and diunsaturated, branched, halogenated, hydroxylated, methoxylated, non-methylene-interrupted. Various unprecedented chemical structures of fatty acids, and lipid-containing fatty acids, have recently been discovered, especially from the most primitive animals such as sponges and gorgonians. This review of marine lipidology deals with recent advances in the field of fatty acids since the end of the 1990s. Different approaches will be followed, mainly developing biomarkers of trophic chains in marine ecosystems and of chemotaxonomic interest, reporting new structures, especially those with biological activities or biosynthetic interest. An important part of this review will be devoted to the major PUFA, their relevance to health and nutrition, their biosynthesis, their sources (usual and promising) and market.
Marine Biotechnology I (0724-6145) (Springer), 2005 , Vol. 96 , P. 49-125

Droits : 2005 Springer-Verlag
http://archimer.ifremer.fr/doc/2005/publication-937.pdf
DOI:10.1007/b135782
http://archimer.ifremer.fr/doc/00000/937/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Sponges are a rich source for investigation of bioactive small molecules. They have been mostly investigated for the search of new pharmacological models or therapeutic agents for the treatment of human diseases. Micro-organisms can also represent a virulent pathogen for marine invertebrates such as sponges, which need to protect themselves against these microbes. Sponges' self defence mechanisms involving dialogue molecules thus represent a pertinent research track for potent anti-infective and anti-biofilm activities such as quorum sensing inhibitors (QSIs). The investigation of the QSI crude extract of Leucetta chagosensis Dendy, 1863 led to the isolation of three new alkaloids, isonaamine D, di-isonaamidine A and leucettamine D, along with the known isonaamine A and isonaamidine A. Isonaamidine A and isonaamine D were identified as inhibitors of the three quorum sensing pathways of Vibrio harveyi (CAI-1, AI-2 and harveyi auto inducer), but isonaamidine A displayed the strongest activity on AI-2 biosensor. Both compounds are new examples of natural QSIs of V. harveyi. These results outline the importance of these secondary metabolites for their producing organisms themselves in their natural environment, as well as the potential of the marine resource for aquaculture needs.
ISSN: 0266-8254

hal-01684926
https://hal.archives-ouvertes.fr/hal-01684926
DOI : 10.1111/lam.12461
PUBMED : 26138555

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
To forecast marine disease outbreaks as oceans warm requires new environmental surveillance tools. We describe an iterative process for developing these tools that combines research, development and deployment for suitable systems. The first step is to identify candidate host–pathogen systems. The 24 candidate systems we identified include sponges, corals, oysters, crustaceans, sea stars, fishes and sea grasses (among others). To illustrate the other steps, we present a case study of epizootic shell disease (ESD) in the American lobster. Increasing prevalence of ESD is a contributing factor to lobster fishery collapse in southern New England (SNE), raising concerns that disease prevalence will increase in the northern Gulf of Maine under climate change. The lowest maximum bottom temperature associated with ESD prevalence in SNE is 128C. Our seasonal outlook for 2015 and long-term projections show bottom temperatures greater than or equal to 128C may occur in this and coming years in the coastal bays of Maine. The tools presented will allow managers to target efforts to monitor the effects of ESD on fishery sustainability and will be iteratively refined. The approach and case example highlight that temperature-based surveillance tools can inform research, monitoring and management of emerging and continuing marine disease threats.
ISSN: 0080-4622

Droits : http://creativecommons.org/licenses/by/
hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/file/20150208.full.pdf
DOI : 10.1098/rstb.2015.0208

Résumé : Les mattes de procaryotes constituent une niche écologique diversifiée. peu étudié!<..en mangrove et jamais décrjte dans les Antilles. L'objectif de cette thèse est de décrire les procaryotes filamenteux reposant sur le sédiment marin et de caractériser les interactions entre la matte, milieu et entre les différents micro-organismes. Nous avons d'abord caractérisé les micro-organismes majoritaires de la matte par le séquençage de l'ADNr 16S et des hybridations moléculaires (FISH). Il a ainsi été possible de décrire deux nouvelles espèces de Beggiatoaceae dont la structure a été étudiée par microscopie électronique. De plus, afin de caractériser l'environnement chimique de ces bactéries, des capteurs potentiométriques ont été utilisés. Ils ont permis de démontrer que les Beggiaotaceae oxydaient les sulfures en prélevant l'oxygène du milieu, tandis que des analyses de microscopie couplées à de l'EDX ont mis en évidence des réserves de soufre intracellulaires dans ces bactéries. Le séquençage de l'ADNr 16S des cyanobactéries filamenteuses a mis en évidence quatre nouvelles espèces de l'ord~e des Oscillatoriales. Deux d'entre elles, du genre Planktothricoides ont révélé une toxicité positive sur les Artemia sp:, les deux autres ont été identifiées comme proches d'Oscillatoria spongeliae, une espèce symbiotique d'éponge, bien que les coupes uItrafines d'une de ces souches aient montré une morphologie interne proche des Tychonema. L'analyse des données a permis d'étoffer les connaissances sur les communautés microbiennes de mangrove et constitue une base intéressante de travail sur la contribution des micro-organismes au fonctionnement de l'écosystème mangrove dans son ensemble
Procaryotic mats are ecological niches, occuring in many ecosystems. Those structures are little studied in marine mangrove sediment and have never been described in West Indies. The purpose ofthis thesis is to characterize the interactions between the mat and the environment, and between the different filamentous micro-organisms living into the mat. In a first place, we characterized the mainly micro-organisrns of the mat by sequencing 16S rDNA. We confirmed these sequences by molecular hybridization (FISH) with specific probes designed from sequences obtained. Thus, it was possible to describe two new Beggiatoaceae strains, whose structure has been studied by electronic microscopy. Furthemore, we used potentiometric captors in situ and in laboratory, by creating a mesocosm, in order to define the chemical environment where involved these bacteria. These experiences proved that the Beggiatoaceae of the mat oxidized the sulfur taking the oxygen from the medium, while the microscopic analysis coupled with EDX showed intracellular sulfur granules into the bacteria. The study of the filamentous cyanobacteria of the mat highlighted four new cyanobacteria strains, all studied by electronic rmcroscopy. Two of them belongs to Planktothrlcoides genus and showed positive toxicity on Artemia salina. The others species are close to Oscillatorla spongeliae, a sponge symbiont, nevertheless, one ofthem showed an intemal morphology close to Tychonema. The analysis of the different results adduces sorne knowledge about mangrove microbial communities. Furthermore, this study can be used as an interesting base to study the micro-organisms contribution in functioning mangrove ecosystem

http://www.theses.fr/2013AGUY0614/document

Éditeur(s) : HAL CCSD Elsevier
Résumé : 00000 ăWOS:000386415300011
International audience
Highly biologically active marine sesquiterpene ilimaquinone was selected for chemical modifications. Its biotransformation was investigated using a combinatorial approach as an original way to screen different strains of microorganisms. Mucor circinelloides ATCC 8541 was able to structurally modify ilimaquinone into three different compounds. A stereospecific epoxidation was observed and compared to chemical epoxidation. A hydroxylation of the decalin ring was also observed as well as an unexpected substitution on the quinone ring by ethanolamine. Compounds were evaluated against several cell lines. (C) 2016 Elsevier Ltd. All rights reserved.
ISSN: 0040-4039

hal-01483185
https://hal.archives-ouvertes.fr/hal-01483185
DOI : 10.1016/j.tetlet.2016.09.075

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
Chemical mediation regulates behavioral interactions between species and thus affects population structure,community organization and ecosystem function. Among marine taxa that have developed chemicalmediation strategies, gastropods belong to a diverse group of molluscs found worldwide, including specieswith a coiled, reduced or absent shell. Most gastropods use natural products to mediate a wide range ofbehaviors such as defense, prey location or interactions with con- and hetero-geners. Their chemicallydefended diet, such as cyanobacteria, algae, sponges, bryozoans and tunicates, provides them witha considerable opportunity either as shelter from predators, or as a means to enhance their own chemicaldefense. In addition to improving their defenses, molluscs also use prey secondary metabolites in complexchemical communication including settlement induction, prey detection and feeding preferences. Theassimilation of prey secondary metabolites further provides the opportunity for interactions withconspecifics via diet-derived chemical cues or signals. This review intends to provide an overview on thesequestration, detoxification, and biotransformation of diet-derived natural products, as well as the role ofthese compounds as chemical mediators in gastropod-prey interactions.
ISSN: 0265-0568

hal-01563402
https://hal-univ-perp.archives-ouvertes.fr/hal-01563402
DOI : 10.1039/c6np00097e

Éditeur(s) : HAL CCSD American Chemical Society
Résumé : International audience
Four bicyclic and three pentacyclic guanidine alkaloids (1–7) were isolated from a French Polynesian Monanchora n. sp. sponge, along with the known alkaloids monalidine A (8), enantiomers 9–11 of known natural product crambescins, and the known crambescidins 12–15. Structures were assigned by spectroscopic data interpretation. The relative and absolute configurations of the alkaloids were established by analysis of 1H NMR and NOESY spectra and by circular dichroism analysis. The new norcrambescidic acid (7) corresponds to interesting biosynthetic variation within the pentacyclic core. All compounds exhibited antiproliferative and cytotoxic efficacy against KB, HCT116, HL60, MRC5, and B16F10 cancer cells, with IC50 values ranging from 4 nM to 10 μM.
ISSN: 0163-3864

hal-01584556
https://hal.archives-ouvertes.fr/hal-01584556
DOI : 10.1021/acs.jnatprod.6b00168

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Archaea may be involved in global energy cycles, and are known for their ability to interact with eukaryotic species (sponges, corals and ascidians) or as archaeal-bacterial consortia. The recently proposed phylum Thaumarchaeota may represent the deepest branching lineage in the archaeal phylogeny emerging before the divergence between Euryarchaeota and Crenarchaeota. Here we report the first characterization of two marine thaumarchaeal species from shallow waters that consist of multiple giant cells. One species is coated with sulfur-oxidizing g-Proteobacteria. These new uncultured thaumarchaeal species are able to live in the sulfide-rich environments of a tropical mangrove swamp, either on living tissues such as roots or on various kinds of materials such as stones, sunken woods, etc. These archaea and archaea/bacteria associations have been studied using light microscopy, transmission electron microscopy and scanning electron microscopy. Species identification of archaeons and the putative bacterial symbiont have been assessed by 16S small subunit ribosomal RNA analysis. The sulfur-oxidizing ability of the bacteria has been assessed by genetic investigation on alpha-subunit of the adenosine-5_- phosphosulfate reductase/oxidase's (AprA). Species identifications have been confirmed by fluorescence in situ hybridization using specific probes designed in this study. In this article, we describe two new giant archaeal species that form the biggest archaeal filaments ever observed. One of these species is covered by a specific biofilm of sulfur-oxidizing g-Proteobacteria. This study highlights an unexpected morphological and genetic diversity of the phylum Thaumarchaeota.
ISSN: 1462-2912

hal-00715219
https://hal.univ-antilles.fr/hal-00715219
DOI : 10.1111/j.1462-2920.2010.02309.x