Éditeur(s) : Université des Antilles AREBio Groupe de recherche BIOSPHERES : BIOlogie, Sciences Physiques & Humaines pour les énergies Renouvelables, l
Extrait de : 1er colloque international BIOSPHERES, du 18 au 20 juin 2019. Université des Antilles
Description : Antarctica is a continent of enigmas. Stunning geographic beauty belies its inhospitable climate. Covered a mile thick in ice, it is the world's largest desert. Fossil ferns found in its mountains speak of its prehistory as a tropical rainforest, but now is largely devoid of life. Its most famous inhabitant, the penguin, is thought of as a flightless bird, but soars underwater much as a falcon glides the sky. Perhaps one of the greatest enigmas is the contrast between the terrestrial and marine environments. On land, monochromatic snow and ice support little life, yet the sea teams with life, life that expresses itself with the full rainbow of colors. Color is but one manifestation of chemical ecology. The Antarctic benthos supports an extensive community of predators and prey, competitors and facilitators. A harsh geographic history has contributed to marine diversification and enhanced what we now recognize as a rich flora and fauna, commensurate in some instances with temperate kelp forests and even approaching the richness of tropical marine environments. Not surprisingly, Antarctic benthic ecology is highly dependent on chemical mediation of interspecific interactions, interweaving chemodiversity with biodiversity in a classical yin and yang feedback loop. The evolution of selective chemical defenses facilitates drug discovery research, producing suites of metabolites that inform structure-activity studies and add breadth to bioactivity profiles. This presentation will focus on recent and contextual research from our lab which has demonstrated the potential for new biomedical lead molecules and scaffolds from these difficult to access biological resources.

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V19067
V19067

Éditeur(s) : EDP Sciences
Résumé : The WFD monitoring requirements for surface waters were adapted to the coastal area with the selection of the relevant parameters to qualify the maritime ecosystems, with appropriate strategies of sampling. Ifremer and Cemagref for the fish indicator in the estuarine waters, are in charge of the elaboration of the monitoring programme in coastal waters (surveillance monitoring and operational monitoring). Ifremer has elaborated technical recommendations for the monitoring of the biological (benthic and phytoplanctonic) and chemical elements, according to many years of observations by the french monitoring networks (RNO, Rephy, Rinbio, RSL, Rebent). These recommendations were established within experts groups They clarify the parameters, the analytical methods, and the strategies of sampling for the classification of the water bodies in five ecological classes and two chemical classes. The work on the relevant indicators of the ecological status still goes on, in relation with the 2006 european intercalibration exercise. Available data and future data will be used in order to set the borders between the classes of high, good, and moderate status, before the monitoring programme starts. Data sets have to be completed to set the borders and to assess the ecological status of water bodies.
Houille Blanche - Revue internationale de l'eau (0018-6368) (EDP Sciences), 2006-07 , N. 4 , P. 68-74

Droits : © Société Hydrotechnique de France 2006
http://archimer.ifremer.fr/doc/2006/publication-3530.pdf
DOI:10.1051/lhb:200604011
http://archimer.ifremer.fr/doc/00000/3530/

Éditeur(s) : Publ. CNEXO (France) (Actes Colloq.)(no. 14)
Résumé : The basic principles of chemical ecology and chemoreception will be discussed and examples given of compounds known to possess biological activity, particularly in the control of feeding behaviour. Many hundreds of marine natural products have been isolated and characterized, but in only a few instances have their biological or ecological roles been determined. Conversely, a wide variety of chemically mediated behavioural responses have been described where the chemical mediator remains unidentified.
On considère les principes de l'écologie chimique et de la chemoréception et on donne des exemples de substances composées qui possèdent des activités biologiques, surtout dans le contrôle de l'alimentation. On a isolé et caracterisé beaucoup de produits naturels marins, mais on n'a déterminé qu'en peu de cas leurs rôles biologiques ou écologiques. D'autre part, on a décrit un assortiment de réactions produites chimiquement dans lesquelles le médiateur chimique ne s'est pas identifié.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1981/publication-5958.pdf
http://archimer.ifremer.fr/doc/00000/5958/

Éditeur(s) : Inter-research
Résumé : Chemical tracers (e. g. stable isotopes or trace metals) are increasingly used to study trophic ecology and feeding habits of marine organisms and various factors can affect their values. The aim of the present study was to provide information on ontogenic effects on stable carbon and nitrogen values (delta C-13 and delta N-15) and on cadmium (Cd) and mercury (Hg) concentrations in 5 cephalopod species from the Bay of Biscay (North-East Atlantic Ocean). To this end, individuals belonging to 3 species showing the widest range of sizes were analysed for muscle delta C-13 and delta N-15 values and muscle Hg, and digestive gland Cd concentrations. Results showed that stable isotope ratios allowed discrimination of specific feeding strategies during ontogenesis. Segregation between 5 cephalopod species in terms of trophic ecology was also evidenced (different isotopic niches). In contrast, Hg concentrations varied over the same order of magnitude in these 5 cephalopod species, despite higher levels in the benthic octopus Eledone cirrhosa. Consistently, Hg concentrations followed the same ontogenic pattern and increased with increasing body size/age of cephalopods. Finally, Cd concentrations varied over 3 orders of magnitude among the 5 species. Despite possible effects of physiology in terms of metal bioaccumulation, Cd concentrations were likely to reflect specific feeding preferences or feeding zones and ontogenic variability within a single species. Thus, ontogenic effects have to be taken into account when stable isotope ratios of carbon and nitrogen or trace metals are used as ecological tracers; the best recommendation being to focus on a given class age.
Marine Ecology Progress Series (0171-8630) (Inter-research), 2011 , Vol. 433 , P. 107-120

Droits : Inter-Research 2011 · www.int-res.com
http://archimer.ifremer.fr/doc/00166/27761/25938.pdf
DOI:10.3354/meps09159
http://archimer.ifremer.fr/doc/00166/27761/

Éditeur(s) : HAL CCSD Springer International Publishing
Résumé : The intensive farming practices that have been developed over the past 60 years are based mainly on the use of chemical inputs such as fertilisers and pesticides, mechanical tillage and monoculture. The limitations of these methods are now clear: long-term degradation of soil fertility, impacts on the environment and human health, high consumption of fossil fuels, low efficiency of inputs and threats to food security in a context of climate change. Would farming practices that rely on the activation of ecological processes be an alternative to achieve a balance between high productivity and environmental preservation? While many studies suggest a positive relationship between soil biodiversity and ecosystem services, there is considerable debate on the form such agricultural systems should take. This study reviewed the state of current knowledge and identified aspects requiring further research to achieve the aim of sustainable intensification of agriculture. The following major points emerged: 1) Most studies focused on the evaluation of individual practices. However, changes in farmers’ cropping practices to take advantage of soil biodiversity services would need to manage not only the interactions between various practices but also the trade-off between the technical and socio economic constraints of cropping systems. Advances in agricultural system design approaches may help to ensure appropriate trade-offs. 2) More attention should be given to drawing on knowledge from different sources: laboratory studies focusing on the ecological functions of soil biodiversity, experimental surveys on farmers’ fields to rank the farming practices and processes to be included in site-specific models, and on- station experiments to test hypotheses and acquire additional reference material. 3) Whereas advances in technical and scientific knowledge provide an increasing number of relevant indicators for characterizing biodiversity and ecological functions, studies are rarely targeted at the development of indicators that are accessible to farmers or their technical advisors. The lack of indicators accessible to grassroots players for evaluating the impacts of their decisions on soil biodiversity remains a serious obstacle to the development of innovative agro-ecological systems.
Sustainable Agriculture Reviews 14

ISBN : 978-3-319-06015-6
hal-01268743
https://hal.archives-ouvertes.fr/hal-01268743
DOI : 10.1007/978-3-319-06016-3_5
PRODINRA : 270786

Éditeur(s) : HAL CCSD John Libbey Eurotext
Résumé : International audience
The diversity of chemicals used in hospitals (detergents-disinfectants, alcohol-based hand sanitizers, drugs, etc.) and recent developments in indoor air quality regulation of public access buildings require a better understanding of chemical risks in this particular environment. We developed a methodology for semi-quantitative chemical risk assessments in this environment to prioritize inhalation risks by sector and chemical. This methodology is based on a similar approach in the workplace that defines classes of exposures and of hazards. Their combination produces a risk matrix. Four criteria were used to determine the exposure classes: quantity and frequency of the chemical's use, volatility (vapor pressure), and the type of collective protective equipment associated with each area. The hazard class is also derived from four criteria: classification as carcinogenic, mutagenic, or toxic to reproduction, the existence of a toxicity reference value, occupational exposure limit values, and risk phrases (official risk descriptions, on labels, data sheets, etc). This methodology was tested in the Rennes University Hospital (Rennes, France) in five different hospital areas, with a specific survey undertaken to collect data about chemicals in each area. The results show the spatial specificity of chemical risks. Among the various sites analysed, the chemical risks of two require priority attention: the parasitology-mycology laboratory and patients' rooms. Because of their wide use in the hospital and the volatility of some of their components (alcohols), detergents-disinfectants contribute to increasing risk levels in all areas. The model is therefore discriminatory in terms of areas and substances.
ISSN: 1635-0421

hal-00952349
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00952349
DOI : 10.1684/ers.2013.0659

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The easy-to-use in vivo model, zebrafish larva, is being increasingly used to screen chemical-induced hepatotoxicity, with a good predictivity for various mechanisms of liver injury. However, nothing is known about its applicability in exploring the mechanism called membrane remodeling, depicted as changes in membrane fluidity or lipid raft properties. The aim of this study was, therefore, to substantiate the zebrafish larva as a suitable in vivo model in this context. Ethanol was chosen as a prototype toxicant because it is largely described, both in hepatocyte cultures and in rodents, as capable of inducing a membrane remodeling leading to hepatocyte death and liver injury. The zebrafish larva model was demonstrated to be fully relevant as membrane remodeling was maintained even after a 1-week exposure without any adaptation as usually reported in rodents and hepatocyte cultures. It was also proven to exhibit a high sensitivity as it discriminated various levels of cytotoxicity depending on the extent of changes in membrane remodeling. In this context, its sensitivity appeared higher than that of WIF-B9 hepatic cells, which is suited for analyzing this kind of hepatotoxicity. Finally, the protection afforded by a membrane stabilizer, ursodeoxycholic acid (UDCA), or by a lipid raft disrupter, pravastatin, definitely validated zebrafish larva as a reliable model to quickly assess membrane remodeling involvement in chemical-induced hepatotoxicity. In conclusion, this model, compatible with a high throughput screening, might be adapted to seek hepatotoxicants via membrane remodeling, and also drugs targeting membrane features to propose new preventive or therapeutic strategies in chemical-induced liver diseases.
ISSN: 0260-437X

hal-01526425
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01526425
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01526425/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01526425/file/Zebrafish%20larva%20as%20a%20reliable%20model-Podechard%20JAT%202016%20revised.pdf
DOI : 10.1002/jat.3421

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: The insecticide chlordecone was extensively used in the French West Indies to control banana root borer. Its persistence in soils has led to the widespread pollution of the environment, and human beings are still exposed to this chemical. Chlordecone has been shown to impair neurological and behavioural functions in rodents when exposed gestationally or neonatally. OBJECTIVES: The aim of the study was to evaluate the impact of prenatal and postnatal exposure to chlordecone on the cognitive, visual, and motor development of 7-month-old infants from Guadeloupe. METHODS: Infants were tested at 7 months (n=153). Visual recognition memory and processing speed were assessed with the Fagan Tests of Infant Intelligence (FTII), visual acuity with the Teller Acuity Card, and fine motor development with the Brunet-Lezine. Samples of cord blood and breast milk at 3 months (n=88) were analyzed for chlordecone concentrations. Postnatal exposure was determined through breast feeding and frequency of contaminated food consumption by the infants. RESULTS: Cord chlordecone concentrations in tertiles were associated with reduced novelty preference on the FTII in the highly exposed group (β=-0.19, p=0.02). Postnatal exposure through contaminated food consumption was marginally related to reduced novelty preference (β=-0.14, p=0.07), and longer processing speed (β=0.16, p=0.07). Detectable levels of chlordecone in cord blood were associated with higher risk of obtaining low scores on the fine motor development scale (OR=1.25, p<0.01). CONCLUSION: These results suggest that pre- and postnatal low chronic exposure to chlordecone is associated with negative effects on cognitive and motor development during infancy.
ISSN: 0013-9351

hal-00875939
https://hal.archives-ouvertes.fr/hal-00875939
DOI : 10.1016/j.envres.2012.07.006
PUBMED : 22910562

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 Ecological Society of America
Résumé : Reliable assessment of fish origin is of critical importance for exploited species, since nursery areas must be identified and protected to maintain recruitment to the adult stock. During the last two decades, otolith chemical signatures (or "fingerprints") have been increasingly used as tools to discriminate between coastal habitats. However, correct assessment of fish origin from otolith fingerprints depends on various environmental and methodological parameters, including the choice of the statistical method used to assign fish to unknown origin. Among the available methods of classification, Linear Discriminant Analysis (LDA) is the most frequently used, although it assumes data are multivariate normal with homogeneous within-group dispersions, conditions that are not always met by otolith chemical data, even after transformation. Other less constrained classification methods are available, but there is a current lack of comparative analysis in applications to otolith microchemistry. Here, we assessed stock identification accuracy for four classification methods (LDA, Quadratic Discriminant Analysis [QDA], Random Forests [RF], and Artificial Neural Networks [ANN]), through the use of three distinct data sets. In each case, all possible combinations of chemical elements were examined to identify the elements to be used for optimal accuracy in fish assignment to their actual origin. Our study shows that accuracy differs according to the model and the number of elements considered. Best combinations did not include all the elements measured, and it was not possible to define an ad hoc multielement combination for accurate site discrimination. Among all the models tested, RF and ANN performed best, especially for complex data sets (e. g., with numerous fish species and/or chemical elements involved). However, for these data, RF was less time-consuming and more interpretable than ANN, and far more efficient and less demanding in terms of assumptions than LDA or QDA. Therefore, when LDA and QDA assumptions cannot be reached, the use of machine learning methods, such as RF, should be preferred for stock assessment and nursery identification based on otolith microchemistry, especially when data set include multispecific otolith signatures and/or many chemical elements.
ISSN: 1051-0761

hal-00644549
https://hal.archives-ouvertes.fr/hal-00644549
DOI : 10.1890/09-1887.1

Éditeur(s) : HAL CCSD
Résumé : International audience
Background Chlordecone is a persistent organochlorine insecticide with well-defined estrogenic properties. It was intensively used in the French West Indies until 1993 to control the banana root borer. Because of the long-term contamination of soils and water, the population is currently exposed to chlordecone through food consumption. Chlordecone has been found in the blood of pregnant women and in cord blood. It has been shown to be an endocrine-disrupting chemical and exposure during pregnancy may affect fetal growth. Objectives The objective of our study was to examine the association between prenatal exposure to chlordecone and fetal growth based on the TIMOUN birth cohort conducted in Guadeloupe, with a focus on the potential modification of this relationship by maternal body mass index (BMI) and gestational weight gain (GWG). Methods Chlordecone was determined in cord plasma at birth in 593 babies. Birth weight was the indicator of fetal growth. Maternal pre-pregnancy BMI and GWG were determined. Adherence to GWG recommendations of the US Institute of Medicine based on maternal pre-pregnancy BMI was assessed. Birth weight was analyzed relative to cord blood chlordecone levels using linear and non-linear regression models. Results Overall chlordecone in cord blood was not associated with birth weight, but we found an interaction between chlordecone exposure with GWG and adherence to GWG recommendations. After stratification by GWG, we found a significant U-shaped association between birth weight and chlordecone exposure, within the upper quartiles of GWG or excessive GWG. Conclusion Chlordecone exposure may affect fetal growth, particularly when excessive GWG is present. © 2016 Elsevier Inc.
Environmental Research

hal-01367154
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01367154
DOI : 10.1016/j.envres.2016.08.004
PUBMED : 27560981

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Pyrethroids are widely-used chemical insecticides, to which humans are commonly exposed, and known to alter functional expression of drug metabolizing enzymes. Limited data have additionally suggested that drug transporters, that constitute key-actors of the drug detoxification system, may also be targeted by pyrethroids. The present study was therefore designed to analyze the potential regulatory effects of these pesticides towards activities of main ATP-binding cassette (ABC) and solute carrier (SLC) drug transporters, using transporter-overexpressing cells. The pyrethroids allethrin and tetramethrin were found to inhibit various ABC and SLC drug transporters, including multidrug resistance-associated protein (MRP) 2, breast cancer resistance protein (BCRP), organic anion transporter polypeptide (OATP) 1B1, organic anion transporter (OAT) 3, multidrug and toxin extrusion transporter (MATE) 1, organic cation transporter (OCT) 1 and OCT2, with IC50 values however ranging from 2.6 muM (OCT1 inhibition by allethrin) to 77.6 muM (OAT3 inhibition by tetramethrin) and thus much higher than pyrethroid concentrations (in the nM range) reached in environmentally pyrethroid-exposed humans. By contrast, allethrin and tetramethrin cis-stimulated OATP2B1 activity and failed to alter activities of OATP1B3, OAT1 and MATE2-K, whereas P-glycoprotein activity was additionally moderately inhibited. Twelve other pyrethoids used at 100 muM did not block activities of the various investigated transporters, or only moderately inhibited some of them (inhibition by less than 50%). In silico analysis of structure-activity relationships next revealed that molecular parameters, including molecular weight and lipophilicity, are associated with transporter inhibition by allethrin/tetramethrin and successfully predicted transporter inhibition by the pyrethroids imiprothrin and prallethrin. Taken together, these data fully demonstrated that two pyrethoids, i.e., allethrin and tetramethrin, can act as regulators of the activity of various ABC and SLC drug transporters, but only when used at high and non-relevant concentrations, making unlikely any contribution of these transporter activity alterations to pyrethroid toxicity in environmentally exposed humans.
ISSN: 1932-6203

hal-01477206
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01477206
DOI : 10.1371/journal.pone.0169480
PUBMED : 28099443

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 Maney Publishing
Résumé : International audience
The strict environmental legislations and increasing ecological awareness among scientists have led to the development of “green” alternatives to mitigate corrosion. In the present work, literature on green corrosion inhibitors has been reviewed, and the salient features of our work on green corrosion inhibitors have been highlighted. Among the studied leaves, extract Andrographis paniculata showed better inhibition performance (98%) than the other leaves extract. Strychnos nuxvomica showed better inhibition (98%) than the other seed extracts. Moringa oleifera is reflected as a good corrosion inhibitor of mild steel in 1 M HCl with 98% inhibition efficiency among the studied fruits extract. Bacopa monnieri showed its maximum inhibition performance to be 95% at 600 ppm among the investigated stem extracts. All the reported plant extracts were found to inhibit the corrosion of mild steel in acid media.
ISSN: 1478-422X

hal-01097106
https://hal-agroparistech.archives-ouvertes.fr/hal-01097106
DOI : 10.1016/j.corsci.2010.10.006

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This paper proposes a new approach for the on-site detection of micropollutants in water in case of accidental or intentional contamination (characterized by high concentration). The technique is based on the use of an automatic multiple solid phase extraction step (MSPE) followed by direct or indirect UV spectrometry (MSPE/UV) for the detection of organic contaminants in water (such as regulated molecules (pesticides ...) as well as emerging pollutants (pharmaceutical products, endocrine disruptors ...)). The development of the system supposes firstly the choice of the most appropriate sorbent(s) and secondly conditions for the detection of targeted micropollutants, from several solid phase extraction cartridges and eluting solvents. Two different extraction sorbents were chosen. These sorbents and several eluting solvents allow the first separation of the compounds based on the physico-chemical properties of each substance (pKa, log Kow) and on the specific interactions with the sorbent. Finally, a UV analysis (either at the maximum of absorbance using a calibration curve or from the whole spectrum using a multicomponent (deconvolution) exploitation method) of each fraction allows a determination and a quantification of each compound. The method is rapid (less than 2 h), sensitive enough for an accidental/intentional contamination (between 5 and 40 μg*L− 1 according to the substances) and with a good precision (between 4 and 14%).
ISSN: 0026-265X

hal-00878024
https://hal.archives-ouvertes.fr/hal-00878024
DOI : 10.1016/j.microc.2012.10.025

Éditeur(s) : HAL CCSD
Résumé : The ecological success of cnidarian-dinoflagellate symbiosis mainly relies on nutrient recycling. Environmental changes, such as global warming or pollution, often result to symbiosis breakdown, also called cnidarian bleaching. The understanding of mechanisms regulating the symbiosis establishment, maintenance and breakdown is essential to prevent massive bleaching phenomena. In this respect, my PhD project focused on the characterization of chemical mediators expressed in the sea anemone Anemonia viridis, their localization and their modulation by stress conditions. A comparative study was first conducted to characterize the chemical mediators and analyze their distribution within the symbiotic sea anemone. We described a great abundance and diversity of lipids in A. viridis tissues. From these results, we proposed possible transfers of FAs between the symbiotic partners. A thermal stress and a chemical stress have also been applied in laboratory-controlled conditions in order to induce symbiosis breakdown and bleaching of the sea anemones, in order to correlate A. viridis metabolome to its symbiotic status. A mapping of these metabolites has been performed by MALDI-MSI of tentacle cross-sections, as well as their evolution following stress. Some betaine lipids have thus been proposed as short-term indicators of stress. A. viridis stress response has also been evaluated with a lipidomic approach, and allowed to identify 3 lipid indicators of early stress response based on membrane fluidity markers. Overall, this study provides insight on key chemical mediators that may regulate the symbiosis maintenance, and may contribute to the symbiosis breakdown.
Le succès évolutif des Cnidaires symbiotiques réside en grande partie dans leurs échanges trophiques établis avec les Dinoflagellés du genre Symbiodinium. Cependant, le réchauffement climatique global ainsi que les pollutions ont un impact fort sur les écosystèmes coralliens, notamment en conduisant à la rupture de la symbiose, phénomène appelé blanchissement. La compréhension des mécanismes qui régissent l’établissement, le maintien et la rupture de la symbiose est essentielle à la prévention des épisodes de blanchissement massif. Dans ce contexte, les objectifs de mon projet de thèse sont de caractériser les médiateurs chimiques de l’anémone de mer Anemonia viridis, de les localiser, et d’analyser leur réponse face à un stress. Parmi les composés caractérisés, les lipides et les bétaïnes sont les plus abondants et présentent une grande diversité. Certains sont transférés des symbiotes vers l’hôte. Des anémones de mer ont ensuite été traitées en laboratoire afin de provoquer la rupture de la symbiose et le blanchissement des individus. Une étude cinétique a été menée par une approche globale comparative identique à celle réalisée sur l’anémone symbiotique. Par ailleurs, une cartographie de l’évolution de composés clé a été réalisée par MALDI-MSI. La réponse au stress a été évaluée et a permis d’identifier des lipides de bétaïne et trois indicateurs lipidiques comme marqueurs de réponse précoce au stress. L’ensemble de ces résultats apporte de nouveaux éléments de réponse concernant le rôle des médiateurs chimiques clés dans le maintien de la symbiose, ainsi que leur influence sur sa rupture.
https://tel.archives-ouvertes.fr/tel-01310668

NNT : 2015NICE4108
tel-01310668
https://tel.archives-ouvertes.fr/tel-01310668
https://tel.archives-ouvertes.fr/tel-01310668/document
https://tel.archives-ouvertes.fr/tel-01310668/file/2015NICE4108.pdf

Éditeur(s) : Elsevier
Résumé : The long-term BIOZAIRE multidisciplinary deep-sea environmental program on the West Equatorial African margin organized in partnership between Ifremer and TOTAL aimed at characterizing the benthic community structure in relation with physical and chemical processes in a region of oil and gas interest. The morphology of the deep Congo submarine channel and the sedimentological structures of the deep-sea fan were established during the geological ZAIANGO project and helped to select study sites ranging from 350 to 4800 m water depth inside or near the channel and away from its influence. Ifremer conducted eight deep-sea cruises on board research vessels between 2000 and 2005. Standardized methods of sampling together with new technologies such as the ROV Victor 6000 and its associated instrumentation were used to investigate this poorly known continental margin. In addition to the study of sedimentary environments more or less influenced by turbidity events, the discovery of one of the largest cold seeps near the Congo channel and deep coral reefs extends our knowledge of the different habitats of this margin. This paper presents the background, objectives and major results of the BIOZAIRE Program. It highlights the work achieved in the 16 papers in this special issue. This synthesis paper describes the knowledge acquired at a regional and local scale of the Equatorial East Atlantic margin, and tackles new interdisciplinary questions to be answered in the various domains of physics, chemistry, taxonomy and ecology to better understand the deep-sea environment in the Gulf of Guinea.
Deep Sea Research Part II: Topical Studies in Oceanography (0967-0645) (Elsevier), 2009-11 , Vol. 56 , N. 23 , P. 2156-2168

Droits : 2009 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-7349.pdf
DOI:10.1016/j.dsr2.2009.04.015
http://archimer.ifremer.fr/doc/00000/7349/

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Lateralization, i.e. the preferential use of one side of the body, may convey fitness benefits for organisms within rapidly-changing environments, by optimizing separate and parallel processing of different information between the two brain hemispheres. In coral reef-fishes, the movement of larvae from planktonic to reef environments (recruitment) represents a major life-history transition. This transition requires larvae to rapidly identify and respond to sensory cues to select a suitable habitat that facilitates survival and growth. This ‘recruitment’ is critical for population persistence and resilience. In aquarium experiments, larval Acanthurus triostegus preferentially used their right-eye to investigate a variety of visual stimuli. Despite this, when held in in situ cages with predators, those larvae that previously favored their left-eye exhibited higher survival. These results support the “brain’s right-hemisphere” theory, which predicts that the right-eye (i.e. left-hemisphere) is used to categorize stimuli while the left-eye (i.e. right-hemisphere) is used to inspect novel items and initiate rapid behavioral-responses. While these experiments confirm that being highly lateralized is ecologically advantageous, exposure to chlorpyrifos, a pesticide often inadvertently added to coral-reef waters, impaired visual-lateralization. This suggests that chemical pollutants could impair the brain function of larval fishes during a critical life-history transition, potentially impacting recruitment success.
ISSN: 2045-2322

Droits : http://creativecommons.org/licenses/by/
hal-01585550
http://hal.upmc.fr/hal-01585550
http://hal.upmc.fr/hal-01585550/document
http://hal.upmc.fr/hal-01585550/file/s41598-017-09381-0.pdf
DOI : 10.1038/s41598-017-09381-0

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The emerging orbicular batfish (Platax orbicularis) aquaculture is the most important fish aquacultureindustry in French Polynesia. However, bacterial infections are causing severe mortality episodes.Therefore, there is an urgent need to find an effective management solution. Besides the supplyingdifficulty and high costs of veterinary drugs in French Polynesia, batfish aquaculture takes place close tothe coral reef, where use of synthetic persistent drugs should be restricted. Medicinal plants andbioactive algae are emerging as a cheaper and more sustainable alternative to chemical drugs. We havestudied the effect of local Polynesian plants and the local opportunistic algae Asparagopsis taxiformis onbatfish when orally administered. Weight gain and expression of two immune-related genes (lysozyme ge Lys G and transforming growth factor beta - TGF-b1) were studied to analyze immunostimulant activityof plants on P. orbicularis. Results showed that several plants increased Lys G and TGF-b1 expressionon orbicular batfish after 2 and 3 weeks of oral administration. A. taxiformis was the plant displaying themost promising results, promoting a weight gain of 24% after 3 weeks of oral administration andsignificantly increasing the relative amount of both Lys G and TGF-b1 transcripts in kidney and spleen ofP. orbicularis.
ISSN: 1050-4648

hal-01381334
https://hal-univ-perp.archives-ouvertes.fr/hal-01381334
DOI : 10.1016/j.fsi.2016.09.011

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitatand surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisionswith chemical information being important for habitat selection at settlement. We explored the sensory worldof crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesti-cide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus)and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. Inthe presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecificcues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropo-genic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitmentwill not replace and sustain the adult populations on degraded reefs
ISSN: 0025-326X

hal-01491052
https://hal-univ-perp.archives-ouvertes.fr/hal-01491052
DOI : 10.1016/j.marpolbul.2016.08.083