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Auteur Gounand, I.; Daufresne, T.; Gravel, D.; Bouvier, C.; Bouvier, T.; Combe, M.; Gougat-Barbera, C.; Poly, F.; Torres-Barcelo, C.; Mouquet, N.
Titre Size evolution in microorganisms masks trade-offs predicted by the growth rate hypothesis Type Article scientifique
Année 2016 Publication Revue Abrégée Proc. R. Soc. B-Biol. Sci.
Volume 283 Numéro 1845 Pages (down) 20162272
Mots-Clés Bacteria; bacterial community; biological stoichiometry; cell-size; escherichia-coli; experimental evolution; fresh-water; growth rate hypothesis; inorganic polyphosphate; intrinsic growth; mechanistic approach; Pseudomonas fluorescens; resource competition; r/K strategies; Stoichiometry; variable environment
Résumé Adaptation to local resource availability depends on responses in growth rate and nutrient acquisition. The growth rate hypothesis (GRH) suggests that growing fast should impair competitive abilities for phosphorus and nitrogen due to high demand for biosynthesis. However, in microorganisms, size influences both growth and uptake rates, which may mask trade-offs and instead generate a positive relationship between these traits (size hypothesis, SH). Here, we evolved a gradient of maximum growth rate (mu(max)) from a single bacterium ancestor to test the relationship among mu(max), competitive ability for nutrients and cell size, while controlling for evolutionary history. We found a strong positive correlation between mu(max) and competitive ability for phosphorus, associated with a trade-off between mu(max) and cell size: strains selected for high mu(max) were smaller and better competitors for phosphorus. Our results strongly support the SH, while the trade-offs expected under GRH were not apparent. Beyond plasticity, unicellular populations can respond rapidly to selection pressure through joint evolution of their size and maximum growth rate. Our study stresses that physiological links between these traits tightly shape the evolution of competitive strategies.
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Langue English Langue du Résumé Titre Original
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ISSN 0962-8452 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2055
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Auteur Escalas, A.; Catherine, A.; Maloufi, S.; Cellamare, M.; Hamlaoui, S.; Yepremian, C.; Louvard, C.; Troussellier, M.; Bernard, C.
Titre Drivers and ecological consequences of dominance in periurban phytoplankton communities using networks approaches Type Article scientifique
Année 2019 Publication Revue Abrégée Water Res.
Volume 163 Numéro Pages (down) Unsp-114893
Mots-Clés blooms; climate-change; Co-occurrence network; Community cohesion; Community functioning; cooccurrence patterns; cyanobacteria dominance; diversity; Dominance; fresh-waters; lakes; light; Periurban waterbodies; Phytoplankton; resource use efficiency; species richness
Résumé Evaluating the causes and consequences of dominance by a limited number of taxa in phytoplankton communities is of huge importance in the current context of increasing anthropogenic pressures on natural ecosystems. This is of particular concern in densely populated urban areas where usages and impacts of human populations on water ecosystems are strongly interconnected. Microbial biodiversity is commonly used as a bioindicator of environmental quality and ecosystem functioning, but there are few studies at the regional scale that integrate the drivers of dominance in phytoplankton communities and their consequences on the structure and functioning of these communities. Here, we studied the causes and consequences of phytoplankton dominance in 50 environmentally contrasted waterbodies, sampled over four summer campaigns in the highly-populated Ile-de-France region (IDF). Phytoplankton dominance was observed in 32-52% of the communities and most cases were attributed to Chlorophyta (35.5-40.6% of cases) and Cyanobacteria (30.3-36.5%). The best predictors of dominance were identified using multinomial logistic regression and included waterbody features (surface, depth and connection to the hydrological network) and water column characteristics (total N, TN:TP ratio, water temperature and stratification). The consequences of dominance were dependent on the identity of the dominant organisms and included modifications of biological attributes (richness, cohesion) and functioning (biomass, RUE) of phytoplankton communities. We constructed co-occurrence networks using high resolution phytoplankton biomass and demonstrated that networks under dominance by Chlorophyta and Cyanobacteria exhibited significantly different structure compared with networks without dominance. Furthermore, dominance by Cyanobacteria was associated with more profound network modifications (e.g. cohesion, size, density, efficiency and proportion of negative links), suggesting a stronger disruption of the structure and functioning of phytoplankton communities in the conditions in which this group dominates. Finally, we provide a synthesis on the relationships between environmental drivers, dominance status, community attributes and network structure. (C) 2019 Elsevier Ltd. All rights reserved.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0043-1354 ISBN Médium
Région Expédition Conférence
Notes WOS:000483006400038 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2636
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Auteur Masroor, W.; Farcy, E.; Blondeau-Bidet, E.; Venn, A.; Tambutte, E.; Lorin-Nebel, C.
Titre Effect of salinity and temperature on the expression of genes involved in branchial ion transport processes in European sea bass Type Article scientifique
Année 2019 Publication Revue Abrégée J. Therm. Biol.
Volume 85 Numéro Pages (down) Unsp-102422
Mots-Clés cftr anion channel; chloride channel; cod gadus-morhua; Dicentrarchus labrax; dicentrarchus-labrax; fresh-water; functional classification; Gill; h+-atpase; Ion transporter; mRNA expression; na+/k+-atpase; na+/k+/2cl(-) cotransporter; Salinity; seawater-acclimated medaka; Thermal acclimation
Résumé The responses of European sea bass to temperature increase and salinity decrease were investigated measuring mRNA expression levels of main genes involved in ion transport. Juvenile fish were pre-acclimated to seawater (SW) at 18 degrees C (temperate) or 24 degrees C (warm) for two weeks and then transferred for two weeks to either fresh water (FW) or SW at the respective temperature. Unlike temperate conditions, there is no change in Na+/K+-ATPase ala (nka ala) and Na+/H+ exchanger 3 (nhe3) mRNA expression following FW transfer in warm conditions. This is linked to the high expression of these genes in warm SW compared to temperate SW. Na+/Cl--cotransporter (ncc2a) expression however is increased following FW transfer in temperate and warm conditions. Main transporters involved in ion excretion (Na+/K+/2Cl-1( )cotransporter, nkcc1 and cystic fibrosis transmembrane conductance regulator, cftr) as well as nitrogen excretion (Rh-glycoproteins, rhcg1 and rhbg) and acid-base regulation (V-H+-ATPase, vha-a and b) are highly expressed in SW warm conditions vs FW warm. Overall, our results suggest a higher activation of ion transport processes in warm conditions and more strikingly in SW. This is linked to a strong interplay between diverse ion transporters in order to coordinate physiological responses at the gill level.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0306-4565 ISBN Médium
Région Expédition Conférence
Notes WOS:000497246100023 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2669
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Auteur Sellami, I.; Charmantier, G.; Naceur, H.B.; Kacem, A.; Lorin-Nebel, C.
Titre Osmoregulatory performance and immunolocalization of Na+/K+-ATPase in the branchiopod Artemia salina from the Sebkha of Sidi El Hani (Tunisia) Type Article scientifique
Année 2020 Publication Revue Abrégée Tissue Cell
Volume 63 Numéro Pages (down) Unsp-101340
Mots-Clés alpha-subunit; Artemia salina; brine shrimp artemia; fresh-water; homarus-gammarus crustacea; Hypo-osmoregulation; Immunolocalization; ionic regulation; Maxillary glands; Metepipodites; na+,k+-atpase; Na+/K+ -ATPase; ontogeny; osmotic regulation; potential difference; salt-gland
Résumé Artemia salina is an extremophile species that tolerates a wide range of salinity, especially hypertonic media considered lethal for the majority of other aquatic species. In this study, A. salina cysts were hatched in the laboratory and nauplii were acclimated at three different salinities (60, 139 and 212 ppt). Once in the adult phase, their hemolymph osmolality was measured. The animals were strong hypo-osmoregulators in the entire range of tested salinities, with up to 10 fold lower hemolymph osmolalities than their surrounding environment. Immunostaining of Na+/K+-ATPase was done on sections and on whole body mounts of adults in order to localize the ionocytes in different organs. An intense Na+/K+-ATPase immunostaining throughout the cells was observed in the epithelium of the ten pairs of metepipodites. A positive immunoreactivity for Na+/K+-ATPase was also detected in the maxillary glands, in the epithelium of the efferent tubule and of the excretory canal, as well as in the anterior digestive tract. This study confirms the strong hypo-osmotic capacity of this species and affords an overview of the different organs involved in osmoregulation in A. salina adults.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0040-8166 ISBN Médium
Région Expédition Conférence
Notes WOS:000522853900012 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2758
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Auteur Compte-Port, S.; Borrego, C.M.; Moussard, H.; Jeanbille, M.; Restrepo-Ortiz, C.X.; de Diego, A.; Rodriguez-Iruretagoiena, A.; Gredilla, A.; Fdez-Ortiz de Vallejuelo, S.; Galand, P.E.; Kalenitchenko, D.; Rols, J.-L.; Pokrovsky, O.S.; Gonzalez, A.G.; Camarero, L.; Muniz, S.; Navarro-Navarro, E.; Auguet, J.-C.
Titre Metal contaminations impact archaeal community composition, abundance and function in remote alpine lakes Type Article scientifique
Année 2018 Publication Revue Abrégée Environ. Microbiol.
Volume 20 Numéro 7 Pages (down) 2422-2437
Mots-Clés ammonia-oxidizing archaea; fresh-water lakes; high-altitude lakes; high-mountain lakes; mcra gene; methanogenic archaea; microbial communities; ribosomal-rna; tibetan plateau; trace-metals
Résumé Using the 16S rRNA and mcrA genes, we investigated the composition, abundance and activity of sediment archaeal communities within 18 high-mountain lakes under contrasted metal levels from different origins (bedrock erosion, past-mining activities and atmospheric depositions). Bathyarchaeota, Euryarchaeota and Woesearchaeota were the major phyla found at the meta-community scale, representing 48%, 18.3% and 15.2% of the archaeal community respectively. Metals were equally important as physicochemical variables in explaining the assemblage of archaeal communities and their abundance. Methanogenesis appeared as a process of central importance in the carbon cycle within sediments of alpine lakes as indicated by the absolute abundance of methanogen 16S rRNA and mcrA gene transcripts (10(5) to 10(9) copies g(-1)). We showed that methanogen abundance and activity were significantly reduced with increasing concentrations of Pb and Cd, two indicators of airborne metal contaminations. Considering the ecological importance of methanogenesis in sediment habitats, these metal contaminations may have system wide implications even in remote area such as alpine lakes. Overall, this work was pioneer in integrating the effect of long-range atmospheric depositions on archaeal communities and indicated that metal contamination might significantly compromise the contribution of Archaea to the carbon cycling of the mountain lake sediments.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1462-2912 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2420
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