Éditeur(s) : Inter-research
Résumé : Environmental conditions experienced by aquatic organisms are archived in biogenic carbonates such as fish otoliths, bivalve shells and coral skeletons. These calcified structures present an accretionary growth and variations in optical properties - color or opacity - that are used to reconstruct time. Full and reliable exploitation of the information extracted from these structures is, however, often limited as the metabolic processes that control their growth and their optical properties are poorly understood. Here, we propose a new modeling framework that couples both the growth of a biogenic carbonate and its optical properties with the metabolism of the organism. The model relies on well-tested properties of Dynamic Energy Budget (DEB) theory. It is applied to otoliths of the Bay of Biscay anchovy (Engraulis encrasicolus) for which a DEB model has been previously developed. The model reproduces well-known otolith patterns and thus provides us with mechanisms for the metabolic control of otolith size and opacity at the scale of an individual lifespan. Two original contributions using this framework are demonstrated. First, the model can be used to reconstruct the temporal variations in the food assimilated by an individual fish. Reconstructing food conditions of past and present aquatic species in their natural environment is key ecological information to better understand population dynamics. Second, we show that non-seasonal checks can be discriminated from seasonal checks, which is a well-recognized problem when interpreting fish otoliths. We discuss further developments of the model and the experimental settings required to test this new promising framework.
Marine Ecology-progress Series (0171-8630) (Inter-research), 2012 , Vol. 447 , P. 151-164

Droits : 2012 Inter-Research
http://archimer.ifremer.fr/doc/00060/17082/14593.pdf
DOI:10.3354/meps09492
http://archimer.ifremer.fr/doc/00060/17082/

Éditeur(s) : Public Library Science
Résumé : Subsurface sediments of the Sonora Margin (Guaymas Basin), located in proximity of active cold seep sites were explored. The taxonomic and functional diversity of bacterial and archaeal communities were investigated from 1 to 10 meters below the seafloor. Microbial community structure and abundance and distribution of dominant populations were assessed using complementary molecular approaches (Ribosomal Intergenic Spacer Analysis, 16S rRNA libraries and quantitative PCR with an extensive primers set) and correlated to comprehensive geochemical data. Moreover the metabolic potentials and functional traits of the microbial community were also identified using the GeoChip functional gene microarray and metabolic rates. The active microbial community structure in the Sonora Margin sediments was related to deep subsurface ecosystems (Marine Benthic Groups B and D, Miscellaneous Crenarchaeotal Group, Chloroflexi and Candidate divisions) and remained relatively similar throughout the sediment section, despite defined biogeochemical gradients. However, relative abundances of bacterial and archaeal dominant lineages were significantly correlated with organic carbon quantity and origin. Consistently, metabolic pathways for the degradation and assimilation of this organic carbon as well as genetic potentials for the transformation of detrital organic matters, hydrocarbons and recalcitrant substrates were detected, suggesting that chemoorganotrophic microorganisms may dominate the microbial community of the Sonora Margin subsurface sediments.
Plos One (1932-6203) (Public Library Science), 2014-08 , Vol. 9 , N. 8 , P. e104427

Droits : This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
http://archimer.ifremer.fr/doc/00203/31408/29801.pdf
DOI:10.1371/journal.pone.0104427
http://archimer.ifremer.fr/doc/00203/31408/

Éditeur(s) : Actes de colloques. Ifremer Brest [ACTES COLLOQ. IFREMER.]. 1986
Résumé : Bacterial density of the coelenteric fluid (CF) of some anthozoan species was determined in situ and under laboratory conditions. In all species examined bacterial density of the CF was higher in the gastral cavity than in ambient ranging from 10 super(5) up to 5 x 10 super(6) cells. ml super(-1). Incubation experiments with the CF indicate that a bacterial population within the coelenteron is efficiently controlled by the CF, favoring bacterial growth if bacterial densities are low in the CF and showing clearance activity at high bacterial densities. Feeding of pre-starved anthozoans caused a rapid response of coelenteric rod-shaped bacteria. Evidence is presented that coelenteric bacteria are digested periodically although they contribute 1% to the respiratory carbon losses of the antozoans tested. Therefore, it is more likely that the coelenteric bacterial population provide other substances which cannot be synthesized by the host.
La densité des bactéries du fluide gastrique de différents anthozoaires a été déterminée in situ et au laboratoire. Pour toutes les espèces étudiées, la densité des bactéries dans le fluide gastrique était plus élevée que dans l'eau ambiante et comprise entre 105et 106 cellules m"1. Des expériences d'incubation du fluide gastrique montrent que la population bactérienne est contrôlée efficacement par ce fluide gastrique, favorisant la croissance de bactéries lorsque la densité est faible mais révélant des activités de digestion lorsque la densité est élevée. En nourrissant des anthozoaires mis àjeun plusieurs jours, on provoque une réaction rapide des bactéries déforme bacillaire. Certaines observations montrent que les bactéries gastriques se développent et sont digérées par cycle dans le coelenteron. Néanmoins, la contribution en carbone de ces dernières, comparée aux pertes d'énergie par Sa respiration, représenterait moins de i ','-£. li est probable que cette population bactérienne fournisse des substances qui ne peuvent être synthétisées par i'hôte.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1984/acte-989.pdf
http://archimer.ifremer.fr/doc/00000/989/

Éditeur(s) : HAL CCSD
Résumé : International audience
Previous studies have reported respiratory, cardiac and muscle changes at rest in triathletes 24 h after completion of the event. To examine the effects of these changes on metabolic and cardioventilatory variables during exercise, eight male triathletes of mean age 21.1 (SD 2.5) years (range 17-26 years) performed an incremental cycle exercise test (IET) before (pre) and the day after (post) an official classic triathlon (1.5-km swimming, 40-km cycling and 10-km running). The IET was performed using an electromagnetic cycle ergometer. Ventilatory data were collected every minute using a breath-by-breath automated system and included minute ventilation (V(E)), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio, ventilatory equivalent for oxygen (V(E)/VO2) and for carbon dioxide (V(E)/VCO2), breathing frequency and tidal volume. Heart rate (HR) was monitored using an electrocardiogram. The oxygen pulse was calculated as VO2/HR. Arterialized blood was collected every 2 min throughout IET and the recovery period, and lactate concentration was measured using an enzymatic method. Maximal oxygen uptake (VO2max) was determined using conventional criteria. Ventilatory threshold (VT) was determined using the V-slope method formulated earlier. Cardioventilatory variables were studied during the test, at the point when the subject felt exhausted and during recovery. Results indicated no significant differences (P > 0.05) in VO2max [62.6 (SD 5.9) vs 64.6 (SD 4.8) ml x kg(-1) x min(-1)], VT [2368 (SD 258) vs 2477 (SD 352) ml x min(-1)] and time courses of VO2 between the pre- versus post-triathlon sessions. In contrast, the time courses of HR and blood lactate concentration reached significantly higher values (P < 0.05) in the pre-triathlon session. We concluded that these triathletes when tested 24 h after a classic triathlon displayed their pre-event aerobic exercise capacity, bud did not recover pretriathlon time courses in HR or blood lactate concentration.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720432
https://hal.univ-antilles.fr/hal-00720432
https://hal.univ-antilles.fr/hal-00720432/document
https://hal.univ-antilles.fr/hal-00720432/file/Article_2.pdf

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: The meiotic developmental pathway in yeast enables both differentiation of vegetative cells into haploid spores that ensure long-term survival, and recombination of the parental DNA to create genetic diversity. Despite the importance of proper metabolic regulation for the supply of building blocks and energy, little is known about the reprogramming of central metabolic pathways in meiotically differentiating cells during passage through successive developmental stages. Results: Metabolic regulation during meiotic differentiation in budding yeast was analyzed by integrating information on genome-wide transcriptional activity, 26 enzymatic activities in the central metabolism, the dynamics of 67 metabolites, and a metabolic flux analysis at mid-stage meiosis. Analyses of mutants arresting sporulation at defined stages demonstrated that metabolic reprogramming is tightly controlled by the progression through the developmental pathway. The correlation between transcript levels and enzymatic activities in the central metabolism varies significantly in a developmental stage-dependent manner. The complete loss of phosphofructokinase activity at mid-stage meiosis enables a unique setup of the glycolytic pathway which facilitates carbon flux repartitioning into synthesis of spore wall precursors during the co-assimilation of glycogen and acetate. The need for correct homeostasis of purine nucleotides during the meiotic differentiation was demonstrated by the sporulation defect of the AMP deaminase mutant amd1, which exhibited hyper-accumulation of ATP accompanied by depletion of guanosine nucleotides. Conclusions: Our systems-level analysis shows that reprogramming of the central metabolism during the meiotic differentiation is controlled at different hierarchical levels to meet the metabolic and energetic needs at successive developmental stages.
ISSN: 1471-2180

inserm-01094132
http://www.hal.inserm.fr/inserm-01094132
http://www.hal.inserm.fr/inserm-01094132/document
http://www.hal.inserm.fr/inserm-01094132/file/s12915-014-0060-x.pdf
DOI : 10.1186/s12915-014-0060-x

Éditeur(s) : HAL CCSD Consejo Superior de Investigaciones Científicas
Résumé : International audience
The temporal variation in carbon and nitrogen isotopic compositions (noted as δ 13 C and δ 15 N) was investigated in the convict surgeonfish (Acanthurus triostegus) at Moorea (French Polynesia). Over a period of 24 days, juveniles were reared in aquaria and subjected to two different feeding treatments: granules or algae. The dynamics of δ 13 C and δ 15 N in two muscles (the adductor mandibulae complex and the epaxial musculature) having different functions were compared. At the end of experiments, a steady-state isotopic system in each muscle tissue was not reached. Especially for the algal treatment, we found different patterns of variation in isotopic compositions over time between the two muscles. The turnovers of δ 13 C showed opposite trends for each muscle but differences are mitigated by starvation and by the metamorphosis. Our study highlighted that the metabolism of coral reef fish may be subjected to catabolism or anabolism of non-protein precursors at settlement, inducing variation in isotopic compositions that are not linked to diet change. Comparación de la dinámica de variación isotópica en dos músculos de un pez de arrecife de coral durante la fase de asentamiento Resumen: La variación temporal en la composiciones isotópicas del carbono y nitrógeno (δ 13 C y δ 15 N) fue investigada en el pez cirujano Acanthurus triostegus en Moorea (Polinesia Francesa). Durante un período de 24 días, peces juveniles se mantuvieron en acuarios y se sometieron a dos tratamientos de alimentación: gránulos o algas. Se compararon las dinámicas de cambio δ 13 C y δ 15 N en dos músculos con diferentes funciones (complejo aductor mandibular y musculatura epiaxial). Al final de los experimentos, no se alcanzó un sistema isotópico de estado estacionario en ningún tejido. Especialmente para el tratamiento de algas, encontramos distintos patrones de variación en composiciones isotópicas en el tiempo entre los dos músculos. Las variaciones en δ 13 C mostraron tendencias opuestas para cada músculo, pero las diferencias fueron mitigadas por la inanición y la metamorfosis. Nuestro estudio destaca que el metabolismo de los peces de arrecife puede ser sometido a catabolismo o anabolismo por los precursores no proteicos durante el asentamiento, induciendo variación en las composi-ciones isotópicas que no están vinculados al cambio de dieta.
ISSN: 0214-8358

Droits : http://creativecommons.org/licenses/by-nc/
hal-01212253
https://hal-univ-perp.archives-ouvertes.fr/hal-01212253
https://hal-univ-perp.archives-ouvertes.fr/hal-01212253/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01212253/file/1598-3145-1-PB.pdf
DOI : 10.3989/scimar.04225.31A

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
The shallow water bivalve Codakia orbicularis lives in symbiotic association with a sulfur-oxidizing bacterium in its gills. The endosymbiont fixes CO2 and thus generates organic carbon compounds, which support the host's growth. To investigate the uncultured symbiont's metabolism and symbiont-host interactions in detail we conducted a proteogenomic analysis of purified bacteria. Unexpectedly, our results reveal a hitherto completely unrecognized feature of the C. orbicularis symbiont's physiology: the symbiont's genome encodes all proteins necessary for biological nitrogen fixation (diazotrophy). Expression of the respective genes under standard ambient conditions was confirmed by proteomics. Nitrogenase activity in the symbiont was also verified by enzyme activity assays. Phylogenetic analysis of the bacterial nitrogenase reductase NifH revealed the symbiont's close relationship to free-living nitrogen-fixing Proteobacteria from the seagrass sediment. The C. orbicularis symbiont, here tentatively named `Candidatus Thiodiazotropha endolucinida', may thus not only sustain the bivalve's carbon demands. C. orbicularis may also benefit from a steady supply of fixed nitrogen from its symbiont-a scenario that is unprecedented in comparable chemoautotrophic symbioses.
ISSN: 2058-5276

hal-01545904
https://hal.archives-ouvertes.fr/hal-01545904
DOI : 10.1038/nmicrobiol.2016.193

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Diploid budding yeast undergoes rapid mitosis when it ferments glucose, and in the presence of a non-fermentable carbon source and the absence of a nitrogen source it triggers sporulation. Rich medium with acetate is a commonly used pre-sporulation medium, but our understanding of the molecular events underlying the acetate-driven transition from mitosis to meiosis is still incomplete. We identified 263 proteins for which mRNA and protein synthesis are linked or uncoupled in fermenting and respiring cells. Using motif predictions, interaction data and RNA profiling we find among them 28 likely targets for Ume6, a subunit of the conserved Rpd3/Sin3 histone deacetylase-complex regulating genes involved in metabolism, stress response and meiosis. Finally, we identify 14 genes for which both RNA and proteins are detected exclusively in respiring cells but not in fermenting cells in our sample set, including CSM4, SPR1, SPS4 and RIM4, which were thought to be meiosis-specific. Our work reveals intertwined transcriptional and post-transcriptional control mechanisms acting when a MATa/α strain responds to nutritional signals, and provides molecular clues how the carbon source primes yeast cells for entering meiosis. Our integrated genomics study provides insight into the interplay between the transcriptome and the proteome in diploid yeast cells undergoing vegetative growth in the presence of glucose (fermentation) or acetate (respiration). Furthermore, it reveals novel target genes involved in these processes for Ume6, the DNA binding subunit of the conserved histone deacetylase Rpd3 and the co-repressor Sin3. We have combined data from an RNA profiling experiment using tiling arrays that cover the entire yeast genome, and a large-scale protein detection analysis based on mass spectrometry in diploid MATa/α cells. This distinguishes our study from most others in the field-which investigate haploid yeast strains-because only diploid cells can undergo meiotic development in the simultaneous absence of a non-fermentable carbon source and nitrogen. Indeed, we report molecular clues how respiration of acetate might prime diploid cells for efficient spore formation, a phenomenon that is well known but poorly understood.
ISSN: 1874-3919

hal-01122122
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122122
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122122/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122122/file/Integrated%20RNA-%20and%20protein%20profiling%20of%20fermentation.pdf
DOI : 10.1016/j.jprot.2015.01.015

Éditeur(s) : Inter-research
Résumé : Benthic primary production and respiration were investigated at 4 sites representative of the major coastal communities bordering the Sahara Desert in the Banc d'Arguin, Mauritania, Western Africa. These sites correspond to intertidal Zostera noltii beds (270 km(2)), intertidal bare sediments (88 km(2)), subtidal Cymodocea nodosa beds (374 km(2)), and subtidal bare sediments (311 km(2)). At each site, production-irradiance relationships were established in situ in November 2008 and January 2010, and used to calculate daily carbon fluxes for these communities. In intertidal areas, compared to emersion, the gross maximal photosynthetic rates for Z. noltii bed and bare sediment communities were on average 8-and 7-fold higher during immersion, respectively; community respiration rates were 3-and 18-fold higher during immersion, respectively. The Z. noltii bed was autotrophic during the 2 study periods, with a mean (+/- 95% probability limit) daily net community production of 71.3 +/- 58.6 mmol C m(-2) d(-1). Conversely, net community production was always negative in intertidal regions and subtidal bare sediments (average -7.3 +/- 46.7 mmol C m(-2) d(-1) and -47.0 +/- 38.9 mmol C m(-2) d(-1), respectively); the C. nodosa bed was negative in November (-96.2 +/- 85.1 mmol C m(-2) d(-1)) and positive in January (33.4 +/- 82.6 mmol C m(-2) d(-1)). Community respiration was highest in subtidal communities, indicating active mineralization of organic matter and demonstrating that Z. noltii beds are likely to increase the bio logical richness of the Banc d'Arguin by exporting energy. Our results confirm the ecological importance of seagrass beds in the net coastal carbon fluxes and justify their protection.
Marine Ecology Progress Series (0171-8630) (Inter-research), 2014 , Vol. 501 , P. 11-23

Droits : Inter-Research 2014 · www.int-res.com
http://archimer.ifremer.fr/doc/00189/29987/28496.pdf
DOI:10.3354/meps10683
http://archimer.ifremer.fr/doc/00189/29987/

Éditeur(s) : Marine Biological Laboratory
Résumé : Hydrothermal vent tubeworms, Riftia pachyptila Jones, were maintained alive and studied on board ship using flow-through pressure aquaria. Simultaneous measurements of O2, SIGMA-CO2, SIGMA-H2S fluxes showed that the intact symbioses reach maximum rates of uptake of SIGMA-CO2 (>2 mu-mole g-1 h-1) at about 90 mu-M SIGMA-H2S. Measurements were made of hemolymph and coelomic fluid SIGMA-CO2, SIGMA-H2S, thiosulfate, pH, and hemoglobin concentrations in worms kept under various conditions of O2 and SIGMA-H2S. Normal hemolymph pH appears to be about 7.5 and is not affected by SIGMA-H2S and SIGMA-CO2 concentrations within the ranges observed. We conclude that Riftia is specialized to provide sulfide to its symbionts with minimal interaction of sulfide with the animal metabolism. The uptake of sulfide is apparently by diffusion into the hemolymph, facilitated by the sulfide-binding properties of the hemoglobins. Both SIGMA-CO2 and P(CO2) are elevated in the hemolymph above their levels in the medium, although they are reduced under autotrophic conditions. Thus inorganic carbon is apparently concentrated from the medium into the hemolymph by an unknown mechanism.
Biological Bulletin (0006-3185) (Marine Biological Laboratory), 1991-02 , Vol. 180 , N. 1 , P. 135-153

Droits : 1991 Marine Biological Laboratory
http://archimer.ifremer.fr/doc/00178/28970/27392.pdf
DOI:10.2307/1542437
http://archimer.ifremer.fr/doc/00178/28970/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Chronic liver damage due to viral or chemical agents leads to a repair process resulting in hepatic fibrosis. Fibrosis may lead to cirrhosis, which may progress to liver cancer or a loss of liver function, with an associated risk of liver failure and death. Chlordecone is a chlorinated pesticide used in the 1990s. It is not itself hepatotoxic, but its metabolism in the liver triggers hepatomegaly and potentiates hepatotoxic agents. Chlordecone is now banned, but it persists in soil and water, resulting in an ongoing public health problem in the Caribbean area. We assessed the probable impact of chlordecone on the progression of liver fibrosis in the population of contaminated areas, by developing a mouse model of chronic co-exposure to chlordecone and a hepatotoxic agent, carbon tetrachloride (CCl4). After repeated administrations of chlordecone and CCl4 by gavage over a 12-week period, we checked for liver damage in the exposed mice, by determining serum liver transaminase (AST, ALT) levels, histological examinations of the liver and measuring the expression of genes encoding extracellular matrix components. The co-exposure of mice to CCl4 and chlordecone resulted in significant increases in ALT and AST levels. Chlordecone also increased expression of the Col1A2, MMP-2, TIMP-1 and PAI-1 genes in CCl4-treated mice. Finally, we demonstrated, by quantifying areas of collagen deposition and alpha-SMA gene expression, that chlordecone potentiated the hepatic fibrosis induced by CCl4. In conclusion, our data suggest that chlordecone potentiates hepatic fibrosis in mice with CCl4-induced chronic liver injury
ISSN: 0378-4274

hal-01274228
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01274228
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01274228/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01274228/file/Chlordecone%20potentiates%20hepatic%20fibrosis%20%281%29.pdf
DOI : 10.1016/j.toxlet.2016.02.005