Éditeur(s) : HAL CCSD
Résumé : International audience
Migration of chemicals from packaging materials to foods may lead to human exposure. Polyfluoroalkyl substances (PFAS) can be used in technical mixtures (TMs) for use in food packaging of paper and board, and PFAS have been detected in human serum and umbilical cord blood. The specific structures of the PFAS in TMs are often unknown, but polyfluorinated alkyl phosphate esters (PAPs) have been characterized in TMs, food packaging, and in food. PAPs can be metabolized into fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Some PFAS have endocrine activities, highlighting the need to investigate these effects. Herein, we studied the endocrine activity of less characterized PFAS, including short-chain PFCAs and FTOHs, PAPs, and TMs of unknown chemical composition. Long-chain PFCAs were also included. We applied seven assays covering effects on estrogen, glucocorticoid, androgen, and peroxisome proliferator-activated receptor (PPAR) activity, as well as steroidogenesis in vitro and ex vivo. In general, PAPs, FTOHs, TMs, and long-chain PFCAs showed estrogenic activity through receptor activation and/or increasing 17β-estradiol levels. Furthermore, short- and long-chain PFCAs activated PPARα and PPARγ. Collectively, this means that (i) PAPs, FTOHs, and PFCAs exhibit endocrine activity through distinct and sometimes different mechanisms, (ii) two out of three tested TMs exhibited estrogenic activity, and (iii) short-chain FTOHs showed estrogenic activity and short-chain PFCAs generally activate both PPARα and PPARγ with similar potency and efficacy as long-chain PFCAs. In conclusion, several new and divergent toxicological targets were identified for different groups of PFAS. © 2016 American Society of Andrology and European Academy of Andrology
Andrology

hal-01367144
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01367144
DOI : 10.1111/andr.12190
PUBMED : 27152447

Éditeur(s) : Université des Antilles. Service commun de la documentation University of West Indies, Barbados
Extrait de : 52e congrès annuel de la Société caribéenne des plantes alimentaires / 52nd annual meeting of the Caribbean food crops society (CFCS), du 10 au 16 juillet 2016. INRA, CFCS
Description : Mulch application of Sargassum seaweed (Sargassum spp.) to soil can help to reduce beach contamination in the Caribbean Region while providing beneficial horticultural effects. This study investigated the effects of fresh Sargassum mulch on soil properties and plant growth in a test crop of tomato (Solanum lycopersicum L. â? ? HA 3019â? TM). Fresh Sargassum material (washed and unwashed) was applied as mulches (0, 5 and 8cm thick) to small field plots one week after transplanting of 3-week-old seedlings. The mulch material was raked away from the plots after three weeks exposure. Observations on soil moisture, electrical conductivity, pH and biological activity, and plant growth were made at 1 to 2-week intervals over a 6-week period with additional soil measurements after 10 weeks. Soil biological activity (respiration) was increased by the Sargassum mulch with values being similar for the 5cm and 8cm mulch layers. Soil moisture content, pH and electrical conductivity (EC) were increased as the mulch layer increased and EC values were only marginally reduced by Sargassum washing. An increase in plant growth compared to the control treatment was noted only in the washed Sargassum treatments. Potential benefits of Sargassum seaweed mulches on soil properties and plant growth can be nullified due to soil salinization effects.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V16269
V16269

Éditeur(s) : HAL CCSD Human Kinetics
Résumé : International audience
The aim of this study was to determine the physiological profile of young triathletes who began triathlon competition as their first sport. Twenty-nine male competitive triathletes (23 regionally and nationally ranked triathletes and 6 elite, internationally ranked triathletes) performed two tests, one on a cycle ergometer (CE VO2max) and one on a treadmill (TM VO2max). Results showed (a) no difference between CE VO2max and TM VO2max in the triathletes (69.1 +/- 7.2 vs. 70.2 +/- 6.2 mL x kg(-1) x min(-1), respectively), (b) values of CE VO2max and TM VO2max in elite triathletes (75.9 +/- 5.2 and 78.5 +/- 3.6 mL x kg(-1) x min(-1), respectively) that were comparable to those reported in elite single-sport athletes in these specialities, and (c) although the ventilatory threshold (Th(vent)) was similar in CE and TM, TM Th(vent) was consistently lower for triathletes than TM Th(vent) usually reported for runners.
ISSN: 1066-7814

hal-00720566
https://hal.univ-antilles.fr/hal-00720566
https://hal.univ-antilles.fr/hal-00720566/document
https://hal.univ-antilles.fr/hal-00720566/file/CJAP.pdf

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by exposure to a vacuum between 30 and 1200 s and then calcined at 400 °C. X-ray diffraction and nitrogen adsorption analyses showed that the crystallite size and particle size of titania increased as a function of vacuum time. All the TM membranes were mesoporous with an average pore diameter of ~3.6 nm with an anatase crystal morphology. Water, glucose, sucrose, and polyvinylpyrrolidone with 40 and 360 kDa (PVP-40 kDa and PVP-360 kDa) were used as feed solutions for MW cut-off and hexadecane solution for oil filtration investigation. The TM membranes were not able to separate glucose and sucrose, thus indicating the membrane pore sizes are larger than the kinetic diameter of sucrose of 0.9 nm, irrespective of vacuum exposure time. They also showed only moderate rejection (20%) of the smaller PVP-40 kDa, however, all the membranes were able to obtain an excellent rejection of near 100% for the larger PVP-360 kDa molecule. Furthermore, the TM membranes were tested for the separation of oil emulsions with a high concentration of oil (3000 ppm), reaching high oil rejections of more than 90% of oil. In general, the water fluxes increased with the vacuum exposure time indicating a pore structural tailoring effect. It is therefore proposed that a mechanism of pore size tailoring was formed by an interconnected network of Ti-O-Ti nanoparticles with inter-particle voids, which increased as TiO2 nanoparticle size increased as a function of vacuum exposure time, and thus reduced the water transport resistance through the TM membranes. © 2016 by the authors.
ISSN: 1996-1944

hal-01683214
https://hal.univ-antilles.fr/hal-01683214
DOI : 10.3390/ma9110938

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The equilibrium phase relations of a mafic durbachite (53 wt.% SiO2) from the TA (TM) ebi pluton, representative of the Variscan ultrapotassic magmatism of the Bohemian Massif (338-335 Ma), have been determined as a function of temperature (900-1,100A degrees C), pressure (100-200 MPa), and H2O activity (1.1-6.1 wt.% H2O in the melt). Two oxygen fugacity ranges were investigated: close to the Ni-NiO (NNO) buffer and 2.6 log unit above NNO buffer (a dagger NNO + 2.6). At 1,100A degrees C, olivine is the liquidus phase and co-crystallized with phlogopite and augite at 1,000A degrees C for the whole range of investigated pressure and water content in the melt. At 900A degrees C, the mineral assemblage consists of augite and phlogopite, whereas olivine is not stable. The stability field of both alkali feldspar and plagioclase is restricted to low pressure (100 MPa) at nearly water-saturated conditions (< 3-4 wt.% H2O) and T < 900A degrees C. A comparison between experimental products and natural minerals indicates that mafic durbachites have a near-liquidus assemblage of olivine, augite, Ti-rich phlogopite, apatite and zircon, followed by alkali feldspar and plagioclase, similar to the mineral assemblage of minette magma. Natural amphibole, diopside and orthopyroxene were not reproduced experimentally and probably result from sub-solidus reactions, whereas biotite re-equilibrated at low temperature. The crystallization sequence olivine followed by phlogopite and augite reproduces the sequence inferred in many mica-lamprophyre rocks. The similar fractionation trends observed for durbachites and minettes indicate that mafic durbachites are probably the plutonic equivalents of minettes and that K- and Mg-rich magmas in the Bohemian Massif may have been generated from partial melting of a phlogopite-clinopyroxene-bearing metasomatized peridotite. Experimental melt compositions also suggest that felsic durbachites can be generated by simple fractionation of a more mafic parent and mixing with mantle-derived components at mid crustal pressures.
ISSN: 0010-7999

hal-00618418
https://hal.archives-ouvertes.fr/hal-00618418
DOI : 10.1007/s00410-009-0430-5

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Predicting the impact of underground engineering on the environment requires the knowledge of natural media at different scales. In particular, understanding basic phenomena controlling the properties of rocks in the presence of complex fluids necessitates a detailed atomic description of the solid/fluid/solid contacts, the subject of Part I of the present study. First, building the solid interspace between two different crystals in a non-periodic situation is achieved using the ab initio and molecular mechanics code GenMol (TM). A description of the fluid confined within the interspace is then derived from the original genetic iterative multi-species (GIMS) algorithm implemented in the same code. This approach consists of equilibrating chemical potentials, cycle after cycle and species after species, between the confined fluid and the free natural fluid. An elementary iteration for a species k consists of different steps incrementing the number N-k of particles k, with other numbers N-k remaining constant. At each step, an optimum fluid composition is obtained by a genetic process distributing the fluid particles on a grid by stochastic shots, followed in fine by a refining process. The effectiveness of the GIMS approach is demonstrated in the case study of a fluid confined between two (0 0 1) kaolinite faces, with apertures h varying between 4 and 10 A. connected to a 9-species external solution [H2O, Cl-, Na+ CO2(aq), NaCl(aq), Ca2+, Mg2+, HCO3-, H3O+] where concentrations are ranging from 55 to 10(-4) mol/L. The results show a drastic variation in the solute/solvent and cations/ions ratios in the confined fluid when aperture h is lowered to less than 1 nm. These results obtained with a very rapid convergence of the iterative algorithm combined with a very competitive genetic optimizer are validated with high precision on a free solution. This description of contacts between crystals is original and unattainable by standard crystal interface approaches. It opens the way to understanding and/or predicting phenomena between crystals in a complex natural environment, such as adhesion or repulsion investigated in the Part II of this study.
ISSN: 0022-0248

hal-00544569
https://hal.archives-ouvertes.fr/hal-00544569
DOI : 10.1016/j.jcrysgro.2010.08.009

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé :  
In this paper, we report a study of the mating system and gene flow of Symphonia globulifera, a hermaphroditic, mainly bird-pollinated tree species with a large geographic distribution in the tropical Americas and Africa.Using three microsatellites, we analysed 534 seeds of 28 open pollinated families and 164 adults at the experimental site 'Paracou' in French Guiana. We observed, compared to other tropical tree species, relatively high values for the effective number of alleles. Significant spatial genetic structure was detected, with trees at distances up to 150 m more genetically similar than expected at random. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGener approach. The estimated multilocus outcrossing rate, tm, was 0.920. A significant level of biparental inbreeding and a high proportion of full-sibs were estimated for the 28 seed arrays. We estimated mean pollen dispersal distances between 27 and 53 m according to the dispersal models used. Although the adult population density of S. globulifera in Paracou was relatively high, the joint estimation of pollen dispersal and density of reproductive trees gave effective density estimates of 1.6 and 1.3trees/ha. The parameters of the mating system and gene flow are discussed in the context of spatial genetic and demographic structures, flowering phenology and pollinator composition and behaviour.
ISSN: 0018-067X

hal-01032178
https://hal.archives-ouvertes.fr/hal-01032178
DOI : 10.1038/sj.hdy.6800560

Éditeur(s) : Elsevier Science Bv
Résumé : Climatic and anthropogenic changes are able to engender modifications in the aerosol composition at different geographical and temporal scales The present study addresses this question for the trace metal concentrations (TM = Al, Fe, Mn, Co, Ni, Cu, Pb, Cd and Zn) of aerosol from the North-western Mediterranean coast of France (Cap Ferrat, nearby Nice) between 1986 and 2008. From seasonal variations (2006-08) and decadal trends (1986-2008) of TM concentrations. three groups of elements can be distinguished They consist of different aerosol sources: crustal-derived elements (Al, Fe. Mn and Co), trace metals of anthropogenic origin (Pb, Cd and Zn) and a third, intermediate, group of trace metals that presented both anthropogenic and natural/crustal influences (Ni and Cu). Reproducible seasonal patterns were observed for crustal and intermediate elements with highest concentrations between May and November. while anthropogenic trace metals did not show a pronounced seasonal cycle Nevertheless, highest concentrations of anthropogenic trace metals occurred mostly in autumn/winter. Aerosol concentrations of anthropogenic TMs decreased remarkably over the last two decades, while crustal trace metals did not show any evolution Nickel and copper aerosol concentrations remained constant, as well. Lead concentrations decreased from 1986 (29.34 ng m(-3)) to 2008 (3.33 ng m(-3)). overall by 90%. Cadmium and zinc aerosol concentrations decreased by 66 and 54%, respectively, between 1998 and 2006-08. from 0.27 to 0.09 ng m(-3) and from 23.9 to 10.9 ng m(-3). respectively. These findings demonstrate the response of the atmospheric environment to the implementation of antipollution policies Possible changes of trace metal emissions sources and local influences are discussed (C) 2010 Elsevier B V. All rights reserved.
Science Of The Total Environment (0048-9697) (Elsevier Science Bv), 2010-06 , Vol. 408 , N. 13 , P. 2629-2638

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00006/11688/8503.pdf
DOI:10.1016/j.scitotenv.2010.02.042
http://archimer.ifremer.fr/doc/00006/11688/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
GenMol (TM) code is used to simulate Atomic Force Microscopy (AFM) tests at a kaolinite/brine/kaolinite contact, the confined fluid in sub-nanometre interspaces being in equilibrium with an external multi-species solution. The attraction/repulsion effort, i.e. the derivative versus the interspace aperture h of the interaction energy between both kaolinite faces, is computed versus the variable composition of the confined fluid (see for the method Part I of this work). Two external solutions are tested. Solution Si is a neutral brine (pH=7.5) leading to a possible attraction for apertures lower than 7 angstrom. Solution S2 is an acidified brine (pH=3.2) leading to repulsion whatever may be the aperture h. These two AFM simulations prove the existence of a critical pH value (3.2 < pH(crit) < 7.5) of the external solution, below which the acidification of a natural brine in a CO2 confinement inhibits adhesion between kaolinite aggregates.
ISSN: 0022-0248

hal-00544678
https://hal.archives-ouvertes.fr/hal-00544678
DOI : 10.1016/j.jcrysgro.2010.08.012

Éditeur(s) : HAL CCSD Elsevier
Résumé : Our method for the simultaneous determination of the four natural Ra isotopes (Ra-226, Ra-228, Ra-224 and Ra-223) in thermal waters involves a separation of Ra on a selective filter (3 M EMPORE (TM) Radium Rad disk), and a single counting using a broad-energy HPGe detector (BE Ge manufactured by CANBERRA (TM)). The calculation of Ra-223 and (228)a activities requires interference and cascade summing corrections. The Ra-226 activities in CO2-rich thermal waters of the Lodeve Basin (South of France) range from 530 to 2240 mBq/l. The low (Ra-228/Ra-226) activity ratios (0.19-0.29) suggest that Ra is mostly derived from the aquifer carbonates. The short-lived Ra-224 and Ra-223 are probably added to the water through recoil or desorption processes from Th-enriched coatings on the fracture walls.
ISSN: 0969-8043

hal-00475587
https://hal.archives-ouvertes.fr/hal-00475587
DOI : 10.1016/j.apradiso.2009.10.056

Éditeur(s) : HAL CCSD
Résumé : International audience
The aim was to identify patterns of work organization characteristics using data from epidemiological surveillance program of musculoskeletal disorders (MSD) implemented in the Pays de la Loire region between 2002 and 2005. A total of 3710 workers were included and completed a administered questionnaire including 16 organizational variables. Ascendant hierarchical clustering (AHC) of organizational variables and AHC of workers had identified five patterns of work organization characteristics: technical constraints and weak decision latitude; internal/external demand and mean decision latitude; weak pace constraints and mean decision latitude; internal/external demand and high decision latitude; weak pace constraints and high decision latitude. Relationships with MSD diagnosed by occupational physicians were then studied.
The specific health programs (SHP) are one of the four mechanisms of prevention planned by the Health and Safety at work Law in the province of Quebec. If the Law appoints only a responsible doctor, it is in reality Health at work teams (HWT) that develop these SHP. In this communication, based on the model of the working situation and the diagram of inter professional practices of collaboration, we study the practices of inter professional collaboration (CIP) in the HWT. The observed practices vary between independent practices, in parallel, of consultation, of dialogue and in shared services. Formalization of the teams, coordination of communication, leadership, respect and professional identities influence particularly the practices of CIP.
L’objectif était d’identifier des patterns de caractéristiques d'organisation du travail à partir des données du programme de surveillance épidémiologique des troubles musculo-squelettiques (TMS) mis en œuvre dans les Pays de la Loire entre 2002 et 2005. Au total, 3 710 salariés ont été inclus et ont répondu à un questionnaire comportant notamment 16 variables organisationnelles. Une classification ascendante hiérarchique (CAH) des variables organisationnelles puis une CAH des salariés ont permis d’identifier cinq patterns de caractéristiques d’organisation du travail : contraintes techniques et faible latitude décisionnelle ; demande interne/externe et latitude décisionnelle moyenne ; faibles contraintes de rythme et latitude décisionnelle moyenne ; demande externe/interne et forte latitude décisionnelle ; faibles contraintes de rythme et forte latitude décisionnelle. Les associations avec les TMS diagnostiqués par des médecins du travail ont ensuite été étudiées.
Actes du 50ème congrès de la Société d'Ergonomie de Langue Française
Paris, France

halshs-01307785
https://halshs.archives-ouvertes.fr/halshs-01307785

Éditeur(s) : Elsevier
Résumé : In order to provide reliable scientific advice and support for fisheries management, it is necessary to evaluate the biological and economic sustainability of complex fisheries, such as multi-species multi-fleet fisheries. Existing policy-screening modelling tools are not fully suitable in this purpose due to either an over-simplified description of population dynamics, or due to the lack of consideration of economic aspects. In this paper, we present a package that enables quantitative bioeconomic assessment of management scenarios. Population dynamics is described through spatially- and seasonally-explicit models. Exploitation dynamics is characterized by several fishing activities with specific spatial and seasonal features, and practiced by several kinds of vessels with specific technical characteristics. Exploitation costs and revenues are considered at several levels: the fishing trip, the fishing unit (vessel and crew), and the vessel owner. The model is generic and can be used for different types of fisheries. A database is attached to the software for the storage and updating of information for each fishery. This includes the specification of model dimensions and of the parameters describing populations and exploitation. Several model assumptions regarding either population or exploitation may be adapted to suit a specific fishery. Both policies and corresponding fishers' response may be interactively specified through JAVA (TM) scripts. This version of ISIS-Fish allows for the calculation of biological and economic consequences of a range of policies, including conventional ones like catch and effort controls, and alternative policies such as marine protected areas. To facilitate policy-screening in a high-dimension parameter space, the software includes features, like interfaces for sensitivity analysis and simulation queues. (C) 2009 Elsevier B.V. All rights reserved.
Ecological Modelling (0304-3800) (Elsevier), 2009-04 , Vol. 220 , N. 7 , P. 1013-1033

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6782.pdf
DOI:10.1016/j.ecolmodel.2009.01.007
http://archimer.ifremer.fr/doc/00000/6782/

Éditeur(s) : HAL CCSD
Résumé : National audience
L’objectif était d’identifier des formes d’organisation du travail et d’étudier leur association avec les douleurs de l’épaule et le syndrome de la coiffe des rotateurs (SCR) chez les salariés, à partir des données du programme de surveillance épidémiologique des troubles musculo-squelettiques mis en œuvre dans les Pays de la Loire.
16ème colloque de l'ADEREST
Lyon, France

hal-01301201
https://hal.archives-ouvertes.fr/hal-01301201
DOI : 10.1016/j.admp.2015.04.036

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
CMAS 3D, developed in MATLAB (R), is a program to support visualization of major element chemical data in three dimensions. Such projections are used to discuss correlations, metamorphic reactions and the chemical evolution of rocks, melts or minerals. It can also project data into 2D plots. The CMAS 3D interface makes it easy to use, and does not require any knowledge of Matlab (R) programming. CMAS 3D uses data compiled in a Microsoft Excel (TM) spreadsheet. Although useful for scientific research, the program is also a powerful tool for teaching.
ISSN: 0098-3004

hal-00413570
https://hal.archives-ouvertes.fr/hal-00413570
DOI : 10.1016/j.cageo.2008.07.002

Éditeur(s) : HAL CCSD BioMed Central
Résumé : Le régime de reproduction de Dicorynia guianensis (caesalpiniaceae), arbre de la forêt guyanaise a été étudié à l'aide des marqueurs enzymatiques. Le matériel végétal a été collecté en 1993 et 1995, sur le dispositif sylvicole de Paracou. Le taux d'allofécondation moyen de la population est élevé, tm = 0,85, stable d'une année à l'autre malgré une variation importante du taux de floraison. Le taux individuel varie entre les arbres mais aucune corrélation n'a pu être établie avec des facteurs spatiaux, densité de floraison ou distance aux plus proches voisins. L'hétérogénéité des nuages polliniques est sensible au niveau des agrégats et des arbres individuels, échelle spatiale où se déploie l'activité des insectes pollinisateurs. Nous n'avons en évidence aucune corrélation spatiale entre compositions des nuages polliniques individuels. Des distances de migration du pollen de 190 mètres ont été mise en évidence grâce aux allèles rares. Aucune différence significative du régime de reproduction de D. guianensis n'a été trouvée entre parcelles traitées et parcelles témoin du dispositif.
ISSN: 0999-193X

hal-01032370
https://hal.archives-ouvertes.fr/hal-01032370

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We performed 31 friction experiments on glassy basalts (GB) and glass-free basalts (GFB) at slip rates up to 6.5 m s−1 and normal stress up to 40 MPa (seismic conditions). Frictional weakening was associated to bulk frictional melting and lubrication. The weakening distance (Dw) was about 3 times shorter in GB than in GFB, but the steady state friction was systematically higher in GB than in GFB. The shorter Dw in GB may be explained by the thermal softening occurring at the glass transition temperature (Tg ~500°C), which is lower than the bulk melting temperature (Tm ~1250°C) of GFB. Postexperiment microanalyses suggest that the larger crystal fraction measured in GB melts results in the higher steady state friction value compared to the GFB melts. The effect of interstitial glass is to facilitate frictional instability and rupture propagation in GB with respect to GFB.
ISSN: 0094-8276

hal-01054139
https://hal.archives-ouvertes.fr/hal-01054139
DOI : 10.1002/2013GL058601

Éditeur(s) : HAL CCSD
Résumé :   Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, F97387 Kourou, Guyane (France) Diplôme : other
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
Avec le projet de création d'un parc dans le sud de la Guyane française, la cartographie des différents types de végétation et de l'occupation du sol d'une zone habitée comme Saül s'est avérée primordiale. La photo-interprétation est une méthode facile pour faire un état des lieux de l'emprise humaine sur le milieu physique, de même que la mise en place d'une base de données à partir de l'interprétation de couvertures aériennes (Landsat TM et photographies aériennes) permet de suivre la progression de la pression anthropique future.
https://hal.archives-ouvertes.fr/hal-01189531

hal-01189531
https://hal.archives-ouvertes.fr/hal-01189531
PRODINRA : 45737

Éditeur(s) : HAL CCSD
Résumé : In this paper we report a study of the mating system and gene flow of Sextonia rubra, a hermaphroditic, insect pollinated tropical tree species with a geographic distribution in the Guyana Plateau and the Amazon. Using five microsatellites we analysed 428 seeds of 27 open pollinated families at the experimental site "Paracou" in French Guiana. We observed, compared to other tropical tree species, a high level of genetic diversity. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGenerapproach. The estimated multilocus outcrossing rate, tm, was 0.992 indicating nearly complete outcrossing. A significant level of biparental inbreeding and a small proportion of full-sibs were estimated for the 27 seed arrays. The differentiation of allelic frequencies among the pollen pools was ΦFT = 0.061. We estimated mean pollen dispersal distances between 65 m and 89 m according to the dispersal models used. The joint estimation of pollen dispersal and density of reproductive trees gave an effective density estimate of 2.1-2.2 trees/ha
Silvae genetica

hal-01031483
https://hal.archives-ouvertes.fr/hal-01031483

Éditeur(s) : HAL CCSD
Résumé : Le régime de reproduction de Dicorynia guianensis (caesalpiniaceae), arbre de la forêt guyanaise a été étudié à l'aide des marqueurs enzymatiques. Le matériel végétal a été collecté en 1993 et 1995, sur le dispositif sylvicole de Paracou. Le taux d'allofécondation moyen de la population est élevé, tm = 0,85, stable d'une année à l'autre malgré une variation importante du taux de floraison. Le taux individuel varie entre les arbres mais aucune corrélation n'a pu être établie avec des facteurs spatiaux, densité de floraison ou distance aux plus proches voisins. L'hétérogénéité des nuages polliniques est sensible au niveau des agrégats et des arbres individuels, échelle spatiale où se déploie l'activité des insectes pollinisateurs. Nous n'avons en évidence aucune corrélation spatiale entre compositions des nuages polliniques individuels. Des distances de migration du pollen de 190 mètres ont été mise en évidence grâce aux allèles rares. Aucune différence significative du régime de reproduction de D. guianensis n'a été trouvée entre parcelles traitées et parcelles témoin du dispositif.
Colloque BRG/USTL. Méthodologie de gestion et de conservation des ressources génétiques
Lille, France

hal-01032382
https://hal.archives-ouvertes.fr/hal-01032382

Éditeur(s) : HAL CCSD Wiley
Résumé : Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis Amshoff, a neotropical tree endemic to the Guiana shield. All adult trees within a continuous area of 40 ha (n = 157) were mapped, and were genotyped with six microsatellite loci. In addition, progenies were genotyped from 22 mature trees. At the population level, the species was mostly outcrossing (tm = 0.89) but there was marked variation among individuals. One tree exhibited mixed mating, confirming earlier results obtained with isozymes that D. guianensis can tolerate selfing. A Bayesian extension of the fractional paternity method was used for paternity analysis, and was compared with the neighbourhood method used widely for forest trees. Both methods indicated that pollen dispersal was only weakly related to distance between trees within the study area, and that the majority (62%) of pollen came from outside the study stand. Using maximum likelihood, male potential population size was estimated to be 1119, corresponding to a neighbourhood size of 560 hectares. Male mating success was, however, related to the diameter of the stem and to flowering intensity assessed visually. The mating behaviour of D. guianensis is a combination of long-distance pollen flow and occasional selfing. The species can still reproduce when it is extremely rare, either by selfing or by dispersing pollen at long distances. These results, together with the observation that male mating success was correlated with the size of the trees, could be implemented in management procedures aiming at regenerating the species
ISSN: 0962-1083

hal-01032227
https://hal.archives-ouvertes.fr/hal-01032227
DOI : 10.1111/j.1365-294X.2004.02127.x