Evaluation of apoptotic- and autophagic-related protein expressions before and after IVM of fresh, slow-frozen and vitrified pre-pubertal mouse testicular tissue Auteur(s) : Dumont, L. Chalmel, F. Oblette, A. Berby, B. Rives, A. Duchesne, V. Rondanino, C. Rives, N. Auteurs secondaires : Gamétogenèse et Qualité des Gamètes (GQG) ; Université de Rouen Normandie (URN) ; Normandie Université (NU) - Normandie Université (NU) - Université Lille 2 - Faculté de Médecine Institute for Research and Innovation in Biomedicine (IRIB) ; Université de Rouen Normandie (URN) ; Normandie Université (NU) - Normandie Université (NU) - Institut National de la Santé et de la Recherche Médicale (INSERM) Institut de recherche, santé, environnement et travail [Rennes] (Irset) ; Université d'Angers (UA) - Université des Antilles et de la Guyane (UAG) - Université de Rennes 1 (UR1) - École des Hautes Études en Santé Publique [EHESP] (EHESP) - Institut National de la Santé et de la Recherche Médicale (INSERM) - Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) Éditeur(s) : HAL CCSD Résumé : International audience STUDY QUESTION: Do freezing and in vitro culture procedures enhance the expression of proteins involved in apoptotic or autophagic pathways in murine pre-pubertal testicular tissue? SUMMARY ANSWER: IVM strongly modified apoptosis- and autophagy-related relative protein levels in mice testicular tissue whereas the impact of cryopreservation procedures was minimal at the end of the culture. WHAT IS KNOWN ALREADY: In vitro spermatogenesis remains a challenging technical issue as it imposes to find a very close balance between survival and death of germ cell natural precursors (i.e. gonocytes and spermatogonia), which will eventually undergo a complete spermatogenesis close to in vivo conditions. The establishment of efficient culture conditions coupled with suitable cryopreservation procedures (e.g. controlled slow freezing [CSF] and solid surface vitrification [SSV]) of pre-pubertal testicular tissue is a crucial step in the fields of fertility preservation and restoration to improve the spermatic yield obtained in vitro. STUDY DESIGN, SIZE, DURATION: Here, we study cryopreservation procedures (i.e. CSF or SSV) and the impact of culture media compositions. A first set of 66 mouse pre-pubertal testes were directly cultured during 30, 36, 38 and 60 days (D) from 2.5 to 6.5-day-old CD-1 mice to evaluate the impact of time-aspect of culture and to endorse the reverse phase protein microarrays (RPPM) technique as an adapted experimental tool for the field of in vitro spermatogenesis. Ninety others fresh, slow-frozen and vitrified pre-pubertal testes were cultured during 30 days for the principal study to evaluate the impact of cryopreservation procedures before and after culture. Thirty-four testes dissected from 2.5, 6.5, 36.5, 40.5, 42.5 and 62.5 days postpartum (dpp) mice, corresponding to the time frames of spermatogenesis orchestrated in vitro, were used as in vivo controls. PARTICIPANTS/MATERIALS, SETTING, METHODS: After in vitro culture, testicular tissue samples originated from 2.5 or 6.5-day-old CD-1 male mice were analyzed using RPPM. This targeted proteomic technique allowed us to assess the expression level of 29 apoptosis- and autophagy-related factors by normalizing blank-corrected signal values. In addition, morphological analyses (e.g. HES, PAS, TRA98 and CREM) and DNA fragmentation in intra-tubular cells (i.e. terminal deoxynucleotidyl transferase dUTP nick end labeling; TUNEL) were assessed for the distinct experimental conditions tested as well as for in vivo control mouse testes. MAIN RESULTS AND THE ROLE OF CHANCE: A validation of the RPPM procedure in the field of in vitro spermatogenesis was completed with assay and array robustness before a principal study concerning the evaluation of the impact of in vitro culture and cryopreservation procedures. The proportion of elongated spermatids and the total cell number per seminiferous tubule tended to be very different between the in vivo and in vitro conditions (P < 0.05), suggesting the presence of a beneficial regulation on the first spermatogenesis wave by intrinsic apoptosis (Caspase₉) and autophagy (Atg5) factors (P < 0.0003 and r2 = 0.74). Concerning the impact of culture media compositions, a basic medium (BM) composed of αMEM plus 10% KnockOut™ serum replacement and gentamicin supplemented with retinol (Rol) and vitamin E (Vit. E) was selected as the best culture medium for fresh 6.5 dpp tissue cultured during 30D with 27.7 ± 8.10% of seminiferous tubules containing elongated spermatids. Concerning the impact of cryopreservation procedures, SSV did not have any impact on the morphological parameters evaluated after culture in comparison to fresh tissue (FT) controls. The proportion of tubules with elongated spermatids on testicular explants cultured with BMRol+Vit. E was not different between SSV (6.6 ± 1.6%) and CSF (5.3 ± 1.9%); however, round spermatids were observed more frequently for SSV (19 ± 6.2%) than CSF (3.3 ± 1.9%, P = 0.0317). Even if the proportion of TUNEL-positive cells for BMRol+Vit. E was higher at D30 after SSV (4.12 ± 0.26%) than CSF (1.86 ± 0.12%, P = 0.0022) and FT (2.69 ± 0.33%, P = 0.0108), the DNA damages observed at the end of the culture (i.e. D30) were similar to respective 6.5 dpp controls. In addition, the relative protein level expression ratio of an apoptotic factor, the phosphorylated FADD on Fas, was reduced by 64-fold in vitrified testes cultured with BMRol+Vit. E. Furthermore, we found in this study that the StemPro®-34 SFM culture medium supplemented with growth factors (e.g. EGF, bFGF, GDNF and LIF) prevented the differentiation of spermatogonial stem cells in favor of a significant proliferation with a better architectural pattern than in vivo 6.5 dpp controls with an increase of seminiferous tubules area for FT (P = 0.0357) and CSF (P = 0.0317). LIMITATIONS REASONS FOR CAUTION: Despite our promising results, the evaluation of apoptotic- and autophagic-related proteins was studied for a limited amount of proteins and on global testicular tissue. WIDER IMPLICATIONS OF THE FINDINGS: The data presented herein will help to improve apoptotic and autophagic understanding during the first spermatogenic wave. Moreover, our findings illustrate for the first time that, using finely-tuned experimental conditions, a testicular in vitro culture combined with proteomic technologies may significantly facilitate the study of cryopreservation procedures and in vitro culture evaluations. This study may also contribute to improve work on testicular tissues from pre-pubertal and adolescent cancer survivors. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by a Ph.D. grant from the Rouen Normandie Université and a financial support from 'la Ligue nationale contre le cancer' (both awarded to L.D.), funding from Institute for Research and Innovation in Biomedicine (IRIB), Agence de la Biomédecine, and co-supported by European Union and Région Normandie. Europe gets involved in Normandie with European Regional Development Fund (ERDF). The authors declare that there is no conflict of interest. Molecular Human Reproduction hal-01647081 https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647081 DOI : 10.1093/molehr/gax054 PUBMED : 29040674 | Partager |
Copy of resignation letter from John F. Stevens to President Theodore Roosevelt Auteur(s) : Stevens, John F. (John Frank), 1853-1943 ( Author, Primary ) Résumé : (Biographical) From Wikipedia: John Frank Stevens (25 April 1853 – 2 June 1943) was an American engineer who built the Great Northern Railway in the United States and was chief engineer on the Panama Canal between 1905 and 1907. Biography: Stevens was born in rural Maine, near West Gardiner to John Stevens, a tanner and farmer, and Harriet Leslie French. He attended Maine State Normal School (now the University of Maine at Farmington) for two years. At the conclusion of his schooling in 1873, bleak economic conditions held little promise of a job, and he chose to go west. Entry into the field of civil engineering evolved from his experience in the Minneapolis city engineer's office. For two years he carried out a variety of engineering tasks, including surveying and building railroads, and at the same time gained experience and an understanding of the subject. He became a practical engineer, self-taught and driven by a self-described "bull-dog tenacity of purpose." In 1878 Stevens married Harriet T. O'Brien. They had five children, two of whom died in infancy.
By the age of 33, in 1886, Stevens was principal assistant engineer for the Duluth, South Shore and Atlantic Railway, and in charge of building the line from Duluth, Minnesota to Sault Ste. Marie, Michigan, across the Upper Peninsula of Michigan. Although a large part of his work involved surveying, he assisted in all phases of railroading: reconnaissance, locating, organizing, and construction.
In 1889, Stevens was hired by James J. Hill as a locating engineer for the Great Northern Railway.
Stevens earned wide acclaim in 1889 when he explored Marias Pass, Montana, and determined its practicability for a railroad. Stevens was an efficient administrator with remarkable technical skills and imagination. He discovered Stevens Pass through the Cascade Mountains, set railroad construction standards in the Mesabi Range of northern Minnesota, and supervised construction of the Oregon Trunk Line. Hill promoted him to chief engineer in 1895, and later to general manager. During his time at the Great Northern, Stevens built over a thousand miles of railroad, including the original Cascade Tunnel. Stevens Pass in the Cascade Range was named for him. (Most other Pacific Northwest landmarks with the word "Stevens" are named after Isaac Stevens, who is of no relation.)
Panama Canal:
Stevens left the Great Northern in 1903 for the Chicago, Rock Island and Pacific Railroad, where he was promoted to vice-president. Then, in 1905, at Hill's recommendation, he was hired by Theodore Roosevelt as chief engineer on the Panama Canal.
Stevens' primary achievement in Panama was to build the infrastructure needed for the completion of the canal. "The digging," he said, "is the least thing of all." He proceeded immediately to build warehouses, machine shops, and piers. Communities for the personnel were planned and built to include housing, schools, hospitals, churches, and hotels. He authorized extensive sanitation and mosquito-control programs that eliminated yellow fever and other diseases from the Isthmus. Reflecting his background, he saw the early stage of the canal project itself as primarily a problem in railroad engineering, which included rebuilding the Panama Railway and devising a rail-based system for disposing of the soil from the excavations. Stevens argued the case against a sea level canal like the French had tried to build. He successfully convinced Theodore Roosevelt of the necessity of a high-level canal built with dams and locks.
Resignation:
Stevens resigned suddenly from the Canal project in 1907 to Roosevelt's great annoyance, as the focus of the work turned to construction of the canal itself. As a railroad engineer, Stevens had little expertise in building locks and dams, and probably realized he was no longer the best person for the remainder of the job. Stevens would also have been aware that the original great Cascade Tunnel, for which he was responsible, was in hindsight built in error too close to the ruling grade and was perhaps turning from a credit to a debit. The true reasons for his resignation have never been known.
Subsequent career:
Following the collapse of Imperial Russia in 1917, leaders of the provisional government appealed to President Wilson for help with their transportation systems. Stevens was selected to chair a board of prominent U.S. railroad experts sent to Russia to rationalize and manage a system that was in disarray; among his work was on the Trans-Siberian Railway. After the overthrow of the provisional government, the board's work ceased. Stevens remained in Allied-occupied Manchuria and in 1919 headed the Inter-Allied Technical Board charged with the administration and operation of the Chinese Eastern and Siberian railways. He remained in an advisory capacity until occupying Allied troops were withdrawn; he finally left in 1923. After his return to the United States Stevens continued to work as a consulting engineer, ending his career in Baltimore in the early 1930s. He was awarded the Franklin Institute's Franklin Medal in 1930. He then retired to Southern Pines, North Carolina, where he died at the age of 90 in 1943. Digital version only, no paper copy in collection archives. Droits : This item is presumed to be in the public domain. The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions may require permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact Digital Services (UFDC@uflib.ufl.edu) with any additional information they can provide. http://ufdc.ufl.edu/AA00029596/00001 | Partager |
Research framework for the developpement of creole pig's niche lmarket in Martinique : a holistic approach" ; Cadre de recherches pour le développement du marché de niches du porc créole martinique : une apprache holistique Auteur(s) : Gourdine, Jean-Luc Année de publication : Loading the player... Éditeur(s) : INRA : Institut National de la Recherche Agronomique Université des Antilles. Service commun de la documentation 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 : The Creole pig has always been part of the rural and suburban landscape of Martinique. Currently, this breed is not integrated into a research and conservation program. The Natural Park of Martinique Region (PNRM) has the objective to maintain and valorize the genetic heritage of Martinique?s Creole pig and develop a niche business. Based on PNRM knowledge, some Creole pigs live freely in the mountains in the North, in the South coast and in a few disparate traditional breeders located in the countryside. It is essential to carry out an inventory of the local pig population to propose a scheme for conservation and economic development. In order to favour the appropriation of the Creole pig niche, the PNRM, as a decision maker, acts in a systemic and holistic way by considering the whole Martinican territory and the pig sub-sector: producers involved in the COOPMAR pig farmers? cooperative, researchers of INRA (FWI), the food chain and at least (in a second phase) the consumers and the Martinican society. First of all, the pig farmers are involved (private family farms and specialised pig producers). Researchers and technicians from PNRM and INRA- URZ (Animal production research unit) and INRA-PTEA (Tropical platform in animal experimentation) are performing experimental studies both in controlled conditions and in farms, in order to: i) determine phenotypic and genetic characteristics of Martinique?s Creole pigs in comparison with other pig breeds from the Caribbean area; ii) help at designing genetic management to maintain the population and avoiding inbreeding; iii) help at defining feeding management by a) establishing, at the whole territorial food chain, an inventory of co or by-products available for pig feeding; b) implementing experimental studies in technology for conservation; c) implementing feeding and growing experiments and finally iv) help at defining eco-friendly production systems a) aiming at generate an adequate revenue and b) focusing on ecosystem services such as meat quality, socio-cultural services and circular economy. Le porc créole a toujours fait partie du paysage rural et suburbain de la Martinique. Actuellement, cette race n'est pas intégrée dans un programme de recherches et de conservation. Le parc naturel de la région de la Martinique (PNRM) a l'objectif pour maintenir et valoriser l'héritage génétique du porc créole de la Martinique et pour développer des créneaux. Basé sur la connaissance de PNRM, quelques porcs créoles vivent librement dans les montagnes dans le nord, dans la côte sud et chez quelques éleveurs traditionnels disparates situés dans la campagne. Il est essentiel d'effectuer un inventaire de la population locale de porc pour proposer un plan pour la conservation et le développement économique. Afin de favoriser l'appropriation du créneau créole de porc, le PNRM, comme décideur, agit d'une manière systémique et holistique en considérant tout le territoire de la Martinique et sous-secteur de porc : producteurs impliqués dans la coopérative d'agriculteurs de porc de COOPMAR, les chercheurs d'AICN (FWI), la chaîne alimentaire et au moins (dans une deuxième phase) les consommateurs et la société Martiniquaise. Tout d'abord, les agriculteurs de porc sont impliqués (les fermes privées de famille et les producteurs de porc spécialisés). Les chercheurs et les techniciens de PNRM et AICN URZ (unité de recherches de production animale) et INRA-PTEA (plate-forme tropicale chez l'expérimentation animale) réalisent des études expérimentales dans des conditions commandées et dans les fermes : i) déterminent des caractéristiques phénotypiques et génétiques des porcs créoles de la Martinique en comparaison d'autres races de porc à partir du secteur des Caraïbes ; ii) aide à concevoir la gestion génétique pour maintenir la population et à éviter l'endogamie ; iii) aide à définir la gestion de alimentation a) en établissant, à la chaîne alimentaire territoriale de totalité, à un inventaire de Co ou aux sous-produits disponibles pour l'alimentation de porc ; b) mise en oeuvre des études expérimentales en technologie pour la conservation ; c) mettant en application des expériences de alimentation et croissantes et finalement iv) aide à définir viser qui respecte l'environnement des systèmes de production a) produisent de à revenu approprié et b) se concentrant sur des services d'écosystème tels que la qualité de viande, des services socioculturels et l'économie circulaire. Siècle(s) traité(s) : 21 Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification Permalien : http://www.manioc.org/fichiers/V16263 V16263 | Partager |
Sources and Fate of Organic Matter in Ocean Sediments Auteur(s) : Tissot, B Pelet, R Éditeur(s) : Gauthier-Villars Résumé : The three main sources of organic matter in oceanic basins are marine plankton, terrestrial higher plants and undifferentiated residual organic matter which has been highly degraded in subaerial environments. The time and areal distribution of marine organic matter is mainly controlled by the conditions of preservation. In deep oceans accumulation occurs mainly in confined anoxic basins, and also in open ocean, where local conditions generate a surplus of supply over bacterial degradation. Moderately degraded terrestrial organic matter is derived from land plants and carried away by rivers and currents. It is mainly deposited in sediments of the river fans. Residual organic matter has been highly degraded in subaerial conditions prior to transportation, and may consist of contemporaneous and/or recycled material. It cannot be degraded any more and may be spread over wide areas, regardless of the local environments. Oceanologica Acta, Special issue (0399-1784) (Gauthier-Villars), 1981 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00246/35680/34188.pdf http://archimer.ifremer.fr/doc/00246/35680/ | Partager |
Depositional environment and processes of formation of the Mn-carbonates in the paleoproterozoic black shales of the Franceville basin (2.1 GA ; Gabon) ; Environnement de dépôt et processus de formation des carbonates de manganèse dans les black shales paléoprotérozoiques du Bassin de Franceville (2.1 Ga ; Gabon) Auteur(s) : DUBOIS, Manon Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Université de Montpellier Michel Lopez Beate Orberger Éditeur(s) : HAL CCSD Résumé : The Franceville Basin (2.1 Ga) in southeastern Gabon, hosts a black shale series well preserved (FB Formation) which represents an exceptional example of unmetamorphised Paleoproterozoic sediment strata. This basin includes the protore of one of the largest Mn-oxide laterite ore worldwide, mined by Eramet-Comilog. The aim of this this work is to determine formation conditions of this protore and to characterize the global sedimentary evolution of the FB Formation which include the protore. This 75 m thick protore is constituted of Mn carbonate-rich black shales which represent a potential ore deposit for the future. It was drilled, on the Bangombé plateau, during a recent campaign of 24 boreholes with an average depth of 125 m.Through multidisciplinary study on these cores and key outcrops of the basin, this work focuses on : i) the depositional environment of the Mn-protore and FB Formation ; ii) the processes of formation of the Mn-carbonates at 2.1 Ga and iii) the architecture and distribution of Mn-rich levels of the protore on the Bangombé Plateau.A detailed sedimentological and petrological study allowed us to redefine the division of the FB into nine units, named U1 to U9 from the base to the top. These units show a fine upward cycle up to U5 and a reverse coarse loop until U9. This division leads to a new interpretation to propose an evolution from a shoreface depositional environment controlled by deltaic currents (U1) to an offshore depositional environment with anoxic conditions (U2). In this basin, a system of submarine fan is developed, feeding a network of sand injections (injectites) covering the Bangombé plateau (70 km²) and with a thickness of 150 m affecting U4 to U7, including the Mn-protore. The protore depositional environment formed below the wave base limit (U4, U5 and U6) in a starved basin, controlled by biochemical sedimentation allowed the formation of Mn-carbonates. The end of starved basin, would allow the re-opening of the detrital input into the offshore basin (U7). This basin is then filled by storm bar deposits intersected by deltaic sub-aquatic channels (U8). The U9 unit corresponds to a quiet lagoon environment, allowing the multicellular organism development for the first time on the planet.A geochemical study allowed the characterization of the depositional environment of Mn-carbonates as an anoxic to sub-oxic and alkaline environment. For the first time, we showed that the manganese carbonates, present as bacteriomorph forms, are precipitated from the seawater by the mediated photosynthetic cyanobacterial activity, which allows CO2 / HCO3 depression of the environment and a local increase of pH. The cyanobacterial activity is controlled by the absence of bottom currents, which increase the detrital input. This would stop the activity of the cyanobacteria and thus would lead to the decrease of the Mn-concentration along the protore.Finally, well-log and a sequential correlation analyses allowed us to detail spatial and timing repartition of FB Formation deposit, controlled by a tectono-sedimentary model. We propose two- tectono-sedimentary phases. A first syn-tectonic phase (U1 to U3) controls the depocentres and sedimentation gaps. Turbidite coarse deposits are located in the most subsident part, clay deposits rather on the slope and carbonates on shoals. A second post-tectonic phase (U4 to U7) allows isopach deposits. The Mn-protore formed during the post-tectonic phase. However, it shows a variable thickness due to subsidence to the north of the Bangombé plateau. So, on the Bangombé plateau, Mn-contents increase towards the south, whereas the protore thickness increases towards the NNE. Moreover sand injectites decrease Mn-content in the eastern part of the Bangombé plateau and impact on the economic evaluation of the Mn-carbonates. Currently, the protore is structured by post-sedimentary faults, which lead to a non-continuity of the high Mn levels on the Bangombé plateau. Le Bassin de Franceville situé au SE du Gabon présente une série de black shales (Formation FB) d'âge Paléoprotérozoïque (2,1 Ga) surmontant les grès de la Formation FA. Ce bassin peu déformé et non métamorphique représente une archive exceptionnelle des processus de dépôt de cette période de l’histoire de la Terre où la vie commence à se développer. En particulier, la Formation FB contient le protore d'un gisement mondial d'oxydes de manganèse exploité par la société Eramet-Comilog. L’objectif de ce travail est de préciser les conditions de formation de ce protore et de le replacer dans l’histoire du remplissage du bassin. Ce protore d'une épaisseur moyenne de 75 m est constitué de carbonates de manganèse ; il a fait l'objet d'une récente campagne de 24 forages carottés d'une profondeur moyenne de 125 m sur le plateau de Bangombé.A travers une approche pluridisciplinaire comprenant l'étude de ces forages et des affleurements clefs du bassin, ce travail porte sur la caractérisation i) de l'environnement de dépôt du protore et des séries qui l'encadrent (du toit du FA au toit du FB) ; ii) du mode de formation des carbonates de Mn à 2,1 Ga et iii) de l'architecture et de la répartition des hautes teneurs en Mn du protore qui représente un gisement potentiel du futur.L’étude pétro-sédimentaire détaillée a permis de distinguer neuf unités (U1 à U9) au sein de la Formation FB organisées suivant un cycle rétrogradant jusqu’à U5 puis progradant jusqu’à U9. Ce découpage montre une évolution du milieu de dépôt depuis un domaine de shoreface contrôlé par des courants deltaïques (U1) évoluant vers des dépôts d’offshore restreint (U2). Ce bassin enregistre ensuite un système de chenaux-levées turbiditiques (U3) qui alimentent un réseau d'injectites reconnu sur l’ensemble du Pl. de Bangombé et qui traverse 150 m de série (U4 à U7) en affectant le protore et ainsi les teneurs en Mn. L'environnement de dépôt du protore (U5 et U6) marque l’isolement du bassin qui devient affamé et contrôlé par une sédimentation biochimique à l’origine du dépôt des carbonates de Mn. L'Unité 7 correspond à la réouverture des apports détritiques en domaine d'offshore supérieur puis en domaine de shoreface dominé par des dépôts de tempêtes et de chenaux sous-aquatiques deltaïques (U8), et enfin lagunaire (U9) dans lequel apparaissent les premiers métazoaires de l’histoire de la planète, suivant une séquence régressive.Une étude géochimique a permis de préciser les conditions de dépôt du protore qui se forme en milieu alcalin anoxique à sub-oxique. Dans ce milieu, nous montrons pour la première fois une précipitation directe des carbonates de Mn sous forme bactériomorphe induite par l'activité photosynthétique des cyanobactéries qui consomment le CO2/HCO3 et conduisent à une augmentation du pH favorable à la formation des carbonates de Mn. L'activité cyanobactérienne est conditionnée par l’absence de courants de fond qui augmentent la turbidité du milieu et stoppent cette dernière.Les corrélations diagraphiques et séquentielles permettent de préciser la répartition spatiale et temporelle du FB permettant ainsi de replacer le protore dans l’histoire tectono-sédimentaire du bassin. Une première phase syn-tectonique (U1 à U3) contrôle l’épaisseur et la mise en place de dépôts turbiditiques dans les parties subsidentes, de dépôts argileux sur les pentes et de dépôt de carbonates sur les hauts-fonds. La seconde phase post tectonique (U4 à U7) permet la mise en place de dépôts relativement isopaques, bien que le protore enregistre une subsidence plus importante au nord du Pl. de Bangombé. On observe ainsi, sur le Plateau de Bangombé, des teneurs en Mn qui augmentent vers le sud alors que l’épaisseur du protore augmente vers le NNE. Postérieurement au dépôt du FB, le protore est structuré par des failles qui le compartimentent en touches de piano limitant ainsi sa continuité sur le Plateau de Bangombé. https://hal.archives-ouvertes.fr/tel-01621460 tel-01621460 https://hal.archives-ouvertes.fr/tel-01621460 https://hal.archives-ouvertes.fr/tel-01621460/document https://hal.archives-ouvertes.fr/tel-01621460/file/these_Dubois2017-MnGabon.pdf | Partager |
Acclimatation de nouvelles espèces d'huîtres creuse du genre Crassostrea: hybridation et conservatoire de souches - Contrat de Plan Etat Région Poitou-Charentes 1994-1998 - Synthèse finale Auteur(s) : Boudry, Pierre Heurtebise, Serge Huvet, Arnaud Chollet, Bruno Ledu, Christophe Phelipot, Pascal Gerard, Andre Résumé : Actions menées de 1994 à 1998 au sein du conservatoire de souches : 1. Résultats des importations, acclimatation et hybridation. a) Rappel des conditions d'introduction de nouvelles souches. L'importation de toute espèce est conditionnée par les résultats d'une enquête préliminaire dont l'objet est de rechercher les exigences écologiques de l'espèce et la situation épidémiologique dans son milieu d'origine. Le travail du LGP et de ses partenaires a été partagé en différentes actions: 1. Recherche de contacts dans divers pays étrangers, en vue de l'importation d'huîtres présentant des caractéristiques intéressantes. 2. Importation : L'importation se fait selon les normes du CIEM (Conseil International pour l'Exploration de la Mer) : contrôles pathologiques sur les lots d'animaux importés, confinement en salle de quarantaine des géniteurs avec stérilisation systématique des eaux de rejet, sacrifice des géniteurs après la production de la première génération. 3. Production d'une première descendance: La ponte est également réalisée en salle de quarantaine. Des contrôles pathologiques auront lieu tout au long de l'élevage. 4. Contrôle des performances : ils se font, dans un premier temps, uniquement au laboratoire avec stérilisation des eaux de rejet. Cette caractérisation intègre différentes approches : résistance aux parasites présents dans le milieu français, caractères quantitatifs (poids, taille, rendement, vitesse de croissance), polymorphisme enzymatique ou ADN, tests physiologiques (mesure de la respiration, du rendement d'assimilation ... ). 5. Hybridation: Des hybridations entre espèces ont été tentées, avec contrôle par marqueurs génétiques. 6. Conservatoire de souches : Les générations F1 des différentes espèces ont systématiquement été conservées. Une salle a été spécialement équipée au LGP dans cet objectif. Droits : 1998 Ifremer http://archimer.ifremer.fr/doc/00044/15520/12907.pdf http://archimer.ifremer.fr/doc/00044/15520/12922.pdf http://archimer.ifremer.fr/doc/00044/15520/ | Partager Voir aussi Génétique Acclimatation Hybridation Marqueurs moléculaire Marqueurs populations Crassostrea Télécharger |
Waterborne nickel bioaccumulation in Gammarus pulex: Comparison of mechanistic models and influence of water cationic composition Auteur(s) : Lebrun, Jeremie D. Perret, Marine Uher, Emmanuelle Tusseau-vuillemin, Marie-helene Gourlay-france, Catherine Éditeur(s) : Elsevier Science Bv Résumé : The biodynamic and saturation models offer promising lines of enquiry to predict the bioaccumulation of metals by aquatic organisms. However, in order to construct these models, the accumulation strategies have to be defined for each metal/organism couple in controlled conditions. This study aims at modelling the waterborne bioaccumulation of Ni and the influence of the water's geochemical properties on this process in a crustacean that is widely distributed in Europe, Gammarus pulex. In the laboratory, G. pulex was exposed to several Ni concentrations (from 0.001 to 100 mg L(-1)) in aquatic microcosms. Our results show that G. pulex is very tolerant to Ni (LC50(48 h) = 477 mg L(-1) Ni). Time course experiments enabled the construction of a biodynamic model by determining the uptake (k(u)) and elimination (k(e)) rate constants. When the exposure concentration exceeded 1 mg L(-1) Ni, the metal uptake reached a maximum due to a limited number of binding sites for Ni. Therefore, the organism's maximal capacity to accumulate the metal (B(max)) and the half-saturation constant (K) were determined to establish the saturation model. We showed that the two models are comparable for the lowest exposure concentrations (<1 mg L(-1) Ni), with k(u)/k(e) = B(max)/K. Then, the bioaccumulation of Ni was recorded in waters exhibiting various concentrations of three major ions (Na(+), Mg(2+) and Ca(2+)). Only Ca had an inhibitory effect on the Ni uptake. This study reports for the first time the bioaccumulation of Ni in G. pulex. Because of its high tolerance to Ni and its high capacity to accumulate this metal, this crustacean could be used as an indicator of Ni bioavailability in freshwaters. (C) 2011 Elsevier B.V. All rights reserved. Aquatic Toxicology (0166-445X) (Elsevier Science Bv), 2011-08 , Vol. 104 , N. 3-4 , P. 161-167 Droits : 2011 Elsevier B.V. All rights reserved. http://archimer.ifremer.fr/doc/00041/15217/18005.pdf DOI:10.1016/j.aquatox.2011.04.011 http://archimer.ifremer.fr/doc/00041/15217/ | Partager Voir aussi Biodynamic kinetics Saturation model Gammarid Bioavailability Water chemistry Aquatic microcosms Télécharger |
Reconstructing individual food and growth histories from biogenic carbonates Auteur(s) : Pecquerie, Laure Fablet, Ronan De Pontual, Helene Bonhommeau, Sylvain Alunno-bruscia, Marianne Petitgas, Pierre Kooijman, Sebastiaan A. L. M. 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/ | Partager Voir aussi Otolith Calcification Metabolism Bioenergetic model Food reconstruction Dynamic Energy Budget theory Télécharger |
Seasonal Pattern of the Biogeochemical Properties of Mangrove Sediments Receiving Shrimp Farm Effluents (New Caledonia) Auteur(s) : Marchand, Cyril Molnar, N. Deborde, Jonathan Della Patrona, Luc Meziane, Tarik Éditeur(s) : OMICS Publishing Group Résumé : Coastal tropical shrimp farming may impact the adjacent ecosystems through the release of large quantities of effluents rich in nutrients. In New Caledonia, mangroves are considered as a natural biofilter to reduce impacts on the surrounding World Heritage listed lagoon. Our main objective was to understand the influence of effluent discharge on the biogeochemistry of mangrove sediments. A monitoring of the physico-chemical parameters of mangrove sediments was carried out during a whole year, including active and non active periods of the farm. The parameters studied were: i) benthic primary production (Chl-a concentrations), ii) physico-chemical parameters of sediments (redox potential, pH, salinity, TOC, TN, TS, δ13C and δ15N), iii) concentrations of dissolved nitrogen, iron and phosphorus. A mangrove developing in the same physiographic conditions, presenting the same zonation, and free of anthropogenic input was used as reference. The concentration of benthic Chl-a measured at sediment surface in the effluent receiving mangrove was twice to three times that measured in the control zone whatever the season. We thus suggest that nutrients inputs significantly increased the phytobenthic production in the effluent receiving mangrove during the whole year, even after the cessation of discharges and because of natural seasonal dynamic of phytobenthos. Although the flow of surface OM was increased, the OM content at depth was not higher than in the control mangrove. However, the contribution of mangrove detritus to the sedimentary organic pool was higher probably as a result of higher density and much greater individual size of the mangrove trees. Unlike the control mangrove sediment, the effluent receiving mangrove sediment was not stratified, redox potential values were high and presence of Fe3+ was detected down to 50 cm depth, probably as a result of a larger root system, allowing a better sediment oxygenation and accentuated OM decomposition processes, and thus limiting ecosystem saturation. Journal of Aquaculture Research & Development (21559546) (OMICS Publishing Group), 2014-07-03 , Vol. 5 , N. 5 , P. 1-13 Droits : 2014 Marchand C, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://archimer.ifremer.fr/doc/00251/36253/34801.pdf DOI:10.4172/2155-9546.1000262 http://archimer.ifremer.fr/doc/00251/36253/ | Partager |
Incipient hydration of mantle lithosphere at ridges: A reactive-percolation experiment Auteur(s) : Godard, Marguerite Luquot, Linda Andreani, Muriel Gouze, Philippe Auteurs secondaires : Manteau et Interfaces ; Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) - Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE) ; École normale supérieure - Lyon (ENS Lyon) - Université Claude Bernard Lyon 1 (UCBL) - Institut national des sciences de l'Univers (INSU - CNRS) - Centre National de la Recherche Scientifique (CNRS) Transferts en milieux poreux ; Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) - Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Éditeur(s) : HAL CCSD Elsevier Résumé : International audience A reactive percolation experiment was conducted by injecting seawater into a permeable olivine aggregate at 190 °C and 19 MPa to explore the relationships between hydration reactions and hydrodynamic properties during the onset of serpentinization in the ultramafic lithosphere exposed at mid-ocean ridges. The experiment was stopped after 23 days when the sample became impermeable. The initial flow rate was 0.2 mL/h and then was decreased down to 0.06 mL/h after 8 days. Permeability decreased continuously throughout the experiment. The analyses of fluid chemistry time series and of the mineralogy and structure of the reacted sample showed olivine dissolution and precipitation of proto-serpentine, brucite and Fe-oxides. These reactions are controlled by coupled hydrodynamic and chemical processes interacting at different time and spatial scales. Their first characteristic is the production of silica rich outlet fluids in disequilibrium with the observed reacted mineral assemblages. These compositions are interpreted as resulting from a suite of coupled dissolution-precipitation reactions, controlled at the pore scale by surface kinetic processes, that rapidly reaches steady-state (constant fluid composition independent of fluid flux). Hence, the effective rate of serpentinization was controlled, to the first order, by the transport of reactants during the experiment. Mass balance calculations show that the rate of olivine conversion was fast (0.2-0.5 wt%/day), yet only ∼8 wt% of the olivine sample reacted, because the permeability drop limited fluid circulation. Porosity varied little during the experiment compared to permeability changes: the decrease of permeability was explained by the structure of the newly formed serpentine favouring the clogging of fluid paths. The rate at which permeability decreased was the fastest at low flux conditions. This suggests that permeability changes were not controlled simply by the kinetics of the serpentinization reactions, but mainly reflected the development of low Peclet pore scale zones forming micro-environments that control the serpentinization reaction-paths. These results outline the need to take into account the coupling of hydrodynamic and chemical processes when modelling the effects of reactive transport within the hydrating oceanic lithosphere. ISSN: 0012-821X hal-00855043 https://hal.archives-ouvertes.fr/hal-00855043 DOI : 10.1016/j.epsl.2013.03.052 | Partager |
Evaluation of floating cages as an experimental tool for marine shrimp culture studies under practical earthen pond conditions Auteur(s) : Chim, Liet Castex, Mathieu Pham, Dominique Brun, Pierre Lemaire, Pierrette Wabete, Nelly Schmidely, P Mariojouls, C Éditeur(s) : Elsevier Résumé : The New Caledonia blue shrimp Litopenaeus stylirostris is commercially produced under semi-intensive rearing conditions. The size of the farming earthen ponds (510 ha) and the subsequent production constraints make it difficult to use them as experimental units for random experiments. Moreover, since every pond has its own characteristics, ponds' effects cannot be ruled out, thus making it hard to define true replicates. In order to design future experiments under conditions resembling those used in production, we evaluated the possible use of floating cages as experimental units with the aim of assessing treatment effects with a reasonable statistical power. To this end, two sets of floating cages were placed respectively in two different ponds in a commercial farm. In both cases the zootechnical conditions in the cages were similar in post-larvae origin, management, and diet and feeding regime. The aim of the study was to evaluate on a technical basis the possibility of rearing shrimps in floating cages set up in earthen ponds and to assess this method from a statistical standpoint. Shrimps reared in and outside the cages showed comparable growth and survival rates. The variability in the zootechnical parameters between cages, expressed as the estimated coefficient of variation (CV) for survival rate, total final biomass (g), final body weight (g), daily increment in body weight (g day− 1) and FCR were 11.0, 13.7, 4.4, 5.4, and 7.0%, respectively. On the basis of these figures, we calculated for a given statistical power (80%) the number of replicates (cages) that would be required to reveal significant differences between two treatments, at a 5% level of significance. We found that for expected differences of 20% from the control mean, 3 and 6 floating cages per treatment would be reasonable to determine statistical differences for growth parameters and survival rate, respectively. Moreover, we showed a significant pond effect in regard to survival and growth between the two sets of cages. These results illustrated the within-farm variability among the ponds, and confirmed that the specific characteristics of each pond from the same farm make it difficult to use the ponds themselves as experimental units. The study demonstrates that rearing in floating cages is an economical, powerful and sensitive experimental tool for shrimp culture studies specifically carried out under conditions close to semi-intensive production. Aquaculture (0044-8486) (Elsevier), 2008-07 , Vol. 279 , N. 1-4 , P. 63-69 Droits : 2008 Elsevier B.V. All rights reserved. http://archimer.ifremer.fr/doc/2008/publication-4363.pdf DOI:10.1016/j.aquaculture.2008.03.053 http://archimer.ifremer.fr/doc/00000/4363/ | Partager Voir aussi Statistical power Replicates Pond experimentation Floating cages Litopenaeus stylirostris Télécharger |
Experimental determination of porosity and permeability changes induced by injection of CO2 into carbonate rocks Auteur(s) : Luquot, Linda Gouze, Philippe Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Éditeur(s) : HAL CCSD Elsevier Résumé : International audience A set of four reactive flow-through experiments at temperature T = 100 degrees C and total pressure P=12 MPa was performed in limestone reservoir samples. By using various ranging from 0.7 to 10 MPa, these experiments mimic mass transfers occurring (1) near the injection well, where the brine is almost saturated with CO2 (i.e. P-CO2 approximate to P), and (2) at increasing distances from the injection well, where the fluid displays lower values and higher divalent cation concentrations due rock dissolution along the fluid pathway. Results for P-CO2 = 10 MPa show non-uniform dissolution features associated with transport-controlled mass transfer, while reaction-controlled uniform dissolution is observed for P-CO2 = 2.5 MPa. The experiment with P-CO2 = 6 MPa allows investigating in detail the transition from transport-to reaction-controlled dissolution. Conversely, the experiment reproducing conditions far from the injection well (P-CO2 = 0.7 MPa), shows a decrease of porosity triggered by the precipitation of Mg-rich calcite. For all the dissolution experiments, the time-resolved porosity phi(t) can be modeled by a simple non-linear equation including parameters that characterise the dissolution regime triggered by the reactivity of the inlet fluid (measured by the Damkohler number, Da). Furthermore, all dissolution experiments display power scaling between permeability (k) and porosity (phi) with distinctly different scaling exponents characterising the reactivity of the fluid percolating the sample, independently from the decrease with time of the reactive surface area. It is shown also that dissolution at moderate positive values of Da seems the most efficient to increase permeability and promote a rapid spreading of the reaction front, while inducing minimal modification of the porosity in the vicinity of the CO2 injection well. These results can be used to parameterize the k-phi function for modeling the earliest dissolution processes occurring in the vicinity of the reaction front. ISSN: 0009-2541 hal-00445277 https://hal.archives-ouvertes.fr/hal-00445277 DOI : 10.1016/j.chemgeo.2009.03.028 | Partager |
Interactions between tectonics and surface processes in Taiwan : insights from sandbox experiments Auteur(s) : Lu, C.Y. Malavieille, Jacques Chang, Kuo Jeng Chan, Y. Konstantinovskaya, E. Auteurs secondaires : Department of Geosciences ; Université du Québec Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Institute of Earth Sciences [Tapei] (IES Sinica) ; Academia Sinica Éditeur(s) : HAL CCSD Résumé : In Taiwan , the subduction of the Chinese continental margin under the Luzon arc results in the progressive growth of an active orogenic wedge. It is one of the best places to study the complex relationships that occurs between the tectonic processes controlling deformation (plate rheology and kinematics, metamorphism and magmatism) and surface processes (erosion and sedimentation). In order to study the kinematics of the present day convergence of Philippine Sea plate to the Asian continent around Taiwan, we perform 2D and 3D sandbox modeling and we analyzed the models with PIV (Particle Image Velocimetry) software. In 2D experiments, a model Coulomb wedge is submitted to erosion and sedimentation under topography and flux steady state conditions. The 3D experiments are mainly used to study the escape tectonics occurring in the middle west and southwest Taiwan. A wedge shaped indenter and a basement relief were used to simulate the mechanical plate boundary between Philippine Sea plate and Eurasia plate and the basement topography to the west of Taiwan respectively. We examine the exhumation patterns, the mode of fault propagation and displacement patterns by strain partitioning of vertical vs. horizontal displacement and convergent parallel vs. orogen parallel components. The preliminary conclusions are: 1. The interactions between tectonics, erosion and sedimentation control geometry and kinematics of the doubly vergent transpressional orogen. 2. Exhumation processes are controlled by the balance between erosion, frontal accretion and underplating in different structural domains of the wedge. 3. Retrowedge erosion favorites backfolding and backthrusting, induces flower structures and fan shaped cleavage distribution. 4. Sedimentation promotes underplating and out-of sequences thrusting. 5. Continental subduction or subduction of topographic highs will enhance underthrusting/underplating, thick-skin tectonics and inversion of sedimentary basin. Bolletino di Geofisica teorica ed applicata hal-00411133 https://hal.archives-ouvertes.fr/hal-00411133 | Partager |
Does the diurnal increase in central temperature interact with pre-cooling or passive warm-up of the leg? Auteur(s) : Racinais, Sébastien Blonc, Stephen Oksa, Juha Hue, Olivier Auteurs secondaires : Adaptations au Climat Tropical, Exercice et Santé (ACTES) ; Université des Antilles et de la Guyane (UAG) Exercise and Sports Science Department ; Qatar Orthopaedic and Sports Medicine Hospital Physical Work Capacity Team ; Finnish Institute of Occupational Health Éditeur(s) : HAL CCSD Elsevier Résumé : International audience Seven male subjects volunteered to participate in an investigation of whether the diurnalincrease in core temperature influences the effects of pre-cooling or passivewarm-up on muscular power. Morning (07:00-09:00 h) and afternoon (17:00-19:00 h) evaluation of maximal power output during a cycling sprint was performed on different days in a control condition (room at 21.8 °C, 69% rh), after 30 min of pre-cooling in a cold bath (16 °C), or after 30 min of passivewarm-up in a hot bath (38 °C). Despite an equivalent increase from morning to afternoon in core temperature in all conditions (+0.4 °C, P < 0.05), power output displayed a diurnalincrease in control condition only. A local cooling or heating of the leg in a neutral environment blunted the diurnal variation in muscular power. Because pre-cooling decreases muscle power, force and velocity irrespective of time-of-day, athletes should strictly avoid any cooling before a sprint exercise. In summary, diurnal variation in muscle power output seems to be more influenced by muscle rather than core temperature. ISSN: 1440-2440 hal-00706159 https://hal.univ-antilles.fr/hal-00706159 DOI : 10.1016/j.jsams.2007.09.008 | Partager |
Alteration patterns of chromian spinels from La Cabana peridotite, south-central Chile Auteur(s) : Barra, Fernando Gervilla, Fernando Hernandez, Elkin Reich, Martin PADRON NAVARTA, Jose alberto Gonzalez-Jimenez, Jose M. Auteurs secondaires : Universidad de Santiago de Chile [Santiago] (USACH) Universidad de Granada (UGR) Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Manteau et Interfaces ; Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) - Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag Résumé : International audience La Cabaña peridotite is part of a dismembered ophiolite complex located within the metamorphic basement of the Coastal Cordillera of south-central Chile, and is the only location in Chile were Cr-spinels have been described so far. The La Cabaña peridotite is part of the Western Series unit, which comprises meta-sedimentary rocks, metabasites, and serpentinized ultramafic rocks. This unit has been affected by greenschist-facies metamorphism with reported peak PT conditions of 7.0–9.3 kbar and 380°–420 °C. Within La Cabaña peridotite Cr-spinels are present in two localities: Lavanderos and Centinela Bajo. In Lavanderos, Cr-spinel occurs in small chromitite pods and as accessory/disseminated grains with a porous or spongy texture in serpentinite, whereas in Centinela Bajo Cr-spinel is present as accessory zoned grains in partly serpentinized dunites, and in chromitite blocks. All Cr-spinels display variable degrees of alteration to Fe2+-rich chromite with a variation trend of major elements from chromite to Fe2+-rich chromite similar to those observed in other locations, i.e., an increase in Fe2O3 and FeO, a decrease in Al2O3 and MgO. Cr2O3 content increases from chromite to Fe2+-rich chromite in chromitite pods from Lavanderos and chromitite blocks from Centinela Bajo, but decreases in ferrian chromite zones in accessory grains from Centinela Bajo. The minor element (Ti, V, Zn, Ni) content is mostly low and does not exceed 0.4 wt.%, with the exception of MnO (<0.9 wt.%), which shows a correspondence with increasing degree of alteration. Cr# (Cr/Cr + Al) versus Mg# (Mg/Mg + Fe2+) and Fe3+/Fe3++Fe2+ versus Mg# plots are used to illustrate the Cr-spinel alteration process. Overall, the Cr-spinels from Lavanderos (chromitite pods and disseminated grains) exhibit Cr# values ranging from 0.6 to 1.0, Mg# (Mg/Mg + Fe2+) below 0.5, and (Fe3+/Fe3++Fe2+) <0.4. Cr-spinels from chromitites in Centinela Bajo have Cr# and Mg# values that range from 0.65 to 1.0, and 0.7-0.3, respectively, and (Fe3+/Fe3++Fe2+) < 0.4. Accessory Cr-spinels from Centinela Bajo have Cr# and Mg# values that range from 0.55 to 1.0, and 0.6- < 0.1, respectively. The (Fe3+/Fe3++Fe2+) ratio is less than 0.4 in chromite cores and Fe2+-rich chromite, and >0.5 in ferrian chromite and Cr-magnetite. Interpretation of the data obtained and Cr-spinel textures indicate that the alteration of Cr-spinel is a progressive process that involves in its initial stages the reaction of chromite with olivine under water-saturated conditions to produce clinochlore and Fe2+-rich chromite. During this stage the chromite can also incorporate Ni, Mn, and/or Zn from the serpentinization fluids. As alteration progresses, Fe2+-rich chromite loses mass resulting in the development of a spongy texture. In a later stage and under more oxidizing conditions Fe3+ is incorporated in chromite/Fe2+-rich chromite shifting its composition to an Fe3+-rich chromite (i.e., ferrian chromite). Depending on the fluid/rock and Cr-spinel/silicate ratios, Cr-magnetite can also form over Fe2+-rich chromite and/or ferrian chromite as a secondary overgrowth. The compositional changes observed in Cr-spinels from La Cabaña reflect the initial stages of alteration under serpentinization conditions. Results from this study show that the alteration of Cr-spinels is dependent on temperature. The degree and extent of alteration (formation of Fe2+-rich and/or ferrian chromite) are controlled by the redox nature of the fluids, the Cr-spinel/silicate and the fluid/rock ratios. ISSN: 0930-0708 hal-01172266 https://hal.archives-ouvertes.fr/hal-01172266 DOI : 10.1007/s00710-014-0335-5 | Partager |
Developpement de la peche de grands pelagiques dans les antilles francaises et organisation du marche des produits de la mer Auteur(s) : Lantz, Frederic Résumé : The development of large pelagic fishing in the French Antilles is an integral part of a difficult economic situation of the fishing sector in Martinique where this development can seem like a solution to increasingly acute problems. Indeed, for the regulatory authorities as well as for many participants in the sector, it is imperative to find solutions to the lack of profitability of a part of the fishing ships and to confront the regular increase of the share of imports in supplying Martinique with seafood. This question about the possibilities of developing large pelagic fishing is not new since it is already mentioned in the Notice from the Economic and Social Committee of the Martinique Region in 1982. We will not show in this document a detailed analysis of small-scale fishing in Martinique. Since the latter has been abundantly studied by the team of the Caribbean Oceanological and Halieutic Research Centre (PROHC) between 1985 and 1987, we will take up these principal conclusions (with which we are in full agreement) and bring them up to date based on data collected during our mission from 11 to 24 April 1988. The first section devoted to the supply structure (local fishing and imports) will attempt to define under what conditions large pelagic fishing can be developed. The second section will address marketing and demand. Indeed, at the same time as the problems of developing large pelagic fishing, we are faced with the question of the organisation of seafood markets. This organisation is a fundamental issue for the small-scale fishing sector in the French Antilles since its long-term future depends upon it by setting different prices and amounts exchanged according to the structure it is given. We will come to a conclusion on the economic conditions of developing a large pelagic fishery and organising a market, this based on research and study work already done. We will indicate which investigations must be conducted to complete the set of factors for decision support in this area. To perform this assessment, we reconstructed from the long series 1970-1986 (sometimes with significant inadequacies): these are presented as an appendix. (OCR non controlé) Le développement de la pêche de grands pélagiques dans les Antilles Françaises s'inscrit dans un contexte économique difficile du secteur de la pêche en Martinique où ce développement peut apparaître comme une solution à des problèmes de plus en plus aigus. En effet, pour les autorités de tutelle ainsi que pour de nombreux intervenants dans le secteur, il est impératif de trouver des solutions au manque de rentabilité d'une partie des unités de pêche et de faire face à l'augmentation régulière de la part des importations dans l'approvisionnement de la Martinique en produits de la mer. Cette question sur les possibilités d'un développement de la pêche de grands pélagiques n'est pas nouvelle puisqu'elle est déjà évoquée dans l'Avis du Comité Economique et Social de la Région Martinique en 1982. On ne présentera pas dans ce document une analyse détaillée de la pêche artisanale en Martinique. Celle-ci ayant été abondamment étudiée par l'équipe du Pôle de Recherche Océanologique et Halieutique Caraïbe (PROHC) entre 1985 et 1987, on reprendra ces principales conclusions (avec lesquelles nous sommes en plein accord) en les actualisant à partir des informations recueillies lors de notre mission du 11 au 24 avril 1988. La première section consacrée à la structure d'offre (pêche locale et importations) s'attachera à définir dans quelles conditions peut être développée une pêche de grands pélagiques. Là seconde section traitera de la commercialisation et de la demande. En effet parallèlement aux problèmes de développement d'une pêche de grands pélagiques, se pose la question de l'organisation du marché des produits de la mer. Cette organisation est un enjeu primordial pour le secteur de la pêche artisanale dans les Antilles Françaises puisqu'elle conditionne son avenir à long terme en définissant des prix et des quantités échangées différents suivant la structure qu'on lui donne. On conclura sur les conditions économiques du développement d'une pêche de grands pélagiques et de l'organisation d'un marché, ceci à partir des travaux de recherche et des études déjà réalisés. On indiquera quelles investigations doivent être menées pour compléter l'ensemble des éléments d'aide à la décision dans ce domaine. Pour effectuer cette évaluation, on a reconstituer des séries longues 1970-1986 (parfois avec des carences importantes) : celles-ci sont présentées en annexe. Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/1988/rapport-2519.pdf http://archimer.ifremer.fr/doc/00000/2519/ | Partager |
Les zones de tolérance à Cuba sous la république : l’enfermement réel et symbolique des femmes publiques Auteur(s) : Moreau-Lebert, Mélanie Éditeur(s) : Université des Antilles Études caribéennes Résumé : La prostitution est une problématique très intéressante d’une part parce qu’elle est transversale à tous les temps, à toutes les classes sociales, à tous les espaces, et d’autre part parce qu’il s’agit d’un fléau qui se conjugue le plus souvent au féminin. Il s’agit à mon sens du versant spécifique d’une problématique universelle dont personne ne peut s’affranchir sans mettre en jeu l’ensemble de la condition humaine. En effet, la prostitution est le lieu où convergent et se concentrent de façon exacerbée tous les maux d’une société. La femme est malgré elle au centre de ce système dans lequel on retrouve les frustrations, les rapports de domination, de pouvoir, la violence, la misère, la corruption, l’aliénation… La prostitution, tout comme le concept de genre, est une construction sociale, dans laquelle les femmes sont enfermées réellement et symboliquement.D’autre part, si les maux d’une société sont décuplés dans le système de la prostitution, nulle part ailleurs n’existe un tel abîme entre fantasme et réalité. C’est le lieu des fausses représentations et des euphémismes comme le montrent ces deux expressions édulcorées « zones de tolérance » et « femmes publiques ». A Cuba, malgré les tentatives d’éradication de la prostitution dans les premières décennies qui suivirent le triomphe de la Révolution de 1959, la chute du bloc soviétique et la période de pénurie qui s’ensuivit donnèrent lieu à un retour de cette prostitution, sous de nouvelles formes qui persistent aujourd’hui. Cependant, il fut une époque, celle de la première République (1902-1958) durant laquelle Cuba, rongée par un système néocolonial, connût une recrudescence de ce phénomène, dans des proportions jamais égalées. Une époque somme toute récente où les zones de tolérance, espaces où étaient regroupées les maisons closes, occupaient une grande partie de La Havane coloniale ainsi que des quartiers entiers à travers l’île. A l’intérieur de ces zones très lucratives dont profitaient à la fois les proxénètes, policiers, politiques et hommes d’affaires, les femmes cubaines, mais également, dans une grande proportion des Françaises victimes de la traite des Blanches, se trouvaient au cœur d’un système qui étaient à lui seul le symptôme de la frustration néocoloniale, mais également de l’exacerbation du patriarcat.Cette problématique, on ne peut plus actuelle, convoque la pluridisciplinarité, c’est pourquoi j’ai eu recours à des témoignages de prostituées depuis le début du siècle jusqu’à la Révolution, recueillis et publiés à Cuba. Je me suis penchée sur les différents discours sur la prostitution de l’époque, discours politiques et féministes. Les rapports de police, les plaintes déposées par des femmes, les comptes rendus de procès, et les descriptions des médecins-hygiénistes sont autant de sources qui viennent corroborer les témoignages. The republican era in Cuba is a complex and difficult one for the Cuban population. 1898 remains engraved in people’s memories as being a time of great disillusion for a population who, having freed itself from Spanish colonial domination, was deprived of independence by the United States of America. Three years of American intervention sufficed to put power bases into place, guarantee maximal exploitation conditions and organize the legal framework of the American domination over Cuba by means of the Platt Amendment in 1901. The protectorate set up by the United States, followed by a neocolonial system in 1934, relies upon the collaboration of presidents and corrupt governments succeeding each other in power. Corruption, nepotism and violence are put in place in a society in which inequality is dramatically worsening and all moral values are disintegrating. In this context and in a Cuban society governed with patriarchal rules, women are the first victims of the system. After the wars of independence, the only options they have are marriage, work or prostitution. Legitimate marriage is only available to a privileged few. With regards to employment, only 9.8% of women have the opportunity to work and this percentage didn’t change until 1959. It was at this time that prostitution reached unprecedented levels. It wasn’t just the case of a few marginalized women but of thousands of mothers, wives, widows and working women who were trapped in this alienating condition, forced to sell their bodies. Legislation and violence are used to control and restrict the work space for prostitutes, removing these ‘streetwalkers’ from the public eye, grouping them together in tolerance zones with very strict rules, which are in reality in the hands of Cuban and French procurers, and subjecting them to constant inspections carried out by hygienists who physically and symbolically assault women’s bodies. What is more, speeches about prostitution, whether made by politicians, feminists, journalists, doctors or mere observers, contribute significantly to a certain representation of these women. While debates about prostitution have recently shaken public opinion, this work refers back to an episode of Cuba’s history which brings us to reflect upon the evolution of the phenomenon and on its protean nature. Cuba Droits : info:eu-repo/semantics/openAccess urn:doi:10.4000/etudescaribeennes.6945 http://journals.openedition.org/etudescaribeennes/6945 | Partager |
Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain Auteur(s) : Heuret, Arnauld Conrad, C. P. Funiciello, F. Lallemand, Serge Sandri, L. Auteurs secondaires : Dipartimento Scienze Geologiche, Università "Roma ; Université du Québec Department of Geology and Geophysics [Manoa] ; University of Hawaii at Manoa (UHM) Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Istituto Nazionale di Geofisica e Vulcanologia, Bologna ; Université du Québec Éditeur(s) : HAL CCSD American Geophysical Union Résumé : International audience Giant earthquake (moment magnitude M-w >= 8.5) forecasts for subduction zones have been empirically related to both tectonic stresses and geometrical irregularities along the subduction interface. Both of these controls have been suggested as able to tune the ability of rupture to propagate laterally and, in turn, exert an important control on giant earthquake generation. Here we test these hypotheses, and their combined influence, by compiling a dataset of trench fill thickness (a proxy for smoothing of subducting plate relief by sediment input into the subduction channel) and upper plate strain (a proxy for the tectonic stresses applied to the subduction interface) for 44 segments of the global subduction network. We statistically compare relationships between upper plate strain, trench sediment thickness and maximal earthquake magnitude. We find that the combination of both large trench fill (>= 1 km) and neutral upper plate strain explains spatial patterns of giant earthquake occurrence to a statistically significant degree. In fact, the concert of these two factors is more highly correlated with giant earthquake occurrence than either factor on its own. Less frequent giant earthquakes of lower magnitude are also possible at subduction zones with thinner trench fill and compressive upper plate strain. Extensional upper plate strain and trench fill < 0.5 km appear to be unfavorable conditions, as giant earthquakes have not been observed in these geodynamical environments during the last 111 years. Citation: Heuret, A., C. P. Conrad, F. Funiciello, S. Lallemand, and L. Sandri (2012), Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain, Geophys. Res. Lett., 39, L05304, doi: 10.1029/2011GL050712. ISSN: 0094-8276 hal-00745636 https://hal.archives-ouvertes.fr/hal-00745636 https://hal.archives-ouvertes.fr/hal-00745636/document https://hal.archives-ouvertes.fr/hal-00745636/file/heuretGRL2012.pdf DOI : 10.1029/2011GL050712 | Partager |
The effect of drought on carbon storage capacity in a tropical rainforest of French Guiana Auteur(s) : aguilos, Maricar Burban, Benoît Cazal, Jocelyn Goret, Jean-Yves Herault, Bruno Bonal, Damien Auteurs secondaires : Ecologie des forêts de Guyane (ECOFOG) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - AgroParisTech - Université de Guyane (UG) - Centre National de la Recherche Scientifique (CNRS) Ecologie et Ecophysiologie Forestières (EEF) ; Institut National de la Recherche Agronomique (INRA) - Université de Lorraine (UL) Éditeur(s) : HAL CCSD Résumé : In a perfect-deficit approach (Yi, 2012), the daily maximum carbon storage capacity (CPC) of a given ecosystem for each year defines the perfect annual CPC curve. Deficits are the differences in the daily observational data for a given year against a perfect curve. The area between this curve and instantaneous canopy photosynthetic rates represents the potential productivity. Using an 11-year (2004 – 2014) eddy covariance flux and meteorological data, this perfect-deficit approach was used to examine the relationship between potential productivity and droughts occurring in 2005 and 2010 in a tropical rainforest of French Guiana, South America. Surprisingly, CPC deficits were only reduced by 24% (2005) and 19% (2010) from their respective perfect CPCs, indicating a subtle effect of drought to ecosystem productivity. Highest precipitation occurred in 2010 but precipitation deficits dropped drastically during this year (71% reduction from its perfect value) which reflects a drought condition. However, its deficits showed no correlation annually and seasonally. Soil water content (SWC) appeared to be the single driver for CPC deficits during long dry periods but is weakly correlated (r = 0.30; P <0.01 and r = 0.31; P <0.01, in 2005 and 2010, respectively). These results indicate that soil water is not a major limiting factor for productivity of this ecosystem during drought periods. In contrast, global radiation (Rg) corresponds to the peak of CPC deficits in 2010, but only 19% had been reduced from its ideal value. Yet, highest gross primary production (GPP) of 4106±231 gCm−2yr−1 occurred this year (mean 3753±231 gCm−2yr−1). Therefore, smaller deficits in Rg coupled with sufficient water may have induced higher productivity in 2010. Nevertheless, weaker correlations between potential productivity and climatic drivers may imply that other controlling aspects such as biological constraints may also have an effect to the dynamics of potential productivity during drought events, hence, must also be considered. AGU Fall Meeting 2015 San Francisco, United States hal-01269439 https://hal.archives-ouvertes.fr/hal-01269439 PRODINRA : 338570 | Partager |
A transmission electron microscopy study of experimentally deformed quartzite with different degrees of doping Auteur(s) : MAINPRICE, David Jaoul, O. Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Laboratoire des Mécanismes et Transfert en Géologie (LMTG) ; Université Paul Sabatier - Toulouse 3 (UPS) - Observatoire Midi-Pyrénées (OMP) - Centre National de la Recherche Scientifique (CNRS) Éditeur(s) : HAL CCSD Elsevier Résumé : International audience TEM Study of Heavitree quartzite deformed at high temperatures and a pressure of 1.5 GPa with three different preparations: water-added, vacuum dried, and sodium doped show a wide range of dislocation microstructure. The vacuum dried sample has a very heterogeneous dislocation distribution varying from almost no dislocations to very high densities. Dislocation nucleation occurs by cross-slip mechanisms, such as Frank-Read sources and Orowan loops around hard inclusions. Shear bands develop in the basal plane composed of two closely spaced shear planes. Dislocations have straight segments and they are aligned along directions of dense packing, suggesting strong Peierls stress control due to the crystal structure. No voids, bubbles or dislocation walls where observed in the vacuum dried sample. The sodium-doped sample had a homogeneous high dislocation density. The water-added sample has a significantly lower, relatively uniform dislocation density. Bubbles associated with dislocations are seen in every grain. Dislocations were either present in loops around bubbles or as straight dislocations with small bubbles spaced along the dislocation line. Some of the long straight dislocations are aligned parallel to the c-axis. Sub-grains where very frequent, sometimes form cells of about 2 p,m in diameter with straight edges. Analysis of dislocations show 1/3 < a > and [c] dislocations in sub-grain walls and free 1/3 < a > dislocations on prism planes. There is clear evidence for dislocation climb with sub-grain walls, dislocation cells, dislocation junctions and dislocation debris of small loops. The major difference between vacuum dried and water-added samples are the homogeneity of the microstructure and evidence for climb in the water-added sample. Glide is clearly difficult, with a high Peierls stress in the vacuum dried sample as shown by areas of very low and very high dislocation density and the crystallographic control of dislocation line direction. The sodium-doped sample indicates that nucleation was easy by the high homogenous dislocation density, but no climb recovery has taken place. The density is high and the dislocations are strongly interacting causing tangles; no evidence for crystallographic control can be observed at these levels of strain. The activation energy for creep in Heavitree quartzite decreases with inferred water content of the specimens form 185 kJ mol(-1) for vacuum dried to 151 for 0.4 wt% water-added samples. Analysis of diffusion data for oxygen under hydrothermal conditions and inferred diffusion data for the hydrogarnet defect and dislocation velocity suggests activation energies for these processes are similar to the activation energy for the dislocation creep of Heavitree quartzite and other quartz aggregates. For data from the previously published experiments with the highest stress resolution there is a correlation between the A pre-factor in the power law creep equation and the activation energy for creep. It is speculated that the correlation may be due to variable hydrogarnet defect concentrations. ISSN: 0031-9201 hal-00413112 https://hal.archives-ouvertes.fr/hal-00413112 DOI : 10.1016/j.pepi.2008.07.009 | Partager |