Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Studies on the periodicity of wood formation provide essential data on tree age and factors related to the control of tree growth. The aim of this work was to investigate the cambial phenology and its relation with leaf phenology and climatic seasonality in two tropical rainforest species belonging to the genus Parkia known for having a contrasted leaf phenology. From wood samples collected at 15 day intervals from April 2009 to February 2012 in five trees of both species, we quantified cambial activity by counting layers of cells in cambial zone, enlarging cells zone and wall thickening cells zone from wood prepared anatomical micro sections. In the same time, we observed leaf shedding behaviors in the crown of the studied trees. In both species, cambial activity was significantly reduced during leafless period. However, the cambial activity of P. velutina was not affected by seasonality while in P. nitida, we found a significant positive effect of the dry season on cambial activity. This diminution of activity associated to leaf shedding occurred annually during the dry season in P. nitida whereas the trees were not synchronous in time for P. velutina. On the contrary that is often admitted, the rest cambial period can be independent of environmental restriction such as dry season. Leaf phenology remains the best proxy to estimate cambial activity.
ISSN: 0931-1890

hal-01135166
https://hal.archives-ouvertes.fr/hal-01135166
https://hal.archives-ouvertes.fr/hal-01135166/document
https://hal.archives-ouvertes.fr/hal-01135166/file/Art_Morel_al_Seasonal_variations_phenological_traits_2015.pdf
DOI : 10.1007/s00468-015-1177-4

Éditeur(s) : HAL CCSD National Academy of Sciences
Résumé : International audience
Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of similar to 12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron. We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered.
ISSN: 0027-8424

hal-01545320
https://hal.archives-ouvertes.fr/hal-01545320
DOI : 10.1073/pnas.1509523113

Éditeur(s) : ISTPM
Résumé : These first results might clarify some problems linked to the biology of tarets and other small lignivorous crustaceans. The systematic of the molluscs Teredinidae, so complex, is only based on the study of pallets, which is a great source of confusion when one has to examine the woods after the molluscs' death. We tried to distinguish the species by examining the striates and denticulations on the shelves. The size of the intervals between the striates and the proportional size of the denticulations, as well as the shape of the denticulation marks of the middle part, can indeed allow us to differentiate between some species. [...]
Ces premiers résultats pourront peut-être jeter quelque clarté sur les problèmes se rapportant à la biologie des tarets et des petits crustacés lignivores. La systématique des mollusques Teredinides, si complexe, a été fondée uniquement sur l'examen des palettes, ce qui est une source de confusion lorsqu'on est obligé, ce qui est le cas le plus fréquent, d'examiner les bois après la mort des mollusques. Nous avons cherché à distinguer les espèces par les stries et les denticulations visibles sur les coquilles. Les dimensions des intervalles séparant les stries et la taille proportionnelle des denticulations, ainsi que la forme de l'empreinte des denticulations de la partie moyenne peuvent différencier, effectivement, quelques espèces. C'est ainsi que Teredo pedicellata et Teredo navalis sont immédiatement distingués à l'examen des stries; de même Bankia minima et Bankia badigaensis. Mais il faut, bien entendu, tenir compte des variations individuelles, les denticulations pouvant être plus ou moins fortes chez une même espèce. Il semble difficile d'interpréter tout le comportement des petits crustacés et même des larves de Térédinides par une simple réaction de chimiotropisme : les animaux peuvent choisir un point ou une zone sur le support. Certaines essences, tout au moins au début de leur immersion, semblent jouer un rôle répulsif ou non attractif pour les crustacés: le Hêtre, Kaya ivorensis et Samba; ces observations ne sont valables que pour une saison chaude. Chez les mêmes crustacés, la préférence pour l'ombre joue un rôle très important. (OCR non contrôlé)
Revue des Travaux de l'Institut des Pêches Maritimes (0035-2276) (ISTPM), 1956-06 , Vol. 20 , N. 2 , P. 185-200

Droits : Ifremer
http://archimer.ifremer.fr/doc/1956/publication-4669.pdf
http://archimer.ifremer.fr/doc/00000/4669/

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
The shallow-water bivalve Codakia orbiculata which harbors gill-endosymbiotic sulfur-oxidizing g-proteobacteria can lose and acquire its endosymbionts throughout its life. Longterm starvation and recolonization experiments led to changes in the organization of cells in the lateral zone of gill filaments. This plasticity is linked to the presence or absence of gill-endosymbionts. Herein, we propose that this reorganization can be explained by three hypotheses: (a) a variation in the number of bacteriocytes and granule cells due to proliferation or apoptosis processes, (b) a variation of the volume of these two cell types without modification in the number, and (c) a combination of both number and cell volume variation. To test these hypotheses, we analyzed cell reorganization in terms of proliferation and apoptosis in adults submitted to starvation and returned to the field using catalyzed reporter deposition fluorescence in situ hybridization, immunohistochemistry, and structural analyses. We observed that cell and tissue reorganization in gills filaments is due to a variation in cell relative abundance that maybe associated with a variation in cell apparent volume and depends on the environment. In fact, bacteriocytes mostly multiply in freshly collected and newly recolonized individuals, and excess bacteriocytes are eliminated in later recolonization stages. We highlight that host tissue regeneration in gill filaments of this symbiotic bivalve can occur by both replication of existing cells and division of undifferentiated cells localized in tissular bridges, which might be a tissue-specific multipotent stem cell zone.
Microscopy Research and Technique

hal-00743036
https://hal-uag.archives-ouvertes.fr/hal-00743036

Éditeur(s) : EDP Sciences
Résumé : The necessity to move from a traditional fishery management to an ecosystem approach is now acknowledged. Indicators are required to support the development of this approach. For example, community indicators have been proposed to assess the impact of fishing. We tested here the applicability of one such community indicator, the abundance-biomass comparison (ABC method), as a measure of the impact of bottom trawling (years of sampling: 2001 and 2003) on the benthic invertebrates-typically starfishes, crabs, squat lobsters, shrimps and large hard-shelled molluscs-of "Grande Vasiere", a major French fishing zone, in the Bay of Biscay. The ABC method is generally used as an impact indicator for different types of physical, biological and anthropogenic disturbances on benthic communities. This method is based on the assumption that increasing disturbance shifts communities from dominance by large-bodied species with low turnover rates toward dominance by small-bodied species with high turnover rates. At less disturbed areas the average biomass of individuals is greater than at more heavily disturbed areas. The ABC method measures this effect by comparing the ranked distributions of abundance and biomass within a given community. We applied the ABC method and compared the size structure and the species diversity at two areas exposed to moderate and high bottom trawl effort. Species diversity was lower in the most exploited area. The highly trawled area was dominated by opportunistic organisms, mainly one species of swimming crab Liocarcinus depurator, one species of squat lobster Munida rugosa and Norway lobsters Nephrops norvegicus, which are large-bodied species. Consequently, the results of the ABC method were inconsistent with the theoretical expectation for these particular macrofaunal communities and the measured levels of fishing intensity.
La nécessité de passer d'une gestion monospécifique des pêches à une approche écosystémique est largement reconnue. Pour mettre en place une telle approche, des indicateurs ont été proposés afin d'estimer l'impact de la pêche sur les communautés. Nous avons testé l'efficacité de l'un de ces indicateurs, la comparaison abondance-biomasse (méthode ABC), pour mesurer l'impact du chalutage de fond (année d'échantillonnage : 2001 et 2003) sur les communautés de la macrofaune benthique de la Grande Vasière, golfe de Gascogne (typiquement des crabes, étoiles de mer, des galathées, de gros mollusques à coquille dure). La méthode ABC est généralement utilisée comme un indicateur d'impact de différents types de perturbations physiques, biologiques et anthropiques sur les communautés benthiques. Cette méthode est basée sur l'hypothèse qu'un régime de perturbation croissant entraîne une modification de la structure des communautés qui deviennent graduellement dominées par des espèces opportunistes de petite taille caractérisées par un renouvellement rapide. Dans une communauté modérément perturbée, la biomasse moyenne des individus est ainsi plus grande que dans une communauté fortement perturbée. La méthode ABC mesure cet effet en comparant les distributions en biomasse et densité dans chaque communauté. Nous avons appliqué la méthode ABC et étudié la structure en taille et la diversité spécifique des communautés benthiques en comparant deux zones, l'une soumise à un effort de pêche modéré et l'autre à un important effort de pêche. La diversité spécifique était plus faible sur les sites fortement chalutés. Ces sites étaient dominés par des organismes opportunistes de grande taille, principalement une espèce de crabe nageur Liocarcinus depurator, une espèce de galathée Munida rugosa et des langoustines Nephrops norvegicus. Dans ces conditions, les résultats de la méthode ABC n'étaient pas cohérents avec la théorie pour ces communautés de macro-invertébrés benthiques et les efforts de pêche mesurés.
Aquatic Living Resources (0990-7440) (EDP Sciences), 2006-07 , Vol. 19 , N. 3 , P. 219-228

Droits : 2006 EDP
http://archimer.ifremer.fr/doc/2006/publication-2133.pdf
DOI:10.1051/alr:2006022
http://archimer.ifremer.fr/doc/00000/2133/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
UNLABELLED: Glioblastoma (GB) is the most frequent and aggressive tumor of the central nervous system. There is currently growing interest in proteomic studies of GB, particularly with the aim of identifying new prognostic or therapeutic response markers. However, comparisons between different proteomic analyses of GB have revealed few common differentiated proteins. The types of control samples used to identify such proteins may in part explain the different results obtained. We therefore tried to determine which control samples would be most suitable for GB proteomic studies. We used an isotope-coded protein labeling (ICPL) method followed by mass spectrometry to reveal and compare the protein patterns of two commonly used types of control sample: GB peritumoral brain zone samples (PBZ) from six patients and epilepsy surgery brain samples (EB) pooled from three patients. The data obtained were processed using AMEN software for network analysis. We identified 197 non-redundant proteins and 35 of them were differentially expressed. Among these 35 differentially expressed proteins, six were over-expressed in PBZ and 29 in EB, showing different proteomic patterns between the two samples. Surprisingly, EB appeared to display a tumoral-like expression pattern in comparison to PBZ. In our opinion, PBZ may be more appropriate control sample for GB proteomic analysis. BIOLOGICAL SIGNIFICANCE: This manuscript describes an original study in which we used an isotope-coded protein labeling method followed by mass spectrometry to identify and compare the protein patterns in two types of sample commonly used as control for glioblastoma (GB) proteomic analysis: peritumoral brain zone and brain samples obtained during surgery for epilepsy. The choice of control samples is critical for identifying new prognostic and/or diagnostic markers in GB.
ISSN: 1874-3919

inserm-00871494
http://www.hal.inserm.fr/inserm-00871494
http://www.hal.inserm.fr/inserm-00871494/document
http://www.hal.inserm.fr/inserm-00871494/file/ManuscritProt-accepted.pdf
DOI : 10.1016/j.jprot.2013.04.031

Éditeur(s) : HAL CCSD
Résumé : The mosquito species Aedes (Stegomyia) aegypti (Linnaeus 1762) was introduced into the Americas some 400 years ago from the African continent. Currently, this species is the primary agent behind dengue and chikungunya outbreaks in the pan-tropical area and its widespread distribution has likely played an important role in the recent expansion of the Zika virus. The biology of Ae. (Stg.) aegypti is particularly well known, which is not the case for its ecology. By adopting a cross-disciplinary approach I attempted to understand the relative contribution of biotic and abiotic factors as well as some evolutionary processes in the distribution of this species at the local and regional scales in French Guiana.Initially, I was interested in revising the core knowledge concerning the diversity of mosquitoes in French Guiana. By combining traditional and molecular taxonomy, this step allowed my colleagues and I to discover several new species and to create the appropriate tools to manage this type of entomological data.Secondly, we studied the spatio-temporal structure of resident aquatic macroinvertebrate communities in urban areas. This highlighted the existence of antagonistic and mutualistic interactions. In particular, the native mosquito Limatus durhamii Theobald 1901 appears to prevent the sustainable establishment of Ae. (Stg.) aegypti in slightly urbanized environments via a mechanism of competitive exclusion.
Le moustique Aedes (Stegomyia) aegypti (Linnaeus 1762) a été introduit dans les Amériques depuis le continent africain il y a environ 400 ans. Actuellement, cette espèce est la principale responsable des épidémies de dengue et de chikungunya dans la zone pantropicale et sa large répartition a très probablement joué un rôle important dans l’expansion récente du virus Zika. La biologie d’Ae. (Stg.) aegypti est particulièrement bien connue, ce qui n’est pas le cas de son écologie, en particulier de ses interactions avec les communautés résidentes. En adoptant une démarche pluridisciplinaire je me suis intéressé à la contribution relative des facteurs biotiques et abiotiques ainsi que de certains processus évolutifs dans la distribution de cette espèce à différentes échelles en Guyane française.Dans un premier temps j’ai participé à la révision des connaissances fondamentales sur la diversité des moustiques de Guyane. En alliant la taxonomie classique et moléculaire, cette étape a permis de découvrir plusieurs nouvelles espèces et de mettre en place des outils adaptés à la gestion de ce type de données, notamment pour une utilisation future.Dans un second temps la structuration spatio-temporelle des communautés résidentes de macro-invertébrés aquatiques a été étudiée en milieu urbain. Cela a permis de mettre en évidence l’existence d’interactions antagonistes et mutualistes avec les taxons des communautés résidentes. En particulier, le moustique autochtone Limatus durhamii Theobald 1901 semble empêcher l’établissement durable d’Ae. (Stg.) aegypti dans les milieux faiblement urbanisés via un mécanisme d’exclusion compétitive.
https://tel.archives-ouvertes.fr/tel-01405425

NNT : 2016YANE0001
tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425/document
https://tel.archives-ouvertes.fr/tel-01405425/file/These_Def_Talaga.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : 51 pages; 15figures; 3 tables, accepted for publication in PloS ONE
International audience
We present a study about AFM imaging of living, moving or self-immobilized, bacteria in their genuine physiological liquid medium. No external immobilization protocol, neither chemical nor mechanical, was needed. For the first time, the native gliding movements of Gram-negative Nostoc cyanobacteria upon the surface, at speeds up to 900microns/h, were studied by AFM. This was possible thanks to an improved combination of a gentle sample preparation process and an AFM procedure based on fast and complete force-distance curves made at every pixel, drastically reducing lateral forces. No limitation in spatial resolution or imaging rate was detected. Gram-positive and non-motile R. wratislaviensis bacteria were studied as well. From the approach curves, Young modulus and turgor pressure were measured for both strains at different gliding speeds and are ranging from 20±3 to 105±5MPa and 40±5 to 310±30kPa depending on the bacterium and the gliding speed. For Nostoc, spatially limited zones with higher values of stiffness were observed. The related spatial period is much higher than the mean length of Nostoc nodules. This was explained by an inhomogeneous mechanical activation of nodules in the Nostoc. We also observed the presence of a soft extra cellular matrix (ECM) around the Nostoc. Both strains left a track of polymeric slime with variable thicknesses. For R. wratislaviensis, it is equal to few hundreds of nanometers, likely to promote its adhesion to the sample. While gliding, the Nostoc secretes a slime layer the thickness of which is in the nanometer range and increases with the gliding speed.
ISSN: 1932-6203

hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765v3/document
https://hal.archives-ouvertes.fr/hal-00769765/file/REsubmission_In-situ_determination_Dhahri_Plos_One_R2_Hal.pdf

Éditeur(s) : HAL CCSD Station Biologique
Résumé : International audience
This study focuses on the diet of the eel Anguilla anguilla, sampled during one month of each of the four seasons from autumn 1998 to summer 1999 in the Languedocian Ingril Lagoon (Gulf ot Lion). The following feeding indices were calculated based on observations of 11 categories of prey found in the contents of full stomachs: coefficient of vacuity (CV), degree of fullness (DR), occurrence frequency (PP, in %), relative abundance (N, in %) and relative weight (P, in %). A parallel monitoring of the benthic macrofauna was conducted in autumn and spring. The interpretation of the results is based on the degree III of the scale of confinement established by Guélorget & Perthuisot (1983) and on the Costello et al. (1990) method, which combines PP and N. A. anguilla mainly feeds on benthic organisms, primarily amphipods crustaceans, polychaetes, insect larvae and small fish. The eel's feeding activity is very low in November and February and usually increases during May. The trophic quality available to the eel population in the Ingril Lagoon depends on its hydrodynamic variables, which are directly related to its close communication with the sea. Changes observed in the eel's diet over this year long study illustrate an opportunist type of feeding behaviour that reflects the typical composition of the macroinvertebrate species assemblage at a given point in time. Eels consume the type of benthic prey that is most available at a given moment without using a particular feeding strategy (e.g., specialisation or generalisation). The eels adapt by shifting their diet according to the energetic resources available in the ecosystem, which vary depending on hydrological regime. Thus, the facultative catadromous migrant species Anguilla anguilla could be used as a bioindicator of changes in the biological zonation and in the available food resources in the brackish ecosystem of Ingril Lagoon during its lagoon-resident ecophase.
ISSN: 0007-9723

hal-00753020
https://hal.univ-antilles.fr/hal-00753020

Éditeur(s) : HAL CCSD
Résumé :   Diplôme : DEA
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
As part of a programme of degraded soils rehabilitation, and in order to follow the biological processes connected with the soils reconstitution, it is a requisite to determine indicators able to account for the evolution of the soil. These indicators can he found on structural and/or functional characteristics of the bacterial communities, such as soil respiration, denitrification or genetic diversity. Theses descriptors are able to characterize the global community or targeted communities chosen for their importance in the ecosystem functioning. In this work, we tried to know whether soil bacteria genetic diversity was able to be a relevant indicator of the soil evolution in a rehabilitated sequence. This diversity is apprehended via a molecular technique: ARISA. A chronosequence situated on a gold mine, already experimented as part of a programme of degraded zones rehabilitation, was at our disposal. Results show that ARISA is a very sensitive technique, able to account for the bacterial community heterogeneity in a soil but unable, at the parcel scale, to discriminate the treatments nor to account for the evolution in lime of planted treatments. Lastly, the advantage of this indicator of genetic diversity may arise from its confrontation to other indicators (functional, for example).
Dans le cadre de la revégétalisation d'un sol dégradé et afin de pouvoir suivre les processus biologiques liés à la reconstitution des sols, il est nécessaire de déterminer des indicateurs pouvant rendre compte de l'évolution de l'état du sol. Ces indicateurs peuvent être fondés sur des caractéristiques fonctionnelles et/ou structurales des communautés bactériennes telles que la respiration, la dénitrification ou la diversité génétique. Ces descripteurs peuvent analyser la communauté globale ou des communautés cibles choisies pour leur importance dans le fonctionnement de l'écosystème. L'objectif de ce stage était de savoir si la diversité génétique des bactéries du sol pouvait être un indicateur de l'évolution des sols au sein d'une séquence de revégétalisation. Cette diversité est appréhendée par une technique de biologie moléculaire : l'ARISA. On dispose d'une chronoséquence située sur une mine d'or étudiée dans le cadre d'un programme de réhabilitation des zones dégradées. Les résultats montrent que l'ARISA est une technique très sensible, qui rend bien compte de l’hétérogénéité des communautés bactériennes présentes dans un sol mais est incapable, à l’échelle de la parcelle, de discriminer ni les traitements ni de rendre compte de l'évolution dans le temps de ces parcelles. Enfin, l'intérêt de cet indicateur de diversité génétique pourra résulter de sa confrontation avec d'autres indicateurs (fonctionnels par exemple).
https://hal.archives-ouvertes.fr/hal-01189155

hal-01189155
https://hal.archives-ouvertes.fr/hal-01189155
PRODINRA : 9464

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : National audience
Les leishmanioses sont des maladies parasitaires à transmission vectorielle observées sur tous les continents, à l’exception de l’Amérique du Nord et de l’Australie. Nous focaliserons ici sur la leishmaniose viscérale méditerranéenne due à Leishmania infantum et dont l’incidence annuelle est estimée entre 1200 et 2000 cas. Son cycle biologique est zoonotique avec un réservoir animal essentiellement canin. Les récentes observations épidémiologiques sont rapportées ici, notamment la mise en évidence du portage humain asymptomatique et l’extension de la zone endémique de la leishmaniose canine. La prise en charge thérapeutique de la leishmaniose viscérale méditerranéenne du patient immunocompétent fait essentiellement appel à l’amphotéricine B liposomale. Le débat existe toujours sur la pertinence d’une prophylaxie secondaire ou des traitements itératifs à chaque rechute chez le patient co-infecté par le VIH. Summary Leishmaniasis are protozoan infections transmitted by the bite of the sandflies, widely reported except in North-America and Australia. Here, we focus on mediterranean visceral leishmaniasis due to Leishmania infantum, with an estimated annual incidence of 1200–2000 cases. Its biological cycle is zoonotic and mainly involves the canine reservoir. The recent epidemiological observations are reported here, particularly the asymptomatic carriage but also the extension of the canine enzooty. Regarding treatment of immunocompetent patients, the drug of choice for mediterranean visceral leishmaniasis is liposomal amphotericin B. In case of HIV-Leishmania co-infection, the interest of secondary prophylaxis is still in debate
ISSN: 2210-6545

hal-01225489
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01225489
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01225489/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01225489/file/Mise%20au%20point%20et%20actualit%C3%A9s%20sur%20la%20leishmaniose%20visc%C3%A9rale%20m%C3%A9diterran%C3%A9enne.pdf
DOI : 10.1016/j.antinf.2014.12.005

Éditeur(s) : HAL CCSD Copernicus Publications
Résumé : Drilling an ultra-deep hole in an intact portion of oceanic lithosphere, through the crust to the Mohorovičić discontinuity (the ‘Moho'), and into the uppermost mantle is along-standing ambition of scientific ocean drilling (Bascom,1961; Shor, 1985; Ildefonse et al., 2007). It remains essential to answer fundamental questions about the dynamics of the Earth and global elemental cycles. The global system of mid-ocean ridges and the new oceanic lithosphere formed at these spreading centers are the principal pathways for energy and mass exchange between the Earth's interior, hydrosphere, and biosphere. Bio-geochemical reactions between the oceans and oceanic crust continue from ridge to subduction zone, and the physical and chemical changes to the ocean lithosphere provide inventories of these thermal, chemical, and biological exchanges.
ISSN: 1816-8957

hal-00564847
https://hal.archives-ouvertes.fr/hal-00564847
DOI : 10.2204/iodp.sd.10.07.2010

Éditeur(s) : HAL CCSD Station Biologique
Résumé : International audience
Four "morphotypes" of Mytilidae were collected from wood falls in the west Pacific (Vanuatu islands) and in the Bohol sea (Philippines) between 300 and 1800 metre depth. Results from our study demonstrated the existence of extracellular bacteria located between microvilli at the apical surface of the cells all along the lateral zone of the gill filaments in the four mytilid morphotypes analyzed. Based on TEM observations, these Gram-negative bacteria were not methanotrophic due to the lack of concentric stacking of intracellular membranes in their cytoplasm. Based on FISH experiments, these bacteria belong to g-Proteobacteria. These preliminary observations described gill symbiosis-like interactions in metazoan species associated with sunken wood, strengthening the hypothesis that decomposing wood may serve as steps for the introduction of symbiotic Mytilidae to vents and seeps. Phylogenetic analysis of these extracellular bacteria are in progress in our lab in order to compare their 16SrDNA sequences to that of other marine invertebrate symbionts described to date.
ISSN: 0007-9723

hal-00753023
https://hal.univ-antilles.fr/hal-00753023

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Wasp nests range from simple to complex structures made of paper or mud. Here, we show that a Neotropical wasp of the genus Nitela builds its nest entirely by weaving endophytic fungal hyphae and spider silk harvested from the leaves growing in the understory of the rain forest in French Guiana.
ISSN: 0006-3606

hal-01095857
https://hal-agroparistech.archives-ouvertes.fr/hal-01095857
DOI : 10.1111/j.1744-7429.2010.00645.x

Éditeur(s) : HAL CCSD
Résumé : International audience
Tension wood, a tissue developed by angiosperm trees to actively recover their verticality, has long been defined by the presence of an unlignified cellulosic inner layer in the cell wall of fibres, called the G-layer. Although it was known that some species have no G-layer, the definition was appropriate since it enabled easy detection of tension wood zones using various staining techniques for either cellulose or lignin. For several years now, irrespective of its anatomical structure, tension wood has been defined by its high mechanical internal tensile stress. This definition enables screening of the diversity of cell walls in tension wood fibres. Recent results obtained in tropical species with tension wood with a delay in the lignification of the G-layer opened our eyes to the effective presence of large amounts of lignin in the G-layer of some species. This led us to review older literature mentioning the presence of lignin deposits in the G-layer and give them credit. Advances in the knowledge of tension wood fibres allow us to reconsider some previous classifications of the diversity in the organisation of the fibre walls of the tension wood.
ISSN: 0928-1541

hal-01636686
https://hal.archives-ouvertes.fr/hal-01636686
https://hal.archives-ouvertes.fr/hal-01636686/document
https://hal.archives-ouvertes.fr/hal-01636686/file/2017_Ghislain-Clair_IAWAJ_DiversityOrganisationLignificationTensionWoodFibreWalls-AReview.pdf
DOI : 10.1163/22941932-20170170

Résumé : Notre étude s’est proposée d’analyser l’incidence du paludisme et son évolution dans le temps et dans l’espace, ainsi que de rechercher les facteurs de risque d’accès palustres chez les enfants d’un village du Moyen-Oyapock (Camopi), peuplé d’Amérindiens wayampi et émerillon, d’une part, et d’un village du Haut-Maroni (Antecume Pata), peuplé d’Amérindiens wayana, d’autre part. L’approche a été multiple avec, pour chacun des deux sites d’étude :- Une analyse de survie (modèle de Cox) à partir des accès palustres confirmés biologiquement dans une cohorte d’enfants de moins de sept ans régulièrement suivis, ainsi qu’un questionnaire de type Connaissances, Attitudes et Pratiques (CAP), puis les caractéristiques des habitats et la description de leur environnement immédiat.- Une analyse spatiale avec une classification de l’occupation du sol à partir d’images satellites SPOT 5, l’extraction de variables environnementales d’intérêt, l’étude de leur effet sur la transmission du paludisme et la mise au point d’une méthode objective de sélection d’un rayon d’observation autour des habitations pour la caractérisation de l’environnement.- Une étude de séries temporelles (ARIMA) afin de déterminer l’effet des évènements climatiques et hydrologiques sur le paludisme, aux niveaux local et plus global (El Niño).Les taux d’incidence d’accès palustres sur la période 2001-2009 se sont révélés particulièrement élevés chez les jeunes enfants, notamment à Camopi avec une moyenne de 773‰ par année. Une diminution brutale de l’incidence a eue lieu en 2007 sur le Haut-Maroni et ce phénomène est observé à Camopi depuis 2010. Une prémunition se développe assez rapidement au cours de la vie (2-3 ans), surtout contre les reviviscences à Plasmodium vivax. Les facteurs environnementaux se sont avérés être les plus nombreux et les plus fortement liés à l’incidence palustre. En effet, le dégagement des alentours du carbet de toute végétation et une certaine distance de celui-ci à la forêt sont des facteurs protecteurs. La composante géographique est également apparue essentielle à Camopi avec une incidence qui variait selon le fleuve d’habitation et en fonction de la distance au hameau principal. Les facteurs météorologiques locaux (température et niveau du fleuve) se sont également révélés être liés à l’incidence du paludisme à court terme (0-3 mois). Par ailleurs, nos résultats ont permis d’émettre un certain nombre d’hypothèses quant à la transmission et au(x) vecteur(s) local(ux), et notamment de suggérer la participation d’un vecteur autre qu’An. darlingi dans la transmission du paludisme à Camopi. Nous avons également prouvé par ce travail que la télédétection et les systèmes d’information géographique sont très prometteurs pour la prise en compte de la dimension spatiale et environnementale dans l’étude des maladies transmissibles, notamment dans les zones d’accès difficile de Guyane.
The aim of our study was to analyze the incidence of malaria in children and its evolution through time and space, as well as to search for risk factors in a village in Mid-Oyapock (Camopi), populated by Amerindians Wayampi and Emerillon, on the one hand, and a village in Upper-Maroni (Antecume Pata), populated by Amerindians Wayana, on the other hand. The approach was multiple with, for both study sites:- A survival analysis (Cox modelling) completed out of biologically confirmed malaria attacks in a cohort of children under seven, as well as a Knowledge, Attitudes, Practices and Behavior (KAPB) questionnaire, and also the characteristics of the houses and the description of their immediate environment.- A spatial analysis with a land cover classification from SPOT 5 satellite images, the extraction of environmental variables, the study of their effect on malaria transmission and the development of an objective method for picking the proper observation horizon around houses in order to characterize the environment.- A time series study (ARIMA) to determine the effect of climatic and hydrological events on malaria at local and global (El Niño) scales.The incidence rates of malaria attacks during the period 2001-2009 were particularly high among young children, especially in Camopi with an average of 773‰ by year. A sharp decline in incidence occurred in 2007 on the Upper Maroni and this phenomenon has been observed in Camopi since 2010. An acquired immunity develops quite rapidly during the life (2-3 years old), especially against P. vivax relapses. Environmental factors were found to be the most strongly associated with malaria incidence. Indeed, living in a hut cleared from the surrounding vegetation and at a larger distance from the forest are protective factors. The geographic component also appeared essential in Camopi with an incidence which varied with the river of living and with the distance from the main hamlet. The local meteorological factors (temperature and river level) also proved to be linked to malaria incidence in the short term (0-3 months). Moreover, our results have allowed issuing a number of assumptions about the transmission and the local vector(s), in particular to suggest the involvement of another vector than An. darlingi in the malaria transmission in Camopi. We also proved by this work that remote sensing and geographic information systems hold great promise for the inclusion of the spatial and environmental dimensions in the study of transmitted diseases, especially in areas of difficult access in French Guiana.

http://www.theses.fr/2011AGUY0448/document

Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd
Résumé : The high heterogeneity of silica cycling in coastal margins and the lack of silica data (compared to nitrogen and phosphorus) prevent the estimation of global silica retention in estuaries. In this study, the spatial and temporal variability of porewater silicic acid (Si(OH)4) profiles e that integrate benthic transport and reaction processes e was investigated at different spatial (metre, longitudinal and crosssection, intra-estuary) and temporal (tidal, seasonal) scales in two macrotidal estuaries, very close geographically but essentially differing in their shape. Studying the spatial and temporal variability of Si(OH)4 concentrations in porewaters provided evidence for the importance of transport processes, e.g. bio-irrigation, tidal pumping, resuspension and any combination of these processes, in affecting Si(OH)4 concentrations and fluxes and therefore temporary or permanent retention along the landeocean continuum. We confirm that aSiO2 (amorphous silicate) transported by rivers and estuaries clearly needs to be better characterized as it provides an important source of reactive aSiO2 to sediments. This study allows us to: (1) interrogate spatial and temporal scales, although both are most often in complete interaction; (2) design the most appropriate sampling schemes to be representative of any given system and to extrapolate at the scale of the whole estuary; (3) quantify uncertainty associated to the estimations of Si(OH)4 stocks and fluxes in this type of ecosystem, essential for budget calculations. We showed that two adjacent small macrotidal estuaries, may exhibit different behaviours regarding Si retention. Temporary retention has been observed in the meanders of the Aulne Estuary and not along the more linear Elorn Estuary, demonstrating the importance of the morphology and hydrodynamic components of the estuarine filter. Research is needed in other systems and climatic zones, but our study suggests that the typology should not only account for the different types of landeocean continuum (fjord, delta, mangrove.), but also incorporate the physical or biological attributes of the estuarine filter.
Estuarine Coastal And Shelf Science (0272-7714) (Academic Press Ltd- Elsevier Science Ltd), 2013-03 , Vol. 119 , P. 31-43

Droits : 2013 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00124/23529/22370.pdf
DOI:10.1016/j.ecss.2012.12.008
http://archimer.ifremer.fr/doc/00124/23529/