92 research outputs found

    Description d'une suceuse à air comprimé économique et utilisable par un seul plongeur = Description of a sucking-pipe sampler

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    A new type of sucking pipe sampler is described, using a scuba diving-tank for air-lift. A series of samplings may be performed by one single diver during one single diving

    Morphology of the <i>Buccal apparatus</i> and related structures in four species of Carapidae

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    The aims of this study were (1) to compare the morphology of the Buccal apparatus, the suspensorium and the opercle in four species of Carapidae (Carapus acus, Encheliophis boraborensis, Encheliophis homei and Encheliophis gracilis) and (2) to investigate the relationships between their cranial anatomy, their carnivorous diet, and their well known ability to enter holothurians.The complex and strong dentition and the wide hyomandibular with thickenings that seem to suit the constraints of the adductor mandibulae muscles partly inserted on the neurocranium are signs of a carnivorous diet.C. acus, E. boraborensis and E. homei have extremely strong buccal pieces and can protrude their upper jaws. However, in E. gracilis, the jaws are more slender, and the insertions of the Al along the entire length of the maxillary associated with the lack of mobility between the maxillary and the premaxillary prevent buccal protrusion. These differences could be related to the diet: C. acus, E. boraborensis and E. homei can feed on fishes and crustaceans, whereas E. gracilis feeds only on holothurian tissue.The cephalic morphology of the four species is not incompatible with entering the host. However, the neutralisation of the suboperculum spine by 'cartilaginous' tissue could be considered to be a particular adaptation to this behaviour

    Morphological particularities of the head in four Carapidae (Ophidiiformes)

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    A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraboreruis, E. homei. E. gracilis and Carapus acus) has been undertaken to compare it with the diet related characters. The cephalic organization of E. boraborensis and E. gracilis seems related to diet (mainly fishes and shrimps for the first one and holothurian tissues for the other): these species are respectively commensal and parasitic. Although the feeding characters of E. homei and C. acus are closely similar to those of E. boraborensis, there are sparse observations of holothurian tissues in their stomach contents. It is suggested that these fishes are commensal when they are adults and have parasitic tendency when they are juveniles

    HETEROGENEITY OF ZOOXANTHELLAE DENSITY IN THE CORAL ACROPORA GLOBICEPS AROUND MOOREA (FRENCH POLYNESIA)

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    Understanding the natural heterogeneity of coral zooxanthellae density appears as very important to understand variations in coral survival due to bleaching (the loss of these micro-algal symbionts). Heterogeneity of coral bleaching at different observation scales (within a colony, among neighbouring colonies of the same species or on a wider scale) remains largely misunderstood. The present work explores intracolonial, spatial and temporal variations of zooxanthellae density in the coral Acropora globiceps Dana 1846, over a period of three months on the forereef of Moorea, French Polynesia. In our study, intracolonial zooxanthellae densities did not vary significantly. However, zooxanthellae densities differed slightly between inner and outer branches but this trend was not significant at 6, 12 and 18 meters depth. On a wider scale, zooxanthellae densities also vary spatially : a positive correlation was observed between depth and symbiont density (density increases when light intensity decreases, so according to depth). Moreover, the location of colonies exposed to different hydrodynamical conditions was not a parameter controling the concentration of zooxanthellae. Finally, the temporal variation of zooxanthellae densities did not show significant variations even if it decreased slightly over the study period. The results of this study highlight the importance of accounting for variations within and among colonies to determine zooxanthellae densities and to assess the evolution of zooxanthellae populations

    Situational Awareness & Incident Management SAIM2014. 5th JRC ECML Crisis Management Technology Workshop

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    The 5th JRC ECML Crisis Management Technology Workshop on Software and data formats used in Crisis Management Rooms and Situation Monitoring Centres for information collection and display, organised by the European Commission Joint Research Centre in collaboration with the DRIVER Consortium Partners, took place in the European Crisis Management Laboratory (ECML) of the JRC in Ispra, Italy, from 16 to 18 June 2014. 32 participants from stakeholders in civil protection, academia, and industry attended the workshop. The workshop's purpose was to present, demonstrate, and explore IT solutions for Situation Awareness and Incident Management and the related design considerations, applied within the context of humanitarian aid and civil protection. During the first day the demonstrators set up in the JRC environment. A week before they were provided the contents to be processed. The second day was devoted to the presentations including: - Beyond the Myth of Control: toward the Trading Zone by Kees Boersma & Jeroen Wolbers, Department of Organization Sciences, VU University of Amsterdam - The organizers’ descriptions, the JRC and the DRIVER project - The software to be demonstrated on day three - Data exchange Challenges (From computer-readable data to meaningful information) by Christian Flachberger, FREQUENTIS AGJRC.G.2-Global security and crisis managemen

    First crenarchaeal chitinase found in Sulfolobus tokodaii

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    This is the first description of a functional chitinase gene within the crenarchaeotes. Here we report of the heterologues expression of the ORF BAB65950 from Sulfolobus tokodaii in E. coli. The resulting protein degraded chitin and was hence classified as chitinase (EC 3.2.4.14). The protein characterization revealed a specific activity of 75 mU/mg using colloidal chitin as substrate. The optimal activity of the enzyme was measured at pH 2.5 and 70 °C, respectively. A dimeric enzyme configuration is proposed. According to amino acid sequence similarities chitinases are attributed to the two glycoside hydrolase families 18 and 19. The derived amino acid sequence of the S. tokodaii gene differed from sequences of these two glycoside hydrolase families. However, within a phylogenetic tree of protein sequences, the crenarchaeal sequence of S. tokodaii clustered in close proximity to members of the glycoside hydrolase family 18

    Glacial to Holocene terrigenous organic matter input to sediments from Orca Basin, Gulf of Mexico — A combined optical and biomarker approach

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    In this study we assessed changes in the contribution of terrigenous organic matter (OM) to the Gulf of Mexico over the course of the last deglaciation (the last 25 kyr). To this end, we combined optical kerogen analyses with bulk sedimentary, biomarker, and compound-specific carbon isotope analyses. Samples were obtained from core MD02-2550 from Orca Basin (2249 m water depth at 26°56.77N, 91°20.74W) with temporal resolution ranging from multi-decadal to millennial-scale, depending on the proxy. All proxies confirmed larger terrigenous input during glacial times compared to the Holocene. In addition, the kerogen analyses suggest that much of the glacial OM is reworked (at least 50% of spores and pollen grains and 40% of dinoflagellate cysts). The Holocene sediments, in contrast, contain mainly marine OM, which is exceptionally well preserved. During the deglaciation, terrigenous input was generally high due to large meltwater fluxes, whereby discrepancies between different proxies call for additional influences, such as the change in distance to the river mouth, local productivity changes, and hydrodynamic particle sorting. It is possible that kerogen particles and the terrigenous biomarkers studied here represent distinct pools of land-derived OM with inputs varying independently
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