Search results for " life science"
showing 10 items of 12151 documents
Reproductive strategy as a piece of the biogeographic puzzle: a case study using Antarctic sea stars (Echinodermata, Asteroidea)
2017
13 pages; International audience; AimTo describe and analyse asteroid biogeographic patterns in the Southern Ocean (SO) and test whether reproductive strategy (brooder versus broadcaster) can explain distribution patterns at the scale of the entire class. We hypothesize that brooding and broadcasting species display different biogeographic patterns.LocationSouthern Ocean, south of 45 °S.MethodsOver 14,000 asteroid occurrences are analysed using bootstrapped spanning network (BSN), non-metrical multidimensional scaling (nMDS) and clustering to uncover the spatial structure of faunal similarities among 25 bioregions.ResultsMain biogeographic patterns are congruent with previous works based on…
Characterization of MRNP34, a novel methionine-rich nacre protein from the pearl oysters
2012
9 pages; International audience; Nacre of the Pinctada pearl oyster shells is composed of 98% CaCO(3) and 2% organic matrix. The relationship between the organic matrix and the mechanism of nacre formation currently constitutes the main focus regarding the biomineralization process. In this study, we isolated a new nacre matrix protein in P. margaritifera and P. maxima, we called Pmarg- and Pmax-MRNP34 (methionine-rich nacre protein). MRNP34 is a secreted hydrophobic protein, which is remarkably rich in methionine, and which is specifically localised in mineralizing the epithelium cells of the mantle and in the nacre matrix. The structure of this protein is drastically different from those …
Mineral phase in shell repair of Manila clam Venerupis philippinarum affected by brown ring disease.
2011
14 pages; International audience; The mineral phase of shell repair in the Manila clam Venerupis philippinarum affected by brown ring disease (BRD) was characterised at various scales and at various stages of shell repair by confocal Raman microspectrometry and scanning electron microscopy. Spherulitic and quadrangular aragonite microstructures associated with polyene pigments were clearly observed. Von Kossa staining showed that at the beginning of shell repair, hemocytes are filled with insoluble calcium carbonate salts in all fluids and then are transported toward the extrapallial fluids and the repair sites. Our analyses suggest that after a Vibrio tapetis attack and BRD deposit some cl…
The shell matrix of the pulmonate land snail Helix aspersa maxima.
2012
12 pages; International audience; In mollusks, the shell mineralization process is controlled by an array of proteins, glycoproteins and polysaccharides that collectively constitute the shell matrix. In spite of numerous researches, the shell protein content of a limited number of model species has been investigated. This paper presents biochemical data on the common edible land snail Helix aspersa maxima, a model organism for ecotoxicological purposes, which has however been poorly investigated from a biomineralization viewpoint. The shell matrix of this species was extracted and analyzed biochemically for functional in vitro inhibition assay, for amino acid and monosaccharides composition…
Shell repair process in the green ormer Haliotis tuberculata: a histological and microstructural study.
2008
In the present paper, juvenile and adult shells of the green ormer Haliotis tuberculata ('Oreille de Saint-Pierre') were perforated in a zone close to the shell edge and the shell repair process was followed at two levels: (1) by observing the histology of the calcifying mantle in the repair zone and (2) by analyzing with SEM the microstructure of the shell repair zone. Histological data clearly show the presence of calcium carbonate granules into the connective tissues, but not in the epithelial cells. This suggests that calcium carbonate granules are synthesized by sub-epithelial cells and actively transported through the epithelium to the repair zone, via a process which may be similar t…
Genetic relationships between Sicilian wild populations of Brassica analysed with RAPD markers
2001
Brassica comprises very variable species, both morphologically and genetically. Among these species, the Sicilian populations of Brassica sect. Brassica, species related to kale crops form a complex group. The genetic relationships among 15 populations occurring in Sicily and one from Calabria, representing the existing diversity, have been investigated using random amplified polymorphic DNA (RAPD) markers. This assay, carried out with 22 arbitrary primers, generated 236 polymorphic fragments, 21 of which were specific for single populations (mainly Brassica insularis, Brassica incana and Brassica macro-carpa). Jaccard's genetic distances were computed and the phylogenic tree was establishe…
Bush pig (Potamochoerus porcus) seed predation of bush mango (Irvingia gabonensis) and other plant species in Democratic Republic of Congo.
2012
4 pages; International audience
Potential of Crotalaria species as green manure crops for the management of pathogenic nematodes and beneficial mycorrhizal fungi
2004
On the basis of preliminary experiments, some Crotalaria species from Senegal were investigated to determine (1) their susceptibility to Meloidogyne javanica and M. incognita compared to a sensitive host (tomato), (2) their mycorrhizal and rhizobial responses, and (3) the effect of their cultivation on the mycorrhizal soil infectivity. The nematode invasion rates on Crotalaria spp. ranked from 0.17 to 7.17% and from 0.58 to 5.25%, respectively, for M. incognita and M. javanica, vs. 97% and 77% on tomato. Moreover, the inoculated J2 which invaded tomatoes developed into adult females, while those on Crotalaria spp. rarely developed beyond the third stage, confirming that all Crotalaria spp. …
Behaviour of alkyl oleates following foliar application in relation to their influence on the penetration of phenmedipham and quizalofop-P-ethyl
1997
Summary The foliar penetration of four alkyl oleates (methyl to butyl) and their influence on the penetration of phenmedipham and quizalofop-P-ethyl was studied in barley (Hordeum vulgare L.), cleavers (Galium aparine L.) and pea (Pisum sativum L.). Loss of alkyl oleates from glass and plant surfaces was inversely related to the length of the alkyl chains and was assumed to be due to volatilization. All four alkyl oleates after application alone, readily penetrated into pea and barley leaves but much less into G. aparine. Penetration of methyl oleate appeared to be faster than that of butyl oleate. Both alkyl oleates were completely metabolized in barley and pea in 27 h, but not in G. apari…
Effect of pulp cell number and assimilate availability on dry matter accumulation rate in a banana fruit (Musa sp. AAA group 'Grande Naine' (Cavendis…
2001
Fruit position on the bunch (inflorescence) is an important part of variability in banana fruit weight at harvest, as fruits at the bottom of the bunch (distal fruits) are approx. 40% smaller than those at the top (proximal fruits). In this study, the respective roles of cell number and cell filling rate in the development of pulp dry weight are estimated. To this end, the source/sink ratio in the plant was altered at different stages of fruit development. Leaf shading (reducing resource availability), bunch bagging (increasing sink activity by increasing fruit temperature), and bunch trimming (decreasing sink size by fruit pruning), applied once cell division had finished, showed that the …