104 research outputs found
Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily
In order to empirically assess the effect of actual seed sampling strategy on
genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have
analysed the genetic composition of two seedling lots (nursery stock and
plantation) and their known natural seed origin stand by means of six nuclear
microsatellite loci. Significant reduction in genetic diversity and significant
difference in genetic composition of the seedling lots compared to the seed
origin stand were detected. The female and the total effective number of
parents were quantified by means of maternity assignment of seedlings and
temporal changes in allele frequencies. Extremely low effective maternity
numbers were estimated (Nfe 2-4) and estimates accounting for both
seed and pollen donors gave also low values (Ne 35-50). These values
can be explained by an inappropriate forestry seed harvest strategy limited to
a small number of spatially close trees
Thin-film transducers for the detection and imaging of Brillouin oscillations in transmission on cultured cells
Mechanical imaging and characterisation of biological cells has been a subject of interest for the last twenty years. Ultrasonic imaging based on the scanning acoustic microscope (SAM) and mechanical probing have been extensively reported. Large acoustic attenuation at high frequencies and the use of conventional piezo-electric transducers limit the operational frequency of a SAM. This limitation results in lower resolution compared to an optical microscope. Direct mechanical probing in the form of applied stress by contacting probes causes stress to cells and exhibits poor depth resolution. More recently, laser ultrasound has been reported to detect ultrasound in the GHz range via Brillouin oscillations on biological cells. This technique offers a promising new high resolution acoustic cell imaging technique. In this work, we propose, design and apply a thin-film based opto-acoustic transducer for the detection in transmission of Brillouin oscillations on cells. The transducer is used to generate acoustic waves, protect the cells from laser radiation and enhance signal-to-noise ratio (SNR). Experimental traces are presented in water films as well as images of the Brillouin frequency of phantom and fixed 3T3 fibroblast cells
Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands
© INRA, EDP Sciences 2002Leaf morphology was assessed in nine mixed oak stands (Quercus petraea and Q. robur ) located in eight European countries. Exhaustive sampling was used in an area of each stand where the two species coexisted in approximately equal proportions (about 170 trees/species/stand). Fourteen leaf characters were assessed on each of 5 to10 leaves collected from the upper part of each tree. Three multivariate statistical techniques (CDA, canonical discriminant analysis; PCA, principal component analysis; MCA, multiple correspondence analysis) were used in two different ways: first on the total set of leaves over all stands (global analysis) and second, separately within each stand (local analysis). There was a general agreement of the results among the statistical methods used and between the analyses conducted (global and local). The first synthetic variable derived by each multivariate analysis exhibited a clear and sharp bimodal distribution, with overlapping in the central part. The two modes were interpreted as the two species, and the overlapping region was interpreted as an area where the within-species variations were superimposed. There was no discontinuity in the distribution or no visible evidence of a third mode which would have indicated the existence of a third population composed of trees with intermediate morphologies. Based on petiole length and number of intercalary veins, an "easy to use" discriminant function applicable to a major part of the natural distribution of the species was constructed. Validation on an independent set of trees provided a 98% rate of correct identification. The results were interpreted in the light of earlier reports about extensive hybridization occurring in mixed oak stands. Maternal effects on morphological characters, as well as a lower frequency or fitness of hybrids in comparison with parent species could explain the maintenance of two modes, which might be composed of either pure species or pure species and introgressed forms.Antoine Kremer, Jean Luc Dupouey, J. Douglas Deans, Joan Cottrell, Ulrike Csaikl, Reiner Finkeldey, Santiago Espinel, Jan Jensen, Jochen Kleinschmit, Barbara Van Dam, Alexis Ducousso, Ian Forrest, U. Lopez de Heredia, Andrew J. Lowe, Marcela Tutkova, Robert C. Munro, Sabine Steinhoff and Vincent Badea
Epicormiques chez le chĂȘne sessile ĂągĂ© de 13 ans : un faible effet provenance et un effet lĂ©gĂšrement plus fort du nombre de branches et dâunitĂ©s de croissance
Variations in Quercus sp. pollen seasons (1996â2011) in PoznaĆ, Poland, in relation to meteorological parameters
Genetic diversity, population structure and phenotypic variation in European Salix viminalis L. (Salicaceae)
Experimental data on the animal pulmonary scrubling
Massé R., Méthivier H., Ducousso Roger. Données expérimentales sur l'épuration pulmonaire animale. In: Bulletin de l'Académie Vétérinaire de France tome 137 n°3, 1984. pp. 397-402
Traitement dâurgence des radiocontaminations respiratoires : gĂ©nĂ©rateurs autonomes dâaĂ©rosols de DTPA.
Des Ă©tudes prĂ©alables ont montrĂ© la nĂ©cessitĂ© dâinhaler un aĂ©rosol de D-T.P.A. sur simple prĂ©somption de contamination respiratoire par des radionuclĂ©ides tels que le plutonium et les transplutoniens, lâyttrium et les terres rares, ce, le plus tĂŽt possible aprĂšs lâaccident. Pour que ce traitement dâurgence puisse ĂȘtre mis en Ćuvre, les personnels exposĂ©s doivent disposer dâun gĂ©nĂ©rateur dâaĂ©rosol individuel et portatif.
Dans ce travail, nous avons essayĂ© deux appareils susceptibles de rĂ©pondre aux critĂšres imposĂ©s par le problĂšme Ă rĂ©soudre. Lâun dâentre eux, le turbo-inhalateur SPINHALER semble devoir convenir de façon trĂšs satisfaisante
Thérapeutique des radiocontaminations internes aspect actuel et perspectives
Faire le point des thĂ©rapeutiques Ă mettre en Ćuvre sur des radiocontaminĂ©s internes et dĂ©gager des perspectives sur lâavenir de ces thĂ©rapeutiques nĂ©cessitent la connaissance du risque et surtout de son Ă©volution.
Actuellement, hormis le cas dâune catastrophe nuclĂ©aire dâordre militaire (aprĂšs laquelle dâailleurs la contamination interne ne serait pas au premier plan des prĂ©occupations), le risque nâintĂ©resse quâun petit nombre de personnes manipulant un nombre limitĂ© de radionuclĂ©ides. JusquâĂ prĂ©sent, lorsque survient un accident, les praticiens ont gĂ©nĂ©ralement affaire Ă un patient contaminĂ© par un nuclĂ©ide et, la plupart du temps, celui-ci est connu.
Dans lâavenir, il nâen sera pas nĂ©cessairement de mĂȘme. On assiste depuis plusieurs annĂ©es Ă une dissĂ©mination de lâutilisation des radionuclĂ©ides les plus divers, soit dans les laboratoires en tant que traceurs chimiques ou mĂ©taboliques, soit dans la petite industrie, par exemple, sous forme de « becs ioniseurs » pour se dĂ©barrasser de lâĂ©lectricitĂ© statique. Lâutilisation de sources de trĂšs grosse activitĂ© telles que celles nĂ©cessaires Ă la gammagraphie est certainement moins dangereuse que lâemploi « sauvage », si lâon peut dire, de petites sources : la grande activitĂ© des premiĂšres oblige Ă prendre un minimum de prĂ©cautions que les secondes nâexigent pas, dâoĂč la multiplication du risque de petites contaminations passant inaperçues en lâabsence de contrĂŽle mĂ©dical spĂ©cialisĂ©.
La prioritĂ© donnĂ©e actuellement Ă lâĂ©lectricitĂ© nuclĂ©aire va entraĂźner une augmentation considĂ©rable du nombre des centrales, multipliant dâautant la probabilitĂ© dâaccident, soit par fuite, soit au cours du transport ou du traitement des combustibles.
Enfin, il semble que de nouveaux nuclĂ©ides aient une vogue croissante d'utilisation et, parmi eux, nous rencontrons le plutonium 238 (pace-maker), lâamericium 241 (scintigraphie thyroĂŻdienne, mesures de densitĂ© osseuse), le californium 252 (cancĂ©rologie), etc. Or, ces Ă©lĂ©ments peuvent ĂȘtre considĂ©rĂ©s comme beaucoup plus dangereux que le 239 Pu en ce sens que leur activitĂ© massique est de 50 Ă 10 000 fois plus grande. Par consĂ©quent, Ă activitĂ© dĂ©posĂ©e Ă©gale, la masse correspondante est 50 Ă 10 000 fois plus faible, donc la diffusibilitĂ© plus grande. Si la thĂ©rapeutique reste la mĂȘme (basĂ©e essentiellement sur lâemploi du D.T.P.A.), lâurgence devient la condition sine qua non du succĂšs
Reproduction and gene flow in the genus Quercus L
In this paper we review the characteristics of the floral biology, life cycle and breeding system in the genus Quercus. The species of this genus are self-incompatible and have very long life spans. The focus of our review is on the effects of gene flow on the structuration of genetic variation in these species. We have examined the influence of gene flow in 2 ways: 1) by measuring the physical dispersal of pollen, seed and vegetative organs; and 2) by using nuclear and cytoplasmic markers to estimate genetic parameters (Fis, Nm). These approaches have shown that nuclear (isozyme markers) as well as cytoplasmic (chloroplastic DNA) gene flow is usually high, so that very low interspecific differentiation occurs. However, intraspecific differentiation is higher for the cytoplasmic DNA than for the nuclear isozyme markers.SystĂšme de reproduction et flux de gĂšnes chez les espĂšces du genre Quercus. Les caractĂ©ristiques de la biologie florale, du cycle de vie et du systĂšme de reproduction ont Ă©tĂ© analysĂ©es pour les espĂšces du genre Quercus. Ces espĂšces sont auto-incompatibles et Ă trĂšs longue durĂ©e de vie. Les effets des flux de gĂšnes sur la structuration de la variabilitĂ© gĂ©nĂ©tique ont aussi Ă©tĂ© Ă©tudiĂ©s de 2 maniĂšres. D'une part, grĂące aux mesures de la dispersion du pollen, des graines et des organes vĂ©gĂ©tatifs, et, d'autre part, en utilisant des paramĂštres gĂ©nĂ©tiques (Fis, Nm) obtenus Ă partir des marqueurs nuclĂ©aires et cytoplasmiques. Il apparaĂźt que les flux gĂ©niques nuclĂ©aires (isozymes) et cytoplasmiques (ADN chloroplastique) sont en gĂ©nĂ©ral importants, d'oĂč une faible diffĂ©renciation interspĂ©cifique. NĂ©anmoins la diffĂ©renciation intraspĂ©cifique est plus forte lorsqu'elle est estimĂ©e Ă partir des marqueurs cytoplasmiques que lorsqu'elle l'est Ă partir des marqueurs nuclĂ©aires
- âŠ