Denombrement et analyse morphologique des chromosomes chez quelques clones issus d'une souche anergiee de tabac: Relation avec l'anergie,le pouvoir tumoral et l'organogenese

Counting and morphological analysis of chromosomes in some clones derived from habituated tobacco callus cultures: relationship with habituation, tumorous properties and organogenesis     

Enrichissement expérimental d'eaux printanières de claires à huîtres en baie de Bourgneuf (Vendée,France): augmentation de la biomasse et utilisation des éléments nutritifs par les algues unicellulaires

Oyster-pond sea-waters with natural populations were experimentally enriched to determine the nutrient limiting algal growth and the resulting effect on species composition. Results show that nitrogen is the limiting factor of growth-potential. N-NO₃ alone is exhausted, while other ion concentrations remain always measurable. Addition of N-NO₃ is needed to increase algal biomass. Favoured species differ when nitrogen is added alone or added with phosphorus.

     

Variabilité et homogénéité des modes de débitage en Chine entre 300 000 et 50 000 ans

The position of lithic industries of Chinese Paleolithic in comparison with those of other regions in the world is always a controversial topic. The typological analysis has made Chinese prehistorians reveal some variability between lithic industries of different regions of China in terms of technical tradition and industrial structure. But this recognition, based upon some morphological characters of stone artifacts, failed to define systematically the modes of production that exist in each site. To answer these problematic some new methods need to be applied. So the lithic materials from 8 Chinese sites dated from 300 ka to 50 ka B.P. were selected and analyzed by means of lithic technological analysis and a new approach for analyzing the structures of cores. This paper presents principally the analytical results of modes of débitage and revealed that the modes of débitage during this period were characterized essentially by system C (“simple débitage”) and E (discoid) and that the concept Levallois was absent during this period in technical systems of lithic production in China. The Chinese lithic industries between 300 ka and 50 ka B.P. saw some homogeneity in the scale of the continent and remarkable difference from those of other regions in the world. So a stable, continuous but independent even isolated evolution in comparison with those of other regions was observed in this period. In addition, despite of apparent homogeneity, some variability exists also between these industries.     

Étude des réactions croisées entre les lectines de légumineuses: In systématique et phylogénétique

Seed extracts from 56 legume species were examined for immunological relatedness using 11 different lectin antisera. The immunological cross-reactions observed indicate that only lectins from species belonging to the tribe Vicieae share common antigenic determinants and are evolutionary closely related. These results suggest that the immunochemical study of the Vicieae lectins may provide a powerful tool for determining the systematic and phylogenetic relationships within the tribe.     

Caractérisation de la production particulaire par l’oursin Echinometra mathaei sur les récifs Indo-Pacifiques : influence des peuplements coralliens et implications sur la dynamique sédimentaire

The characteristics of the sedimentary grains produced by the sea urchin Echinometra mathaei were described from two reef sites: a fringing Acropora-dominated reef at La Reunion island (Indian Ocean) and a barrier Porites-dominated reef at Moorea island (French Polynesia). The composition of the sediment produced by Echinometra was determined from SEM observations. The size and shape of the particles were measured by using image analysis method. The grain diameters range between a few micrometres and 2 mm, with a large predominance (more than 80 %) of particles smaller than 400 μm. The grain size distribution is dependent on the nature of the grazed substratum. Echinometra individuals collected at La Reunion on branching Acropora colonies produce a higher proportion of particles smaller than 200 μm compared to those collected at Moorea on massive Porites colonies. At Moorea, more grains having a diameter comprised between 200 and 500 μm are produced. The microstructure of coral substrata affects the mean particle diameter, which is 192,17 μm for a Acropora substratum and 244,69 μm for a Porites substratum. Since the sediment derived from Acropora erosion is finer, the proportion of suspended material that is exported from the reef is greater at La Reunion than at Moorea. We estimate that, for similar erosion rates and hydrodynamic conditions, the production of sands by Echinometra mathaei is higher and the retention of this erosional sediment more effective on reefs dominated by massive Porites than on Acropora-dominated reefs. This result is in accordance with the proportions of suspension-moving grains that have been previously measured on Moorea and La Reunion reefs. This study highlighted the effect of coral communities on the production of particles related to the bioerosion and on the sedimentary budget.     

Scintigraphie des parathyroïdes double isotope Tc-MIBI/I dans l’hyperparathyroïdisme primaire : comparaison entre un protocole d’acquisition planaire et une TEMP de soustraction couplée à la TDM

In patient with primary hyperparathyroidism, preoperative imaging first objective is to determine accurately and reliably position and anatomic localization of enlarged parathyroid gland in order to guide surgeon for gland removal and to permit minimally invasive surgery. Although subtraction planar scintigraphy is an efficient imaging to diagnose hyperfunctioning parathyroid, the lack of anatomical reference for this single imaging technique could be obviated by hybrid imaging. We compared, in 23 patients with primary hyperparathyroidism, a planar scan of neck and mediastinum associated with a cervical anterior pinhole scan to a subtraction (¹²³I/^99mTc-MIBI) SPECT scan of neck and mediastinum fused with CT. Surgical and histopathologic findings were used as the standard of truth. Subtraction SPECT/CT appeared to be more sensitive and specific than planar protocol to diagnose and to accurately localize pathologic parathyroid. Sensitivity was 76 and 56 %, specificity was 100 and 80 % for hybrid SPECT/CT and planar protocol respectively. SPECT protocol was typically more efficient to diagnose pathologic parathyroid derived from upper gland and for patient with concomitant nodular goiter.     

Proposition méthodologique pour une étude des esthétiques du Mésolithique : une analyse sociologique-anthropologique de la fin du Tardiglaciaire et durant le Postglaciaire en Europe occidentale

Do the decorated productions cover esthetics, i.e. the whole of the symbolic systems of a culture of hunters-gatherers? How to leave this glance with the aesthetic requirements that we other Westerners, pose on all things… and to exceed the debate of the artistic expressions thought from the aesthetic point of view, like “works of art” objects and “stylistics” objects? It is out of question “to make a fetish” of the productions decorated “works of art” while placing them at the starting point with our reflexion, (Studying them from a functional, technological, typological, art for art, meaningful point of view…) but to associate another of dimensions of the aesthetic experiment, i.e., the context of the decorated productions.