Risque viral en AMP

Detection of virus (VIH, CMV, HSV, HPV, HCV, HBV) in semen raises the issue of the risk of transmission of infection to the mother and the future baby, to other gametes and embryos in the incubator, and to technicians related to the manipulation of contaminated biological fluids in the standard IVF laboratory. The transmissibility of virus through medical techniques is a critical question in public health care. For each virus, it becomes essential to assess transmission risk in ART, especially inin vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI), to define the management of couples according to their viral status. Here, we studied different virus: CMV, HCV, HBV and HIV and proposed practical attitudes towards virus screening and management in infertility centers.     

Reactions chimiques couplees considerees en tant que filtres passe-bande

An investigation is made as to whether or not the existence of a band-pass filter function, analogous to that in electronics, can be proved from the fundamental laws of chemical kinetics. The problem is important for better understanding of the preference of certain biological rhythms to others. It is shown with simple examples that such behavior is possible for a number of systems of coupled chemical reactions far enough from the thermodynamic equilibrium. It is of interest to generalize this behavior since it could conceivably play a role in the transmission of “usable information” in biology.      

Relations entre le benthos,la derive,le rythme alimentaire et le taux de consommation de truites communes (S. trutta L.) en canal experimental

Relationships between benthos, drift, feeding rhythm and consumption rate of brown trout were investigated in an artificial stream in late spring. There are good correlations between insects activities and feeding rhythm of the trout. There are two feeding periods, the first one, more important, occurs at dusk and the second one in early morning. Daily ration is 6% of trout dry weight.     

Réflexion sur la coexistence de flores hygrophile,mésophile et mésoxérophile durant le Paléozoïque Supérieur en Euramérie

At the end of Namurian A, in Eurameria, we see agreat change in the composition of the flora, probably instigated by a great modification in the climatic conditions. This flora adapted to very humid places persist during whole the Westphalian and up to the end of Stephanian where it is relayed by a mesoxerophytic flora of which the most typical elements are the Coniferales of the family Lebachiaceae. This «autunian flora is usualy considered as subsequent to the stephanian hygrophytic flora and as the transition to the permian flora which is determined by a new modification of the general climatic conditions.Some observations about the macroflora and about the microflora lead to prove the coexistence of hygrophytic, mesophytic and mesoxerophytic floras, not only during the upper Stephanian but also during Westphalian and Namurian B and C. So, from Devonian to Permian, in Eurameria, there was probably continuity of a mesoxerophytic and mesophytic type floras on which was superimposed during the upper Carboniferous an hygrophytic flora adapted to the swamps surrounding the coal-lakes and coal-lagoon. The time of the appearance of Coniferales is older as we think usually.     

Mollusques septentrionaux en Mediterranée occidentale: Datation par le C

In the Western Mediterranean, heaps of shells lying in the upper part of the continental slope between 90 and 340 m include boreal species which do not occur at present in this basin. The most common are Arctica arctica, Chlamys septemradiata, Modiolus modiolus. This malacological fauna seems to have been living when the sea-level was 80 m lower than at present.     

Les structures d’occupation gravettiennes en Europe centrale : le cas de Grub/Kranawetberg,Autriche

Grub/Kranawetberg, a multilayered Gravettian site in Lower Austria, is one of many Gravettian open-air sites of Central Europe. These sites are well-known since a long time for their settlement structures, but also rich lithic inventories as well as organic tools, personal adornments, and art objects (e.g., Pavlov, Dolní Vestonice). While old excavation and recording techniques do not allow a detailed intrasite spatial analysis of these sites, the ongoing fieldwork at Grub/Kranawetberg provides us with abundant and detailed information about spatial organization of a Gravettian open-air site in Central Europe. The site is excavated since 1993 and yielded four archaeological horizons with abundant finds (including numerous personal adornments) and some evident structures. The main focus of this paper is on the GIS-based methodology of intrasite spatial analysis, especially emphasizing the possibilities of recognizing formation processes, size-sorting and locating a possible dwelling. Application of various methods, among them piece-plotting, mapping of find quantities, application of kernel density estimates and ring and sector analysis, in the 1995 and 1996 excavation area showed latent structures which are interpreted as evidence for a dwelling in this area of the site. In the last part of the paper the evidence of Grub/Kranawetberg is discussed and compared with other European Gravettian sites.     

Mise en Evidence de la Carcinine Synthétase, une Nouvelle Enzyme Catalysant le Métabolisme de l''Histamine dans le Systeme Nerveux Central de Carcinus maenas

Carcinine biosynthesis was induced in vitro from its two components, beta-alanine and histamine. The reaction was catalyzed by muscle, heart, and CNS extracts from Carcinus maenas. The specific activity of the enzyme, carcinine synthetase, was 15 times higher in CNS than in other organs. Only CNS extracts induced biosynthesis of carcinine from histidine, and only in the presence of pyridoxal-5'-phosphate. Hence the seat of carcinine biosynthesis seems to be the CNS. It is highly probable that in the CNS, histidine is transformed into histamine, which is then catabolized into carcinine. The latter would then be transported and accumulated in the cardiac tissue. Thus histamine--the metabolism of which takes place totally within the CNS--would be implicated as a participant in the neuronal activity of Carcinus maenas. Carcinine synthetase is a soluble enzyme that requires the presence of ATP, beta-alanine, and histamine. Mg2+ and dithiothreitol are also essential for activity. Optimum pH is approximately 7.6. Carcinine synthetase differs from carnosine synthetase and gamma-glutamylhistamine synthetase in that it does not catalyze synthesis of beta-alanylhistidine or gamma-glutamylhistamine.     

Yeast pseudohyphal growth is regulated by GPA2, a G protein alpha homolog.

Pseudohyphal differentiation, a filamentous growth form of the budding yeast Saccharomyces cerevisiae, is induced by nitrogen starvation. The mechanisms by which nitrogen limitation regulates this process are currently unknown. We have found that GPA2, one of the two heterotrimeric G protein alpha subunit homologs in yeast, regulates pseudohyphal differentiation. Deltagpa2/Deltagpa2 mutant strains have a defect in pseudohyphal growth. In contrast, a constitutively active allele of GPA2 stimulates filamentation, even on nitrogen-rich media. Moreover, a dominant negative GPA2 allele inhibits filamentation of wild-type strains. Several findings, including epistasis analysis and reporter gene studies, indicate that GPA2 does not regulate the MAP kinase cascade known to regulate filamentous growth. Previous studies have implicated GPA2 in the control of intracellular cAMP levels; we find that expression of the dominant RAS2(Gly19Val) mutant or exogenous cAMP suppresses the Deltagpa2 pseudohyphal defect. cAMP also stimulates filamentation in strains lacking the cAMP phosphodiesterase PDE2, even in the absence of nitrogen starvation. Our findings suggest that GPA2 is an element of the nitrogen sensing machinery that regulates pseudohyphal differentiation by modulating cAMP levels.     

Le site de Tögi Ndrawa, île de Nias, Sumatra nord : les premières traces d'une occupation hoabinhienne en grotte en Indonésie

The site of Tögi Ndrawa, Island of Nias, North Sumatra: The first record of a Hoabinhian cave occupation in Indonesia. Although in Indonesia, Hoabinhian sites usually refer to large shell midden dated back from the Holocene period, the Tögi Ndrawa cave in the Island of Nias (North Sumatra) has revealed a thick shell accumulation, sealed in a cavity, and beginning with the end of the Late Pleistocene. Excavations have produced classical Hoabinhian pebble artefacts, a forest and coastal fauna, and human bones. Beyond the new chronological landmarks provided by these findings, they question the extension of the Hoabinhian phenomenon originating from continental Asia, and provide hints about human settlement and use of the environment at this period of prehistory. Pour citer cet article : H. Forestier et al., C. R. Palevol 4 (2005).     

L'Indole et le Tryptophane régulateurs de croissance, en culture in-vitro, pour les tissus de parenchyme médullaire de Tabac, normaux et tumoraux

Indoleacetic acid, tryptophan and indole promote growth of pith tissues of tumorous Nicotiana glauca×N. langsdorffii amphidiploïd hybrid, but only indoleacetic acid gives the potentiality of continuous development to the tumorous tissues after some days of contact on a medium without growth substances. In combination with 6-benzylaminopurine, tryptophan and especially indole are promoting substances like auxin for the non-tumorous pith tissues of tobacco, and allow a considerable organogenesis.     

Caractérisation d'une Mosaïque Forestière et de sa Dynamique en Forêt Tropicale Humide Sempervirente1

Using a 0.78 ha transect in an undisturbed forest in French Guiana, we sought a typology of forest mosaic units (5 × 5 m quadrats) based on diameter distribution with three main classes of trees ≥5 cm DBH. We identified nine basic structural types corresponding to potential stages of a sequence of development from colonization of gaps to filling of the vertical space among three layers. Two enumerations made over a 10-year interval (1981 and 1991), enabled a transition matrix to be estimated. This summarizes movement between structural types over the period and enables ideas on dynamics to be discussed.     

Les ongulés en périgord et Nord-Ouest du Quercydurant le würm III. Chronoclimatologie,paléobiogéographie,palethnologie

The studies of Ungulate associations present in Würm III deposits of Southwest France lead to state biological paleoenvironments and paleoclimates more precisely. The second climatic phasis brought to light by H. Laville in Perigord seems cold and dry and the third one (Arcy) would be the most temperate and humid phasis during the Würm III period. Two posterior climatic ameliorations (fifth phasis = «Kesselt and seventh phasis = Tursac) are separated by a colder period. From the eighth phasis, a climatic threshold is crossed; paleontological as well as geological and palynological studies show the establishment of global cold conditions which would continue after Würm III–IV «interstadial (Laugerie). This one looks like a minor humid oscillation.Although data come from geographically close sites, clear differences appear between contemporary faunal associations. In Perigord, Ungulate associations strongly vary during the first seven phasis whereas in Northwest Quercy, in Auniac plain, Reindeer dominates all along this period.Lastly, comparisons between the results of paleontological,geological and palynological studies enable us to approach the question of the game choice made by prehistoric men. The perigordian men who inhabit La Ferrassie rockshelter during the sixth climatic phasis preferentially hunt Reddeer. They deliberately give up hunting other Ungulates yet well represented in contemporary levels of not distant sites.