Tchernobyl : le vrai, le probable et le faux

The Japanese earthquake and tsunami drew attention worldwide to nuclear power plant accidents and associated health risks. Since Chernobyl 25 years ago, several studies were published and we now have precise information concerning the long-term health of the population living near nuclear power plants and also in different European countries. The authors hope to bring some answers to the key questions from the public concerning radioactive units used and their significance, the evaluation of the number of radio-induced cancers within the different countries of Europe, other eventual health effects and the problem of possible congenital anomalies. Finally, French public perception on nuclear risk is examined and the feedback of the Japanese experience is evoked.     

L'évolution parallèle des Juraphyllitidae euroboréaux et téthysiens au Pliensbachien: le rôle des contraintes internes et externes

Au Pliensbachien, un trend morphologique se developpe chez les Tragophyllocerassimpliquant un mécanisme hétérochronique (paedomorphose par néoténie) pour I'acquisition d'une morphologie suboxycône. Ce changement morphologique majeurest concomitant avecl'ingression de ces formes dans les mers de plateforme euroboréale ob la compétition inter-taxons est forte. Cette option morphofonctionnelle et évolutive, canalisée essentiellement par des contraintes externes étant amorcée, le genre va I'exploiter dans la mesure de ses possibilités (potentialités intrinsèques) en perfectionnant son oxycônie. Au contraire dans les mers téthysiennes, les Juraphyllites ne montrent pas d'évolution pour la morphologie de la coquille; celle-ci reste subplatycône durant tout le Lias moyen et il n'y a pas de changements environnementaux majeurs (milieux tamponnés). En outre la prolifération d'ornementations plus grossières, aussi bien chez les Juraphyllites que chez les Tragopbylloceras, correspond probablement à une meilleure exploitation des biomes d'Europe du NW et de la Téthys à une période bien précise qui est le Carixien moyen. Ce développement d'ornementation similaire chez des taxons partageant un héritage évolutif commun mais séparés paléogéographiquement, évoque le rôle prépondérant des contraintes internes. Ainsi l'évolution des Juraphyllites des Tragophyllocerasau Lias moyen paraît donc ètre un exemple de parallèlisme au sens strict du terme.□Évolution, hétérochronies, Juraphyllitidae, Lias, ontogenèse, Paléogéographie. A morphological trend in the Pliensbachian Tragophyllocerns involves a heterochronic process (paedomorphosis by neoteny) to acquire a suboxycone morphology. This major morphological change is concomitant with the ‘ingression’ of Tragophylloceras in the Euroboreal platform seas, where competition between taxa was strong. This functional-morphological and evolutionary option is mainly canalized by extrinsic constraints. Exploring these possibilities, Tragophylloceras then exploits and improves the oxycone option. By contrast, in the Tethyan seas, Juraphyllites shows no change in shell coiling; it stays subplatycone during all the Pliensbachian. There is no major environmental change. Moreover, the proliferation of coarser ornamentation in Juraphyllitesand Tragophylloceras probably corresponds to a better exploitation of the Euroboreal and Tethyan marine habitats during the Middle Carixian. The development of similar ornamentation in palaeogeographically separate taxa with a common evolutionary origin is mainly canalized by intrinsic constraints. The evolution of Juraphyllites and Tragophylloceras appears to be a good example of parallelism sensu stricto. □ Evolution, heterochrony, Juraphyllitidae, Lios, ontogeny, palaeogeography.     

L'homme et le Langage

Sans résumé     

Isolement d'une alcool déshydrogénase chez Rhizobium et rôle dans le métabolisme indolique

Rhizabium meliloti contains an alcohol dehydrogenase (E.C.1.1.1.1.) which can be isolated by breaking the cells. This soluble enzyme was purified 16.1-fold by fractional precipitations with ammonium sulfate followed by gel filtration on Sephadex. The activity of the enzyme was tested with various aldehydes as substrates in the presence of NADH. Indole-3-acetaldehyde (IAAld) can be reduced to tryptophol (Tr-ol), and the optimal pH for this reaction is ca. 6.5. The reaction can be reversed, and Tr-ol is oxidised in the presence of NAD, but is was found that the yield was very poor; the optimal pH was ca. 8.6. This alcohol dehydrogenase is responsible for Tr-ol formation in Rhizobium, but under our experimental conditions tryptophol cannot really be considered as a precursor of IAAld and indole-3-acetic acid.     

Corrélations de croissance entre le mycélium et les rhizomorphes chez le Sphaerostilbe repens

Correlation of Growth between Mycelium and Rhizomorphs in Sphaerostilbe repens In Sphaerostilbe repens Berkeley and Broome, cultured on a solid medium in Petri dishes, growth of mycelium and chizomorphs depends on the thickness of the culture medium underlying the thallus. On shallow layers of agar medium, aggregated units were fewer and rhizomorph growth reduced. Vegetative mycelium which starts growth earlier than rhizomorphs contributed to inhibit the development of these latter. On deep layers of substrate, rhizomorphs were numerous, elongated rapidly, and eventually inhibited undifferentiated mycelium. – There was no evidence for the involvement of any inhibitor substance diffusing into culture medium or located in the thallus. Development of aerial mycelium and rhizomorphs, could, on the contrary, be interpreted as nutritional competition between these two parts of the colony.     

Analogues et dosages d’insuline : le cas général et le cas particulier de la glargine

Since 1996, genetic engineering has allowed modifications of insulin yielding to multiple modified insulins with different pharmacokinetic and/or pharmacodynamic properties. Molecules with maintained pharmacodynamic and modified pharmacokinetic profiles have been selected. Currently available rapid-acting analogues (lispro, aspart and glulisine) achieve plasma peak concentrations about twice as high and within approximately half the time compared with regular human insulin thus closely mimicking the physiological insulin response to a meal. Long-acting analogues (glargine and detemir) ensure the steady supplement of basal insulin plasma levels, with a plateau type of profile. Main analytical pitfalls of commercially human insulin immunoassays include crossreactivity with analogues and their metabolites. These crossreactivities are of great concern for interpreting insulin levels in patients treated with analogues. The development of more specific analytical methods to quantify separately the concentrations of endogenous insulin, rapid-acting and long-acting analogues and metabolites would be of utmost importance: (1) to further understand long-acting analogue variability in terms of efficiency; (2) to perform analogue kinetic studies; (3) to measure analogues in routine toxicology (forensic medicine) and (4) to assess intact glargine or glargine metabolite in vivo toxicity: recent debates about glargine safety have highlighted the lack of data about metabolite status (proportion of metabolized glargine and bioactivity of its metabolite). This goal could be achieved by specific immunoassay development or/and mass spectrometry analysis.     

Rôle des facteurs de croissance et cytokines dans le testicule normal et pathologique

Since 4 years ago, intracytoplasmique sperm injection (ICSI) represents a new therapeutic approach of different forms of male sterility including obstructives and spermatogenic failure azzospermia. However, the evaluation of the male infertility begins with the study of semen characteristics particularly sperm count and motility assessment. However, testicular activites are not only under the control of the neuroendocrine system but also under that of local growth factors and cytokines. In this review, we report, in the first part, the different observations indicating the key role of growth factors and cytokines in the fetal testis development as well as in the differentiated functions, steroidogenesis and gametogenesis. In a second part, we report the data, obtained by different teams, related to the evaluation and/or actions of these factors in infertile men. Moreover, the low number of data related to the use of these factors in order to improve sperm fuction are mentioned. Finally, in a prospective context, we indicate some points which seem of interest for elucidating some aspects of growth factor and cytokine role in fertility/infertility.     

Évolution et transformation des industries lithiques taillées et polies durant le Chalcolithique et l’Âge du Bronze en Corse

Lithic industries in Corsica have been subject to important modifications during the 3rd and 2nd millennium cal. BC. Polished tools changed almost totally during that period, the majority of all lithic tools disappeared. The development of metallurgy is probably the main reason for these changes; they show the new place of lithic productions in the activities of the different communities within the island.     

Panxian Dadong et le Levallois chinois

The immense cave of Dadong is located in the southernmost part of China in Guizhou Province. Opening to the east, it contains typically cryoclastic deposits alternating with soliflucted clays in a several meters’ thick sequence. Several excavation seasons have been conducted by Chinese colleagues since 1991 and a series of dates was obtained by an international team. The material presented here comes from a chronological phase between 300 and 130 ka, a period equivalent to the Middle Pleistocene, represented here by rich evidence of technological activities and abundant fauna, the stegodon in particular. In southern China, many sites show the same methods as at Dadong-Panxian, essentially core reduction to obtain large Levallois flakes. These sites, found across the south, all apply a very elaborate method to extremely hard stone, primarily basalt. The massiveness of the tools corresponds to the concept of the tools themselves, more violent even than the stones. The human mind that was able to organize these different phases in a precise and effective order arises universally, it overcomes all of the mechanical constraints of stone and imposes its laws on it. This technological unit so impresses the modern observer that it has often been interpreted as the result of waves of migration with limited diffusion. However, such systematic emergence manifests only spiritual capacities, also distributed globally. Somewhat like inventing the bow or the hammer, the mechanical constraints “carry” humanity toward similar material formulas. The availability of raw materials remains an adjustable material element, but without causing the essential structure that went into its use. Thus, the Levallois method is found in the middle of the Pacific Ocean (Admiralty Islands), in Africa (the Victoria West industry) and even in South. Like the invention of writing or agriculture, no cultural link connects these regions; the method develops spontaneously and convergently from the human mind, adapted to new constraints. The Chinese Levallois thus does not belong to a diffusion mode, but to several emergences, penetrated by the human mind in the constraints introduced between the mechanical laws of stone and the entirely universal intentions of humans to seek effectiveness and freedom.     

Relations entre production et localisation de mycosporine et morphogenèses reproductrices chez le Pyrénomycète Gnomonia leptostyla

Relations between production and localisation of mycosporin and reproductive morphogenesis in the Pyrenomycete Gnomonia leptostyla.
The production of mycosporin (P310) has been analysed in Gnomonia leptostyla (FT.) Ces. et de Not. during mycelial growth and reproductive morphogenesis (macroconidiogenesis, microconidiogenesis and differentiation of perithecia). Conidiogenesis is induced in illuminated cultures while darkness promotes perithecial development. At 20°C, the cultures produce either macroconidia or perithecia with abortive sporophyte. Microconidia differentiation and perithecia maturation require low temperature (10°C). Mycosporin is, at all times, present in the thallus. However, the concentration of mycosporin in highest in the conidiogenous thallus, intermediate in the perithecial thallus. and lowest in the vegetative mycelium. In the conidiogenous thallus, macroconidia and microconidia are both sites of mycosporin accumulation. On the contrary, in the perithecial thallus, mycosporin levels are not higher in perithecia than in mycelia, even during their maturation period. The quantitative variations of mycosporin during the thallus development and its accumulation inside conidia suggest translocation from sites of synthesis towards reproductive cells.