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.     

Le cancer radio-induit,le kangourou,et le petit lapin. Ou « la déclinaison radiobiologique du mythe de la Licorne Rose »

The linear no-threshold (LNT) model, which has become a dogma in its own right, leads to affirming the existence of the harmfulness of low doses of ionizing radiation as long as their harmlessness could not be demonstrated. It seems important to understand how we came to make dogmatic a scientifically “non-theory”. We propose in this article, after having shown how much RLSS stems from a myth and not from a scientific approach, to expose its origins and genesis, essential to the understanding of its current character of so-called incontestable truth, then to illustrate the worrying practical and epistemological consequences that this reference to RLSS entails. We rely for this on the critical analysis of some of the epidemiological studies that claim to demonstrate or confirm it.     

Rôle des polyphénols dans la croissance. Définition ďun modèle expérimental chez Lycopersicum esculentum

Using young plants of Lycopersicum esculentum Mill., we attempt to define a system for a new evaluation of the physiological role of polyphenols, particularly of their regulating properties on growth and development, Exogenously supplied qoinic acid causes an important increase of the phenolic content and a reduced growth of the plants. The decrease in size is proportional to the stimulation of the phenolic pool and is equally obtained using other precursors of aromatic compounds like phenylalanine and cinnamic acid. Non-precursors of polyphenols structurally related to quinic acid are ineffective. It appears from these data that polyphenol levels and growth could be related in tomato plant and that this material would be convenient for studies on interactions between growth and polyphenols.