Sur l'origine du suboculaire des Actinopterygiens fossiles

The embryological study of ArapaimaMüller 1843, the only modern teleost still possessing a subocular, shows that that bone has an opercular and not ocular origin as generally thought.     

Note preliminaire concernant la decouverte d'une faune et d'une flore du niveau de Ronzon dans l'Oligocene inferieur du Bassin d'Aquitaine

The new locality of Ruch (Gironde), from a lateral facies of the “Calcaire de Castillon” formation has yielded an important flora and fauna. From the biostratigraphic point of view the mammalian fauna allows to show that Ruch is contemporaneous of the reference locality of Ronzon (Auvergne).     

Sur les conditions de gisement de l'ichthyofaune oligocene d'Aix-en-Provence (Bouches-du-Rhone): Essai de definition d'un modele paleoecologique et paleogeographique

The study of the fossil fishes preserved in 19 successive fossiliferous beds sampled while excavating in the city ofAix-en-Provence permits the elaboration of a sedimentary model for the Oligocene gypsiferous marls. These seem to have been deposited on a coastal plain, in continental waters characterized by a fluctuating, very low, salt-content.     

Regulation d'activité de l'α-Amylase à différentes températures d'adaptation et en fonction de l'ablation des pédoncules oculaires et du stade de mue chez Palaemon serratus

The influence of thermal acclimatisation of the shrimp Palaemon serratus on the specific activity of α-amylase and the soluble proteins of the hepato pancreas show the presence of a metabolic compensation kinetic within this organ. The kinetic properties of partially purified α-amylase show that 2 sites are able to fix starch in the absence of NaCl but only 1 site when NaCl is present. The importance of conformational changes of the enzyme is shown by examining its regulatory properties according to the different temperatures of adaptation, and to the removal of eyestalks and the molt cycle. During these changes there are no qualitative variations in α-amylase isoenzymes.     

Isoenzymes de l'anhydrase carbonique d'un poisson euryhalin: Variations en relation avec l'osmoregulation

A chemical study of carbonic anhydrase (EC 4.2.1.1) from the red blood cells and the gills of an euryhaline fish (Anguilla anguilla) is presented. Animals adapted to fresh water were compared to those adapted to sea water.The physicochemical constants of the various molecular forms isolated by chromatograhy and isoelectric focusing were determined; isoeleletric pH, molecular weight, and the K_m and V/E of the enzyme dehydration activity were compared.In both red cells and gills of fish adapted in either media various forms were isolated, characterized by different enzymatic kinetics (high- and low-activity forms) but having the same molecular weight (27 250). Some isoenzymes isolated from the gills differed significantly from those isolated from the red cells.Adaptation to fresh water or sea water is accompanied by modifications in the distribution of yhe isoenzymes in both red cells and gills: adaptation to sea water is characterized by a shift of the molecular forms towards an isoelectric pH higher than pH = 6.The role of these enzymes is discussed under both a physiological and biochemical point of view in relation to the electrolyte exchange across fish gill. The origin of the different molecular forms of the carbonic anhydrase is discussed in relation to the prevailing theories on this subject.     

Modalités de la contamination d'une chaine trophique marine benthique par l'argent 110 m: 4. Influence du mode de contamination sur l'élimination du radionucléide

The elimination of ^110mAg by Navicula incerta Grunow ex Van Heurck, Navicula biskanteri Hustedt, Scrobicularia plana (da Costa) and Carcinus maenas (L.) depends upon the duration of contamination or the number of intakes of radioactive food. The longer the contamination occurred, the slower will be the climination.The decontamination is slower after (chronic) ingestion of radioactive food than after immersion in contaminated water. The physico-chemical forms of ^110mAg likely play a rôle in elimination kinetics. So, external organs, whose contamination results mainly from adsorption, get rid of ^110mAg faster than the digestive gland in which silver seems to be retained in a hardly exchangeable form.Consequently, the total radiation dose for contaminated organisms will depend greatly upon the way and the duration of the contamination.     

Les crustaces decapodes du Cenomanien de Navarra (Espagne):Premiers resultats de l'etude des Galatheidae

Preceded by a short report on the fauna associated with Decapods in the Cenomanian from Orobe and by historical references, this note is an account on the results obtained after elaborate study of 187 specimens of Anomura belonging to Galatheidae family. Those results allow the systematic delimitation of two genera: ParagalatheaPATRULIUS, 1960 and Eomunidopsis n. gen., which produce the revision of 5 species belonging to those two genera. A provisional determination of the rest of the material (14 Brachyurans), still under consideration, is proposed.     

Contribution a l'etude biostratigraphique du Cretace superieur d'une coupe du Massif du Braus (Aples Maritimes,SE France)

The Cretaceous beds of the “Massif du Braus” contains a rich planctonic microfauna. A biostratigraphic study of this country is precised from Lower Cenomanian to Middle Campanian. Planktonic forminifera and Nannoplankton assemblages and events recognized in a continuous section in the “Massif du Braus” are given and discussed. The stratigraphical distribution of the different species is presented in three figures.     

Indications de l'ultrastructure d'une espèce de forme du crétacé supérieur,Oculopollis maximus W. Krutzsch

Some varieties of the pollenform species Oculopollis maximus Krutzsch have been studied by means of transmission and scanning electron microscopy. Contrary to the observations made by means of light microscopy, major differences appear between those with a psilate exine and the others with a sculptured exine. This result makes it clear that the Oculopollis maximus pattern could be a network phyletic system rather than a single phylogenetic line.     

Effets des marées sur la variation circadienne de la capacité photosynthétique du phytoplancton de l'estuaire du saint-laurent

The photosynthetic capacity of phytoplankton was measured at an anchor station in the Middle Estuary of the St Lawrence, over a period of 120 h. Hourly incubations were made in constant light conditions, under three different colour filters of 3, 4 and 23 W · m^?2. Differences in the oscillations of the photosynthetic capacities were observed in relation to the tidal regime. During spring tide, variations in the photosynthetic capacity are circadian, whereas a tidal pattern was also observed during the neap tide period. Differences in the patterns of photosynthetic capacity were probably due to changes in the gradients of physical factors and to the physiological state of phytoplankton relative to these gradients. The circadian rhythms appeared to be endogenous since they were apparent at non-saturating light intensities and since the photosynthetic potential (U_max) changed during the day.     

Decouvertes recentes de mammiferes et de mollusquesdans des formations d'age oligocene terminal et aquitanien du SE de la France; comparaison avec les gisements deja connus dans la meme region

The first brackish levels of the Aquitanian (s. lat.) of Cap Janet (B. du Rh.), contemporaneous with thoseof Carry-le-Rouet, have provided rodents and continental molluscs. They belong to the same level as the mammals of Coderet and so are correlated to the “série grise” of Barrême, the “calcaire de Reillanne”, the marls and limestones of Rougier, the gypsun of Aix. Older faunas found in the localities of “St-Henri” and “Les Milles” show that they belong to the same detritic flow as the “marnes de Viens”.     

Utilisation des isotopes stables pour l’identification de l’origine du carbone dans la datation du charbon de bois du Paléolithique

Recent years have brought many results of radiocarbon dating the earliest periods of the Upper Palaeolithic that can bring light on the origins of figurative art by Sapiens or Neanderthals. These dates are often close to the limit of the field of radiocarbon dating; because they require measurements of the lowest amounts of radiocarbon, controls are particularly essential. Here we examine the case of the dating of charcoal, whose identification after decontamination is difficult. We suggest a method that does not require additional manipulation to determine whether carbon comes exclusively from charcoal: using the proportion of stable carbon isotopes 13C/12C which is often regarded as a signature (δ13C).     

Un exemple de sequence d'estrandans le Portlandien du Jura meridional

The study of the portlandian limestones of the Vouglans dam outcrop in the southern Jura mountains hasprovided the elements to establish the theoretical succession of the sediments (virtual sequence) and to show the similarities with the recent western Andros tidal flats. Their respective bathymetry is here compared, allowing to think that a part of the jurassian portlandian limestones are located from the shallow subtidal to the supratidal, creating short rhytmic sequences, sometimes only a few centimeters high.     

L'age des “Calcaires a petites huitres” de l'Ile Cremieu (Jura meridional tabulaire); Correlation des formations du Bajocien superieur de la region lyonnaise

Parkinsonids (Ammonitina) of the Subfurcatum Zone (Upper Bajocian) were found in the “Calcaires à petites huitres” formation from the northern part of Ile Crémieu. Correlations are established between different Upper Bajocian lithostratigraphic units of Mont d'Or lyonnais, Ile Crémieu and folded Jura.