Impact de la pollution sur un écosystème méditerranéen cǒtier. II. Relations entre la composition spécifique des populations phytoplanctoniques et les taux de pigments et de nucléotides adényliques (ATP,ADP, AMP)

Influences of unsalted waters penetration, in the Gulf of Fos, are marked as much on the primary step structuration level as on the component cellular physiology one. At their outlet, the weak structuration and the considerable biomasses resulting from an intense eutrophication go with a strong mortality clearly shown as well as by ATP/chlorophyll ratio than these of ATP, ADP and AMP inside the adenylic nucleotides pool. The primary step acquires a larger maturity in the salt share of the south eastern area. Spectrum variations of the population specific cellular volumes in terms of population importance can in a certain measure explain the intracellular rate variations into biochemical components.     

Structure primaire de l'anhydrase carbonique érythrocytaire B humaine: II. Clivage par le bromure de cyanogène et séquence des résidus 1–148

The amino acid sequence of the IICNBr fragment of the human erythrocyte carbonic anhydrase B has been determined. This fragment contains the first 148 of the 260 residues of the N-acetylated single polypeptide chain of the protein. After tryptic hydrolysis of this fragment, eleven peptides have been isolated by gel filtration and chromatography on Dowex 50 W-X₂ or DEAE-Sephadex. Eight of them were identified with already sequenced peptides previously isolated from tryptic hydrolysate of the whole protein. The other three ones were obtained in pure form and sequenced. The combined amino acid content of these eleven peptides only account for 124 of the 148 amino acid residues in the IICNBr fragment. The tryptic attack of the maleylated IICNBr fragment gave three peptides as was expected from the number of arginine residues (2) in this fragment: two arginyl peptides (II₁, II₃) and one homoseryl peptide (II₂). They were purified by gel filtration. The unidentified 24 residue tryptic peptide has been isolated from the demaleylated II₂ tryptic hydrolysate and sequenced. The order of the twelve tryptic peptides of IICNBr fragment has been obtained by study of chymotrypsic peptides isolated from II₁ and IICNBr fragment.     

Faunes et paléoenvironnements des principaux sites archéologiques plio-pléistocènes de la formation de Nachukui (Ouest-Turkana, Kenya)

Faunas and paleoenvironments from main archaeological Plio-Pleistocene sites of the Nachukui Formation (West Turkana, Kenya). The Nachukui Formation is currently under archaeological investigation, especially within the Kalochoro (2.35 – 1.9 Myr) and Kaitio (1.9 – 1.65 Myr) Members. Six main archaeological sites have been excavated from this time period, which yield rich vertebrate faunas collected in situ or in close vicinity to the site. Paleontological studies help to precise the specific diversity for each site and increase our documentation for each Member with the discovery of new taxa. They allow to provide new informations about the biotope diversities exploited by Hominids and show a climatic tendency towards more humid environment between the Members. To cite this article: J.-P. Brugal et al., C.R. Palevol 2 (2003).     

Etude ultrastructurale comparée du processus de dégradation de l'hémoglobine par P. berghei (Vincke et Lips, 1948) en fonction de l'état de maturité de la cellule hǒte1

By serial sectioning and 3D reconstruction we have been able to demonstrate that the type of system for hemoglobin digestion in two strains of Plasmodium berghei, N and RC, is dependent on the maturity of the host cell. In parasites growing in erythrocytes, both systems for the endocytosis of hemoglobin—micropinocytosis and the cytostomal system (i.e. a cytostome budding a cytostomal tube that releases food vacuoles)—are fully functional and produce a great quantity of residual pigment. Parasites growing in reticulocytes have a disrupted cytostomal system; no tube is formed and only food vacuoles are visible in their cytoplasm. Residual pigment is smaller in size and in quantity. The reduced quantity of pigment in reticulocytes is explained by our observation of the exocytosis of pigment. We propose a hypothesis that relates the process of degradation of hemoglobin to the maturity of the host cell and a possible mechanism of protection against chloroquine, a drug known for its affinity for malarial pigment.     

Ultrastructure de la spermiogenèse et du spermatozoïde de Loimosina wikoni et affinités phylétiques des Loimoidae (Plathelminthes, Monogenea, Monopisthocotylea)

In Loimosina, during spermiogenesis, the zone of differentiation of the spermatid contains two centrioles continued as two 9 +‘1’axonemes. One of the axonemes lengthens and will become the principal axoneme of the spermatozoon. The other axoneme is as long as the first one at the beginning of spermiogenesis, but is shorter in the mature sperm cell. The spermatozoon consists of several regions: (a) at the anterior end, the centriolar derivative of the principal axoneme; (b) a short region which shows cortical microtubules coinciding with external ornamentations; (c) a long uniflagellate region, with mitochondrion; (d) a biflagellate region containing the anterior slender part of the nucleus; (e) the posterior part of the nucleus, with no accompanying cytoplasmic organelles. Spermiogenesis and sperm structure in Loimosina differ from what is known in all other described monogeneans, excepting the monocotylid Heterocofyle to which they show close resemblances. However, the alteration of the second axoneme is more complete in Heterocofyle than in Loimosina. Comparative study of spermiogenesis and sperm ultrastructure thus shows an interesting coincidence with classical phylogenies of the monogeneans, in which the families Loimoidae and Monocotylidae are closely related. Chez Loimosina, pendant la spermiogenèse, la zone de différenciation de la spermatide contient deux centrioles prolongés par deux axonemes de type 9 +‘1′. L'un des axonemes s'allonge et deviendra l'axonème principal du spermatozoïde mûr. Le deuxième axontme est aussi long que le premier au début de la spermiogenèse, mais il est plus court dans le spermatozoïde mûr. Le spermatozoïde comprend: (a) à l'avant, le dérivé centriolaire de l'axonème principal; (b) une courte région contenant quelques microtubules corticaw longitudinaux coincidant avec des omementations extramembranaires; (c) une longue région miflagellée avec mitochondrie; (d) une région biflagellée contenant La partie antérieure effilée du noyau; (e) la région postérieure du noyau, sans organites cytoplasmiques accompagnateurs. La spermiogenèse et la structure du spermatozoïde de Loimosina sont différentes de ce qui est connu chez tous les autres Monogènes décrits, excepté le Monocotylidae Heterocofyle auquel elles ressemblent beaucoup. Toutefois, l'altération du deuxième axonème est moins complète chez Loimosina que chez Heterocotyle. L'étude comparée des spermatozoïdes et des spermiogenèses montre une bonne coincidence avec les phylogenèses classiques, dans lesquelles les familles Loimoidae et Monocotylidae sont proches.     

Patines et cortex de météorisation de grès du site rupestre d’Oum La Leg (Anti-Atlas, Maroc)

Within the framework of the European Commission's program “Patine du Desert” (DG Research; INCO-CT-FP6-2004-509100), partially concerning the preservation of Saharan engraved rock art, the approach led to the study of the sandstone patina from the rock art site of Oum La Leg (Anti-Atlas, Morocco). The rock and its Tazina school engravings are sometimes covered with a thin brown-ochre coating which only shows a dark patina, the desert patina. This film corresponds to a weathering cortex whose formation is contemporary with wet events from the Holocene period. On the surface, the patinas’ diversity is linked to the heterogeneous distribution of manganese oxides (birnessite and todorokite) due to a reorganisation which led to the incorporation of aeolian silts. Some dating suggestions are made to establish an ante quem age for the engraved lines.     

Signification des caractères partagés entre Bennettitales et Cycadales. Implications de la découverte d''une Cycadale nouvelle du Cénomanien de l''Anjou (France)

The lagoonal Cenomanian formation (Lower Cretaceous) of clays of the region of Baugeois (north of Angers) has supplied an exceptionally well-preserved fossil flora: leaves, woody structures or/and reproductive organs of pteridophyta, gymnosperms and angiosperms. A well-preserved fossil plant found in a quarry “Le Brouillard” (8 km from Angers), has allowed a detailed morphological and structural study of this species. A comparative study with extant plants has confirmed an undoubted link between the contemporary genus Dioon (an endemic cycad from Mexico) and the fossil species. However, features observed on the lower epidermis of the leaflets, present a similarity with some Jurassic Bennettitales. This discovery, added to other common features shared by these two orders, raises questions about their relationships, thought to be different from a phylogenetic viewpoint.

Résumé

La formation lagunaire cénomanienne (Crétacé inférieur) des Argiles du Baugeois, au nord d'Angers, a fourni une flore fossile riche et exceptionnellement bien conservée: feuilles, structures ligneuses ou/et organes reproducteurs de ptéridophytes, de gymnospermes et d'angiospermes. L'excellent état de conservation d'un fragment de plante fossile, récolté dans la carrière Le Brouillard à 8 km d'Angers, a permis une étude détaillée de la morphologie et de la structure foliaire de cette plante. L'étude comparative avec des plantes actuelles a démontré l'existence d'un lien de parenté entre le genre Dioon (cycadale endémique du Mexique) et le fossile, mais des caractères originaux observés sur l'épiderme inférieur des folioles, présentent des similitudes avec certains genres de Bennettitales du Jurassique. Une telle découverte, ajoutée aux autres caractères communs préalablement décrits par d'autres auteurs, soulèvent à nouveau quelques questions sur les relations de parentés entre ces deux groupes supposés phylogénétiquement éloignés actuellement.     

Deux nouvelles tortues de l'Éocène inférieur de Saint-Papoul (Aude, France)

Two new turtles from the Lower Eocene of Saint-Papoul (Aude, France). Among the fossil turtles from of the Lower Eocene of Saint-Papoul (Aude, France), two new taxa of freshwater Testudinoidea are described. The first is a new species of the genus Palaeoemys, known before in the Lutetian of Germany. The second taxon is a new genus, also described on material of Pépieux-Cesseras and Eygalayes. To cite this article: S. Hervet, C. R. Palevol 2 (2003).     

Les Diatomées des Sédiments Holocènes du Bassin du Lac Afrera (Giulietti) (Afar Septentrional,Ethiopie). Essai de Reconstitution de l'Évolution du Milieu

The calcareous holocene sediments found in the outlying areas around Lake Afrera (Ethiopia) contain diatoms in abundance, some of which seem to be new species. Qualitative and quantitative studies, with informatory treatment of the data, allow us to reconstruct the main characteristics of the sedimentation conditions and their variations in the course of time. During periods of warm and humid climatic conditions, the basin was progressively filled up with alkaline, lightly saline and quickly eutrophic water. At this time, the lake covered an area of 250 km². This period occurred from 9800 years B. P. to around 7800 years B. P. It was followed by a short interruption, showed by important modifications in the diatom flora and a marked increase in the depth and salinity of the water. It has been hypothesized that this phenomenon had a tectonic origin. Soon thereafter, the previous ecological conditions reappeared. In the following period the lake began to dry up and the diatoms began to disappear. The present-day highly saline Lake Afrera is all that remains of this large holocene water area. Diatoms of the Holocene Sediments in the Afrera Lake Basin. (Northern Afar, Ethiopia). Reconstruction of the Environmental Evolution     

Etude préliminaire des effets de la mise en eau du Réservoir de LG-2 (Territoire de la Baie James,Québec) sur le seston grossier et le zooplancton des rivières et des lacs inondés

Preliminary Study of the Effects of Impoundment of LG-2 Reservoir (James Bay Territory, Quebec) on the Net Seston and the Zooplankton of Impounded Rivers and Lakes The effects of impoundment on the biomass of net seston and zooplankton in lakes and rivers of Northern Quebec were investigated from 1978 to 1980, before, during and after the completion of LG2 Reservoir on the River La Grande (53° 54′ N, 76° 78′ W). In lotic stations, a 41–77% decrease in net seston was observed due to sedimentation of mineral particles (36–80 mg/m³ in 1978 to 10–21 mg/m³ in 1979). The ratio of organic to total seston increased from an average of 0.18 before the impoundment to 0.65 after. The flooding phase brought about a trophic upsurge; the biomass of the zooplankton increased by one to two orders of magnitude at the various sites; the greatest increases occurred in the central stations near the dam, the smallest in the upper stations near the inflow. In lake stations, no significant difference between years could be detected; the mean zooplankton biomass for all three years ranged from 6.59 mg/m³ to 34.34 mg/m³. Spatial variations between lakes were however significant. Results are compared with those in other natural lakes in Canada and reservoirs in the United States. Comparative examination of phytoplankton biomass before and after impoundment of LG2 Reservoir suggests that bacterioplankton and allochthonous organic material are key elements in the pelagic food chain after impoundment.     

Étude expérimentale de l'auto-association des molécules modèles dipeptidiques. II. Association stéréosélective des molécules énantiomères

Modes of aggregation fo alanine-, norvaline- and valine-contaiing dpepetides with the general formula R₁? C₁O₁? N₂H₂? CHR₂? C₂O₂? N₃H₃? R₃ have been studied in CCl₄ solution by using infrared and nuclear magnetic resonance spectroscopies. Solutions of the pure L isomer and of the racemic mixture do not give identical data. At a given concentration, the racemic mixtrue is more aggregated than the pure enantiomer, and the difference, negligible in the case of alanine derivative, increases wiht the bulkiness of the side cahin R₂. The results show that a selective interaction takes place between enantiomeric molecules, resulting ina dimer associating tow inverse configurated C₅ conformers. The stabilizaion of this dimer proceeds from two symmetrical and intermolecular H₃ … O₁ hydrogen bondings.     

Réponses électroantennographiques de deux parasitoïdes Ichneumonidés,Diadromus pulchellus et D. collaris,aux odeurs de végétaux,du phytophage-hôte Acrolepiopsis assectella et du partenaire sexuel

Résumé Chez Diadromus pulchellus WSM et D. collaris Gr., Hyménoptères Ichneumonidés parasitoïdes spécialistes des nymphes d'A. assectella lépidoptère inféodé aux Allium, des EAG sont enregistrés en réponse à l'odeur du poireau sain ou attaqué par les larves du phytophage, odeurs actives par ailleurs sur leur comportement locomoteur (cinèses). Le thiosulfinate de dipropyle (Ti-P₂) très spécifique et abondant dans les Allium, et instable, est le mieux perçu par les deux parasitoïdes mais n'a aucun effet locomoteur chez D. pulchellus contrairement aux disulfures et thiosulfonates, plus stables et moins spécifiques. Les propriétés de l'acétate d'éthyle, actif sur l'antenne des deux parasitoïdes, et sur la locomotion de D. pulchellus expliqueraient en partie les activités biologiques du poireau attaqué sur ces parasitoïdes. Des EAG sont aussi obtenus chez les deux espèces avec l'odeur du chou et de composés soufrés plus ou moins spécifiques des Crucifères. Le thiocyanate de méthyle (TCN-M), le plus actif sur l'antenne et seul efficace sur le comportement locomoteur (de D. pulchellus), expliquerait en partie l'installation reconnue de D. collaris sur Plutella maculipennis spécialiste des Crucifères et rend celle de D. pulchelles vraisemblable.L'odeur des larves de dernier stade d'A. assectella est seule efficace sur l'antenne et la locomotion des femelles de D. pulchellus. Les mâles de ce dernier réagissent (EAG, locomotion) à des odeurs de cocons de l'hôte et particulièrement à ceux occupés par une femelle de leur espèce.     

Utilisation préhistorique de la technique minière d’abattage au feu dans le district cuprifère de Cabrières (Hérault)Prehistoric use of the fire-setting method in the copper-mining district of Cabrières (Hérault, France).

Fire-setting to open up mines has been used on hard rock since prehistoric times. In the copper-mining district of Cabrières, the existence of metre-sized spherical or sub-spherical cavities, sometimes spaced along the same vertical in an ore seam, has usually been ascribed to this method 12; 13 and 20. Two AMS ¹⁴C dating of micro-charcoal found in dolomite and of burnt ore breccias related to extraction in these cavities give the ages 3830 ± 40 BP, cal BC 2340–2130 and 3900 ± 40 BP, cal BC 2480–2280, which is the first evidence in France of the use of fire-setting in prehistoric mines.

Résumé

L’abattage, ou l’ouverture des mines, par le feu, a été pratiqué dans le cas de roches dures depuis la Préhistoire. Dans le district minier cuprifère de Cabrières, l’existence de cavités sphériques ou sub-sphériques métriques, parfois échelonnées sur une même verticale le long des filons minéralisés, a été classiquement attribuée à cette technique 12; 13 and 20. Deux datations ¹⁴C par AMS des micro-charbons de bois récoltés dans les brèches de dolomie et de minerais brûlés liés au dépilage minier de ces cavités ont donné les âges de 3830 ± 40 BP, cal BC 2340–2130 et de 3900 ± 40 BP, cal BC 2480–2280, confirmant, pour la première fois en France, l’utilisation dans les mines préhistoriques de l’abattage au feu.