Teneurs en éléments majeurs et traces de spirulines (Arthrospira platensis) originaires de France,du Tchad,du Togo,du Niger,du Mali,du Burkina-Faso et de République centrafricaine

Data on mineral elements in spirulinas being limited, we analyzed macrominerals and trace elements of samples from France and Africa. Spirulinas cultivated in France have a composition in macromineral elements similar to those of the literature. The entire contents of trace elements are low. Unlike marine cyanobacteria, they do not concentrate rare-earth elements. Spirulina harvested in Chad has high levels in macrominerals and trace elements, due to traditional drying and harvesting methods. Rare-earth element levels are attributed to this pollution and not to their concentration in spirulinas, because rare-earth element normalized profiles of spirulina are strictly parallel to those of ouadis mud and very different from those of ouadis water. Despite the sometimes high content of total As, normal water consumption in Chad presents no health problems. Spirulinas grown in Togo, Niger, Mali, Burkina-Faso and Central African Republic have chemical compositions similar to those of Chad spirulinas, but with a lower content of macromineral and trace elements, reflecting a lower mineral pollution. Rare-earth element normalized patterns dismiss an aeolian pollution and the pollution is rather of pedological origin. They show no toxicity problem except spirulinas from Burkina-Faso, whose Pb content is too high. The variability of composition of spirulinas can be largely attributed to the mineral pollution of the samples. Significant levels of rare-earth elements sometimes found in the literature reflect this pollution.     

Le bassin de l’homme du Pléistocène supérieur de Liujiang, Sud de la Chine : taille du corps, forme du corps et encéphalisation

The Late Pleistocene hominin fossil assemblage from Liujiang, South China include a fairly well-preserved cranium, a right os coxa, a complete sacrum, and other postcranial elements all belonging to a single individual. This rare discovery offers us a unique and singular opportunity in understanding this Late Pleistocene hominin's body proportion and relative cranial capacity (encephalization quotient [EQ]), and also pelvic morphology. Using the available right innominate and its mirror-imaged left side, we reconstruct Liujiang hominin's pelvis. Our analysis of the pelvis indicates that the Liujiang hominin has a very gracile and modern-like pelvic morphology. Indeed, all of the pelvic dimensions are smaller than those of other Pleistocene hominins. Moreover, the pelvic characteristics typical of Middle and Late Pleistocene hominins including Neanderthals cannot be identified in the Liujiang pelvis. In contrast, both Liujiang's metric and non-metric features indicate affinities to more recent human populations including our modern Chinese collections from Guangxi of south China. Further support of this assessment comes from the EQ value of 5.754 for Liujiang which is closer to Minatogawa 2 and modern Chinese populations than to Middle and Late Pleistocene fossil hominins. Our analysis of body shape shows that Liujiang has body proportion (i.e. body height relative to body breadth) typical of warm-adapted populations. Based on these findings, we reason that the modern physical characteristics of Liujiang may allude to a more recent geological age. Alternatively, its morphological “modernity” could also point to a much higher degree of skeletal variation within Late Pleistocene hominins in East Asia.     

Implications phylogénétiques de I'ultrastructure de la spermatogenèse, du spermatozoïde et de I'ovogenèse du TurbellariéUrastoma cyprinae ("Prolecithophora", Urastomidae)

Spermiogenesis in Urastoma cyprinae (Graff. 1882) involvcs a progressive lengthening of the spermatid. Free flagella are only transitory. The mature spermatozoon is fusibrm. 45μm in length and 2.5 μm in width. It contains two incorporated axonermes of the flatworm 9+"1" pattern, two elongated mitochondria. an elongated nucleus and a row or cortical longitudinal microtubules. Observations on oogenesis concerncd only the immuturc ovary. lmmature oocytes contain few dense granules and accssory cells were not ohserved. Phylogenetic implications of a biflagellate spermatozoon in a Prolecithophora are important. The presence of two 9 +"1" axonemes confirms that Urastoma (and the Prolecithophora) belongs to the taxon Trepaxonemata Ehlers. Previous electron microscope studies on spermitozoa of Prolecithophora (four genera) only dealt with aflagellate spermatozoa. On this basis, Ehlers (1985) proposed two autapomorphics for the taxon Prolecithophora: aflagellate spermatozoon and spermatozoal mitochondrial derivatives with abundant membranes. The present observations on Urastoma contradict these two autapomorphics. The taxon Prolecithophora cannot be defined by autapomorphies of the spermatozoon.     

Interaction du photopériodisme et des effets de la zéatine, du saccharose et de ľeau dans la floraison du Chenopodium polyspermum

Interaction of photoperiodism and zeatin, sucrose and water effects on the flowering of Chenopodium polyspermum Root removal in Chenopodium polyspermum, a quatitative short-day plant, enhances flowering under non-inductive conditions. Presence of roots may be mimicked by zeatin applications on buds. Induction of flowering by short days may be counteracted by applications of zeatin, and appearance of flowers depends on the balance between number of inductive short days and zeatin quantity applied. Sucrose added in the culture medium or applied on buds acts as zeatin. Applications of water on buds may also delay flowering. These results show the plurifactorial regulation of the floral development of this plant. The relations between the non-specificity of the induction and the specificity of the morphogenetic response are discussed.     

Les nodules du Carbonifère supérieur du Lagerstätte de Montceau-les-Mines,France : historique de la Collection Sotty 2

The Muséum national d’Histoire naturelle, Paris (France), housed in its palaeontological collections numerous fossil specimens from a French locality of exceptional fossil preservation: the Montceau-les-Mines Lagerstätte (Late Carboniferous). The collection on the Montceau-les-Mines Lagerstätte was given to the Museum of Paris in 1997. Under the MNHN direction, it is managed in the regional museum of Autun. It contains more than 100,000 nodules bearing animal and fossil plants, three-dimensionally preserved in sideritic concretions. These collections are computerized and regularly consulted and studied by scientists from the whole world.     

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).     

Les Spatangus du Miocène et du Pliocène de l’Ouest de la France

Numerous fragments of spatangoid echinoids have been discovered in the Pliocene deposits of Challans, in Vendée (western France). In spite of the fragmentary data of the samples, a reconstitution of a complete test could be realized using the different fragments and their symetrization. The general shape of the test, and its architectural and ornemental characters allow establishing the presence of the genus Spatangus in western France during the end of Neogene. It allows to precise the biogeography of the genus Spatangus and of the morphological group S. (S.) purpureus on the Atlantic coast after the Messinian crisis. The Pliocene species is compared to the Miocene Spatangus (Phymapatagus) brittanus, abundant in Anjou, Brittany and Touraine. This older species was refered to the subgenus Phymapatagus according to the presumed lack of primary tubercles on its posterior interambulacrum. The discovery of well-preserved specimens, with primary tubercles on every parts of the test, in the Middle Miocene of Brittany allows to refute this subgeneric distinction and to refer the species brittanus to the subgenus Spatangus (Spatangus). The presence of this subgenus in western France is finally confirmed from Middle Miocene to Pliocene.     

Réexamen du contexte géologique,chrono- et biostratigraphique du site de Moulin Quignon à Abbeville (Vallée de la Somme,France)

The geological context of the discoveries made by Boucher de Perthes at Moulin Quignon in 1863–1864 was examined through the testimonies left by himself, by his detractors, then by geologists and archaeologists who later worked on the alluvial deposits of the Somme at Abbeville. This critical approach has been completed by specific studies, through a restricted excavation performed at Carpentier Quarrya locality known since the end of the 19th century as a sequence analogous to Moulin Quignon, and by a series of new analyses (microvertebrate, malacofauna, dating). The main results of these studies confirm the fluvial nature of the ‘archaeological’ layers at Moulin Quignon that correspond to a high terrace of the Somme River, about 40 m above the current valley incision at Abbeville. Dating results provide an age of 584 ± 48 ka for the fluvial levels at Carpentier Quarry, in good agreement with the available biostratigraphic data, inferred from malacofaunas collected at both Moulin Quignon (Boucher de Perthes collection) and Carpentier Quarry, and from mammals fauna recovered since the end of the 19th century from the white marl at Carpentier Quarry which allow the allocation of these alluvial deposits to an interglacial stage of the second half of the Cromerian, the marine isotopic stage (MIS) 15. From these data and taking into account the identification of the human remains of Moulin Quignon as an anatomically modern man, the contemporaneity of these remains with the alluvial deposits of a high terrace of the Somme River is virtually impossible and supports the hypothesis of a hoax. Besides, it is possible that at least some of the lithic material collected at the time of the discovery by Boucher de Perthes could derive from fluvial levels dated of approximately 600,000 years. They would be then the oldest evidence of a human presence in the Somme Valley.     

Les kystes de dinoflagellés des Argiles Ostréennes du Bassin de Paris, France

Palynological studies realized from a borehole drilled on the site of ANDRA (Agence Nationale pour la gestion des Déchets RAdioactifs; Aube Centre near Soulaines, Paris Basin, France) show a sedimentary discontinuity between, on one hand, the Argiles à Plicatules (lower Aptian in age) and Argiles Ostréennes (Lower Barremian/Upper Barremian in age) and, on the other hand, between these same Argiles Ostréennes and the Calcaire à Spatangues (Lower Hauterivian). These conclusions argue against the chronostratigraphical subdivision recently proposed on the basis of sequence stratigraphical and sedimentological interpretations.     

Analyse du débitage laminaire du site de Mezhyrich : habitations n 1, 2 et 3

This article presents the results of technological analyses of the laminar products from three bone dwelling structures from the Mezhyrich site (dated to Upper Palaeolithic; 15,000–14,500 years BP). More than 2500 blades and bladelets were studied from technological point of view. We find close similarity between the three dwellings, which reflects similar ways of preparation of core fracture zone (overhang reduction, butt abrading, and flaking surface isolation), as well as in the organization of the negative of the dorsal surfaces of the blades. The comparison with materials from the Kostenki 1 layer 1 site (upper layer, 22,000–24,000 years BP) shows some differences with the artefacts from Mezhyrich site, despite same technological methods. This could be explained by differences in cultural tradition and large time gap between these two sites. The complexes from Mezhyrich to follow the Kostenki 1/1 tradition but with their own particularities.     

Organismes filamenteux de l’ambre du Santonien de Belcodène (Bouches-du-Rhône,France)

Millimetric amber grains associated with lignite debris were recently reported in the Santonian marine series from Belcodène (Bouches-du-Rhône, France). These are mainly yellow to reddish drop-shaped grains, more or less transparent. They reveal the presence of various microorganisms, belonging to prokaryotes (bacteria, actinomycetes) and eukaryotes (filamentous fungi) here described for the first time. These microorganisms form sometimes crusts around the amber grains and grew centripetally into the ancient resin before its solidification. The depositional environment of amber was open to marine influences, while the original environment of resin flow was a coastal forest with dominant angiosperms.