Contribution nouvelle à l'étude des ferrobacteriacées

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Contribution à la connaissance des Desmidiées du Congo belge

Résumé Le présent travail s'occupe de 85 Desmidiées, dont la plupart ont été trouvées dans le matériel que j'ai recueilli au Congo, à Stanley-Ville.Quant aux Micrasterias, ce genre a été étudié avant tout sur du matériel provenant des environs de Léopoldville et recueilli par les Docteurs W. Bervoets et Fr. Evens. Une partie des déterminations et des figures ont été faites par le Dr. Evens. Je l'en remercie ici tout spécialement.Les espèces et variétés traitées se répartissent comme suit:Des 85 espèces trouvées dans le matériel examiné, 76 sont nouvelles pour le Congo et 5 variétés sont décrites comme nouvelles pour la science. Ce sont: Pleurotaenium subcoronulatum (Turner) W. & G. S. West, var. maximum Euastrum malmei Borge, var. congolense Micrasterias tropica Nordstedt, var. ndjiliensis van Oye & Evens Cosmarium obsoletum Reinsch, var. glabra Staurastrum orbiculare Ralfs, var. maxima De beaucoup d'espèces des données systématiques sont mentionées et discutées.La dispersion des différentes espèces est examinée là o\u on dispose d'assez de données.Enfin, des conclusions générales sont faites quand le matériel le permettait. En général, les données du travail permettent de confirmer les conclusions faites antérieurement.     

Contribution à la connaissance des Copépodes de la Région Parisienne

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Contribution à l'analyse expérimentale des phénomènes karyocinétiques chez Ascaris megalocephala

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Deuxième Contribution à la Connaissance des Peridinium

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Dépression à long-terme des synapses excitatrices dans le cortex et l'hippocampe

The efficacy of excitatory synapses terminating on cortical and hippocampal pyramidal cells may be persistently depressed as well as potentiated. Homosynaptic long-term depression (LTD) seems to be triggered by an entry of calcium into a post-synaptic cell less than that needed to initiate long-term potentiation (LTP). Theoretical work predicted, and experimental studies confirmed, that moderate elevations of calcium initiate LTD via a cascade of biochemical interactions involving calcium-dependent phosphatases. Genetically modified animals confirmed the prediction of a sliding threshold that defines the limit between LTD and LTP. While mechanisms for the initiation of LTD are quite well established, it remains unclear whether pre- or postsynaptic mechanisms, or both, are involved in its maintenance. A role for LTD in processes of learning and forgetting in the adult animal remains to be firmly established. It seems probable, however, that a persistent reduction in synaptic weight is a basic process used in the establishment and refinement of neuronal circuirs during development.     

Continu versus discontinu,linéaire versus non linéaire dans l’évolution des espèces

Continuity versus discontinuity, linear versus nonlinear in species evolution. Species evolution is a topic where concepts of continuity and discontinuity have been opposed for two centuries. What is the situation today in biological evolution ? The statistical distribution of appearances and disappearances among rodent species follows power laws, suggesting nonlinearity and fractal structures. Thus, the domain of living beings seems to be extended, through critical physical phenomena, to the analysis of linear versus nonlinear biological phenomena. These observations are consistent with the new scale relativity theory of Nottale, which predicts many domains of resolution in nature separated by scale dependence or scale independence. Despite some scale-dependence particular to various levels of biological organization, the fact that they are also characterized by scale-independence suggests that they could be described by new fundamental laws revealing their potentially fractal and irreversible character. In the proximity of the critical time, specific to each system, the system becomes unstable and fractal, and shows precursor events at an accelerated rate leading up to the critical time. After the critical time, the system shows replicate events, in a decelerating manner. The discontinuous appearance of a number of clades follows a log-periodic law with a middle scale report of 1.73. This law, first applied to earthquakes, stock market crashes, demography, and physical turbulences, and now also being applied with success to macroevolutionary patterns, seems to have a certain universality. To cite this article : J. Chaline, C. R. Palevol 2 (2003).     

Contribution à la systématique du genre Pichia

The presence of intracellular osidases, nitrite and nitrate reductases, vitamin requirements and GC content in the DNA, have been investigated for in 18 species of Pichia.According to their typical characters and their biocaracters, a pattern is suggested for the integration of these new species into the formerly existing groups of the genus Pichia. A new way of classifying the species of the genus Pichia is proposed.     

Candida vanriji,dans des jus de raisin conservés à basse température

Résumé Candida vanriji Capriotti a été trouvée dans des jus de raisins non sulfités conservés à basse température, au voisinage du point de congélation. Ce travail étudie les caractères physiologiques et le métabolisme jusqu'à maintenant peu connu de cette nouvelle levure.     

Contribution à la connaissance des occupations préhistoriques au Pléistocène supérieur en Tunisie

The Upper Pleistocene in Tunisia is characterized by cyclic climatic alternations between rainy and arid phases. The steppic landscape occupies a large area of the country, in particular in the Centre and the South. Even during the humid phases, the savannah landscape still dominant. The Upper Pleistocene prehistoric sites in Tunisia, such as Oued el Akarit, Aïn Mhrotta, Oued el Bey, El Guettar, Aïn Métherchem and Aïn el Guettar, which are the subject of this study, are all open-air sites, located mainly in Central and southern Tunisia, usually to the south of the springs that are still functioning today, or on the border of the wadis from which their names derive. Prehistoric occupations and human behavior are mainly subject to the climatic shifts occurred during the Upper Pleistocene.     

Contribution à l'étude de la bryoflore Lorraine

Contribution to the knowledge of the bryophyte flora of Lorraine (France). The bryophyte flora of Lorraine (France), which was not extensively studied during the second half of this century, has been visited again over the last four years. Seligeria acutifolia Lindb. has been collected for the first time in that region. New localities of several rare or poorly known bryophytes are given. A perspective view is proposed as to the future of bryological research in Lorraine.     

Catalogue systématique de larves de trichoptères recoltées dans la région des Eyzies (Dordogne,France). Espèces à Fourreau

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La démonstration histochimique des épimérases de l'acide uridine diphospho-d-glucuronique

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Les hyphes à anses latérales des Eumycètes et les affinités floridéennes de ces Champignons

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Contribution à la connaisance des Rotifères et des Cladocères de la Région parisienne

Sans résuméStagiaire de Recherches au Centre de Recherches Hydrobiologiques du C.N.R.S.