Spermatogenèsein vitro: une nouvelle voie de recherche

Studies in our laboratory have aimed to settle two culture systems allowing some steps of rodent spermatogenic cell differentiation to occurin vitro. The first system is a coculture of pachytene spermatocytes from adult rats together with Sertoli cells from 20-day-old animals. In the second system, small pieces of spermatogenic tubules are seeded. In that way the cell-cell junctions which are presentin vivo are better maintainedin vitro; in addition every type of germ cell present in the tubule segments at the time of seeding can be studied. Our results have shown that the two meiotic divisions or even most of the meiotic process can occur over a 2 to 4 week-culture period. These results should have applications in basic research, toxicology, clinical studies and biotechnology. However, for these latter, some improvements and verifications are still needed in order to assess the feasibility and the innocuity of these procedures.     

Contribution nouvelle à l'étude des ferrobacteriacées

Sans résumé     

Une nouvelle espèce d'Euglène,Euglena Penardii

Sans résumé     

Une nouvelle fonction pour la transferrine exprimée par le testicule

In men, oligozoospermia corresponds with a low level of transferrin in semen. Transferrin appears to be a relevant indicator of gonadal function. Transferrin expression in normal testes is perfectly controlled. Transferrin contributes to iron transport. However, recent results show the existence of a dimeric form, which acts as a powerful regulator of phagocytosis of residual bodies by Sertoli cells. A disturbance of this new highlighted function may account for some forms of oligozoospermia.     

Sur l'espace topologique lié à une nouvelle théorie de l'apprentissage

There have been two contrasting doctrines concerning learning, more generally about acquisition of knowledge: empiricism and rationalism. The theory of learning in such a field as artificial intelligence seems to fall within the empiricist framework. On the hand, N. Chomsky and his followers have discussed, during the last decade, concerning learning, especially about language learning, from the rationalist point of view (Chomsky, 1965). The main feature in the rationalist approach toward a theory of learning lies in the speculation that in order to acquire knowledge it is indispensable for a learner to be endowed with “innate ideas”, and that “experience” in the external world are merely subsidiary types of information for the learner. If this is acceptable, we can inquire: Under what kind of innate ideas can the learner understand the structure of the external world? In our previous paper (Uesaka, Aizawa, Ebara, and Ozeki, 1973), we formalized this by introducing the mathematical notion of “learnability”, and gave a partial answer to the above inquiry. In this formalization we assumed that the set F of objects to be learned consists of mappings of N to itself, where N is the set of positive integers. Then, constructing a topological space (F, \(\mathcal{O}\) ) by an appropriate family \(\mathcal{O}\) of open sets, we observed that the notion of learnability can be well described in terms of topological properties of the learning space (F, \(\mathcal{O}\) ). Many problems must be solved, however, before we raise the theory to a complete model of the rationalist theory of learning. The topological study of the space (F, \(\mathcal{O}\) ) is, we believe, the first step toward this approach. In this context, we discuss the topological aspects of this space. Now we define \(\mathcal{O}\) as follows: By N ² we mean the direct product of two N's. Let s be a subset of N ². If, for any (x, y), (x′, y′) in s, x=x′ implies y=y′, then we say that s is single-valued. Let f ∈ F, If, for any (x, y) in s, y=f(x), then f is said to be on s, denoted as \(f\underline \supseteq s\) . Let \(\pi \left( s \right) = \left\{ {g;g \in F,g\underline \supseteq s} \right\}\) . A single-valued finite subset of N ² is called datum. Let D denote the family of all data. Let \(\mathcal{O}* = \left\{ \phi \right\} \cup \left\{ {\pi \left( d \right);d \in D} \right\}\) , and \(\mathcal{O}\) denote the family of all subsets of F, each of which is written as \(\mathop \cup \limits_\alpha W_{\alpha }\) , where W _α is in \(\mathcal{O}*\) . Then, it is easily seen that \(\mathcal{O}\) satisfies the axiom of the open system of a topological space. It is shown that the learning space (F, \(\mathcal{O}\) ) has the following properties:

1. It satisfies the first and the second countability axioms.
2. It is separable and is totally disconnected.
3. It is a Hausdorff space and, further, is regular and normal.
4. It is neither compact nor locally compact.
5. It is metrizable, or more precisely there exists a complete but not totally bounded metric space which is homeomorphic to learning space.
6. Any of its subspace can be embedded into its special subspace.

     

Mollusques terrestres et températures : une nouvelle fonction de transfert quantitative

Terrestrial molluscs are reliable environmental proxies in Quaternary sequences. Correlations between the geographic distribution of the species and the minimum mean monthly temperature and the annual thermal magnitude distributions have been characterised. New temperature estimates based on the Mutual Climatic Range method were then performed. The latitudinal thermal gradient has been reconstructed using modern assemblages from Western Europe, and a calibration on modern temperature values has been calculated. The application to the sequence of Achenheim (Alsace, France) allowed the reconstruction of the temperature variations of the last climatic cycle. To cite this article: O. Moine, D.-D. Rousseau, C. R. Palevol 1 (2002) 145–151.     

Une nouvelle famille est nécessaire pour des microscorpions humicoles de madagascar et d'afrique

The sub-family Microcharminae is raised to the rank of family as Microcharmidae so as to contain humicolous microscorpions of Madagascar and Africa belonging to the genera Microcharmus and Akentrobuthus. Phylogenetic considerations are proposed in relation to the morphological characters but also in association with their adaptation to the humicolous environment of the soil.     

Une nouvelle méthode de marquage pour certains groupes d'Insectes et de Crustacés

A new technique of labelling, based on making series of microscars on the compound eye of immature insects, allows to recognize individual specimens, even after several moults.

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Une nouvelle méthode de marquage pour certains groupes d'Insectes et de Crustacés

     

Mise en évidence de structures internes des chromosomes par une technique nouvelle (Scanning video)

The basic principle of the technique is the analysis of photomicrographs (light microscope) with a system of closed television chain. By suitable settings of the video scanning (e.g. black and white level, contrast) it is possible to bring out some particular structures of chromosomes, by a kind of optical density selection. — Chromosomes in mitosis and meiosis from different species (man, rat, sloth) have been studied up to now; all of them show a similar inner organization. The double spiralization of each chromatid appears clearly. Each chromonema contains a more or less dense heap of fine loops; these appear to be made of a folded fibril of 200–300 Å thickness. In less condensed zones of the chromonema, e.g. in uncoiled parts, four filaments arranged in two more or less twisted pairs are clearly distinguishable; these filaments seem to correspond to 1/8 chromatid. From our first investigations it seems that the inner fibrils of the chromosomes are organized according to one of the DuPraw's models (combined transverse and longitudinal folding with quaternary coiling). — Some arguments are proposed and discussed as to explain how it is possible to reach such a high resolution with a conventional light microscope.

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Recherches effectuées avec l'aide du Fonds de la Recherche Scientifique Médicale (Belgique).     

L’electromyographie du penis: Une nouvelle exploration du muscle lisse caverneux et de son controle neurologique?

The authors have investigated the electrical activity of corpus cavernous, first according to Wagner and Gerstenberg’ method, then, since one year, according to Stief method, in the basal state and following intracavernosal injection of vasoactive agents, or following various stimulation tests. They have found again the electrical activity described by these authors, but have been confronted with the difficulty in quantifying the data. Specially single potential analysis seems to them little reliable and reproducible for an objective interpretation. At this stage of their experience, they test two simpler criteria interpretation: the richness of the electrical activity, and the reactivity of the recording to various stimulations. Their preminary results suggest a correlation between those criteria and the state of the autonomic nervous system of the penis.     

Une nouvelle espèce de Fuciniceras du Domérien des Causses:Fuciniceras fontaneillesi Nov. sp.

The biostratigraphical sequence of the Domerian Fuciniceras is refinded with new data from the Causses (France). A new species, last representative of the genus in this country, is described and the beginning of a biogeographical differenciation is analysed.     

Le Ptychodio plicati—Lescureetum incurvatae,une nouvelle association bryophytique des massifs montagneux calcaires du Jura et des Alpes

The Ptychodio plicati—Lescureetum incurvatae is proposed as a new bryophytic association known in the limestone mountains of Western Europe. This new community is described and characterized.     

Proposition d’une nouvelle biozonation par ammonites de l’Albien du Bassin andin (Pérou)

The study of the ammonite fauna of the Albian formations allows a major revision of its biostratigraphic frame in northern and central Peru. A carving in ammonite biozones is proposed for the Inca, Chulec and Pariatambo Formations and the Pulluicana group. The Lower Albian is represented by the Nicholsoni Biozone (subdivided into the umbilicostatus, and nicholsoni biohorizons, followed by an interval subzone) and by the Raimondii Biozone (carved in three subzones: Haasi, Raimondii – itself subdivided into the ebrayi and alternum biohorizons – and Mathewsi, including the pseudolyelli biohorizon). The Middle Albian is characterised by the Carbonarium Biozone, carved in the Ulrichi and Carbonarium Subzones. The base of Upper Albian is represented by the Cristatum Subzone.     

Carcinome urothélial de l’urètre: une nouvelle observation et revue de la littérature

Urothelial carcinoma of the male urethra is a rare tumour. We report a new case of urothelial carcinoma of the urethra in a 64-year old man who was examined due to a dysuria. Retrograde and voiding urethrocystography carried out had shown images of bulbopenile urethral stricture treated by urethroplasty. Histological examination of the urethrectomy part revealed a urothelial carcinoma of the urethra. The patient refused any additional treatment and survived 14 months after diagnosis.     

La citréomontanine,nouvelle α-pyrone polyéthylénique isolée de Penicillium pedemontanum

Citreomontanin, a new polyene 2-pyrone was isolated from the mycelium of P. pedemontanum. Based upon spectral data, it was assigned the structure: (all-E)-4-methoxy-5-methyl-6-(7,9,11- trimethyl-1,3,5,7,9,11-tridecahexaenyl)-2 H-pyran-2-one.     

Observations sur une nouvelle couche pariétale dans les cellules associées aux vaisseaux du Robinier et du Sycomore

Résumé Après avoir achevé leur différenciation, les cellules associées aux vaisseaux élaborent une nouvelle couche pariétale bien distincte des parois primaires et secondaires classiques. Cette couche est située uniquement le long de la paroi commune avec un vaisseau; il n'existe pas de formation semblable le long des parois communes à deux cellules vivantes du parenchyme. Plusieurs méthodes ont été utilisées pour déterminer l'origine, la structure et la composition chimique de cette couche; en particulier, un traitement par le PATAG en révèle la nature polysaccharidique. Son rôle n'a pas été défini avec certitude: il est possible que les substances pariétales qui la composent soient utilisées lors de la formation des thylles.Ce travail a été effectué dans le cadre de l'Equipe de Recherche Associée n 179 et de l'Institut de Biologie Végétale, Université Paris VI, France.

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Observations on a new wall layer in vessel associated cells ofRobinia andAcer

Summary In mature vessel associated cells, a new wall layer is built (after cell differentiation). This layer is quite different from primary and secondary wall and is deposited only on the cell side which abuts a vessel element; no similar structures are seen along the wall separating two living parenchyma cells. Several methods were used to study the origin, structure, and composition of this layer; in particular, polysaccharides are visualized with PATAG technique. The role of this layer is discussed: the new wall materials may be used later during tylose formation.