Les mécanismes de contrôle de la méiose dans la lignée germinale mâle

In 1883, it was discovered that whereas the fertilized egg of a particular worm (Parascaris Equorum) contains four chromosomes, the nucleus at the egg and that of the sperm each contains only two chromosomes. This finding implied that germ cells must be formed by a special kind of nuclear division in which the chromosome complement is precisely halved. This type of division is called meiosis. Meiosis and mitosis share many regulatory elements. Among them, are the cyclindependent kinases (CDK) and the cyclins which control all transitions of the cell cycle. The activity of the CDKs is regulated by their association to specific cyclines and by phosphorylation/dephosphorylation reactions. Moreover, recent reports reveal the existence of a variety of small proteins which bind to and modulate G1/S CDK-cyclin complexes: the CKI. Two more proteins appear of great importance in regulating the cell cycle: Rb and p53. The central role of MPF (maturation producing factor=M-phase promoting factor) has been established, mostly by studies conducted on either invertebrates oocytes and eggs that resume the meiotic division. MPF is the cyclin B-p34cdc2 kinase. As for the cytostatic factor (CSF), it is reasonably certain that it is, in part or entirely, MOS. The cell cycle signalling mechanisms in oocytes include cAMP, Ca⁺⁺ and the agonists of PKC. Much less informations on the control of meiosis in spermatogenesis are available. Indeed, it is difficult to get rather high number of germ cells at some precise steps of their maturation and there is a lack of culture system allowingin vitro germ cell differentiation. However, most of the genes involved in the regulation of the cell cycle are expressed in the testis (c-mos, cyclins, CDK, cdc 25…). Their expression has striking cellular, lineage and developmental specificity. It has also been shown that FSH, interleukin-1a, and MIP-1a enhance stagespecific DNA synthesis in rat seminiferous tubule segments, while interleukin-6 decreases it. In our laboratory, we have settled recently two cell culture systems allowing the expression of germ cell specific genes for 2 to 3 weeks. This should help to study more easily the genetic control of meiosis during spermatogenesis and to understand better which growth factors and/or cytokines are really important for the regulation of this process.     

Etude ultrastructurale et cytochimique de la formation des inclusions intra-nucléaires dans les ovocytes de l'Annélide Nereis diversicolor O. F. Müller

Résumé Chez N. diversicolor, les ovocytes proches de la maturitée sexuelle ou ayant évolués en l'absence d'hormone cérébrale renferment dans leur nucléoplasme des vésicules localisées à proximité de l'enveloppe nucléaire. Ces vésicules contiennent un nombre variable de granules denses élaborés par un processus d'invagination de la paroi vésiculaire.Ces inclusions intra-nucléaires semblent résulter de l'évolution de petites vésicules applaties, accolées à la membrane nucléaire interne. Dans le cas de l'ovogenèse expérimentale, ces petites vésicules peuvent s'associer pour former des lamelles annelées intra-nucléaires. Ces dernières sont fréquemment en relation avec les vésicules à grains denses et semblent jouer un rôle dans leur élaboration.L'action de la pepsine sur des ultra-coupes d'ovocytes inclus au GMA entraîne une forte diminution de la densité du contenu des granules intra-vésiculaires qui apparaissent constitués essentiellement de protéines.

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Ultrastructural and cytochemical study of the formation of intranuclear inclusions in the oocytes of the annelid Nereis diversicolor O. F. Müller

Summary In Nereis diversicolor, oocytes close to or having reached maturity in the absence of brain hormone, contain in their nucleoplasm vesicles that are located in close proximity to the nuclear envelope. These vesicles contain a variable quantity of dense granules which are derived from the vesicular wall by a process of invagination.The intranuclear inclusions seem to be derived from small flattened vesicles located close to the inner membrane of the nuclear envelope. In the case of experimentally induced oogenesis these small vesicles may join to form intranuclear annulate lamellae. The latter are frequently affiliated with the vesicles containing dense granules and seem to play a role in their formation.The effect of pepsin, applied to ultrathin sections of oocytes embedded in glycol-methacrylate, is a pronounced reduction in the density of the contents of the intravesicular granules which, therefore, appear to consist essentially of protein.

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Remerciements. Je remercie le Service de Microscopie Electronique de l'Institut Pasteur de Lille (Directeur: Prof. Vivier) pour l'aide apportée à la réalisation des inclusions de GMA, et M. Himpens, dessinateur du Laboratoire de Biologie Animale de la Faculté des Sciences, pour le tracé de la Fig. 12.     

Sur les transports de réserves et les transports de couvain dans la ruche

Résumé Dans cet exposé, nous avons montré que les Abeilles sont capables de changer de place les réserves sucrées et le couvain. Ces comportements ne correspondent pas à des conditions de vie normales de la colonie.Cependant, le transport des réserves indique la possibilité, pour les Abeilles, de réagir à une perturbation importante selon un ordre que nous avions déjà établi dans l'élevage des larves (Montagner, 1962). C'est ainsi qu'en cas de nourrissement brutal et pendant une période de disette, elles tendent à grouper la majeure partie des réserves près de la reine, tout en laissant une place sur un cadre pour la ponte. La reine représenterait donc bien, dans la ruche, le potentiel survie à partir duquel les ouvrières auraient tendance à répartir leurs activités de façon décroissante.Par contre, les transports de couvain ne semblent répondre à aucun plan d'organisation comme chez les Fourmis. Nous avons montré qu'ils étaient associés à de profondes perturbations, telles que le manque de nourriture ou la perte de la reine.

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Summary The results of these studies indicate that bees are able to remove sugary stores and brood.We have established that bees remove their stores according to a certain order that we also made evident when studying brood rearing (Montagner, 1962). So, the bees hoarded the most part of their stores in the side of the hive where the queen stood, when we fed them suddenly during a dearth time.Then, the queen would be in beehive the attractive center from which the workers would share theirs activities in a decreasing way.On the contrary, it never seemed to us that the removals of brood were connected to any right order as for ants. We have established that they were associated to great troubles in beehive such as a want of food or the death of the queen.

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Zusammenfassung In diesem Bericht haben wir bewiesen, dass die Bienen die Zuckervorräte und die Brut an andere Plätze zu bringen vermögen. Dieses Verhalten entspricht nich den normalen Lebenszuständen der Kolonie.Soch bezeugt der Transport der Vorräte die Möglichkeit für die Bienen, gegen eine erhebliche Störung, nach einer bestimmten Regel zu reagieren, die wir schon bei der Aufzucht der Larven festgestellt haben (Montagner, 1962).Also, im Falle einer plötzlich verstärkten Zufuhr und während einer Mangelperiode haben sie die Neigung, den grössten Teil der Vorräte um die Königin zu sammeln, indem sie aber einen Platz für das Eierlegen auf einem Rahmen frei lassen. Die Königin würde also im Bienenstock die Möglichkeit der Fortdauer darstellen. Von dieser Tatsache ausgehend würden die Arbeiterinnen also ihre Tätigkeit in abnehmender Weise ausüben.Im Gegenteil scheinen die Brutversetzungen keinem Organisationsplan zu entsprechen, wie es bei den Ameisen der Fall ist. Wir haben gezeigt, dass sie mit schwerwiegenden Störungen, wie z. B. dem Nahrungsmangel oder dem Tod der Königin, in Verbindung stehen.

     

Etude de la distribution générale des 46 chromosomes dans les cellules humaines en métaphase

Summary This study, based on the square distances of chromosome centromeres from the center of a cell, shows after circular transformation, that the general dispersion of the 46 chromosomes is uniform, except on the periphery of the cell. It is found that the chromosomes taken separately have not a random distribution, but have peculiar positions. In males, chromosomes 1, 13-14-15 and 21–22 tend to lie nearer the middle of the nucleus, while chromosomes, Y, 6-X and 4–5 tend to lie nearer the periphery. In female mitoses the chromosome 13-14-15, 21–22 and 19–20 and 19–20 have a more central position, while chromosomes 4–5, 3, 2 and 16 tend to lie nearer the periphery.

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Prière d'envoyer les demandes de tirés-à-part à cette adresse.     

Thérapies ciblées et biomarqueurs compagnons dans les cancers de la prostate métastatiques

Treatment of castration-resistant prostate cancer has undergone a revolution over the past 3 years with the approval of five new therapies, including new hormonal therapies (abiraterone and enzalutamide) and bone-targeted agents (denosumab, radium-223). New targeted agents have improved survival and quality of life. Currently, companion biomarkers are lacking for a better individualization of treatment.     

Etude des premiers stades de développement de la Coccidie Coelotropha durchoni

Summary This study considers the earlier growth stages of Coccidium Coelotropha durchoni in its host, Nereis diversicolor. Before evolving into free trophozoites and gamontes in coeliac fluid, the parasites remain in muscular and coeliac cells in microscopic intracellular form. Electron microscope reveals that these stages show an intermediary fine structure between that of a sporozoite — from which they keep some typical characteristics such as the conoid, the fibers and the involuted tubuli — and that of the future free trophozoites. The wall consisting in two clear membrans is provided with one or several micropores. The classical cytoplasmic organites clearly stand out: dictyosomes show constant relationship with ergastoplasm, the mitochondria contain short inner tubuli. Besides the paraglycogen granules and lipoid vacuoles, at least three types of vacuoles may be observed. Peculiar topographic relationship connects mitochondria and paraglycogen granules probably in formation. In the nucleus with classical membrane and heterogeneous structure, a rather voluminous nucleolus may be seen.     

Etude floristique et écologique de la florule algale de deux biotopes dans la vallée de la Dyle

Sans résumé     

Etude des fluctuations annuelles des copépodes et du phytoplancton dans la manche et le golfe de gascogne par la méthode d'analyse de la variance et du coefficient de correlation

2275 samples have been collected with the Continuous Plankton Recorder of Hardy at a standard depth of 10 meteres in the English Channel and the Bay of Biscay between 1958–1965. Biological as well as statistical analyses have been carried out to provide data on annual fluctuations of 34 species of copepods and phytoplankton. Methods of analysis of variance and the correlation coefficient analysis were used for this purpose. The results are presented in the form of triangular matrices showing the annual fluctuations of species in the different areas considered and the relationship between different species in each area. These methods allowed us to define separate groups of species that could be called annual communities.

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Extrait d'une thèse de Doctorat en Oceanographie biologique, soutenue à la faculté des Sciences de Paris le 19 décembre 1967. Ce travail a été subventionné par the Office of Naval Research, Department of the United States Navy en vertu du contrat No 62558-3612.

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Extrait d'une thèse de Doctorat en Oceanographie biologique, soutenue à la faculté des Sciences de Paris le 19 décembre 1967. Ce travail a été subventionné par the Office of Naval Research, Department of the United States Navy en vertu du contrat No 62558-3612.     

Etude de la migration des cellules somitiques dans le mésoderme somatopleural de l'ébauche de l'aile

Summary In chick embryos, observations were made on serial semithin transverse sections of the wing level. In addition homo- or heterotopic replacements of the wing or leg somitic mesoderm by labelled somitic or nonsomitic mesoderm were made in 2-to 2.5-day embryos. The nuclear label used was either natural (quail donor embryos in heterotopic transplantations) or isotopic (chick donors labelled with tritiated thymidine).Histological examination revealed that the first somitic cells to leave somite 15 apparently did so at the 20 to 22 somite stage, while the last ones to leave somite 20 apparently did so shortly before the 36 somite stage.Transplantation experiments with labelled donor cells revealed the routes of migratory somitic cells and the time-course of their invasion into the outgrowing limb bud (non-somitic graft cells did not noticeably invade the limb anlage). They showed furthermore that the somitic mesoderm is not regionalized with respect to its limb myogenic properties.These results are compared with those obtained in other classes of vertebrates.

Ce travail a été subventionné en partie par la D.G.R.S.T. et le C.N.R.S.     

Pratique de la circulation extracorporelle et médecine basée sur les preuves

The history of cardiopulmonary bypass (CPB) goes back to 1953, when Dr. Gibbon operated on a patient with atrial septal defect. Since, then a tremendous amount of knowledge has accumulated in this field. However evidence-based medicine (EBM) is scarce because practice of CPB relies mainly on current experience. The goal of EBM is to produce systematic reviews and clinical guidelines that summarise scientific knowledge about a topic in a single publication that preferably is updated regularly.EBM is more concerned by clinical outcome rather than by surrogate outcome. When available, meta-analyses are summarized on the role of surgical myocardial revascularization on CPB, intra-aortic balloon pump, priming and temperature of CPB, antibiotic prophylaxis, inhaled anaesthetics, haemostatic drugs, r-erythropoietin, fresh frozen plasma, blood washing and autologous transfusion, glucose-insulinpotassium infusion, fast-track, thoracic drain manipulations, respiratory physiotherapy and prevention of arrhythmias. However, many clinical issues persist (e.g., perfusion ouput and pressure, haemoglobin concentration, analyse of blood gases…) and new prospective randomised clinical studies should be encouraged.     

A propos de l'intervention des aéroions dans les processus de régulation de la lipémie et de la cholestérolémie

Resume Les expériences ont porté sur des lapins repartis en deux groupes parallèles — un groupe étant traité avec des aéroions négatifs en concentrations moderées (n^– = 10 – 40.000; n⁺ = 1.000) et l'autre sans aéroionothérapie (témoins). Par rapport aux animaux témoins (pas exposés aux aéroions),on a enregistré,sous l'influence de l'aéroionothérapie, que: (1)il y a une tendence de normalisation de la motilité spontanée, deprimée par une alimentation contenant un excès de cholestérol(0,3 g/kg/jour); (2) la lipémie et la cholestérolémie sont restées à un niveau plus bas chez les animaux alimentés au cholestérol; (3) la lipémie et la cholestérolémie, de même que l'iode thyroïdien, sont restées aux valeurs voisines de celles normales,chez les animaux nourris avec un excès (20 mg/kg/jour), de substances antithyroïdiennes naturelles (provenant du chou).

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Groups of rabbits were exposed to negative air ions of moderate concentrations (n^– = 10 – 40,000; n⁺ = 1,000) while others served as controls. (1) When rabbits were fed a cholesterol-rich diet (0.3 g/kg/day)causing reduction of motility in the control animals, their motility was normalized under air ion treatment. (2) The blood cholesterol and lipid levels of rabbits on a cholesterol-rich diet were lower with air ion treatment than in controls.(3) When rabbits were fed a diet with thyroid blocking agents from cabbage the blood cholesterol and lipid levels and the thyroid iodine content remained unchanged with air ion treatment.

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Zusammenfassung Gruppen Kaninchen wurden mit negativen Luftionen in mässigen Konzentrationen (n^– = 100 000 – 40 000; n⁺ = 1 000) behandelt, während andere als Kontrollen dienten. (1) Die durch Fütterung von cholesterinreicher Diät (0,3 g/kg/Tag) verminderte Motilität der Tiere wurde unter der Luftionenbehandlung normalisiert. (2) Der durch Fütterung von cholesterinreicher Diät erhöhte Blutcholesterin- und-fettspiegel fiel durch Luftionenbehandlung ab. (3) Der durch Fütterung von strumipriven Substanzen aus Kohl erhöhte Cholesterin- und Fettspiegel im Blut und verminderte Jodgehalt der Schilddrüse wurde durch Luftionenbehandlung nicht beeinflusst.

     

Le rôle de la taille et de la nutrition dans le déterminisme de la gemmulation chez les Spongillides

Small freshwater sponges of the species Ephydatia fluviatilis were cultivated in petri dishes, on a diet consisting of killed bacteria. They were investigated with respect to their gemmulation speed.This speed depends in a complex way on the number of gemmules from which the individual sponges have hatched, and on the nature and quantity of the diet they are fed.The hatching of a gemmule within a sponge already differentiated accelerates its gemmulation. However, this in vivo hatching is possible only in particular conditions. The sponge exerts an inhibitory influence on the hatching of any live gemmule it contains, the strength of this inhibition depending on the physiological state of the sponge.The following hypotheses can be suggested as a tentative explanation of the observed facts: (a) The onset of gemmulation would be related to the accumulation within the sponge of some kind of blastogenic material. (b) The triggering itself of the formation of gemmules would be performed by an inducer able to diffuse within the sponge and even from one sponge to another. (c) Inhibition by the sponge of the hatching of gemmules it contains would also be exerted by means of a diffusible agent, perhaps identical with the gemmulation inducer itself.The agreement between these hypotheses and the experimental and ecological data is discussed.