Recherches cytochimiques sur la présence de certaines hydrolases au cours de la cytocinèse chez les plantes supérieures

Résumé Les granulations qui constituent les structures les plus primitives de la plaque cellulaire contiennent des enzymes hydrolytiques caractéristiques pour les sphérosomes de la cellule végétale; la plupart de ces enzymes sont présentes dans les lysosomes de la cellule animale. Dans les granulations de la plaque cellulaire nous avons constaté l'activité des enzymes suivantes: estérases non spécifiques, lipases, phosphatases acide et alcaline, aryl-sulfatase, désoxyribonucléase acide et probablement-glucuronidase. Le caractère chimique et morphologique de ces granulations, ainsi que leur équipement enzymatique correspondent aux sphérosomes.Dans la littérature les images de la cytocinèse au microscope électronique étant divergentes, le problème de l'origine et de la nature des granulations en question ne peut pas être pour le moment totalement résolu.

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Zusammenfassung Die Körnchen, die die ursprünglichen Strukturen der Zellplatte bilden, enthalten die hydrolytischen Enzyme, die für die Sphärosomen der pflanzlichen Zelle und meistens für die Lysosomen der tierischen Zelle charakteristisch sind. Es sind die folgenden Enzyme: Esterasen (nicht spezifisch), Lipasen, saure Phosphatase, Aryl-sulfatase, saure Desoxyribonuklease und-Glukuronidase. Außerdem enthalten diese Körnchen die alkalische Phosphatase. Der morphologische und chemische Charakter dieser Körnchen und ihr enzymatischer Inhalt entsprechen den Sphärosomen.Wegen großer Unterschiede der in der Literatur vorhandenen Beschreibungen der Zellplatte in elektronenmikroskopischen Bildern kann das Problem der Entstehung und der Natur dieser Körnchen zur Zeit nicht völlig entschieden werden.

     

Recherches expérimentales sur l'action de la compression mécanique intervenant au cours de l'ontogenèse des oiseaux

Sans résumé     

Utilisation des lichens dans la mise en évidence des éléments traces présents dans les cours d'eau

The authors demonstrated the possibility to use lichens as biodetectors of the presence of copper and cadmium in rivers. The authors showed that the lichen biomass fixes rapidly metals in solution. This caption is proportional to the quantity of metal present, without any toxic threshold being observed, even at high concentration levels. Furthermore, Dermatocarpon luridum (With.) Laundon syn. D. weberi (Ach.) Mann was a better biodetector of metallic micropolluants than other aquatic macrophytes (brypophytes and phanerogames). Transplantations of this lichen were made in the Vienne river (Massif Central, France) in the upstream and downstream section of an electrolytic copper refining plant. The results revealed an aquatic pollution generated by this industry.     

Apoptose au cours de la spermatogenèse et dans le sperme éjaculé

It has become clear in recent years that programmed cell death occurs spontaneously in the cycle of the seminiferous epithelium. Induced germ cell apoptosis occurs at specific stages of the spermatogenic cycle and the existence of supracellular control of germ cell death during spermatogenesis has been documented. If apoptosis is a key phenomenon in the control of sperm production, the existence and role of apoptosis in ejaculated sperm cells remain controversial. Apoptosis — as determined by DNA fragmentation (TUNEL) and ultrastructural analysis — is abnormally frequent in the sperm cells of the ejaculate of sterile men with classical biochemical and ultrastructural pattern. In this review, we discuss the possible origins of DNA damage in ejaculated human spermatozoa and the consequences of DNA damage if the apoptotic spermatozoa is used for ICSI. Percentages of DNA fragmentation in human ejaculated sperm are correlated with fertilization rates both after FIV and ICSI. Detection of DNA fragmentation in human sperm could provide additional information about the biochemical integrity of sperm and may be used in future studies for fertilization failures not explained by conventional sperm parameters. However, the analysis of other molecular markers of apoptosis (Fas, Annexine V ...) is necessary to assess the role of apoptosis in human ejaculated sperm cells.     

Recherches sur la morphogénèse du canal de Müller chez les Oiseaux

Résumé L'analyse de certains points de la morphogénèse du canal de Müller et du rôle joué par le canal de Wolff dans la formation de l'oviducte a été abordée à l'aide de diverses méthodes expérimentales (blocage de l'ébauche müllérienne par un obstacle mécanique ou par une irradiation localisée par les rayons X).Les résultats obtenus soulignent la formation et l'évolution indépendante des 2 tissus, l'epithélium interne et le mésenchyme périphérique, qui composent la jeune ébauche müllérienne.L'épithélium interne se met en place par le jeu de la croissance crânio-caudale d'une ébauche primitive formée au niveau de l'ostium et induite par le canal de Wolff.Le mésenchyme périphérique se forme «in situ», aux dépens de la crÊte mullérienne qui est elle-mÊme induite par le canal de Wolff.Chez les Oiseaux, le développement de l'oviducte reste donc dépendant de l'uretère primaire, du fait de la double action inductrice exercée par le canal de Wolff sur les deux tissus constituant primitivement le canal de Müller.

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Researches on Mullerian duct morphogenesis in birdsII. Experimental study

Summary Certain points in the Mullerian duct morphogenesis, and the role played by the Wolffian duct in oviduct formation, were studied with some experimental methods (by stopping the mullerian anlage with a mechanical obstacle, or by a localized irradiation with X-rays).The results emphasize the independent formation and evolution of the two tissues, the inner epithelium and the mesenchyme which compose the young mullerian anlage.The inner epithelium is formed by the cranio-caudad outgrowth of a primitive anlage, formed at the level of the ostium, and induced by the Wolffian duct.The peripheric mesenchyme is formed in situ, from the mullerian strip, which itself is induced by the Wolffian duct.In Birds, oviduct development depends upon the primary ureter, by means of the double inductive action exerted by the Wolffian duct upon both tissues constituting the Mullerian duct anlage.

     

Fluctuations des nutriments au cours de la marée sur les parcs Ostreicoles de la rivière Penze (Nord-Finistère)

The design and performance of a simple, community level ecotoxicological testsystem is reported. Samples of periphyton communities, established on artificial substratum in natural streams were used to study effects on photosynthetic activity in short-term experiments. Photosynthesis was measured as light-dependent oxygen evolution or as ¹⁴CO₂-incorporation. The variability in photosynthetic activity between samples collected at the same time, expressed as coefficient of variation, was ca 20%. The variation in sensitivity of periphyton photosynthesis as dependent on sampling season was less than threefold for the two long-chained aliphatic amines and the textile industry effluent studied. Effects of the amines on periphyton from five different streams were also investigated. The ratio between maximum and minimum values of sensitivity was 5.6. It is concluded that the variation in sensitivity between different periphyton communities is similar to or less than that observed for fresh-water algal species. Some advantages with regard to ecological realism of using periphyton communities as test systems are discussed.     

Etude ultrastructurale de l'évolution du tégument de la Sangsue Hirudo medicinalis L. (Annélide,Hirudinée) au cours d'un cycle de mue / Developmental changes in the integument of the leech Hirudo medicinalis L. (Annelida,Hirudinea) during a molting cycle. An ultrastructural study

Summary

The integument of the leech Hirudo medicinalis is mainly composed of a single layer of cuticle-secreting epidermal cells. The cuticle is made up of collagen fibers which support a layer of membrane-bound epicuticular projections.

Shedding of the old cuticle is preceded by the formation of a new cuticle. The epicuticular projections are the first to develop: they originate from the tips of numerous microvilli of the epidermal cells. As soon as it appears, the newly-formed collagen layer is firmly attached to the epidermal cells by numerous hemidesmo-somes, whereas the old cuticle is no longer connected with the epidermal surface. The epidermal cells exhibit marked characteristics of secretory activity during the laying down of the new cuticle.

The observations are discussed in connexion with recent findings of high ecdysteroid levels in leeches at the beginning of the molting cycle.     

Polymorphisme electrophorétique de la post-albumine et de la transferrine dans les différentes sous-espèces de singes anthropoïdes

Summary The electrophoretic polymorphism of post-albumin and transferin was investigated in 46 apes of the Pan troglodytes. Gorilla gorilla and Pongo pygmaeus subspecies. This type of study enables the different subspecies to be distinguished and the ancestral from to be identified. The pattern of individual variability is found to be different between the various ape species and Homo sapiens.

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Polymorphisme electrophorétique de la post-albumine et de la transferrine dans les différentes sous-espèces de singes anthropoïdes

Résumé Le polymorphisme électrophorétique de la postalbumine et de la transferine est étudié chez 46 individus apprrtenent à diverses sous-espèces de Pan troglodytes, Gorilla gorilla et Pongo pygmaeus. Il est ainsi possible de distinguer les différentes sous-espèces et de proposer lesquelles d'entre elles sont les formes ancestrales. L'étendue du polymorphisme est différente chez les différentes espèces de singes et chez Homo sapiens.

     

Diminution de la capacité de surfusion au cours de l'embryogenèse et du développement larvaire chez un coléoptère

Potential cold resistance of non-diapause eggs and first instar larvae of Osmoderma eremita (Coleoptera, Cetoniidae, Trichiinae) during embryogenesis and post-embryonic growth was assessed by measuring individual supercooling points (SCP): sterile eggs had a mean SCP of −24.3 ± 2.0 °C; fertilized newly laid eggs a mean SCP of −23.4 ± 3.2 °C and eggs about to hatch a mean SCP of −9.2 ± 2.9 °C. Water absorption by fertilized eggs is a necessary requirement for the development of the embryo and results in an increase in weight and water content: fertilized newly laid eggs had a mean fresh weight of 10.687 ± 1.072 mg and a mean water content (expressed as a percentage of the dry weight) of 79.5 ± 10.83%; eggs about to hatch had a mean fresh weight of 19.127 ± 3.183 mg and a mean water content of 250.10 ± 74.15%. The ex-ovo larvae, hatched 30 days after oviposition, had a mean SCP of −10.1 ± 3.6 °C (no significant difference with eggs about to hatch) and had gained in weight (24.845 ± 3.911 mg) and in water content (499.72 ± 55.49%). Feeding 1st instar larvae had a decreased supercooling ability (mean SCP = −5.7 ± 0.4 °C) whereas their mean fresh weight (99.858 ± 53.091 mg) and mean water content (665.83 ± 82.74%) increased. The eggs and larvae of O. eremita are freezing intolerant. Before overwintering, all larvae switch to being freezing tolerant and can survive ice formation in their tissues and body fluids, whereas their mean SCP stays at around −5 °C. However, recent experiments in the winter of 1996 have shown that frozen larva mortality does occur at temperatures lower than about −12 °C.     

Les éléments cytoplasmiques au cours de la spermiogenèse du TritonPleurodeles waltlii Michah

Summary The development of the different components of thePleurodeles spermatozoon neck region have been investigated and described from the early beginning spermiogenesis process. In some cases their origine is not well defined. Some dictyosomes remain in a constant relationship with the pericentriolar granule and the two different rings, even after they had left the acrosomal region.The development of the neck in a deep postnuclear niche, does not seem related with the centrioles. The nuclear origine of some basic proteins of the neck is discussed in relation to the close correspondence between their appearance and the substitution of the lysine rich histone by the arginine rich histone in the nuclear. The various morphologic signs of transit at the nuclear envelope level have been investigated. The ways along which some materials is eventually transferred out of the nucleus remained an open question. ThePleurodeles spermatid neck region is compared with the same region of the insect and mammalian sperm.Some components of thePleurodeles young spermatids display common characters with the mammalian chromatoid body. Their development are fairly similar. Thus the Urodele spermatid seems to posses a chromatoîd body like most other vertebrate spermatids.

Equipe de Recherche Associée au C.N.R.S., E.R.A. n^o 129.     

Les éléments cytoplasmiques au cours de la spermiogenèse du TritonPleurodeles waltlii Michah

Résumé L'origine et la morphogenèse des différents éléments de l'acrosome du spermatozode dePleurodeles waltlii ont été suivies et décrites depuis le tout début de la spermiogenèse. La formation de la vésicule acrosomienne et son évolution en une coiffe acrosomienne se fait selon le schéma classique. Son extrémité apicale se différencie tardivement en un bouton terminal et un crochet. Les trois parties de la coiffe diffèrent dans leur composition et leur structure fine.Les volumineux et complexes éléments situés sous la coiffe acrosomienne: axe, baguette puis manchon périphérique et manchon moyen, sont dépourvus de polysaccharides. Leur origine est envisagées. Ils sont comparés aux éléments situés dans l'espace sous-acrosomien des spermatozodes des autres vertébrés.

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The cytoplasmic elements during spermiogenesis in the triturusPleurodeles waltlii MichahI. Acrosome genesis

Summary The origin and the morphogenesis of the acrosome different parts ofPleurodeles spermatozoon, have been investigated and described from the early beginning spermiogenesis process. The acrosomal vesicle and acrosomal cap formation take place according to the classical scheme. The acrosomal anterior tip cap late differentiate in a blunt terminal knob and a hook. The three cap parts differ in their composition and fine structure.The large and complicated structure stretching under the acrosomal cap: axis, peripheral muff and middle muff, are devoided of polysaccharides; their origin is discussed. They are compared with the subacrosomal components lying in the other vertebrates spermatozoon subacrosomal space.

Equipe de Recherche Associée au C.N.R.S., E.R.A. n^o 129.     

Inclusions cytoplasmiques lamellaires dans les tubes collecteurs du rein au cours de la néphrose osmotique

Summary Osmotic nephrosis was induced in mice by intraperitoneal injections of a solution of sucrose or glucose. In most of the animals, the pale cells of the initial segment of the collecting tubules contain extremely peculiar dense granules. These inclusions contain lamellar systems of which the appearance closely resembles that of lecithine-cholesterol dispersions, as observed with an electron microscope after negative staining. These inclusions, which are probably related with the resorbtive function of the pale cells, are considered as residual bodies, and classified as belonging to the lysosome family.

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Zusammenfassung Osmotische Nephrosen wurden durch intraperitoneale Injektionen von Saccharose bzw. Glukose erzeugt. Bei den meisten der untersuchten weißen Mäuse findet man in den hellen Zellen der Pars proximalis der Sammelrose dunkle Einschlüsse von besonderem Aussehen. Diese Einschlüsse enthalten eine lamellenartige Innenstruktur, welche an Dispersionen von Lecithin oder Lecithin-Cholesterin in elektronenoptischen Aufnahmen nach negative staining erinnern. Diese Einschlüsse der Sammelrohrzellen stehen wahrscheinlich zu der Funktion der Reabsorption in Beziehung; sie gehören nach unserer Auffassung mit den Residualkörpern (residual body) zur Gruppe der Lysosomen.

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Ce travail a partiellement bènèficiè de l'aide du Fonds National Suisse de la Recherche Scientifique et de la contribution du «Consiglio Nazionale délie Ricerche», Italie.     

Modifications des cellules gonadotropes de la préhypophyse chez la ratte injectée de testostérone au cours du cycle oestral

Summary 4-day cyclic adult female Wistar rats were injected subcutaneously with testosterone propionate on diestrus 1 at 16:00 and on diestrus 2 at 10:00 respectively. Non-injected females served as controls. Autopsy was performed on diestrus 2 at 23:00, and on proestrus at 14:00 and 17:00 respectively. The blue Alcian-PAS staining was used to evidence FSH () and LH () pituitary cells.In control animals and in diestrus 2 injected females only a small number of FSH cells could be detected on diestrus 2 at 23:00. This number increased markedly on proestrus at 14:00 and decreased on proestrus at 17:00. A similar evolution was observed in diestrus 1 testosterone injected females, but the number of FSH cells appeared higher at any stage of autopsy in these females than in diestrus 2 injected females and in control rats.In control females, numerous LH cells were observed on diestrus 2 at 23:00. The number of these cells was diminished on proestrus at 14:00 and still more at 17:00. On the contrary few LH cells were detected in testosterone injected females on the evening of diestrus 2. An increase of these cells occurred on proestrus at 14:00, followed at 17:00 by only a weak diminution as established by comparison with control animals.An inhibition of FSH release and a suppression of the proestrus surge of LH were therefore supposed to cause, on one hand, the slowing up of follicular growth observed in diestrus 1 injected females and, on the other hand, the blockage of ovulation noted in both diestrus 1 and diestrus 2 treated animals.

Travail effectué avec l'aide de la D.G.R.S.T. Contrat n^o 72.7.0030.     

Variations du taux des ecdystéroïdes au cours des cycles de mue et de vitellogenèse chez le Crustacé Amphiphode,Orchestia gammarellus

Ecdysteroid titer in whole extracts of female O. gammarellus varies during the course of the moult cycle: it is minimal at the beginning of the intermoult cycle (stages A, B and C_a) and in D₀, and maximal in D₂. In hemolymph, the hormone content presents a single peak level in D₂; this peak is constituted by ecdysterone, as revealed by HPLC. Ovaries, at the end of vitellogenesis, contain ecdysterone and low polarity substances. Ecdysteroids are also present in eggs after laying.

Variations in ecdysteroid levels seem to influence oocyte growth; vitellogenin synthesis, however, is independent of hormonal fluctuations.     

Répartition de l'activité phosphatasique acide dans les cellules gonadotropes de la Grenouille au cours de leur cycle sécrétoire

Résumé Dans les cellules de l'hypophyse de la Grenouille, Rana temporaria, produisant l'hormone gonadotrope, nous avons analysé la localisation et l'évolution de l'activité phosphatasique acide au cours du cycle sécrétoire.Durant l'élaboration des sécrétions, l'activité enzymatique est essentiellement localisée au niveau de l'ergastoplasme, des saccules et des vésicules golgiennes, avec quelques accumulations plus importantes dans les grains juxta-golgiens et dans certains grains de diamètre plus important. A ce stade, quelques vésicules du réticulum endoplasmique lisse et un petit nombre de formations globuleuses présentent également une réaction positive. Ces images pourraient être en relation d'une part avec un processus de formation des lysosomes, d'autre part avec le fonctionnement normal de l'appareil de Golgi.Dans les cellules en phase de stockage et en cours d'excrétion, aucune activité n'est décelable dans la région golgienne. On note, par contre, la présence d'un grand nombre de corpuscules lytiques dispersés parmi les grains de sécrétion. Dans la matrice de ces corpuscules on distingue parfois des formations granulaires qui pourraient être en voie de résorption.Ces formations qui interviennent dans le processus de résorption intracellulaire des produits de sécrétion non excrétés pourraient également à certains moments du cycle cellulaire jouer un rôle, dans le processus de libération de l'hormone.

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Localization of phosphatasic acid activity in gonadotrophs of the frog during their secretory cycle

Summary The localization and evolution of acid phosphatase activity during the secretory cycle of the gonadotropic cells of Rana temporaria are described.During the secretory phase of the cells the enzymatic activity is demonstrable in the rough endoplasmic reticulum, the Golgi saccules or vesicles and in granules of different diameters. Some vesicles of the smooth endoplasmic reticulum and a few number of globular formations contain also acid phosphatase. This picture corresponds to the normal function of Golgi zone or to the first step of the formation of lysosomes.During the phases of accumulation and excretion of secretory granules acid phosphatase activity is concentrated in lytic bodies which sometimes contain secretory granules. This picture may be interpreted as an intracellular digestion of secretory products. At this time the Golgi zone lacks acid phosphatase activity.From these findings it may be concluded that in gonadotropic cells lysosomes act in the regulation of secretory process, specially the resorption of accumulated secretory granules, but a role in the hormone releasing process cannot be excluded.

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Avec la collaboration technique de Mme R.-O. Clauss.