Bases moléculaires et cellulaires de l'invasion des cellules épithéliales intestinales par Shigella flexneri

A key step in the pathogenesis of shigellosis is the capacity of the causative bacteria, shigellae, to invade colonic and rectal epithelial cells in humans. This invasive process encompasses several steps: entry into epithelial cells by induction of a macropinocytic event caused by secreted Ipa proteins. The bacterium then escapes from the vacuole and reaches the cytoplasmic compartment in which it divides rapidly and becomes motile via the expression of a surface protein, IcsA, whose polar localization achieves directed polymerization of actin filaments that push the bacterial body forward. Bacteria then engage the inner face of the cellular membrane in the junctional area and form protrusions allowing their passage into the adjacent cell. Lysis of the double membrane eventually allows access to the cytoplasmic compartment of the adjacent cell, thus providing the bacterium with a very efficient mechanism of epithelial colonization.     

Ultrastructure,innervation et fonction de l'épiphyse de l'orvet (Anguis fragilis L.)

Summary The pineal organ of Anguis fragilis contains two essential cell types: pinealocytes and interstitial cells. The scarce outer segments are of different appearance; they show cyclic degenerative changes. Only one intraepithelial ganglion cell has been identified in the material of this study. Although an intracommissural pineal nerve is present, the absence of synaptic junctions of pinealocytes with ganglion cells indicates a loss of photosensory function. Three kinds of vesicles (also dense-core vesicles) originating from Golgi complex are described in the pinealocytes. These secretory vesicles show a vascular polarity. The pinealocyte processes extend to the basement membrane. Secretory material is released into the peripineal space. Efferent sympathetic nerve fibers are described near the pineal epithelium. The nerve endings of these fibers contain three types of vesicles. It is suggested that the pineal organ of Anguis fragilis has a well established secretory function.

---

Zusammenfassung Die Epiphysis cerebri von Anguis fragilis enthält zwei wesentliche Zelltypen: Pinealocyten und Zwischenzellen. Die Außenglieder, die nur selten vorkommen, sind verschiedenartig gestaltet und erleiden einen zyklischen Degenerationsprozeß. Im Pinealepithel ließ sich nur eine einzige Ganglienzelle mit Sicherheit nachweisen. Obwohl eine intracommissurale Nervenbahn vorhanden ist, spricht das Fehlen von Synapsen zwischen Pinealocyten und Ganglienzellen für einen Schwund der Lichtsinnesfunktion. In den Pinealocyten werden drei aus dem Golgiapparat stammende Bläschenarten, darunter auch solche mit einem elektronendichtem Inhalt (Granula), beschrieben. Diese Sekretbläschen sind polar auf die Blutgefäße ausgerichtet. Fortsätze der Pinealocyten stehen mit der Basallamina in Verbindung; allem Anschein nach werden hier Substanzen in den periepiphysären Raum abgegeben. Efferente sympathische Nervenfasern sind in der Nähe des Epiphysenepithels zu beobachten. Die Endigungen dieser Fasern enthalten drei verschiedene Bläschentypen. Die Epiphyse der Blindschleiche scheint eine sekretorische Funktion zu haben.

     

Ultrastructure et physiologie des organes épipharyngiens et hypopharyngiens (chimiorécepteurs cibariaux) de Blabera craniifer Burm (Insecte,Dictyoptère)

Résumé Il est démontré, par une méthode électrophysiologique, que les organes épi-et hypopharyngiens de Blabera sont des chimiorécepteurs de contact. Chaque organe est un groupe de sensilles polyneuroniques. A chaque sensille est associée, dans la région sous-épidermique, une cellule nerveuse périphérique de type II sans doute mécanoréceptrice. Chaque sensille possède en outre une cellule accessoire glandulaire, condition qui semble caractéristique des chimiorécepteurs de contact chez les Insectes. La sécrétion élaborée emprunte le canalicule du sensille, baigne les surfaces réceptrices des dendrites et peut être rejetée à l'extérieur. Cette sécrétion intervient sans doute dans le mécanisme de transduction.Tous les Insectes possèdent des organes épi-et hypopharyngiens. Leur importance dans le déterminisme du comportement alimentaire, démontrée chez les Criquets (Haskell et Mordue, 1969), est probable chez tous les Insectes. Certains au moins de ces organes peuvent intervenir dans la régulation du fonctionnement du système endocrinien (corps cardiaques). Par contre — contrairement à ce qui a été soutenu — il n'est pas démontré qu'ils interviennent dans la régulation du transit intestinal (pas plus que n'est démontrée l'existence d'un osmorécepteur pharyngien chez les Insectes).

---

Ultrastructural and physiological study of the epi-and hypopharyngeal organs (cibarial chemoreceptors) of Blabera craniifer Burm

Summary An electrophysiological study showed that the epi-and hypopharyngeal organs of Blabera are contact chemoreceptors (Fig. 9). Each organ is a group of epidermal sensilla (Fig. 4). In the subepidermal region, a multiterminal nervous cell—which may be a mechanoreceptor—is associated with each sensilla (Fig. 10A). In addition, each sensilla possesses an accessory glandular cell—a condition which seems to be characteristic for contact chemoreceptors of Insects. The secretion produced goes out through the cuticular sheath of the sensilla (Fig. 10B). The receptive surfaces of the dendrites are bathed in this secretion which is probably active in the transducing mechanism.All insects have epi-and hypopharyngeal organs. The last are important in the feeding behavior of Locusta and Schistocerca (Haskell and Mordue, 1969) and probably of all other insects. At least some of these organs can intervene in the regulation of the hormonal release by the corpora cardiaca. The importance of these organs in the regulation of crop emptying is not known and it is not possible to claim that one of these organs is an osmoreceptor.

     

Régulation des fonctions de l’épithélium épididymaire des mammifères: état des lieux

Male gametes formed in the testis, the site of spermatogenesis, continue their maturation outside of the gonad in the genital tract. The epididymis is at the centre of this process of post-testicular maturation of spermatozoa, responsible for acquisition of their mobility and their ability to recognize and penetrate an oocyte, essential events for fertilization. During their transit in the epididymal ducts, gametes evolve in a perpetually changing luminal environment due to complex interactions of secretion and reabsorption activities of the epididymal epithelium. These numerous secretion and reabsorption activities are closely regulated in space and time, which makes this epididymal epithelium a very complex tissue subject to an elaborate network of cross-regulations. Apart from classical endocrine and paracrine regulations, the proximal part of the epididymis is also subject to lumicrine regulation by testicular factors which increase the complexity of the regulation networks involved. The present study tries to present an exhaustive review of the factors demonstrated in the literature to exert a modulation of epididymal activity.     

Etude cytochimique et ultrastructurale de l'évolution ovocytaire de Nereis pelagica L. (Annélide Polychète)

Résumé Les ovocytes de N. pelagica d'un diamètre inférieur à 100 ne renferment dans leur cytoplasme que des inclusions lipidiques et vitellines. Les lobules vitellins s'accroissent par l'adjonction de vésicules golgiennes.L'approche de la maturité sexuelle est caractérisée par l'apparition de mucopolysaccharides acides. Corrélativement à l'élaboration de ce matériel, l'appareil de Golgi présente, à ce stade, de profondes modifications morphologiques: dilatation des saccules distaux et libération dans le cytoplasme de vacuoles golgiennes. Les processus de vitellogenèse cependant ne sont pas entièrement stoppés.Dans les ovocytes matures, les lobules mucopolysaccharidiques forment une gangue corticale. Les dictyosomes sont refoulés vers l'intérieur du cytoplasme et présentent des figures d'involution.La présence de lamelles annelées intra-nucléaires a été observée de façon constante dans tous les ovocytes matures examinés.

---

Cytochemical and ultrastructural study of oocyte development in Nereis pelagica L.I. Normal ovogenesis

Summary The oocytes of N. pelagica, the diameter of which is smaller than 100 , contains only lipid and yolk inclusions in their cytoplasm. The yolk bodies grow by confluence of Golgi vesicles.The advent of the sexual maturity is marked by the appearance of acid mucopolysaccharides. Concomitantly with the production of this material, the Golgi apparatus shows typical morphological modifications: dilatation of the distal saccules and release of Golgi vacuoles into the cytoplasm. However vitellogenesis is not completely terminated at this point.In the mature oocytes the mucopolysaccharid material forms a cortical layer. The dictyosomes are pushed toward the center of the cytoplasm and show signs of degeneration.The presence of intranuclear annulate lamellae is a constant feature in all mature oocytes examined.

     

Contribution à l'étude ultrastructurale des cellules interrénales de Salamandra salamandra L. (Amphibien Urodèle)

Summary The interrenal (adrenocortical) cells of spotted Salamanders seriously affected by a mycotic disease for a long period, have a strikingly large dimension. Their nuclei and nucleoli show a marked hypertrophy. The cytoplasm is sometimes completely deprived of liposomes; it is very rich in mitochondria, smooth-surfaced reticular tubules and free ribosomes. Ergastoplasmic cisternae are frequently encountered in the vicinity of the nuclei. The Golgi apparatus is considerably developed. This organisation, which is common to all the cells, characterizes a stage of intense activity of hormonal synthesis, probably induced by high levels of ACTH. Beside these typical features, small dense bodies are particularly abundant at the periphery of the cells. No mitotic division could be seen.In Salamanders which suffer only moderately from the disease, the cells of the central part of the interrenal islets are the only ones to show the characteristics of great activity. On the other hand it can be noted that such cells are the more numerous the more the situation of the islet is cranial. As opposed to this, the cells of the periphery of the islets show only signs of a poor activity.During the extension of the disease, the number of highly active cells increases progressively, probably as a consequence of the activation of the peripheral cells. This activation usually begins with the hypertrophy of the nucleus and the nucleolus. The cytoplasmic modifications (namely the lipid depletion and the apparition of numerous dense bodies in the vicinity of the Golgi apparatus) seem to appear during a second stage only.

---

Zusammenfassung Die Interrenalzellen von Feuersalamandern, welche seit längerer Zeit an einer Pilzkrankheit schwer leiden, zeigen einen ungewöhnlich großen Durchmesser. Ihre Zellkerne samt Nukleoli sind überentwickelt. Das Zytoplasma ist hie und da frei von Liposomen, zeigt aber überaus zahlreiche Mitochondrien, glatte Tubuli des endoplasmatischen Retikulums und freie Ribosomen. In der Nähe des Zellkerns trifft man häufig ergastoplasmatische Zisternen an. Der Golgi-Apparat ist stark ausgebildet. Diese Organisation, die man in allen Zellen wiederfindet, deutet auf eine starke Aktivität der Hormonsynthese hin, die wahrscheinlich unter dem Einfluß von hohem und andauerndem ACTH-Gehalt steht. Ferner findet man kleine elektronendichte Körper, vor allem häufig an der Peripherie der Zellen. Mitotische Zellteilungen wurden nicht beobachtet.Bei Salamandern, die von der Erkrankung weniger befallen waren, zeigen nur die inneren Zellen der Interrenalinseln Äquivalente einer starken Aktivität. Sie sind im übrigen desto zahlreicher, je weiter cranial die Interrenalinsel liegt. Die Zellen in der Peripherie dagegen tragen die Merkmale einer schwachen Aktivität.Im Laufe der Krankheit nimmt die Zahl der hochaktiven Zellen fortwährend zu, wahrscheinlich infolge der Aktivierung der Zellen der Peripherie. Diese Aktivierung beginnt mit der Vergrößerung der Zellkerne und Nukleoli. Die zytoplasmatischen Veränderungen, insbesondere das Verschwinden der Liposomen und das Erscheinen von elektronendichten Körpern in der Nachbarschaft des Golgi-Apparates, scheinen in einer zweiten Phase aufzutreten.

     

Etude comparée expérimentale de l'électrophorèse des protéines et des électrolytes chez des chiens

A higher survival rate and faster wound healing in dogs on a controlled and well-balanced diet have been demonstrated when compared with those not under dietetic control.Electrophoretic comparison of serum proteins was carried out in two groups of dogs. The first was on a well-controlled and well-balanced diet; the second group received an uncontrolled diet. The dogs in Group 2 had a lower concentration of total proteins, and globulins, especially gamma-globulins, were diminished; however, the serum albumin was higher. The albumin/globulin ratio was 0.93 in Group 1 and 2.07 in Group 2.Serum electrolyte levels also showed some slight differences. Sodium and potassium levels were higher in well-nourished dogs, while chloride and bicarbonates were slightly lower.     

Effets du gemmage sur l'ultrastructure des cellules sécrétrices des canaux de l'écorce des tiges dePinus sylvestris L. etPicea abies (L.) Karst.

Résumé La synthèse des terpènes par les cellules sécrétrices des canaux de l'écorce des rameaux dePinus etPicea est terminée à la fin de la période d'élongation de la pousse de l'année. Les cellules épithéliales subissent ensuite une dédifférenciation progressive et accumulent des substances de réserve. La potentialité sécrétrice peut Être réactivée par gemmage. Elle se traduit initialement par une multiplication des leucoplastes et des membranes du reticulum endoplasmique lisse. Ces deux systèmes sont donc responsables de la production d'oléorésine dans les conditions normales ou sous l'effet d'une blessure.

---

Effects of tapping on the ultrastructure of the secretory cells of the bark of stems ofPinus sylvestris L. andPicea abies (L.) Karst

Summary The terpene synthesis by the resin canal cells of the bark in the twigs ofPinus andPicea ceases at the end of the elongation period of the first year shoot. After this secretory period, the epithelial cells undergo a progressive dedifferentiation and store ergastic material. The secretory potentiality may be reactivated by tapping. The first obvious features are the multiplication of leucoplasts and membranes of the agranular endoplasmic reticulum. Therefore these two systems are the site of the oleoresin production in normal conditions and after wounding.

     

Diversité des formes d'accumulation de la phytoferritine dans les cellules constituant l'épithème des hydathodes de Taraxacum officinale Weber et Saxifraga aizoon Jacq.

Summary In Taraxacum officinale and Saxifraga aizoon particular aggregations found in plastids of epithem are considered to be phytoferritin. The diversity of plant ferritin arrangement within the plastids is studied. High magnification study of these inclusions indicates that they can be classified morphologically into three distinct groups: dense and amorphous aggregate (F₁), crystalline inclusion (F₂) and diffuse paracrystalline arrangement (F₃). The crystalline (F₂) and amorphous (F₁) structures are both present in the plastids of Saxifraga aizoon; similarly, paracrystalline (F₃) and amorphous inclusions (F₁) are both present in the plastids of Taraxacum officinale. Because of their location and the nature of their organization, we think that the phytoferritin complexes under discussion may be important in phytoferritin synthesis or phytoferritin utilization within the living plant.     

Etude histochimique comparée des mucopolysaccharides des organes récepteurs de type ampullaire de certains poissons électriques à faible décharge: Gnathonemus petersii (Mormyridés), Gymnotus carapo (Gymnotidés) et Gymnarchus niloticus (Gymnarchidés)

Résumé Des substances muqueuses ont été examinées par des méthodes histochimiques au niveau des organes récepteurs cutanés de type ampullaire (organe de type A, Szabo, 1965) faisant partie du système de la ligne latérale des poissons électriques à faible décharge Gnathonemus petersii (Mormyridés), Gymnotus carapo (Gymnotidés) et Gymnarchus niloticus (Gymnarchidés).Les réactions à l'acide périodique Schiff (P.A.S.) et au bleu de toluidine en solution tampon montrent que les polysaccharides de tous ces organes possèdent des groupements vic-glycols responsables de la positivité au P.A.S.On trouve des mucopolysaccharides neutres au niveau de chaque organe ampullaire. Le cytoplasme des cellules sensorielles de l'organe ampullaire du Gymnotus carapo et lui seul contient du Glycogène. En dehors des mucopolysaccharides neutres, on observe des mucopolysaccharides acides notamment dans le canal épidermique de l'organe de type A de Gymnarchus niloticus et au contact de la région apicale des cellules sensorielles de l'organe de Gnathonemus petersii. Ces derniers sont métachromatiques, leur métachromasie étant dûe à un radical acide carboxylé.

---

Comparative histochemical study of mucopolysaccharids in the ampullary sense organs of weakly electric fish: Gnathonemus petersii (Mormyridae), Gymnotus carapo (Gymnotidae) and Gymnarchus niloticus (Gymnarchidae)

Summary The mucoides substances of lateral line receptors of ampullary type have been examined in the weakly electric fish Gnathonemus petersii (Mormyridae), Gymnotus carapo (Gymnotidae), Gymnarchus niloticus (Gymnarchidae), by different histochemical methods. Periodic acid Schiff reaction (P.A.S.) and puffered Toluidine Blue tain show, that the polysaccharid of all these three organs contain a vic-glycol groupe, responsible for the positive P.A.S. reaction.Neutral polysaccharids were found at the level of all ampullary type of organ. Only the cytoplasm of the sensory cells in Gymnotus carapo contains glycogen.Acid mucopolysaccharids were observed in the epidermal canal (extracellularly) of Gymnarchus niloticus and also in the close neighbourghood of the sensory cells in Gnathonemus. These acid mucopolysaccharids are metachromatic because of their acid carboxylic radicle.

---

---

Ce travail a été réalisé grâce au Contrat n 659-594, accordé au Dr. T. Szabo par la Direction de Recherches et Moyens d'Essais (D.R.M.E.).     

Les forêts sacrées de Guinée : entre écologie et conservation

Guinea has very little ecological data available regarding its sacred forests. This study shows the important conservation role of these forests in a local context of strong human impacts. We present four representative case studies from the Sudano-Guinean zone in Upper Guinea. Our phytoecological inventories recorded a total of 431 species, 312 genera, and 87 families including 242 species, 187 genera, and 64 families in the forests. Twelve plant groups have been identified, including five in forests and seven in the surrounding vegetation. Geomorphology, texture, soil hydromorphism, microclimate, and human impacts are significant in explaining the spatial distribution of plant groups. The study reveals that in these Sudano-Guinean savannas, vegetation is dominated by micro-phanerophytes. The Guinean-Congolese flora is better represented in gallery forests.     

Diatomées épilithiques du fleuve Esino (Italie centrale) et leur utilisation pour l'évaluation de la qualité biologique de l'eau

In the monitoring programme of the Italian rivers which enter the Adriatic Sea, a relatively closed and small sea with high pollution risk, the assessment of the water quality of the River Esino, a typical central Apennine watercourse, was carried out. The eutrophication/pollution index (EPI-D) proposed for Italian rivers and based on the sensitivity of the diatoms to organic matter, nutrients and mineralization of the water, with particular reference to chloride, was adopted in this analysis. The good results obtained with respect to the various situations of pollution present at the eighteen stations selected along the river, as well as with regard to other diatom-based indices generally used in Europe, seem to confirm the validity of this index for monitoring Italian watercourses.     

Maladie de Basedow et maladie de Crohn : étiopathogénie croisée ou association fortuite ? (À propos de deux cas)

An increased prevalence of the association between autoimmune thyroid diseases and ulcerative colitis has been suggested, while the association with Crohn's disease has only been reported in about ten cases. We describe two patients, one with Crohn's disease complicated with Graves’ disease and the other one with the reverse sequence. The treatment of hyperthyroidism in such cases must be early and efficient in order to avoid an intensification of the systemic manifestations of Crohn's disease. Genetic, environmental and immunologic aetiologies have been suggested for the pathogenesis of this association, although the exact mechanism remains unclear.     

Ultrastructure des cellules germinales au cours du développement embryonnaire du Lézard vivipare (Lacerta vivipara Jacquin)

Résumé Les gonocytes primaires sont relativement pauvres en polysomes et l'ergastoplasme granulaire est très réduit. Le reticulum endoplasmique de type lisse se développe au cours du développement embryonnaire. L'appareil de Golgi est bien représenté et localisé au niveau de la calotte juxtanucléaire mitochondriale. Les liposomes cytoplasmiques sont très nombreux.Cette étude précise la structure du nucléole «annulaire» et de la «masse paranucléolaire» observés en microscopic photonique. Des modifications nucléolaires sont constatées au cours du développement embryonnaire. Certains aspects ultrastructuraux sont vraisemblablement en rapport avec le déplacement autonome des gonocytes. La signification physiologique du nucléole «annulaire» et de la «masse paranucléolaire» est envisagée.

---

Ultrastructural study on the primordial germ cells during embryonic development of Lacerta vivipara Jacquin

Summary The primordial germ cells of Lacerta vivipara have relatively few free polysomes and little ergastoplasm. Smooth endoplasmic reticulum increases during embryonic development. The Golgi apparatus is well developed and lies close to the mitochondrial juxtanuclear cap. This study shows the ultrastructure of the ring-shaped nucleoli and the masse paranucléolaire. Modifications in nucleolar structure are observed during embryonic development. Some ultrastructural features are probably related to the ameboid movement of the primordial germ cells. The physiological meaning of the ring-shaped nucleoli and the masse paranucléolaire is considered.

Avec la collaboration technique de Mme. M. Hubert.     

Contribution a l'étude des groupements végétaux de la contrée de Goma-kisenyi (Kivu1)-ruanda

Sans résumé     

Prédation exercée par le chabot (Cottus Gobio L.) sur l'alevin de truite commune (Salmo trutta L.): taille maximale de capture des alevins par les chabots

In laboratory conditions, where predation by sculpins (Cottus gobio L.) upon brown trout fry (Salmo trutta L.) was strong, predation was shown to be closely linked to total length of prey and predator. The limit of this predation can be defined by the equation: Y = 0.484 X + 5.8 (Y = total length of the trout fry in mm and X = total length of the sculpin in mm).

     

Influence comparée de l'(±)-acide abscissique,de la coumarine,de l'acide p-coumarique et de certains de leurs dérivés sur la croissance de la première feuille de blé

Summary The activities of (±)-abscisic acid and a number of compounds derived from p-coumaric acid and coumarin and their interaction with gibberellic acid in the control of the elongation of the first wheat leaf are examined. (±)-Abscisic acid strongly inhibits leaf growth in the presence as well as in the absence of gibberellic acid, but the inhibition is greater in the presence of gibberellic acid (3 g/l already have an observable effect). Among other compounds, only ferulic acid and coumarin significantly reduce leaf elongation, and they are effective only at high concentrations (1.44 · 10^-4 M/l).