Polyéthisme et défense de la société chez la fourmi champignonnisteAtta laevigata (Fr. Smith)

Résumé L'étude du comportement de défense du nid chezAtta laevigata permet de classer les 4 castes physiques d'individus stériles étudiés en deux groupes. Le premier groupe, constitué par les ouvrièresminor etmedia, rassemble des individus pouvant reconnaître avec précision des intrus de même espèce. Menacés et mordus, ces derniers sont alors mutilés ou transportés puis abandonnés par les fourmis résidentes aux frontières de leur territoire. Les ouvrièresmajor et les soldats, formant le second groupe, nécessitent quant à eux le marquage de l'ennemi par la phéromone d'alarme de leurs congénères pour pouvoir prendre part aux affrontements intraspécifiques avec efficacité. Les soldats se montrent en revanche très performants dans la défense du nid contre des envahisseurs appartenant à d'autres espèces, développant dans ce cas une agressivité supérieure à celle observée chez les ouvrières. L'âge de ces dernières ou le type de tâche qu'elles assument ne semble pas influencer leur comportement agonistique qui est comparable dans les deux castes temporelles de récolteuses et d'architectes.

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Polyethism and nest-defense in the leaf-cutting ant Atta laevigata (Fr. Smith)

Summary The study of the nest-defense behavior inAtta laevigata makes out the four physical castes of sterile individuals studied in two groups.Minor andmedia workers (first group) are able to recognize precisely the intruders of the same species that they threat, bite and mutilate or carry outside the territorial limits of the nest. As formajor workers and soldiers (second group), they need their ennemy to be impregnated by the alarm pheromone of their nestmates before they can take part with efficiency in the intraspecific fights. Soldiers though appear to be quite performent in the nest-defense against invaders from other species, showing in this case an aggressiveness superior to the one observed amongst workers. Age, for these, or the sort of work they assume don't seem to interfere with the agonsitic behavior that can be observed in both architects and foragers temporal castes.

     

Rôle et activités de l'Administration Générale Belge de la Coopération au Développement

Résumé L'AGCD gère 60% de l'aide publique belge au développement. Celle-ci consiste essentiellement en l'envoi de personnel belge qualifié ou d'experts, en l'apport d'équipement et de matériel, en le financement d'études ou en la formation de cadres locaux. En pratique l'AGCD travaille soit en responsabilité directe soit en collaboration avec des institutions spécialisées, universités, centres de recherche, organisations non gouvernementales ou internationales. De plus l'AGCD dispose de moyens d'intervention de type financier tels que le Fonds des Prêts à des Etats Etrangers et le Fonds de la Coopération au Développement.

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Summary The Belgian Administration for Development Cooperation (AGCD) is responsible for 60% of the Belgian public cooperation with Developing Countries. In addition to the standard means of cooperation like training, fellowships, Belgian experts, feasibility studies, donation of equipment and materials, etc., AGCD has been recently given two new instruments of cooperation, namely: the Fund for Loan to Foreign Countries and the Fund for Development Cooperation. Thanks to these new instruments AGCD is now in a position to assist by offering concessional loans, by participating in the equity of state-owned companies and by granting credit lines to national development banks. In the field of anaerobic digestion AGCD is presently undertaking two main projects: one in Burundi with the University of Louvain-la Neuve and another in Indonesia with the University of Ghent. It also co-finances punctual initiatives of non-governmental organisations and is finalizing the negotiations for the Belgian contribution to the World Bank Energy System Management Assistance Programme (better known as the ESMAP). Furthermore, Belgium is preparing a cooperation programme jointly with the World Bank to promote the biomethanation of organic domestic refuse.

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Resumen La Administración General de Cooperación para el Desarrollo es responsable del 60% de la cooperación belga con países en desarrollo. Además de los sistemas tradicionales de cooperación tales como ayudas para formación, becas, profesionales belgas, proyectos, donación de equipo y materiales, etc. se ha dotado recientemente a la AGCD con dos nuevos instrumentos de cooperación, más concretamente: la Fundación de Crédito a países Extranjeros y la Fundación para la Cooperación al Desarrollo. Gracias a estos nuevos instrumentos la AGCD puede ahora ofrecer asistencia mediante la concesión de prestamos, participando en la gestión de empresas públicas y asegurando lineas de crédito para los bancos nacionales de desarrollo. En el area de la digestión anaerobia la AGCD tiene dos proyectos en curso: uno en Burundi en colaboración con la Universidad de Louvain-la-Neuve y otro en Indonesia con la Universidad de Ghent. La AGCD también co-financia iniciativas puntuales de organizaciones extra gubernamentales y esta en vías de finalizar las negociaciones para determinar la contribución belga al programa del Banco Mundial de asistencia para la gestión de recursos energéticos (conocido como ESMAP). Belgica esta además preparando un programa de cooperación con el Banco Mundial para promover la biometanación de desechos orgánicos domésticos.

     

Étude expérimentale des variations de la teneur en eau au cours de la déshydratation et de la réhydratation chez la Fougère:Notochlaena vellea R. Br.

Experimental Study of changes in water content during dehydration and rehydration of the Fern: Notochlaena vellea R. Br.—This study takes place after studies made on otherPolypodiaceen Ferns. We have shown that, in these ferns, the survival duration was longer for the subterranean organs than for aerial ones. The problem was to show that this difference is due to a lower dehydration of the subterranean tissues. As far as we looked at the total water deficiency, we did not find any significant difference between the leaves and the meristematic parts of the subterranean organs: the main difference is the rate of rehydration which is higher in subterranean parts.     

Variations de quelques aclivités enzymatiques (peroxydase, catalase, AIA-oxydase) et de la teneur en polyphénols au cours de la germination de I'Orge. Influence de la kinétine

Peroxidase catalase, IAA-oxidase and polyphenol content of growing barley coleoptile. Effect of kinetin. - Kinetin strongly inhibits root and coleoptile growth of germinating barley in the dark. Treated coleoptiles become senescent before the untreated ones. Soluble proteins content, peroxidase, catalase and IAA-oxidase activity were greatly increased in treated coleoptiles while the level of polyphenols was reduced. These biochemical effects joined with the other property of kinetin to diminish α-amylase synthesis in the endosperm are discussed in relation to growth and in connection with the classic view of a cytokinin retarded senescence.     

Etude autoradiographique de la proliferation et de la migration cellulaires au cours de la croissance larvaire de l'appareil visuel chez Aeshna cyanea Müll. (odonata : Aeshnidea)

Sites of cell proliferation in the ocular apparatus of Aeshna cyanea have been studied by an autoradiographic method (³H-thymidine). This technique was used to locate at the compound eye and optic lobe levels the zones of cellular multiplication and the migration of newly formed cells. In addition, the effect of the differential growth of the compound eye on the development of the optical lobe was studied. In the compound eye, two distinct levels of cell proliferation were revealed: the first one was the ocular budding zone itself, i.e. the ocular edge adjacent to the cephalic epidermis. A second mitotic focus, where the cells gather into ommatidial columns, was demonstrated. Thus, two closely related successive mitotic waves occur in the eye of this heterometabolous insect, whereas in holometabolous insects these two phases are much more distinct. Migration of ganglionic cells from the neuroblast masses, where they are formed, to the optical ganglions, where they differentiate, was also followed by this method. In addition, a differential growth of optic lobes was revealed: at the end of the nymphal life, the development was much greater in the posterior area of the optic lobes than in the anterior, although the numbers of cells produced in the neuroblast masses were, at the beginning, identical in both areas. This observation has been interpreted in the light of the experimental results.     

Hommes et climats au Paléolithique supérieur dans le bassin de la Somme (France)

Nearly 40 years of intensive research conducted in the Somme basin has demonstrated the discontinuity in the human occupation of the area during the Upper Palaeolithic. The northern position of the Somme basin within the loessic region appears to be an explanatory factor in this discontinuity, the nature of which increasingly appears related to climate and environmental factors. Archaeological occupations have been systematically attributed to phases of warming or climate improvement. On the other hand, an absence of human occupation has been consistently observed during the coldest periods. The extreme poverty of the biomass contemporary to the loessic deposits of the Upper Pleniglacial could partly explain this discontinuity specific to the far northwest of Europe (southern England, northern Belgium, Netherlands, and northern Germany). Although only 150 or 200 km away, the southern Paris Basin, which is located on the fringes of the loessic region of northern France and Normandy, presents a more continuous human occupation, which appears to have benefitted from more favourable conditions.     

Types cellulaires et étapes de la différenciation de l'adénohypophyse chez l'embryon de roussette (Scyllium canicula,chondrichthyens)

Résumé L'identification et la répartition des cellules endocrines dans l'ébauche adénohypophysaire de Scyllium canicula, et la chronologie de la différenciation cellulaire et de l'histogenèse de cette glande ont fait l'objet de ce travail.Plus nettement encore que chez l'adulte on démontre qu'il y a quatre populations de cellules hormonogènes, localisées chacune dans un lobe différent. Les grains de sécrétion des cellules du lobe rostral sont glycoprotidiques et ont un diamètre modal, de 170 nm, ceux du lobe médian, de la même taille, sont protidiques ou polypeptidiques. Les gros granules du lobe neuro-intermédiaire (diamètre modal 260 nm) sont glycoprotidiques, les petits granules du lobe ventral (diamètre modal 120 nm), protidiques au polypeptidiques.Au stade 10 mm, les cellules de la poche de Rathke sont différenciées de celles de l'épithélium stomodéal par la présence d'inclusions énigmatiques, les godd bodies de Schechter.Au stade 35 mm les cellules des noyaux préoptiques et du tuber comportent des grains de neurosécrétion, de même diamètre, variant autour de 100 nm. A ce même stade, des granules apparaissent simultanément dans les quatre lobes de l'hypophyse, notamment dans le lobe neuro-intermédiaire où aucune fibre neurosécrétrice n'est encore décelée. L'innervation directe des cellules endocrines de ce lobe ne s'effectue qu'au stade 45 mm et s'accompagne de modifications de la taille des granules.La fin du développement embryonnaire se caractérise par une charge de plus en plus importante des cellules endocrines, en granules.

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Cellular types and differentiation of Scyllium canicula embryo adenohypophysis (chondrichthyes)Electron microscopical investigation

Summary The identification and distribution of endocrine cells in embryonic adenohypophysis of Seyllium canicula, and chronology of cellular differentiation and histogenesis of this gland have been investigated in this work.More clearly than in the adult, the presence of four populations of endocrine cells, each one located in a different lobe, is demonstrated. Secretion granules of rostral lobe cells are glycoprotidic, their modal diameter is 170 nm; median lobe ones, of same dimensions, are protidic or polypeptidic. The nemo-intermediate lobe big granules (modal diameter: 260 nm) are glycoprotidic, the ventral lobe small granules (modal diameter: 120 nm), protidic or polypeptidic.At stage 10 mm, Rathke's pouch cells are recognized from stomodeal epithelium by enigmatic inclusions, the odd bodies of Schechter.At stage 35 mm, preoptic and tuberal nucleus cells include neurosecretory granules of same diameter varying about 100 nm. At this same stage, granules appear simultaneously in the four hypophyseal lobes, including the neuro-intermediate lobe where no neurosecretory fiber is present. Direct innervation of endocrine cells of this lobe is accomplished at stage 45 mm and is accompanied by changes of granules dimensions. The end of embryonic development is characterized by increasing granular load of endocrine cells.

Travail effectué avec l'aide du C.N.R.S. (Bénéficiaire: J. Mellinger). Collaborateurs techniques: Meile F. Wrisez et Mme P. Iglesias.     

Variations des activités peroxydasique et phénoloxydasique au cours de la croissance de Coleus blumei Benth. var. Automne

Summary The specific peroxidase (1.11.1.7) and phenoloxidase (1.10.3.1) activities are quantitatively measured during the life of Coleus, from germination until flowering. In most organs investigated, the peroxidase activity increases rapidly with growth while the phenoloxidase activity remains low. The latter activity is higher in root apices than in more differentiated regions of roots. From the results obtained it may be concluded that the phenoloxidase activity accompanies cellular proliferation. It is suggested that the peroxidase activity plays an indirect role in root initiation through its role in cellular differentiation.

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Extrait d'une thèse de doctorat soutenue à la Faculté des Sciences de l'Université de Liège.     

Analyse de la transmission des chromosomes surnuméraires chez Locusta migratoria migratorioides R. et F. (Orthoptera,Acrididae)

In a African grasshopper population of Locusta migratoria migratorioides reared in the laboratory, B chromosome transmission is analysed in progeny of pairs taken at random from the population. An accumulation mechanism of Bs exists in the females which presumably results from preferentiel segregation of the Bs in the female pronucleus. The analysis also shows B chromosome elimination during embryonic and larval development by means of mitotic non-disjunction: these non-disjunctions induce interfollicular variations in the number of Bs but all the cells of a follicle have the same number of Bs. The frequency of animals with B chromosome rises from 34% to 75% as the diurnal temperature rises from 27° C to 35° C. Thus frequency is controlled by genetic and environmental factors.     

Contribution à la connaissance de la végétation rupicole des hautes vallées de l'ubaye et de l'ubayette. (Alpes cottiennes)

Summary The study of the saxatile vegetation of the alpine zone in the Upper Ubaye Valley shows a very sharp demarcation from a phytogeographical point of view.The saxatile groupings on limestone show septentrional affinities. It is interesting to note that the associations described have at least as much relationship to the Swiss Alp groups as to those of The Maritime Alps in fact closer.In our opinion, the explanation is not to be found in very different climatical or ecological considerations but in the presence of important barrier-mountains which have deprived the Upper Ubaye Valley of alien postglacial immigrants.There endemism is apparent but less important than in the neighbouring zone of The Maritime Alps; here it concerns surviving endemic species proceeding from an old native preglacial or interglacial element.These characters are to be found more in the northern areas of Queyras, Embrunais and Briançonnais, regions which have an incontestable relationship with our district.     

Utilité de la TEP au 18FDG dans l’épilepsie. Méthodes et indications

Positron emission tomography (PET) using ¹⁸fluorodeoxyglucose (¹⁸FDG) is currently used in presurgical work-up for drug-resistant partial epilepsies in children as in adults, in addition to MRI. Recent cameras with less than 5 mm spatial resolution allow to obtain thin slices (about 2 mm thickness) in 3D planes. ¹⁸FDG is intravenously injected at the mean dose of 3 MBq/kg of body weight in interictal and resting state, in a quiet, dimly lit environment and careful monitoring for head movements and ictal events. In children, sedation may be necessary. Image acquisition starts 30 min after injection and ended 15 to 20 min later. Semiquantitative analysis is visually assessed in clinical practice using colour scales. PET sensibility is improved by superimposition of metabolic imaging on MRI. Statistical analysis with SPM may be useful but comparison with health subjects database is required. In medial temporal lobe epilepsy associated with hippocampal sclerosis, hypometabolism ipsilateral to the epileptogenic focus is found in 70 to 90% of the cases and is predictive of surgical outcome. In other types of temporal and extratemporal epilepsy with negative MRI, focal hypometabolism can be detected, allowing identification of minor gyral abnormalities corresponding to focal cortical dysplasias. In such MRI negative cases, PET findings may improve surgical outcome.     

Azote et phosphore chez un crustacé macroplanctonique, Meganyctiphanes norvegica (M. Sars) (Euphausiacea): Excrétion minérale et constitution

Ammonia and phosphate excretion by the Mediterranean euphausiid Meganyctiphanes norvegica (M. Sars) (mean individual dry weight, 60 mg) has been measured for one year. Experiments were conducted at 13°C on single, freshly caught animals maintained in unfiltered sea water. Possible influence of these experimental procedures upon values obtained are discussed. Phytoplankton re-uptake and bacterial activity proved insignificant, because of the short duration of the experiments (4–38 h). NH₄ and PO₄ excretion rates are higher shortly after collection and then decrease, reaching a steady level after 8 h for NH₄, but continuously decreasing during the 38 h of the longer experiment in the c case of PO₄. It is considered that earlier higher values are likely to be more representative of in situ rates despite possible ‘stress’ effects, because they are close to those of moderately fed animals kept in captivity; more stable values observed after 8–12 h are close to those of starved animals. Nevertheless, lower stabilized values are best used when investigating seasonal variations. Excretion rates are low (0.07 to 0.11 μg-at.NH₄-N.mg^?1.day^?1, and 0.009 to 0.010 μ-at.PO₄-P mg^?1.day^?1) in summer, autumn and early winter. They rise sharply from January–February (0.12 μg-at.NH₄-N.mg^?1.day^?1 and 0.015 μg-at.PO₄-P.mg^?.day^?1) to peak spring values (0.25 μg-at.NH₄-N.mg^?1.day^?1 and 0.026 μg-at. PO₄-P.mg^?1.day^?1). The significance of inorganic excretion with regard to total (inorganic + organic) excretion is discussed. The nitrogen and phosphorus content of the animals were simultaneously measured and amount, respectively, to 9.5 and 0.8% of body dry weight (mean yearly value). Based on inorganic excretion only, the mean values of turnover are 66 days for nitrogen (61–92 days from May to February, 28–32 days in March–April) and 16 days for phosphorus (12–22 days with limited seasonal variation). Mean N/P ratio by atoms for excretion amounts to 9.1 after 8–12 h (it increases afterwards due to continual decrease in PO₄ excretion) but there are significant seasonal variations. The mean N/P ratio by atoms for the animals is 27.4; it is lower (22.4) between March and August, and higher (29.2) from September to February. With a view to investigating the change in the N/P ratio in the chain prey → predator → excretion, which allows calculation of growth efficiency factor (k₂) and hence secondary production, the nitrogen and phosphorus of the stomach contents of the animals were measured. Due to unknown bias (possibly a terrestrial origin of food particles, or loss of phosphorus during conservation of samples), the results were disappointing (N/P by atoms = 69, instead of a value necessarily ranging between 9.1 and 27.4), and did not allow calculation of k₂.     

Malladaites nov. gen. et Spinammatoceras (Hammatoceratidae,Ammonitina) de l'Aalénien de la zone subbétique,Sud de l'Espagne

The aim of this paper is to remark some morphologicaldifferences among the type-species of the genus ZurcheriaDouvillé and those species attributed to this genuf by Buckman & Brasil: the group of H. pugnaxVacek for which Schindewolf (1964) defined the genus Spinammatoceras, and the group of H. pertinaxVacek for which we propose Malladaites gen. nov.; new species of both genera are described. The stratigraphical range of these species is established in the Betic Cordillera.     

Pinéale et troisième oeil de Lacerta vivipara (J.), au cours de la vie embryonnaire et postnatale

Résumé Par la technique de Falck et Hillarp, nous avons étudié la localisation des monoamines indoliques et catéchniques épiphysaires durant la vie pré- et postnatale, chez Lacerta vivipara. A partir du stade 36 de l'embryogenèse, le traitement par les vapeurs de paraformaldéhyde induit en U.V. une fluorescence jaune, labile, dans l'épithélium épiphysaire dont la localisation est étudiée en fonction de la différenciation épiphysaire. L'analyse microspectrofluorimétrique des fluorophores jaunes permet de garantir, à tous les stades de la vie, un stockage de 5-HT et peut-être de 5-HTP, dans les cellules de type photorécepteur rudimentaire sécrétoire. Chez l'embryon, la confrontation des recherches histochimiques et ultrastructurale montre que les cellules «interstitielles» de type épendymaire (= «cellules de soutien») jouent un rôle dans le captage des acides aminés, dont les précurseurs de la sérotonine.Grâce à la technique de culture des embryons, en chambre noire, l'application de traitements pharmacologiques renseigne sur les modalités d'incorporation, et de stockage des dérivés indoliques. Le problème des systèmes enzymatiques impliqués dans la biosynthèse et le catabolisme de la sérotonine est discuté chez l'embryon.La fluorescence verte des fibres nerveuses pinéalopètes n'apparaît qu'au stade 39. L'analyse microspectrofluorimétrique des fluorophores verts, chez l'adulte, montre que le neurotransmetteur de ces fibres est la noradrénaline. L'apparition de la sérotonine et de ses rythmes éventuels ne dépendent donc pas de l'innervation adrénergique, aux jeunes stades de la vie embryonnaire.Dans les conditions normales et expérimentales, les monoamines (5-HTP, 5-HT et catécholamines) ne peuvent pas être mises en évidence dans l'oeil pariétal embryonnaire.

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Monoamines in the pineal organ and the parietal eye of Lacerta vivipara A fluorescence microscopic and microspectrofluorometric study

Summary The distribution of monoamines (indole- and catecholamines) was studied in the pre- and postnatal pineal organ of the lizard Lacerta vivipara (J.) using fluorescence histochemistry. After formaldehyde treatment, a yellow (U.V.-labile) fluorescence first appears at stage 36 in the parenchyma. The distribution of this fluorescence is considered with regard to cellular differentiation. Microspectrofluorometric analysis of the yellow fluorophores shows a storage of 5-HT, and possibly 5-HTP, in secretory rudimentary photoreceptors throughout life.The fluorescence histochemistry and electron microscopy of the embryonic pineal organ indicates that the interstitial cells of the ependymal type play a role in the uptake of tryptophan and 5-HTP (precursors of serotonin).Dark chamber culture of embryos was used to clarify the incorporation and storage of indole compounds. The presence of enzymatic systems, involved in the metabolism of indoleamines is discussed.From stage 39 onwards a green fluorescence can be demonstrated in sympathetic nerve fibres running in the pineal capsule. Microspectrofluorometric analysis of the green fluorophores in the adult showed noradrénaline to be the normal neurotransmitter. Evidently the appearance of 5-HT during embryonic life does not depend on the adrenergic innervation of the pineal organ.In normal and experimental series, monoamines could not be demonstrated in the embryonic pariétal eye.

Que le Dr. Björklund (Institute of Anatomy and Histology, University of Lund, Lund) trouve ici l'expression de notre profonde reconnaissance, pour avoir accepté de nous conseiller dans l'application de la technique microspectrofluorimétrique et dans la correction des courbes.Ce travail doit également à la collaboration technique de Mme. Benay, et à Frl. Vaihinger pour la réalisation des schémas. Nous remercions également la firme Beckman (BRD) qui nous a autorisé à modifier l'un de ses schémas, concernant le microspectrophotomètre MS 1206, la firme Leitz (BRD) qui nous a procuré une lampe à tungstène calibrée et les Laboratoires CIBA, PFIZER-CLIN et ROCHE (France) qui nous ont gracieusement fourni des drogues.Avec l'aide de la Deutsche Forschungsgemeinschaft.     

Ultrastructure de la glande de la spermathèque chez Phosphuga atrata L. (Coleoptera Silphidae)

Résumé Chez les Silphes et en particulier chez Phosphuga atrata, la glande de la spermathèque présente une structure particulière liée à la présence d'une intima cuticulaire tapissant la lumière de la glande. Elle comporte trois types cellulaires: les cellules sécrétrices, les cellules de l'épithélium sous-cuticulaire et les cellules-manchons. Les cellules sécrétrices de grande taille contiennent une invagination de la membrane cytoplasmique formant une «vacuole» extracellulaire bordée de microvillosités. Dans cette vacuole plonge l'extrémité, différenciée en ampoule poreuse, d'un canalicule de nature cuticulaire, qui véhicule la sécrétion jusqu'à la lumière de la glande. Le canalicule est élaboré par une cellule-manchon qui l'accompagne sur toute sa longueur sauf à son extrémité intravacuolaire.Ce type de glande, qui se retrouve chez de nombreux Insectes, y assurant des fonctions diverses (sécrétion odorifique, sécrétion de défense, sécrétion spermale, etc.), est susceptible de nombreuses variations.

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Ultrastructure of the spermathecal accessory gland in Phosphuga atrata L. (coleoptera: silphidae)

Summary The spermathecal accessory gland in the female of Phosphuga atrata (Silphidae), exhibits a special structure which is due to the presence of a cuticular intima lining the lumen. The wall of the gland shows three cellular types: the secretory cells, the epithelial cells and the ductule carrying cells. Each large secretory cell contains a cavity formed by an invagination of the cytoplasmic membrane and lined by many microvilli. The secretory cell is connected with a cuticular ductule ending in the cavity of the glandular cell, in a porous organelle. This ductule, which carries the secretory material to the lumen, is surrounded by the ductule carrying cell.This type of integumentary gland is very common in insects, where it assumes various functions (attraction, defense, conservation of sperm, etc.) and its morphology varies considerably.