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.     

Place de l’embolisation percutanée de la varicocèle dans le traitement de l’infertilité

Objectives

To describe percutaneous embolization of varicocele and to evaluate the effect on fertility disorders.

Materials and methods

One hundred nineteen patients, aged 11 to 48 years, underwent percutaneous embolization for varicocele indicated by a fertility disorder in 23% of cases. Correction of the varicocele and resolution of associated pain, improvement of testicular trophicity and the effect on fertility were studied and a review of the literature was performed.

Results

Percutaneous embolization was performed using neuroleptanalgesia on an outpatient basis. The technique combined venous sclerotherapy and placement of coils in the gonadal vein. The technique was successful in 95% of cases and one complication was observed. At 3 months, the varicocele and related pain had resolved in 98% of treated patients. According to previous reports in the literature, the relations between varicocele and fertility disorders are still unclear, but improvement of fertility (semen quality and conception rates) after varicocele repair has been established.

Conclusion

Although the consequences of varicocele on fertility have not been fully elucidated, treatment of varicocele appears to be beneficial. Percutaneous embolization of varicocele is a safe and effective alternative to surgery. This technique, based on a urological and radiological consensus, is the first-line treatment for varicocele in our institution.     

Biologie comparée des interactions entre les macrophages et Trypanosoma cruzi,Leishmania spp. et Toxoplasma gondii

Macrophages have a central role in the immune system by eliminating a lot of pathogens. Nevertheless, they are often infected by pathogenic microorganisms in particular parasitic protozoa. They thus play the role of host cell by harbouring the intracellular survival and multiplication of these pathogens. Various mechanisms (receptors/ligands interactions, enzymes…) are involved in recognition and adhesion steps. When suitably activated, they become effector cells and they can control infection at least partially through the production of reactive oxygen derivatives. But parasitic protozoa can escape these defence mechanisms. In addition, macrophages are also antigen presenting cells and they are inductor cells of the immune response. Once again, parasitic protozoa interfere with these functions and induce chronic infections. Biology of Trypanosoma cruzi, Leishmania spp. and Toxoplasma gondii will be briefly reviewed to illustrate these various aspects of cellular parasitism.     

Préhistoire et art rupestre dans le nord de l’Uruguay. De nouveaux programmes d’étude,de conservation et de valorisation

Since a few years, the study of prehistoric Uruguay and of its symbolical expression, rockart, has become a new subject of interest. Important programs of prospection, researches, protection and valorization of sites have been conducted, especially in the north of the country and contribute to the knowledge of an archeological heritage of an exceptional quality and a great density, that was until now unknown. Thanks to the international scientific cooperation and exchange program “ECOS-Sud”, the Department of Prehistory of the natural history national Museum of France (Paris) and the department of archeology of the Faculty of Human Sciences and Education of the Republic University in Uruguay (Montevideo), an important scientific and technical partnership have been set up. It reinforces and diversifies the existent links between our institutions and more generally between France and numerous countries of South America.     

Testostérone et contrôle central de l’érection

Testosterone orchestrates the perinatal organization and activation of cerebral and spinal neuronal structures involved in the expression of male sexual behaviour in adults. The present review briefly describes testosterone effects in the regulation of sexual motivation and erection, as well as the genetic models developed to date in order to unravel its central mechanisms of action.     

Un cas de leishmaniose féline disséminée dans le sud de la France

We report a case of disseminated feline leishmaniasis in a FIV-seropositive 14-year-old male cat (Felis catus) living in the Alpes-Maritimes (south of France). The cat presented with erythematous ulcerated papules on the head and withers, and with an ulcerated proliferative lesion on the left pinnae. The condition was diagnosed, along with a squamous cell carcinoma of the pinnae, after histopathological examination of the cutaneous lesions. Total remission of the cutaneous lesions was obtained after oral administration of 100 mg of allopurinol once a day for four months. Necropsic samples revealed that the parasite was still present in the organism after six months of treatment. This case discusses of the cat sensibility to the leishmaniasis pathology and of his potential ability of being a reservoir host.     

Production primaire dans les eaux de surface de la Méditerranée occidentale. Calcul de la production journalière

We have found a relationship between the net absorption of carbon at time t divided by the net absorption of carbon in 24 h (A_N(t)/A_N(24)) and the incubation duration after sunrise, in surface waters of the western Mediterranean sea. This ratio is quite similar whatever the sample location, the sample depth and the 24-h net-absorption level. Considering this result, we have established a correction factor which may be used to convert primary production rates obtained from incubation durations ≤ 24 h to daily rates (24 h dawn-to-dawn).     

Développementin vitro de la lignée germinale foetale mâle chez le rat, la souris et l’homme

The key role of the foetal germ cell line in the reproductive capacity of the adult has been known for a long time. More recently, the observed increase in male reproductive disorders such as the decline of sperm count and quality and the increased incidence of testicular cancer has been postulated to be due to alterations of foetal and neonatal testicular development in response to increasing environmental pollution. However, few tools are available to study foetal and neonatal germ cell line development and the effects of physiological or toxic substances on this process. The authors have developed an organ culture system in which foetal or neonatal testis is grown on a filter floating on a synthetic medium free of serum, hormones or biological factors. This study, using rats and mice, first compared the long-term morphological and functional development of Sertoli and germ cells in thisin vivo system. In rats, these cells developed normally over a period of two weeksin vitro. Fewer cells were produced thanin vivo, but a similar level of differentiated function was observed. Germ cells, which are difficult to maintainin vitro, resumed mitosis after a quiescent period, at the same time asin vivo. Similar results were obtained with mouse fetuses, but this model was less efficient. This culture model can be used to study post-natal development of the germ cell lineage in testes derived from foetuses on the last day of foetal life and invalidated for P63, that do not survive after birth. This gene was found to be involved in the regulation of germ apoptosis which resumes after birth in the mouse. Lastly, this model applied to the human species (from 6 to 12 weeks of gestation) showed that testicular architecture and germ cells can be maintained for 4 days with better efficiency at younger stages than at older stages. p]In conclusion, testicular architecture and intercellular communications are sufficiently preserved to sustain gametogenesisin vitro with no added factors. This method is potentially useful to study the effects of various factors, particularly xenobiotics.     

Lutte biologique et intégrée en vergers de pommiers,poiriers et abricotiers

Résumé La lutte biologique contre les organismes nuisibles aux vergers évolue par étape vers une Protection intégrée. Dans cette optique, les recherches se développent en France sur les points suivants: effets indésirables des pesticides sur l'entomofaune auxiliaire, r?le d'abri-refuge pour l'entomofaune autochtone joué par l'environnement végétal des vergers, diversification des procédés de lutte, mise au point de méthodes plus sélectives, sélection de variétés résistantes ou moins sensibles aux attaques de plusieurs organismes nuisibles, amélioration des méthodes de surveillance des vergers pour la prévision des risques de dégats, lutte raisonnée contre les maladies cryptogamiques. La mise au point de programmes de lutte intégrée dépend essentiellement des possibilités de lutte disponibles contre les ennemis-clés. Dans les vergers de pommiers et de poiriers fran?ais, les ennemis-clés appartiennent à groupes d'arthropodes: Carpocapse (Cydia pomonella L.), Tordeuses de la pelure, Aphides, Psylle du poirier (Psylla pyri L.) Acariens phytophages et aussi à trois maladies fongiques: Tavelure du pommier (Venturia inaequalis Cke.) Wint., O?dium du pommier (Podosphaera leucotricha Ell. et Ev.), Tavelure du poirier (Venturia pirina (Bref.) Aderh. Les méthodes de lutte sélective sont passées en revue: régulateurs de croissance des insectes, lutte biologique par lachers de parasites et de prédateurs insecticide microbiologique, lutte par confusion avec les phéromones sexuelles. L'application de certaines d'entre elles dépend des possibilités de production industrielles d'agents biologique ou biotechnique. Les principaux éléments ayant contribué à une application pratique des programmes de lutte raisonnée et de lutte intégrée ont été: l'amélioration des connaissances biologiques et de la nuisibilité des organismes phytophages, ainsi que des méthodes de surveillance et de prévision permettant l'utilisation des seuils de tolérance économique l'aménagement de la lutte chimique contre le Carpocapse en vergers de pommiers, la démonstration de la bonne efficacité des prédateurs du Psylle du poirier, spécialement desAnthocoris. La lutte raisonnée, appliquée sur plusieurs milliers d'hectares de vergers de pommiers et de poiriers en France, a permis de réduire de plus de 50% le nombre de traitements avec un bon niveau économique de protection. Dans les vergers d'abricotiers, les maladies parasitaires, principalement l'Enroulement chlorotique causé par un mycoplasme, représentent les problèmes les plus importants. Des essais sont en cours pour parvenir à une lutte raisonnée contre la Petite mineuse (Anarsia lineatella Zell.) et le puceronHyalopterus pruni Geoffr. qui est l'agent de dissémination de la Sharka (maladie due à un virus de type I.L.A.R.).      

Relation entre aphides et fourmis dans la production et la récolte du miellat sur oranger

Résumé La fréquence des gouttelettes de miellat excrétées par Toxoptera aurantii (Boyer de F.) augmente en la présence de Tapinoma simrothi Krausse., mais le phénomène est seulement important quand les aphides sont familiarisés avec la visite des fourmis. En présence d'ouvrières pourvoyeuses âgées, le nombre de gouttelettes de miellat excrétées par une colonie d'aphides est multiplié par 4,9. Les meilleures performances sont obtenues avec les larves, qui défèquent plus vite que les adultes. Les jeunes ouvrières âgées de moins de deux semaines et isolées juste avant la naissance, sont capables d'augmenter la production de gouttelettes, et ceci sans apprentissage. Mais l'effet est plutôt faible. Dans tous les cas, le nombre de sollicitations pour la nourriture est plus élevé que le nombre des gouttelettes excrétées. Habituellement, les fourmis collectent le miellat directement sur les aphides. Néanmoins, le miellat restant sur les feuilles peut être ramassé, mais cette récolte n'est pas très importante.

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Summary The frequency of honeydew droplets excreted by Toxoptera aurantii (Boyer de F.) increases in the presence of Tapinoma simrothi Krausse., but the phenomenon is only important when aphids are familiarized with ant-attendance. In presence of old foraging workers, the number of honeydew droplets excreted by an aphid colony is multiplied by 4.9. The best performances are obtained with larvae, which defecate faster than adults. Young workers less than two weeks old and isolated just before birth, are able to increase the droplets production, and this without apprenticeship. But the effect is rather slight. In all cases, the number of food sollicitations is higher than the number of excreted droplets. Usually, ants collect honeydew directly on aphids. Nevertheless, honeydew remaining on leaves can be picked up, but this gathering is not very important.

     

Hypoglycémie spontanée et insuffisance rénale chronique.

Although glucose intolerance occurs as a consequence of chronic renal failure, improvement of a diabetic state by deterioration of renal function is a well known phenomenon. Recently occasional cases of spontaneous hypoglycemia in patients with chronic renal failure have been reported; two such cases and the results of metabolic studies are described in this paper. Pituitary, thyroid and adrenal function appeared to be normal. The results of an oral glucose tolerance test were normal; an appropriate insulin response was demonstrated in one patient, and a slightly elevated basal insulin value with a delayed insulin response to oral administration of glucose was demonstrated in the other. An insulin tolerance test did not support the hypothesis of increased insulin sensitivity as a factor, and the growth hormone response to hypoglycemia was normal. An intravenous glucagon test caused a subnormal increase in plasma glucose concentration, and the intravenous administration of tolbutamide produced hypoglycemia without an increase insulin sensitivity as a factor, and the growth hormone response to hypoglycemia was normal. An intravenous glucagon test caused a subnormal increase in plasma glucose concnetration, and the intravenous administration of tolbutamide produced hypoglycemia without an increase in insulin values. The plasma alanine concentration was low and the proinsulin/insulin ratio was increased. The origin of this hypoglycemia is not clear but is probably multifactorial. However, low hepatic glycogen stores and inadequate gluconeogenesis due to substrate deficiency seem to be involved.     

L'effet de β-mercaptoéthanol et de l'urée sur la structure du phragmoplaste

Résumé Les fibrilles constitutives du phragmoplaste sont de nature protéique. L'action du-mercaptoéthanol permet de conclure que ces protéines sont liées par des ponts S-S. En présence d'urée, la structure du phragmoplaste est détruite, ce qui indique l'existence de liaisons hydrogènes.

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Zusammenfassung Unsere Arbeit führt zu folgenden Resultaten: 1. Die im Phragmoplast befindliche Faserstruktur besitzt einen Eiweißstoffcharakter. 2. Der Effekt des-Merkaptoäthanols gestattet die Annahme, daß die Proteine mit S-S-Brücken verbunden sind. 3. Bei Anwesenheit von Harnstoff wird die Phragmoplaststruktur zerstört, was für das Vorhandensein von H-Brücken spricht.

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Boursière de la Fondation Rockefeller     

Biogéographie et spéciation des Odonates de l’île de la Réunion

Du fait de l’histoire géologique des Mascareignes et des trajectoires cycloniques dans le sud-ouest de l’océan Indien, l’affinité de la faune odonatologique de la Réunion est essentiellement mauricienne. L’étude de la distribution des Odonates en fonction des différents écosystèmes aquatiques de l’île montre que: 1. Les espèces indigènes ayant une vaste répartition géographique se rencontrent essentiellement dans les écosystèmes ouverts de basse et moyenne altitude (de 0 à 800 m d’altitude). Ces écosystèmes peuvent héberger jusqu’à 13 espèces et possèdent les plus fortes densités odonatologiques. 2. La faune odonatologique de la Réunion se distingue de celle des autres îles de la sous-région malgache par la présence de deux espèces continentales cantonnées à des altitudes supérieures à 1000 m. 3. Les espèces endémiques fréquentent surtout les écosystèmes forestiers. Ces écosystèmes ne présentent au plus que cinq espèces de la faune odonatologique de l’île. En définitive, il apparaît donc que la spéciation des Odonates à la Réunion ne se fait pas dans les écosystèmes diversifiés comportant des espèces à large répartition géographique, mais dans un ensemble d’écosystèmes marginaux à faible diversité odonatologique.