Présence de Pleurothyrella knodi (Brachiopoda,Terebratulida dévoniens) en Guinée-bissau. Implications paléogéographiques

Pleurothyrella knodi, known only from Bolivia and Argentina, is recorded from Guinea-Bissau (West Africa). It represents a new and sure point of the faunistic Malvinokaffric Realm extension during the Early Devonian.     

Life style — An emergent concept in the sociomedical sciences

The concept of life style recently has gained prominence in sociomedical research; yet the term remains poorly defined. This paper traces the evolution of the life style concept from its origins in sociological and personality studies to its current use in reference to behavioral risk factors for disease. Particular attention is given to the changes in meaning that have taken place over the past few decades. Similarities between the notion of life style and concepts of cultural integration are noted, and the various uses of life style are categorized along an idealist-materialist continuum. Finally, the authors fault medicalized notions of life style for failing to acknowledge the importance of the context and meaning of health-related behavior.     

An experimental test of the effect of food and antioxidants on blue‐green eggshell coloration in mountain bluebirds Sialia currucoides

Evolutionary biologists have long debated the functional relevance of the ornamental traits that occur in many animal taxa, and yet, female ornaments have received relatively little attention compared to those produced by males. A greater understanding of these traits, particularly those that are unique to females, may shed light on the potential for sexual selection to shape female phenotypes. Recently, blue‐green eggshell colour, derived from the antioxidant pigment biliverdin, has been proposed as a candidate trait that advertises female quality to males in species of birds with biparental care. However, studies have been equivocal in their support for blue‐green eggshell colour being an informative signal, and correlations between eggshell colour and other female characteristics have been inconsistent. We conducted a supplementation experiment to test if improving the access of female birds to food resources and micronutrients, thereby improving their condition prior to egg laying, would intensify the blue‐green colouration of the eggs they laid. We provided mountain bluebirds Sialia currucoides with food and carotenoids during nest building and egg laying in two breeding seasons, and assessed both within‐ and among‐clutch variation in colour. Supplementation did not affect patterns of within‐clutch variation, but did result in differences in colour among clutches. Specifically, we found that food, but not carotenoids, resulted in higher colour saturation, and decreased the brightness of blue‐green eggshells. Although this trend was observed in both years, the effect was statistically significant only in one year. Our results suggest that food supplementation influences eggshell colour, but that conditions, such as weather and natural food availability, which can vary annually, may also determine how female birds allocate pigment to eggshells.     

Révision taxonomique du genre d'ammonite téthysien Simoceras et création d'un nouveau genre Volanoceras (Ammonitina,Simoceratidae)

The type-species of the genus SimocerasZittel isS. biruncinatum (Qu.). This genus includes the species-group biruncinatum (Qu.) — admirandum (Zitt.). The new genus Volanoceras is created for the volanense (Opp.) species-group which is excluded from the genus Simoceras.     

Genetic variation in progeny allocation in Trichogramma maidis

A considerable amount of work has been recently devoted to the study of progeny allocation strategies by insect parasitoids under different environmental constraints (see Waage, 1986, for a review). All these studies present each of the oviposition strategies (e.g. number of eggs laid per host, superparasitism) as a phenomenon which is progressively settled by natural selection during the course of generations. However, this optimal progeny allocation theory is conceivable only if the variation in wasp's biological traits involved are under a genetic control on which natural selection could act. We have decided therefore to look for a genetic variability in these traits in a Trichogramma maidis Pintureau & Voegelé (Hym.; Trichogrammatidae) population.Based on histological staining which allows to count the number of Trichogramma eggs deposited in each host (Ephestia kuehniella Zeller), we compared different wasp isofemale lines (i.e. families) each of which was submitted to different conditions (i.e. parasite/host ratios).The results show that the control of superparasitism seems to be genetically determined. This appears true both for the average number of eggs deposited in each host, and for the frequency distribution of wasp eggs among hosts.The evolutionary consequences of such results and their possible applications in order to improve the wasp's mass-rearing conditions are discussed.

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Résumé Récemment, de nombreux travaux ont été publiés dans le but de mieux comprendre les différentes stratégies de reproduction (i.e. répartition de la progéniture parmi les hôtes) présentées par les insectes parasitoides sous différentes contraintes environnementales (cf. Waage, 1986, pour une synthèse). L'ensemble de ces travaux considère chacune de ces stratégies (e.g. nombre d'ufs déposés par hôte, décision de superparasiter) comme un phénomène progressivement mis en place par la sélection naturelle au cours des générations. Ceci n'est cependant concevable que si les caractères biologiques en cause chez les parasites sont sous la dépendance d'une variation génétique sur laquelle la sélection naturelle peut agir.Les expériences présentées ici ont donc eu pour but de voir si ces caractères sont effectivement déterminés génétiquement dans une population de Trichogramma maidis Pintureau & Voegelé (Hym.; Trichogrammatidae).Grâce à l'utilisation d'une coloration histologique qui permet de compter le nombre d'ufs de trichogrammes déposés dans chaque hôte, différentes lignées isofemelles (i.e. familles) ont été comparées, et ce selon différentes conditions expérimentales correspondant à différentes valeurs du rapport nombre de femelles parasites sur nombre d'hôtes offerts.Les résultats obtenus motrent que le phénomène du superparasitisme semble être déterminé génétiquement. Ceci est constaté aussi bien au niveau du nombre moyen d'ufs de trichograme déposés par hôte, que dans les caractéristiques des distributions des ufs de parasites parmi les hôtes.Les conséquences évolutives de tels résultats, ainsi que leurs applications possibles dans le but d'améliorer les conditions d'élevage de masse de ces insectes, sont discutées.

     

Identification et localisation des fibres aminergiques dans léminence médiane de la Grenouille verte (Rana esculenta L.), par autoradio graphie au microscope électronique

Résumé Après injection de DL-noradrénaline tritiée et autoradiographie au microscope électronique, l'une des 5 catégories de fibres de l'éminence médiane se marque intensément. Ces fibres (type 1) contiennent de fins granules (800 à 1000 Å) et des vésicules synaptiques claires. La fixation de DL-noradrénaline tritiée permet de définir quelles sont les fibres aminergiques qui correspondent aux fibres fluorescentes mises en évidence par d'autres méthodes. Le rôle physiologique de ces terminaisons est discuté.

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Identification and localization of the aminergic fibres in the median eminence of the frog (Rana esculenta L.) by electron microscopic autoradiography

Summary After administration of DL-noradrenaline H³ and autoradiography on electron microscope, one of the 5 types of fibres which terminate at the median eminence is strongly labeled. The terminals of these fibres (type 1) contain fine granules (800 to 1000 Å) and clear synaptic vesicles. This fixation of DL-noradrenaline H³ demonstrates the aminergic fibres which are in the median eminence corresponding to the fluorescent fibres described by others. The physiological significance of these terminals is discussed.

Nous remercions Madame R. O. Clauss et Monsieur Cl. Chevalier pour leur excellente collaboration technique.