Étude complémentaire de la structure de trois galactoxyloglucanes (amyloïdes) de graines

D-Galacto-D-xylo-D-glucans (amyloids) from Balsamina, Tropaeolum, and Tamarindus seeds behave in a similar manner in the presence of various glycosidase preparations: slow depolymerization by enzymes from several germinated or non-germinated seeds, and hydrolysis into monosaccharides and oligosaccharides by commercial cellulase and hemicellulase preparations from fungi. A purified cellulase from Penicillium notatum gave a dialyzable fraction almost exclusively composed of α-D-xylopyranosyl-(1→6)-D-glucose residues and a nondialyzable fraction composed of chains of β-D-(1→4)[withsome (1→3)]-glucopyranosyl residues; β-D-galacto-pyranosyl-(1→2)-α-D-xylosyl groups are linked to some of the β-D-glucosyl residues at 0-6. The presence of (1→3)-linkages in the D-glucan chain of the Balsamina was verified by methylation and sequential periodate oxidation-borohydride reduction; the distribution of the substituents on the D-glucan chain is not regular. The main D-glucan backbone, where the β-D-glucosyl residues are partly linked at 0-6 to β-D-galactosyl-(1→2)-D-xylosyl groups, is linked to D-glucan chains where almost all the D-glucose units are linked at 0-6 by one α-D-xylosyl group. The presence of 3,6-di-O-methyl-D-glucose after permethylation and hydrolysis suggests that the xyloglucan chains are linked to 0-2 of the D-glucosyl units of the galactoxyloglucan backbone.     

Indications de la recherche des anticorps anti-spermatozoïdes

The clinical significance of antisperm antibodies (ASA) is highly controversial. A significant percentage of infertile men and women present immunity to spermatozoa, suggesting that ASA may interfere with the fertilizing capacity. ASA can act negatively on sperm parameters, sperm-cervical mucus interaction, gamete fusion and possibly also on the first step of embryonic development. ASA are present in approximately 2.8% to 26% of the male population and 0.2% to 1.6% of women. The pathogenesis of immunity to spermatozoa had not been fully elucidated: breakdown of normal protective mechanisms, i.e. blood-testis barrier, or epithelial barrier in women, and other mechanisms of immunological sperm tolerance, such as regulation of suppressor T lymphocytes. The indication for antisperm antibody testing is based on clinical and laboratory findings of infertile patients. In men, indictions for ASA testing include a history of genital disease, surgery for genital abnormalities, vasectomy, obstruction or injuries of the male genital tract, infection of accessory glands, long-standing infertility, alteration of semen parameters (agglutination, motility), mucus penetration, and reduced fertilizing capacity in IVF. In many cases, no etiological cause of autoimmunity is found and a genetic predisposition has been suggested. A majority of women do not develop antisperm antibodies, despite repeated contact with spermatozoa during their sexual life. Upper genital tract infection is the main cause of isoimmunization in females, although sexual practices, endometriosis, surgery for cervical neoplasia, recurrent spontaneous abortion and long-term infertility may also be involved. Sperm-cervical mucus impairment is the most obvious effect of immunization in women associated with IVF failure. Autoantibodies are frequently associated with antisperm antibodies. One of the consequences of the success of ICSI has been a decreased research effort to further the understanding of the origin and relevance of antisperm antibodies and specific antibody-antigen interactions. A better understanding of the natural history of immunological infertility would be useful for patient conseiling and to develop the most effective, efficient and safest management strategies. Such data could also be useful for the development of new tests and immunological methods of male contraception.     

Perspectives de l’analyse de la mobilité des spermatozoïdes

Several studies have shown a good correlation between sperm motility and fertility though the microscopic evaluation of the percentage of motile sperm is highly subjective by nature. Therefore in the last decade, various objectives methods have been proposed to overcome this problem. Two types of methods were developed: The methods based on the analysis of images obtained by microphotography, microcinematography and microvideography and the global, undirect methods based on physical principles. Several systems based on video and image analysis (Computer Aided Sperm Analysis, CASA) have been developed and are used in numerous laboratories of reproductive biology. CASA technology offers the possibility to analyse some characteristics of sperm motion which are related to the fertilization potential and to develop new parameters related to some important aspects of sperm behavior such as hyperactivation. However, there is a large amount of interactions between the operator and the CASA machine. CASA instruments are not “ready-to-use” robots: the reliability of CASA depends largely on the expertise and training of the user and the application of standardized procedures and quality control schemes. By contrast, there is only minimal interaction between the operator and the Sperm Quality Anlyser which is a new device measuring and index of sperm motility highly correlated to the concentration of progressively motile sperm. The device uses light passed through a small sample of semen introduced in a capillary tube to detect variations in optical density that result from moving particles. The reproducibility of the measurements is excellent, the device is easy to use and this is a potentially useful tool for field-work studies. Further investigations of this device in the managment of male infertility is warranted. Finally, both types of objectives approaches are complementary to the conventional analysis of sperm motility and they will not replace it. Standardized procedures have been proposed by the World Health Organization for the subjective evaluation of sperm motility. Such procedures are very useful to reduce significantly the intra- and interlaboratory variations but internal and external quality controls schemes indicate that they are not sufficient to achieve acceptable levels of variation and regular quality controls followed by the definition and the application of corrective procedures are required.     

Nouveaux genres de Squaliformes (Chondrichthyes) du Paléogène des Landes (Sud-Ouest de la France)

Résumé  Parmi les nombreux squaliformes récoltés dans le Lutétien des Landes (SO de la France), deux genres et espèces nouveaux ont été reconnus:Squaliodalatias weltoni n. gen. n. sp. etAngoumeius paradoxus n. gen. n. sp. La morphologie dentaire du premier permet de le rapprocher des Dalatiidae. Les relations phylétiques du second taxon sont pour 1’instant moins claires, en raison de sa denture supérieure inhabituelle pour un Dalatiiforme aussi évolué au niveau de la denture inférieure. Ces taxa nouveaux viennent enrichir nos connaissances sur un groupe encore mal connu à l’état fossile en raison de son habitat bathyal ainsi que sur la mise en place et la radiation, encore trop peu documentée, des faunes profondes.      

Controle de la multiplication et de la polyploïdie des hepatocytes du rat

Résumé L'injection de substances irritantes de nature chimique variée perturbe les mécanismes qui contrÔlent la multiplication des hépatocytes du rat.Les très jeunes rats réagissent de faÇon intense et reproductible. 15 heures après l'injection il se produit une augmentation brève et intense du nombre des cellules entrant en phase S de sorte que les divisions cellulaires, qui normalement auraient été réparties sur les 30 ou 40 prochaines heures, débutent en l'espace de 2 heures seulement. La croissance hépatique a pris une importante avance qui est suivie par une période de diminution du nombre des mitoses due à une rétroaction inhibitrice.La réaction des rats plus âgés met en évidence un mécanisme inhibiteur permanent qui entraÎne une réponse moins intense et moins régulière.La production d'hépatocytes binucléés et polyploÏdes parait liée à ce mécanisme inhibiteur.La régularité et la sensibilité des réactions des très jeunes rats en fait un matériel de choix pour l'étude des mécanismes régulateurs de la croissance hépatique.

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Control of multiplication and polyploidy of rat hepatocytesA study of the perturbations of physiological regulation induced by injection of irritants

Summary The injection of irritating substances of various chemical nature disturbs the mechanisms regulating the multiplication of rat hepatocytes.The reaction of baby rats is intense and reproducible. It results, 15 hours after the injection, in an increase of the number of cells entering the S phase, so that practically all the divisions which would normally have been scattered over 36 hours are initiated within 2 hours. This burst of synchronized mitosis corresponding to a 36 hours advance in the hepatic growth is followed by a decrease of mitoses due to a feed-back inhibition.The reaction of older rats brings to evidence a permanent inhibitory mechanism that results in a less regular and intensive response.The production of binucleated and polyploÏd hepatocytes seems to be correlated to this inhibitory mechanism.The regularity and sensivity of the baby rat reactions make them a choice material for the study of hepatic growth.

     

Réponse des Larves de Perla burmeisteriana Claassen (Plecoptera) aux variations de la pression hydrostatique

In order to explain the reactions of larvae of P. burmeisteriana to an ecological change following the impoundment of a Man-made lake on River Bistritza (Roumania), we made some experiments on the responses of this species to variations of hydrostatic pressure. Experiments were carried out in the lake of Bicaz. Observations were direct, either by diving or by monitoring the situation visually from a submerged laboratory. Sets of 40 specimens were exposed to pressure of 1, 1.5 or 2 atmospheres. It was found that survival time of the larvae decreased as pressure increased. A temperature dependance of this phenomenon was stated. Pressure influences gaseous exchanges, by altering the rate of elimination of CO₂. This finally leads to hypercapnia. Je tiens à exprimer ici toute ma gratitude aux PROF. Dr. P. Jitariu, Membre Correspondant de l'Académie RSR, pour le privilège de me diriger vers l'étude écologo-physiologique et le Prof. Dr. L. De Conincl et le Dr. H. Dumont de l'Instituut voor Dierkunde de l'Université de Gand, où j'ai trouvé toute l'aide désirable pour pouvoir rendre définitif ce travail.      

Contribution à l'etude des thecamoebiens de la Province de Buenos Aires

Résumé La faune des Thécamoebiens fut étudiée dans deux étangs (La Brava et De los Padres) situe dans la Province de Buenos Aires (Argentina). Le nombre d'espèces trouvé en tout a été de 14, quelques-unes desquelles représentées par de différentes formae. Une nouvelle forma Centropyxis compressa (Cushman), forma brava n.f. a été trouvée et décrite, et une espèce de Pontigulasia a été proposée en nomenclatura aperta.

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Summary The Thecamoebiens of two lakes (La Brava and de los Padres) located in the Province of Buenos Aires (Argentina) were studied. The total number of species found is 14, several of them are represented by various formae. A new forma was found and described, namely Centropyxis compressa (Cushman), forma brava n.f. and one species of Pontigulasia was put in nomenclatura aperta.

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Departamento de Ciencias Biologicas, Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires     

Les effets de recristallisation sur la paroi des Involutinidae (Foraminifères) triasiques

The different types of recrystallization which can be observed in the Triassic involutinids should be considered in the taxonomic treatment of this foraminiferal family. If the diagenetic modifications of the test are neglected the same form could be placed into different suborders. Our inclusion of the genusTriasina Majzon in the Involutinidae proposed earlier on purely morphologic grounds, seems to be supported by the fact that the same types of recrystallization exist inTrocholina, Involutina undTriasina.     

Le dosage des séromuco?des dans la cardite rhumatismale: (Etude de 120 cas)

Seromucoid values were determined in 120 patients with rheumatic carditis, aged 5 to 20 years, who were in the acute, subacute or chronic phase of the disease. The following results were obtained: (1) Seromucoid values were elevated in all 32 of the acute cases and remained above normal as long as rheumatic activity was present. (2) Seromucoid values were unaffected by cortisone therapy, unlike the sedimentation rate and the level of C-reactive protein. (3) Greater values for seromucoid were found in severe cases.This study suggests that seromucoid determination is a useful method for following rheumatic activity and may be of value in assessing the severity of the disease.     

Action de l'acide gibbérellique (GA3) sur la photosynthèse,la respiration et la transpiration des limbes de seigle (Secale cereale L.)

Gibberellic acid GA₃ (50 ppm) decreases the photosynthetic rate and increases respiration rate of rye leaves (Secale cereale L., cv. Dankowskie Zlote). The effect of GA₃ on transpiration rate is not distinctly marked.     

Influence de la nature et de l'abondance des proies sur l'augmentation des effectifs de deux coccinelles prédatrices de la cochenille du manioc au Congo

Résumé Les variations d'abondance des 2 cochenillesPhenacoccus manihoti Matile-Ferrero etFerrisia virgata Cockerell et des 2 prédateurs CoccinellidaeHyperaspis senegalensis hottentotta Mulsant etExochomus flaviventris Mader sont étudiées dans une parcelle de manioc. La colonisation de cette dernière parE. flaviventris est précoce, en présence de faibles niveaux numériques des 2 proies, mais avec une dominance deF. virgata; celle d'H. s. hottentotta intervient un mois plus tard en relation semble-t-il avec la présence d'une population deP. manihoti abondante et jeune. Nos observations font ressortir une dynamique des populations propre à chaque espèce de coccinelle, conditionnée par l'abondance de l'une ou l'autre des proies, la structure des colonies de chaque cochenille et les conditions climatiques (température) qui interviennent en synergie. Ainsi, la réponse numérique deH. s. hottentotta, plus forte que celle d'E. flaviventris, semble en relation plus étroite avecP. manihoti. PourE. flaviventris il appara?t difficile de séparer ce qui revient à chaque espèce de cochenille:F. virgata joue sans doute un r?le important pour son implantation dans les champs, puis sa raréfaction, mais c'est probablementP. manihoti qui permet l'augmentation de ses effectifs.      

Apports de la palynologie a la connaissance du Pliocène du Roussillon (sud de la France)

The present study illustrates clearly how pollen analysis may be applied to stratigraphy from a botanical point of view. Within a chronologically reliable frame (Middle Pliocene for the marine deposits on the basis of Foraminifera record; two subzones for continental deposits on the basis of Mammals record: Hautimagne for Terrats fauna, Sète for Serrat-d'en-Vacquer fauna), palynology provides a good stratigraphical boundary: the extinction of the Taxodiaceae. In a remblayage area, it is established that a continental level is not necessarily younger than a marine one unless they are superposed. Many profiles are replaced according to the «progradation of the pliocene gulf of Roussillon. The boundary between marine and continental deposits cuts through the chronological line of the Taxodiaceae extinction. The flora investigated (93 taxa) is the first known for the Pliocene of this area. The extinction of the Taxodiaceae in southern France has a climatic cause: the setting in of a mediterranean rhythm (dry summers). This extinction is much older than the one which took place in Italy (Tiberian boundary) and in the Netherlands (Reuverian-Pretiglian boundary).     

Analyse multiparamétrique de la composition minérale des pollens d'une population de Bactris gasipaes (Arecaceae)

Bactris gasipaes Kunth is important both economically and as a food resource in several countries of tropical Africa. The profitability of cultivation can be increased by genetic amelioration of natural morphotypes. We observed that pollen characteristics influence the morphological and physiological features of the fruits. This prompted us to undertake a study based upon ten morphotypes from the Yurimaguas (Peru). We here complete the morphological and ultrastructural investigation of pollen, previously started by one of us, with an analysis of the elements with respect to the importance of the role they play in relation to pollen function. A determination of the 8 major elements, which corresponds to a precise analysis of the exine, was performed by micro-X-Ray diffraction analysis using an electron probe coupled with a scanning electron microscope. At the same time, the determination of calcium, magnesium and twelve oligo-elements by inductive coupled plasma spectrometry (ICP) provided a complete mineral analysis of the pollen. A comparison of the element patterns of the morphotypes, obtained by both was carried out through a number of numerical data reduction techniques (Factor analysis and clustering). This led us to suggest two classifications: (1) that of pollen based upon mineral elements (2) that of mineral elements based upon pollen and further to look for possible multiple correlations between elements and pollens.

From the results obtained the following conclusions may be drawn: (1) the sequence of elements in descending order of concentration in the exine is an indication of the functional integrity of pollen and depends upon conservation and storage; (2) further, this sequence is a good fertility criterion; (3) variations in oligo-element concentrations in one cultivar allows infraspecific groups to be distinguished. This multiparametric approach also allow the location of an unknown pollen sample of Bactris gasipaes in the population under investigation.

Bactris gasipaes Kunth, ressource économique et alimentaire importante pour plusieurs pays d'Amérique tropicale, fait actuellement l'étude de recherches intensives. La rentabilité de sa culture pourra être augmentée par l'amélioration génétique des morphotypes naturels. Les caractéristiques du pollen ayant montré leur influence sur les caractères morphologiques et physiologiques des fruits, nous avons entrepris une étude sur la base de dix morphotypes originaires de Yurimaguas, au Pérou. Nous avons compléte l'étude morphologique et ultra-structurale du pollen, réalisée précédemment par l'un de nous, par une analyse des éléments minéraux qu'il contient en raison de l'importance qu'ils revêtent dans les différentes fonctions du pollen. Ainsi, la teneur en huit éléments minéraux majeurs, qui correspond à une analyse ponctuelle de l'exine, a été déterminée par micro-analyse X par sonde électronique couplée au microscope à balayage. De même, le dosage du calcium, du magnésium et de douze oligoéléments, effectué par spectométrie à plasma à couplage inductif (ICP), correspond à l'analyse minérale globale du pollen. L'étude comparative des profils en éléments minéraux des différents morphotypes, obtenue par chacune de ces deux méthodes d'analyse, a été réalisée par différentes techniques d'analyse mathématique de réduction de données multidimensionnelles (analyse factorielle et classifications automatiques). Nous avons ainsi pu proposer une double classification: (1) celle des pollens sur la base des éléments minéraux, (2) celle des éléments minéraux sur la base des pollens, puis rechercher les corrélations multiples éléments minéraux/pollens. Les résultats obtenus ont montré: (1) que la séquence des éléments minéraux dans l'ordre de concentration décroissante dans l'exine est caractéristique de l'intégrité fonctionnelle du pollen et dépend de ses conditions de conservation et de stockage, (2) que çette même séquence constitue un bon marqueur de la fertilité de pollen, (3) que la variabilité entre les concentrations en oligoéléments observée entre les différents cultivars permet la constitution d'un marqueur chimiotaxonomique satisfaisant pour discriminer sur la base du pollen les groupes d'individus au sein même de l'espèce végétale considérée. Cette approche multiparamétrique offre également la possibilité de positionner a priori un nouvel échantillon de pollen de Bactris par rapport à la population initiale étudiée.     

Modélisation de l'impact des mollusques cultivés sur la biomasse phytoplanctonique de l'étang de Thau (France)

A model coupling a 2D transport equation and a simple model of the nitrogen cycling was developed for the Thau lagoon (France). The model took into account the wind forcing on the hydrodynamism, the effect of the temperature on the biological processes, the input of the watershed area, the light dependence of the pelagic primary production and the prédation of the phytoplankton by the cultivated filter feeders. The model ran under two steady-state situations of wind with constant temperature and light values corresponding to spring weather conditions. Simulations showed that the biological flows were very sensitive to the wind. The budget of the nitrogen flows were computed for the three areas devoted to the filter feeder cultivation and the results highlighted the impact of cultivated oysters as a source of nutrients and an important nitrogen flow through the predation of phytoplankton.     

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.     

Consanguinité et effectifs de la population des communes

Summary In a previous paper, we have used the density of the population as a sort of measure of the unknown size n of the isolates in Dahlberg's model, and shown an inverse relation between the coefficient of inbreeding and the density of the arrondissements. In the present paper, as the considered communes are smaller territorial subdivisions than arrondissements, we used, instead of the density, the population size of the communes. The results are even more eloquent as before: the inbreeding coefficients are large when the observed population size is small; the relative importance of second cousin marriages (233) versus cousin marriages (222) is greater in the latest period considered. The basic data have been collected for each commune in Belgium by Centre National de Radiobiologie et de Génétique.     

Le zooplancton de la baie de Sh?diac (Nouveau-Brunswick)

Analyses of boreal zooplankton of Shediac Bay demonstrate theabundance of copepods (81%) and meroplankters (18%). Whetherexclusively pelagic or not, 67 species are mentioned for thefirst time in this Northumberland Strait area, out of 76 recordedwithin 23 higher taxa. The fluctuations were observed from Mayto November and pointed out the dominance of such copepods asAcartia tonsa, A. clausi, Oithona similis and Centropages hamatusin relation with temperature, salinity and food distributions. ¹Adresse actuelle: Station marine de Tul?ar, B.P. 141, Universit?de Madagascar, (R?p. Malgache)