Modalités de l'inhibition de la croissance et de la synthèse des acides nucléiques des plantules de blé par l'acide abscissique

The growth of wheat seedlings (Triticum sativum) is inhibited by abscisic acid (ABA). The inhibition increases with the concentration of ABA (from 10^-6M to 5 × 10^-5M) and is stronger in the case of coleoptiles and first leaves than in roots. In contrast, naphthaleneacetic acid (ANA), at 10^-5M, exerts its greatest inhibitory effect on the roots. The inhibitory effect of ABA on coleoptiles can be partially overcome by kinetin and to a much smaller degree by gibberellic acid. Neither of these two compounds, at 10^-5M, had any effect on the ABA-induced inhibition of root growth. The RNA and DNA contents per plant organ are considerably reduced after treatment of the seedlings with ABA, particularly in the coleoptiles and the first leaves. The incorporation of uracil-2-¹⁴C and uridine T (G) into RNA of treated seedlings is reduced in the case of coleoptiles and first leaves, but considerably enhanced in roots. The mechanism of the action of ABA is discussed in the light of these results.     

Le site des Vachons : étude de la partie gravettienne de la collection de l’IPH

This article firstly summarizes the process of study of an old collection, which had not been considered since the excavations at the site Les Vachons, started before 1914 and completed around 1939. The studied collection of J. Coiffard, both excavator and inventor of this site, includes four-fifths of the artefacts because, in 1940, he donated approximately one fifth to the Eyzies Museum. For his part, J. Bouyssonie who participated in the excavations for 3 years gave the major part of his own collection to the Archaeological Society of Charentes Angouleme where its condition makes it difficult to analyze. Despite these restrictions, based on statistical comparisons with counts many other sites, I came to the conclusion that the top three layers of Les Vachons are a confirmation of the Gravettian model, developed by B. Bosselin and F. Djindjian through their factor analysis. This model seems much better suited to the stratigraphy of Les Vachons, than all assumptions made by previous analysts in their attempt to bring the industries from the three layers in what remains from the Peyrony model.     

Évolution des caractères technologiques et typologiques des industries lithiques dans la stratigraphie de la Caune de l'Arago

The thick Quaternary deposits of the Caune de l’Arago (Pyrénées-Orientales, France) are dated to between 690 000 and 90 000 years old. At least fifteen different archeostratigraphical units have been identified within these deposits, each corresponding to distinct prehistoric occupations. Numerous stone tools made from several different rock types, have been discovered in each unit. The tools present specific characteristics concerning the choice of raw materials, the typology, and the technology used to produce them. Morpho-technological study of the different components of the assemblage contributes to a better understanding of the debitage methods used for their production. Each raw material is considered individually in order to ascertain its origin in the environment, its typological role and the technology applied during its exploitation. Defining production systems leads to the characterisation of the assemblages from each unit. When compared, they reveal common elements, as well as differences, suggesting evolutionary trends. Some observations are also made concerning the extent to which changing uses of the site may have influenced the general morphology of each assemblage, therefore taking into account exterior factors. Analysis of this rich stone tool assemblage helps to situate the Caune de l’Arago industry within the larger evolutionary context of the Lower Paleolithic in Mediterranean Europe.     

Évaluation de la réponse au traitement des lymphomes : rôle de la TEP-FDG

Positron emission tomography (PET) with FDG has a prominent role in the staging of lymphoma, including Hodgkin's lymphoma and aggressive non Hodgkin's lymphoma. Its value in the assessment of end therapy response is also well established, especially with residual masses on CT scan to differentiate between fibrosis (scar) and active tissue. International experts with the International Harmonization Project of lymphoma have proposed a set of interpretation criteria. Finally, FDG-PET looks very promising in the early response assessment; it has shown to be predictive of chemosensitivity and of therapy response. Interpretation criteria have been improved and proposed. FDG-PET usefulness is being evaluated in national and international research protocols where therapeutic strategies are based on FDG-PET results.     

Stimulation par la lumière rouge lointain de la synthèse de la δ-aminolévulinate déshydratase des cotylédons de radis

Stimulation of de novo synthesis of δ-aminolevulinate dehydralasc of radishes grown under far-red light .
Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish ( Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes.     

Renouvellement des protéines et effet spécifique de la kinétine sur des cultures de cellules de Tabac

Determination and fractionation of proteins of tobacco cell suspensions requireing kinetin for cell division. — Cell suspensions either in stationary phase without kinetin in the medium or dividing in the presence of this factor have been compared. It was found a) that the specific rates of protein synthesis and protein degradation were not changed by the addition of kinetin during the early period of growth. A quantitative change ocurred only after the first generation period, b) Soluble proteins of these cells were mapped by polyacrylamide gel electrophoresis. The observed protein patterns were very similar as well as the patterns or radioactivity incorporated into the same proteins during the incubation period of the cells. However, a small number of specific discrepancies appeared in the pattern of cells growing in the presence of kinetin matched to the patterns of stationary cells. At least one specific difference in these patterns could be observed before the first cell division occurred.     

Organisation spatiale des fibres de collagène de la plaque basale des écailles des Téléostéens

Spatial organization of collagenous fibrils in the basal plate of elasmoid scales has been studied in 36 species among 24 teleost families which include the whole order. Angle measurements of the various fibrillary directions were performed on fracture surfaces in frozen scales observed with the scanning electron microscope. The organization of the basal plate is arrayed in three basic patterns. The most remarkable one, found in the more "primitive" families, is a double twisted plywood with a left-handed rotation of the fibrillary directions. The remaining two are an orthogonal plywood, more or less regular, and an "intermediate" plywood, both found among the more "advanced" families. However, an orthogonal plywood is also observed in some "primitive" families, for example in Clupeidae and Salmonidae. We tentatively interpret the left-handed double twisted plywood of the lower teleosteans and of Amiidae as a synapomorphy in relation to the primitive condition of an actinopterygian lineage. On the other hand, within the teleosts, we would consider that the double twisted plywood is a plesiomorphic condition and that the orthogonal plywood is an apomorphy among the "advanced" teleosts families.     

Activité oxydasique de l''oxydoréductase de la xanthine, spécifique de la classe des mammifères

In every species other than mammals xanthine oxidoreductase behaves as a dehydrogenase, never as an oxidase. In three mammalian species, the enzyme acts intracellularly as a dehydrogenase, but its class-specific ambivalence allows its extracellular conversion into an oxidase.

Résumé

En dehors de la classe des Mammifères, l'oxydoréductase de la xanthine ne se comporte jamais comme une oxydase. Chez les Mammifères, une ambivalence de la molécule permet l'expression d'une activité déshydrogénasique (NAD) dans la cellule, et d'une activité oxydasique en dehors de la cellule.     

Évolution de la composante lipidique de la membrane plasmique des spermatozoïdes durant la maturation épididymaire

One aspect of mammalian post-testicular sperm maturation is the progressive change in their plasma membrane lipid composition. These modifications in lipids allow sperm cells to fuse with oocytes during fertilization. A significant share of these sperm lipid changes occurs during their descent through the epididymal tubule. It then continues within the female genital tract during the capacitation process, an essential prerequisite for acrosomic reaction and hence fertilization. This review presents what is known concerning the sperm plasma membrane lipid changes during epididymal maturation in various mammalian models. In the first section, after a brief presentation of the classic eukaryotic cell plasma membrane lipid organization, the emphasis is on the particularities of sperm plasma membrane lipids. The second section presents the different changes occurring in the three major classes of lipids (i.e. phospholipids, sterols and fatty acids) during the sperm’s epididymal descent. The final section briefly describes the mechanisms by which these lipid changes might happen in the epididymal lumen environment. The role played by lipid-rich vesicles secreted by the epididymal epithelium via apocrine secretory processes is highlighted.     

Influence des inflorescences de la plante hôte (Vigna unguiculata) sur la levée de la diapause reproductrice de Bruchidius atrolineatus

Bruchidius atrolineatus (Pic) présente en zone sahélienne une diapause reproductrice durant la saison sèche et une partie de la saison des pluies. Les femelles diapausantes ne produisent pas de vitellogénine et le germarium des ovarioles est seul développé. Chez les mâles la spermatogenèse est très ralentie et les glandes annexes sont inactives. Lorsque les insectes diapausants sont placés en présence d'inflorescences de Vigna unguiculata Walp, leurs organes reproducteurs deviennent fonctionnels après un temps de latence de 15 à 20 jours. Il n'y a par contre aucune levée de la diapause chez des bruches placées en présence de gousses sèches de V. unguiculata dans une atmosphère saturée. Des informations sensorielles issues des pièces florales ou (et) des facteurs nutritionnels sans doute liés a la consommation de nectar semblent être à l'origine de cette levée de la diapause. Le pollen fort peu consommé n'a par contre aucun rôle. Cette régulation du cycle reproducteur de B. atrolineatus par les inflorescences de V. unguiculata permet l'émission des oeufs dès que les gousses commencent à se former à la fin de la saison des pluies.

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Summary Bruchidius atrolineatus (Pic) is a widely distributed bruchid in the Sahelian zone which shows a reproductive diapause during the dry season and part of the rainy season. Diapausing females do not produce vitellogenin and their ovaries are reduced to the germarium. Spermatogenesis is very much reduced and male accessory glands are inactive. When these insects were placed in the presence of inflorescences of Vigna unguiculata which were renewed daily, the reproductive diapause of both males and females was interrupted after 15–20 days. Vitellogenesis occurred in the females and spermatogenesis increased in the males whilst their accessory glands became functional. When diapausing bruchids, found in stores of on V. unguiculata seeds during the dry season, were placed near the host plant's inflorescences, diapause was also terminated. In all cases, diapause was not interrupted when the insects were offered dry pods of V. unguiculata in a water-saturated atmosphere. The pollen, which is hardly eaten by this bruchid, did not seem to stimulate termination of diapause. Sensory stimulations derived from the flowers or/and nutritional factors may be the cause of the development of the reproductive organs. After termination of the diapause the males showed normal sexual activity whereas female fecundity was rather low, at least in our experimental conditions. This type of reproductive regulation allows this sahelian bruchid to resume its sexual activity when the host plant's flowers appear in the field at the end of the rainy season. Then the beetles lay their eggs on the pods as soon as the pods are developed.

     

Cancer de la prostate : les niveaux de preuve des biomarqueurs de la détection précoce

As part of an overall review on the role of PSA and other emerging biomarkers in the detection, diagnosis and treatment of prostate cancer, we present here a part of a review of the literature made by the working group Biologie de la Prostate (AFU, CNBH, SFBC, SFMN) on the use of PSA and other biomarkers in the early detection of prostate cancer with an assessment of the level of evidence.     

Action de la kinétine sur la croissance et la teneur en chlorophylles des racines

Lens roots form chlorophylls in well-developed chloroplasts when they are cultivated in continuous light. Chlorophyll accumulation was increased when kinetin (10^?4M) was added for a short time (24 h) of treatment. For a long time (72 h), the increase of chlorophyll content was reduced when roots were cultivated in light and with kinetin. When the roots were transferred from light to dark, chlorophyll content was decreased. This reduction was inhibited when roots were treated with kintin. From these present result it was supposed that kinetin acts on the catabolism and the anabolism of chlorophyll. The necessity of kinetin for chloroplast from amyloplast maturation and differentiation was discussed.     

Biosynthèse des acides gras polyinsaturés des glycérolipides de la feuille d'olivier

The patterns of incorporation of [l-¹⁴C]-acetate into the glycerolipid fatty acids of leaves of olive plants ( Olea europea L. cv. Chétoui) suggested a specific pathway for a-linolenic acid biosynthesis. The results confirmed the involvement of phosphati-dylcholine in galactolipid metabolism, and seemed to exclude the role of that mole-cule as a substrate for desaturation of oleate to linoleate. The two oleate desaturation steps seemed to occur rapidly on the diacylgalactosylglycerol molecule for biosynthesis of galactolipid linolenate. In addition, the results indicated a slow sequen-tial desaturation of oleate to linolenate via linoleate in the phospholipid molecules (phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol).     

Influence de l'intensité et de la longueur d'onde de la lumière sur le rendement des radicaux libres dans les semences de tomate et de carotte

Influence of light intensity and wavelength on the yield of free radicals in seeds of tomato and carrot.
Seeds of tomato ( Lycopersicum esculentum L. cv. Gribovsky-1180) and carrot ( Daucus carota L. cv. Santanet) were irradiated by continuous light of different wavelengths (white, blue, green, red, far-red and He-Ne laser) and different power density. Free radical output was measured using Electron Spin Resonance spectra (ESR). The dependence of the content of free radicals (FR) on the light power density was established. The yield of FR in the seeds irradiated with monochromatic light of the same power density was inversely proportional to the wavelength. The ESR spectra showed maximum absolute number of FR for white light. Successive irradiations gave cumulative effects on the output of free radicals in both directions: increase by the action of white light and decrease by the action of red and far-red light. The contact of irradiated seeds with steam decreased the amount of FR.     

Codification des regles de la nomenclature des groupements vegetaux

Sans résumé