Purification de l'alcool deshydrogénase de tomate par chromatographie d'affinité

Tomato alcohol dehydrogenase has been purified 99-fold by affinity chromatography on Blue Sepharose CL-6B with 37% yield. The enzyme so obtained is homogenous in polyacrylamide gel electrophoresis. By adding 20% glycerol to the extraction and purification buffers, an enzyme is obtained which is stable for several months at 4°. The molecular weight values determined by gel filtration (Sephadex G 200) and polyacrylamide gradient gel electrophoresis on one hand and by polyacrylamide gel electrophoresis in sodium dodecyl sulfate on the other, show that the enzyme exists in dimeric form.     

Analyse biostratigraphique et paléontologique de l'Albien marin d'Estremadura (Portugal)

The marine Albain from Estremadura is splited up into four Orbitolinidae zones, adjusted to biostratigraphic scales from mesogean province: zone with Orbitolina (Mesorbitolina) minuta (lower to middle Albian); zone with Neorbitolinopsis conulus (base of upper Albian); zone with Orbitolina (Orbitolina) concava (top of upper Albian) and zone with Orbitolina (Orbitolina) duranddelgai (Vraconian). The vertical extension of the main fossils is replaced in the framework of these zones. The most interesting species for biostratigraphy, paleoecology or taxinomy are summarily described.     

Structure cristalline d'une deuxième forme de mélézitose monohydrate. Effet de l'environnement sur la géométrie d'un oligosaccharide

Melezitose [O-α-d-glucopyranosyl-(1→3)-β-d-fructofuranosyl α-d-glucopyranoside] monohydrate crystallizes in two polymorphic forms (I and II). The structure of form II, studied by X-ray crystallography, shows an orthorhombic cell having a 7.135 (4), b 15.362 (8), c 19.134 (8) Å, space group P2₁2₁2₁, and Z 4. The structure, solved by direct methods, was refined to a final value of R 0.045. The molecule of form II seems to be more constrained by its crystalline environment than that of form I. These constraints imply not only little variations in glycosidic bonds, but also a change of conformation for the furanose ring, and a perceptible deformation of the sucrose pyranose ring. This study gives an example of estimation of oligosaccharide molecular-flexibility.     

Scolécodontes,assemblage et appareil de vers annelidespolychetes errantes de l'aptien de la région d'Agadir,Maroc

From the Aptian scolecodonts inventory of the Agadir area one jaw apparatus and one joining of polychetes are reconstructed. One is the elementary species Schistomeringos expectatusSzaniawski & Gazdzicki, 1978, the oldest representative of the multielementary family Dorvilleidae Chamberlin 1919. The other is a representative of either the multielementary families Atraktoprionidae Kielan Jaworowska 1966 emend. Kozur, 1970 or Arabellidae Hartman 1944. This joining is considered as an hypothesis since all the necessary criteria, defined by H. Szaniawski & A. Gazdzicki 1978, are not all present.     

Caractéristiques sérologiques des antigènes HLA-A,B et C.

Human leukocyte antigens (HLA) are transmembrane bicatenar glycoproteins; their heavy chain is coded by chromosome 6 and carries allotypic determinants. These molecules are present in nearly every cell, tissue and biologic fluid. Their congenital absence from fibroblasts is associated with progeria, while their absence from lymphocytes is associated with immunodeficiency. HLA antigens are usually studied microlymphocytotoxicity tests. The numerous cross-reactions encountered make the interpretation of results quite difficult. To clearly understand these reactions a complex-complex model is mandatory. The antigen, the HLA molecule, is complex since it carries many antigenic determinants; some of them are private ("subtypic"), while others are public ("subtypic"). Anti-HLA antibodies are also complex since they are heterogeneous, reacting with variable affinity with different antigenic determinants. The in vitro cross-reactions represent a partial explanation for varying cross-immunogenicity in vivo.     

Cycles embryonnaires et sécrétion de la cuticule chez l'embryon de blatte, Blabera craniifer

Cuticle deposition has been studied with the electron microscope in cockroach embryos (Blabera craniifer) during normal incubation in situ and in culture in vitro, in the absence or presence of inokosterone (a phytoecdysone).Two cuticles are deposited successively during embryonic life, respectively between stages 11 and 17, and stage 21 and 24 hr after hatching. The occurrence of two embryonic cycles is thus demonstrated, the first ending at stage 17 without exuviation since there is no old cuticle to be shed, the second one at hatching.In embryos explanted at stage 17 and cultured in vitro, the formation of cuticle 2 occurred at the same rate as in situ. The addition of inokosterone (50 μg/ml) to the medium resulted in the early onset of cuticle deposition (in 3 days as compared with 15 days in situ) in legs previously cut at the base of the tarsus. Cuticle 2 was completed within 9 days after explantation (as compared with about 20 days elapsing in the normal embryo between stage 17 and the completion of cuticle 2). Unsectioned appendages were insensitive to the hormone.Regeneration of sectioned legs, which occurred normally n vitro in non-treated embryos, was completely inhibited in the presence of inokosterone, presumably because the hormone caused early immobilization of cells through accelerated cuticle formation.Results suggest that embryonic cycles are controlled by the same hormonal mechanism as larval cycles.     

Modalités d'installation et d'évolutiondes Harpocératinés (ammonitina A) au Domérien inférieur dans le sud-Ouest de l'Europe (France,Portugal)

In Mesogea, the Harpoceratinae were known asearly as the end of the Lower Carixian. They later reached the sub-boreal province through the Alps or the South of the Iberic Peninsula. The analysis of the populations met in four crosssections of the Lower Domerian (Causses, Mâconnais, Franche-Comté, Portugal) showed the settling down of the Protogrammoceras isseli group that set up and evoluated in a similar way in the different areas in spite of a certain originality.On the one hand, it gave the cladogenetic groupP. monestieri-nitescens by diminution of the ribing density, strengthening of the ribs and simplification of the suture.On the other hand, a slower evolution give, near the end of the Stokesi zone, P. normanianum in the Paris Basin and in Burgundy, and P. lusitanicum in Portugal. At the same time, a new invader, P. celebratum, arrived in the Causses (and in Portugal).     

Scintigraphie de perfusion cérébrale positionnelle : résultats physiologiques et applications cliniques

To assess the impact of standing on brain perfusion, 125 brain perfusion scans in the upright and supine position were performed, including 108 patients. Perfusion values were compared using a relative quantitative approach and a segmentation of vascular territories with the help of an atlas of brain perfusion. We found a change in the distribution of the perfusion in favor of the vertebro-basilar system in the upright position. We discuss the case of a patient whose symptoms could be explained with the help of the comparison of brain perfusion scans in the upright and supine position. Atheromatous and post-dissection stenosis and their influence on perfusion are also discussed.     

Caractérisation de souches cultivées d'un nouveau champignon comestible: Stropharia rugoso-annulata. II. Anatomie,développement mycélien et fructification

To establish a performing production strategy for the edible mushroom Stropharia rugoso-annulata, investigations on anatomy and physiological characteristics of the basidiomycete were carried out. Scanning electron microscopy analysis of Stropharia strains revealed no significant morphological differences. Spore germination was only obtained in the presence of growing mycelium. On the basis of the influence of temperature on the growth rate of Stropharia strains, three groups were defined without relation to phenotypic classification. Moreover, every strain exhibited a higher growth rate at 25 °C, and residual growth was observed above 35 °C The pH of the medium did not affect mycelium development. Regardless of the initial pH value, after 2 weeks of mycelium growth, the pH was established at a value close to 3.5. However, no acidic compounds were detected in this medium. A preliminary cultivation trial indicated that carpophore formation is strongly affected by spawn run time.     

Action de l'ecdystérone sur l'apolysis et l'ecdysis de divers crustacés isopodes

Ecdysterone acts differently according to the period of the moulting cycle when it is applied. In period C it induces apolysis, while at the beginning of apolysis it delays ecdysis. Experiments show that the exoskeleton cannot be rejected in the presence of ecdysterone. The possibility of stopping exuviation or ecdysis with ecdysterone seems to prove that this phenomenon is controlled by a particular factor called the factor of exuviation or the ecdysis factor. Ecdysterone would control only the release of this specific factor but would not prevent its action.     

Ultrastructures nouvelles et non identifiées dans les calcaires de l'oxfordien supérieur de la champagne berrichonne

A scanning microscope study of the upper Oxfordian foliated limestones of the western part of the Berry region of France has revealed new, but unidentified, well-conserved organisms, which are described and illustrated in this publication.     

Activité cytokinine de dérivés acylés,alkylés,acyl-alkylés de l'adénine et d'isost`eres azotés de la γ,γ-diméthylallyladénine

The cytokinin activities of various 6-acylaminopurines, 6-alkylaminopurines, 6-acylamino-9-benzyl-purines as well as a series of isosteric-nitrogen derivatives of N⁶-(γ, γ-dimethylallyl)adenine (I⁶Ade) have been tested using the tobacco pith and the pea bud bioassays. The interactions between active, slightly active and inactive compounds have been studied with the last assay. Acylation decreases the biological activity; e.g., N⁶-benzoyl and N⁶-furoyladenines are less active than Na⁶-benzyladenine and kinetin. Substitution at the 9-position reduces (tobacco-pith assay) or suppresses (pea-bud assay) the phytohormonal activity of otherwise active 6-acylaminopurines. In isosteric derivatives, maximum activity occurs when the side chain has the same length as in 1⁶Ade. After the analysis of interactions between more or less active compounds, it is suggested that the differences in cytokinin activity could be related to unequal affinities for a hypothetical receptor site.     

Testostérone circulante et cancer de la prostate. Revue de données récentes

In vitro andin vivo studies show that androgens stimulate prostate cancer. However, evidence from epidemiological studies of an association between circulating levels of androgens and prostate cancer risk has been inconsistent, but most studies have likely been undersized given that the association may be relatively weak. We review prospective studies on the association of serum levels of free and total testosterone, the principal androgen in circulation with risk of prostate cancer. No significant association between total or free testosterone and risk of prostate cancer was found in studies that together included 1,525 cases of prostate cancer and 4,349 controls. No support was found for the hypothesis that high levels of circulating testosterone within a physiological range stimulate development and growth of prostate cancer. Intraprostatic androgen metabolism may still be of importance for prostate cancer development.     

Caractères morphologiques et propriétés physiologiques de souches d'Aspergillus flavus,productrices ou non d'aflatoxine B1

Comparison between about 80 strains of Aspergillus flavus, belonging to the series flavus and oryzae, obtained from international collections but also isolated from French or African substrates revealed the following observations: Cultural and morphological characteristics of toxicogenic and atoxicogenic strains of A. flavus are similar. However, the former produce a diffusible yellow pigment in 83% of isolates. The two groups of conidiospores have the same resistance to UV irradiation (254 nm, 5 and 10 min). All the strains are equally sensitive to 4 antifungal antibiotics: nystatine, ketoconazole, clotrimazole and amphotericine. A difference was seen in the capacity to produce enzymes as -galactosidase, -galactosidase and - glucosidase, implicated in the glucid metabolism. The specific hydrolytic activity has been confirmed by the characterization of a large amount of -galactosidase and by a diauxic growth on glucose medium supplemented by lactose.Possible relationship between these characters and aflatoxin B₁ production by A. flavus strains is discussed.