Ultrastructure des disques de patte de drosophile cultivésin vitro. Evagination,sécrétion de la cuticule nymphale et apolysis

Summary Ultrastructural observations were made on imaginal leg discs ofDrosophila cultured in vitro in Mandaron's medium M in the presence of - or -ecdysone.During evagination of discs in vitro the tight epidermal folds of the disc flatten out progressively and the cells change their shape.As the discs evaginate, the pupal cuticle is secreted at the apex of the cells: it comprises a three-layered cuticulin, an epicuticle and a thick endocuticle. Secretion of pupal cuticle always starts by the appearance of dense deposits at the apex of microvilli. Only the latter apparently participate in the construction of the three successive layers of the pupal cuticle.During disc development an abundant rough endoplasmic reticulum is formed. Nuclei and nucleoli become progressively enlarged. At the same time, the nucleus, initially located near the base of the cell, moves closer to the apical cell surface. Microtubules become fragmented as soon as evagination begins and are reorientated parallel to the cell surface (i.e. parallel to the new long axis of the cell) at the end of evagination.

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Ce travail a été réalisé avec l'aide du CNRS (Action thématique programmée) «Différenciation cellulaire», contrat n^o A 6554324.

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Ce mémoire représente une partie de la thèse qui sera soutenue par l'auteur devant l'Université Scientifique et Médicale de Grenoble.     

Synthèse d'ARN dans le chondriome au cours de la spermiogenèse chez la Drosophile

Résumé L'incorporation d'uridine-³H dans l'ARN nucléaire et dans l'ARN mitochondrial est détectée à l'aide de l'autoradiographie à haute résolution au cours de la spermiogenèse chez la Drosophile.Le marquage apparaît simultanément sur le noyau et sur le chondriome jusqu'au début de la condensation de la chromatine. Le nebenkern, qui caractérise un des premiers stades de la spermiogenèse, est le territoire cellulaire le plus radioactif. La synthèse de l'ARN nucléaire cesse au cours de la condensation de la chromatine. Pendant ce temps, le marquage des dérivés mitochondriaux se poursuit; il persiste jusqu'à leur complète transformation en paracristal. Ces observations mettent en évidence une synthèse autonome d'ARN par les mitochondries à la fin de la spermiogenèse.

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Autonomous mitochondrial RNA synthesis during spermiogenesis in Drosophila

Summary The incorporation of ³H-uridine into nuclear and mitochondrial RNA has been followed by electron microscope autoradiography during spermiogenesis in Drosophila.Nuclei and mitochondria are simultaneously labeled up to the beginning of the chromatin condensation. The nebenkern, characteristic of the first stages of spermiogenesis, is the most radioactive cellular component. During chromatin condensation, nuclear RNA synthesis ceases, but mitochondrial derivatives continue to be significantly labeled up to their complete paracrystalline transformation. These data show an autonomous RNA synthesis by mitochondria at the end of spermiogenesis.

Ce travail a bénéficié de l'aide du C.N.R.S. (E.R.A. 174), de la D.R.M.E. (contrat 70/414) et du C.E.A. (participation à l'achat de molécules marquées).     

Etude comparée expérimentale de l'électrophorèse des protéines et des électrolytes chez des chiens

A higher survival rate and faster wound healing in dogs on a controlled and well-balanced diet have been demonstrated when compared with those not under dietetic control.Electrophoretic comparison of serum proteins was carried out in two groups of dogs. The first was on a well-controlled and well-balanced diet; the second group received an uncontrolled diet. The dogs in Group 2 had a lower concentration of total proteins, and globulins, especially gamma-globulins, were diminished; however, the serum albumin was higher. The albumin/globulin ratio was 0.93 in Group 1 and 2.07 in Group 2.Serum electrolyte levels also showed some slight differences. Sodium and potassium levels were higher in well-nourished dogs, while chloride and bicarbonates were slightly lower.     

Les protéines phosphatases et protéines kinases des plantes supérieures

The recent gain in knowledge concerning enzymes involved in signal transduction pathways is a direct consequence of the considerable advances made in molecular biology. Protein kinases and protein phosphatases, the two major enzymes implicated in post-translational modifications, have been studied in particular. The number of characterized plant genes and/or cDNAs encoding these enzymes is increasing everyday. Since 1991, 26 genes and cDNAs coding for plant protein phosphatases have been isolated and characterized. The huge number of protein kinases (estimated at several thousands) makes it impossible to give an exhaustive list of the genes already identified, but a classification of these enzymes, based on phylogenetic criteria, allows us to appreciate the range of functions this protein family may play in plants.     

Nature et évolution des protéines basiques au cours de la spermiogenèse chez Pleurodeles waltlii Michah., Amphibien urodèle

Résumé La spermatogenèse du Triton Pleurodeles waltlii a été étudiée au moyen de techniques cytochimiques et autoradiographiques. Les phénomènes spermiogénétiques ont été divisés en six stades caractéristiques en fonction de la forme du noyau et de l'évolution des structures extranucléaires: cou et filament de soutien de la queue.Les protéines basiques du noyau du spermatozoïde sont du type protamine, tandis que certaines structures extranucléaires se montrent riches en protéines basiques libres. Les transitions depuis les histones de type somatique présentes dans les jeunes spermatides I et II jusqu'aux protamines du spermatozoïde mûr par l'intermédiaire d'histones enrichies en arginine, montrent des phénomènes intéressants.La première transition depuis les histones de type somatique riches en lysine vers les histones enrichies en arginine est progressive. Elle se produit au cours des stades III et IV. Un gradient apparaît dans le noyau depuis la base vers le sommet. Au même moment, les protéines basiques libres apparaissent dans le cou.La perte des histones enrichies en arginine puis leur substitution par des protamines au niveau des noyaux des spermatides V est beaucoup plus brutale, elle intéresse tout le noyau. Ce dernier montre de même une disparition complète des acides aminés soufrés. Au même moment, les protéines basiques apparaissent dans la queue, de même que des acides aminés soufrés.Toutes ces observations plaident en faveur d'une origine nucléaire possible de certains composants de ces structures extranucléaires originales et riches en protéines basiques libres.

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Nature and development of the basic proteins during the spermiogenesis in Pleurodeles waltlii michah., urodele amphibian

Summary The spermiogenesis of the newt Pleurodeles waltlii has been studied with cytochemical and autoradiographical methods. The process of spermiogenesis has been divided into six characteristic steps in relation with the nuclear shape and the evolution of the extranuclear structures: the neck and the supporting filament of the tail.The nuclear basic proteins of the spermatozoon are of protamine type while the well developed extra-nuclear structures show a free basic proteins rich content. The transition from early spermatids somatic type histone to the mature sperm protamine via arginine-rich histone and the appearance of the free basic proteins in the tail show different interesting features. The first transition from the somatic rich lysine histone to the arginine rich histone which occurs at the spermatid III and IV steps, is gradual. A gradient appears in the nuclei from the base to the apex. Concurrently the free basic proteins appear in the neck. The loss of the arginine rich histone and its substitution by protamine in the spermatid V is more sudden and affects all the nuclei without a gradient, the sulfhydryl group content of the nuclei also disappear. At the same time, the basic protein of the tail appear as well as the sulfhydryl group.All these results are discussed in view of the hypothetical nuclear origin of these very unusual extranuclear basic proteins.

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Equipe de Recherche associée au C.N.R.S. Cytologie Ultrastructurale No. 129.

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Avec la collaboration technique de Melle F. de Sallier Dupin et de M. B. Morille.     

Synthèse et étude R.M.N. de disaccharides et trisaccharides dans la série du l-rhamnose

Various di- and tri-saccharides containing l-rhamnose were synthesized by condensation of 2,3,4-tri-O-acetyl- or 2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl bromide with an unblocked glycopyranoside. The determination of the anomeric configuration of l-rhamnose saccharides by n.m.r. is difficult because structure has a greater effect on the spectra than does configuration. The α and β configurations and the position of the substitution may be assigned from the chemical shifts of H-5 and CH₃. In all the compounds having a β configuration, a shielding of the methyl group and a deshielding of the H-5 proton have been observed as compared to the compounds having an α configuration. The H-5 proton and the methyl group of peracetylated, (1→3)-linked α-l derivatives always resonate at higher fields than the corresponding protons of (1→6)-linked α-l derivatives.     

Synthèses et réductions de sucres fonctionnels mono et diinsaturés

Attempts to prepare 1,2:5,6 and 2,3:5,6 di-unsaturated sugars starting from 3,4,6-tri-O-acetyl-1,5-anhydro-1,2-dideo xy-d-arabino-hex-1-enitol or from ethyl 4,6-di-O-acetyl-1,5-anhydro-2,3-dideoxy-α-d-erythro-hex-2-enopyranoside led to 1,5-anhydro-1,2,6-trideoxy-l-threo-hex-5-enitol and its 3,4-diacetate. Hydrogenation and hydrogenolysis of the unsaturated chloro and fluoro derivatives afforded 1,5-anhydro-1,2,6-trideoxy-d-arabino-hexitol and ethyl 4-O-acetyl-2,3,6-trideoxy-α-d-erythro-hexopyranoside.     

Synthèse des méthyl-2,4,6-tridésoxy-4-trifluoroacétamido-l-hexopyranosides. Accès à de nouvelles anthracyclines

The four diastereoisomeric methyl 2,4,6-trideoxy-4-trifluoroacetamido-l-hexopyranosides have been synthesized. Coupling of the corresponding 1-O-acetyl-3-O-benzoyl-l-lyxo and 1-O-acetyl-3-O-p-nitrobenzoyl-l-arabino derivatives with daunomycinone in the presence of p-toluensulfonic acid as catalyst afforded two new anthracyclines.     

Synthèse de phosphoramidates de 2-désoxy-2-iodoglycosyles

Addition of iodazide to acetylated, benzylated, and methoxymethylated glycals yielded 2-deoxy-2-iodoglycosyl azides with 1,2-trans configuration. Stereoselectivity of the reaction favored the manno and talo configurations starting from d-glucal and d-galactal, respectively. With d-xylal derivatives, the stereoselectivity depended on the nature of the substituents. The Staudinger reaction of 2-deoxy-2-iodoglycosyl azides with trimethylphosphite led to the corresponding 2-deoxy-2-iodoglycosyl phosphoramidates in high yield.     

Les protéines des corps d'inclusion des baculovirus

La comparaison des protéines des polyèdres des Baculovirus deGalleria mellonella L.,Lymantria dispar L.,Autographa californica Speyer,Mamestra brassicae L.,Arctia caja L.,Bombyx mori L. etAntheraea pernyi Guer. en immunodiffusion montre qu'il existe entre elles une étroite parenté antigénique. Des différences entre ces protéines peuvent être mises en évidence à l'aide de sérums spécifiques obtenus dans des conditions particulières d'immunisation.     

Inhibiteurs anti-trypsine et activités protéolytiques des Albumines de graine de Vigna unguiculata

Summary The extracellular space of tentacles of Drosera capensis L. is divided into two compartments by cuticular material between cells of an endodermoid layer and by the nonporous cuticle of the stalk and neck. The distal compartment includes the mucilaginous secretion as well as the free space of the secretory cap, since the cuticle covering the cap is perforated by numerous 0.05–0.3 m pores. The proximal compartment includes xylem and the intercellular space of the stalk. The existence of the endodermoid partition is consistent with the observation that action potentials recorded extracellularly from the head may be positive-going while those recorded extracellularly from the stalk are negative-going. The partitioning is also consistent with the hypothesis previously proposed to explain why the amplitude of action potentials recorded from the mucilage varies as a function of the amplitude of the receptor potential.The living cells are united by plasmodesmata. Unusually abundant plasmodesmata were observed in the walls between endodermoid cells and neck cells, between neck cells and the next row of outer stalk cells, in the end walls connecting the outer stalk cells, and the end walls connecting the inner stalk cells: these strategically located plasmodesmata presumably permit the electrotonic spread of receptor potentials and action potentials between cells.     

Synthèse du méthyl-2-acétamido-2-désoxy-β-D-glucofuranoside et de dérivés

Methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside was prepared in excellent yield from methyl 2-benzamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside by alkaline hydrolysis, followed by selective N-acetylation. Treatment with 60% acetic acid at room temperature gave syrupy methyl 2-acetamido-2-deoxy-β-D-glucofuranoside, characterized by a crystalline tri-O-p-nitrobenzoyl derivative. The same treatment, at 100° gave methyl 2-acetamido-2-deoxy-β-D-glucopyranoside. In an alternative procedure, the selective N-acetylation was performed after acetic acid hydrolysis of methyl 2-amino-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside. Several derivatives of methyl 2-acetamido-2-deoxy-β-D-glucofuranoside were prepared and compared with the corresponding pyranosides. The furanoside structure was clearly demonstrated by mass spectrometry and periodate oxidation.     

Altérations de la spermiogenèse de Locusta migratoria migratorioïdes après implantation de corps allates et après irradiation

Résumé Une faible dose de rayonnement gamma appliquée à des larves de Locusta migratoria provoque des altérations de la spermiogenèse et entraine la stérilité des mâles. Ces résultats sont comparables à ceux obtenus après implantation des corps allates.Au niveau des organites cellulaires, les altérations morphologiques des spermatides sont semblables dans les deux cas: vacuolisation des mitochondries et transformation du Nebenkern, pycnoses nucléaires, multiplication centriolaire, invagination de la membrane plasmique. Certaines de ces altérations se manifestent tardivement, au moment de la fixation des spermatides sur les cellules pariétales. Celles-ci n'élaborent pas les matériaux de la coiffe des spermatodesmes: leur fonction physiologique est donc également perturbée.Le rapport entre cette altération physiologique et l'évolution anormale des spermatides est envisagé. Le mode d'action de l'hormone juvénile sur la gonade est également discuté.

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Alterations in spermiogenesis of Locusta migratoria migratorioïdes after corpora allata implantation and after irradiation

Summary Low doses of gamma-rays, given to larvae of Locusta migratoria, lead to alteration of spermiogenesis and male sterility. These results are similar to those which follow corpora allata implantation.At cellular level, morphological alterations in spermatids are the same in both treatments: mitochondrial vacuolization, nuclear pycnosis, centriole multiplication, plasmic membrane invagination. Some of these alterations reveal themselves late, at the time the spermatids fix on the parietal cells. These don't elaborate the substances of the spermatodesm's cap: their physiological functions are therefore also disturbed.The relationship beetween this physiological disturbance and abnormal evolution of spermatid are considered and the way in which juvenile hormone acts upon gonads is discussed.

     

Synthèse et greffage de polymères bioactifs sur des surfaces en titane pour favoriser l’ostéointégration

Titanium is widely used in orthopedic and dental implants for its excellent resistance to corrosion and its biocompatibility. In order to improve the long-term osteointegration of titanium, bioactive polymers bearing ionics groups such as sulfonates (sodium polysytrene sulfonate, polyNaSS) are grafted by a covalent way onto titanium surface. The surface is chemically modified and then bioactive polymers are grafted by radical polymerization. The chemical composition of grafted surfaces is given by ATR/FTIR and XPS which certified the presence of sulfonate groups at the surface of grafted titanium. Quantitative grafting of polyNaSS is determined by a colorimetric method and evaluated at 5 μg/cm².In vitro study is performed in order to see the effect of these bioactive polymers on the mineralization of human osteoblast (line MG63). After 28 days of cultured cells on grafted titanium surfaces and non-grafted ones, the amount of calcium onto surfaces is quantified. The results show that the mineralization of these cells is improved with the presence of polyNaSS. The amount of calcium is increased on grafted surfaces compared to non-grafted ones. Cell adhesion was evaluated. Cells were seeded onto grafted and non-grafted titanium and then subjected to detachment forces. The results show that the attachment of human osteoblasts-like cells is increased for grafted titanium with polyNaSS. A study on titanium surface grafted by polymers bearing ionics groups such as carboxylate and phosphate is in progress.     

Les synoviorthèses radio-isotopiques : synthèse des indications et des différents résultats rapportés dans la littérature

Radiosynoviorthesis is used for the local treatment of recurrent joint effusions and leads to synovial pannus necrosis after radionuclide administration. This procedure provides the opportunity to full recovery of normal synovium function after local corticosteroids and systemic modifying drugs failure.     

Etagement des algues et des invertébrés sessiles dans l'Archipel de Glénan

The Glénan Archipelago was investigated, from the surface to a depth of 60 m, byScuba diving. Four distinct communities (“peuplements”) have been determined that fit into the system of zonation defined by the Genoa Symposium (1957). The results are compared with observations made in the English Channel (Cabioch 1968) and in the Atlantic Ocean (Glemarec 1971). Since illumination depends upon the angle of the rocky face, photophilic species exhibit a maximum range when the rock surfaces are horizontal. The sublittoral zone is dominated by laminarians. They form two distinct communities with the animal and vegetal species they overshadow. The upper community is characterized byLaminaria digitata (Linné)Lamouroux (horizontal rocky face from 0 to 6 m; vertical rocky face from +0.5 to ?3 m). The lower cummunity, characterized byL. hyperborea (Gunner)Foslie has a greater vertical extension (horizontal: ?6 m to ?26 m; vertical: ?3 to ?30 m). The circalittoral zone is colonized by several animal species growing in a ramified manner: the upper community is characterized by Axinellidae (?30 m), the lower byDendrophyllia cornigera (Lamarck) (?55 to ?60 m). Upright algae disappear somewhere between ?40 and ?47 m.