Expression in vitro du gène de l'aromatase dans les cellules testiculaires du rat

The ability of the male gonad to convert androgens into estrogens is well known ; the microsomal enzymatic complex involved in this transformation is named aromatase and is composed of a specific cytochrome P450 aromatase (P450arom) and a ubiquitous reductase. Using a highly specific RT-PCR method we have measured the amount of P450arom mRNA in purified Leydig and Sertoli cells prepared from 20, 40 and 70–80 day-old rats. The amount of P450arom mRNA in the Leydig cells is independent of age (40 × 10⁻³ attomoles/μg of total RNA); in contrast, in the immature rat Sertoli cells, after 5 days of culture the amount of P450arom mRNA is 20-fold lower when compared to that of 20-day-old rat Sertoli cells (71 × 10⁻³ attomoles/μg of total RNA). Nevertheless, irrespective of the age, the addition of either FSH or dbcAMP for 6 h increases the level of P450arom mRNA in the rat Sertoli cell preparations. Therefore, we evidenced that during testicular maturation not only the Leydig cells but also the Sertoli cells of the rat have the capacity to express the gene for cytochrome P450 aromatase.     

Contribution a l'étude de l'ontogenèse sensori-nerveuse du termiteCalotermes flavicollis Fab.

Summary The author studies the developpement of the neuro-sensorial organs on the legs ofCalotermes flavicollis Fab. He has found that the outline of the neuro-sensorial organs developing in the larvae of the first instar do not change their structure. After each molt the number of sensorial organs increases and in correlation with this the small sensorial nerves ramify and secondary nerfs branch off the primary nerfs. On the legs of the larvae of the forth and mainly on those of the fifth instar the number of sensorial organs increases considerably. These latter are of different size and sit according to the region of the leg more or less densely together. The same is observed on the nymphs and imagines.A regression of the number and size of the sensorial organs accompanies the development of the pseudergates.The anatomy of the neurosensorial system of the third pair of legs is alike that of the second pair. The first pair of legs shows on the front surface the anatomy found inthe hind surface of the second pair of legs and the hind surface of the first pair the one of the front surface of the second pair.

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Zusammenfassung Die Studie behandelt die Innervation der Beine vonCalotermes flavicollis Fab. Es wurde festgestellt, dass die gesamte sensoriel-nervöse Anlage schon bei den Larven des ersten Entwicklungsstadiums vorhanden ist und sich nicht mehr verändert, und dass nur mit jeder stattfindenden Häutung die Anzahl der sensoriellen Organe zunimmt und begleitet ist von einer reicher werdenden Verzweigung der Sinnesnerven. Gleichzeitig entstehen sekundäre Abzweigungen der Sinnesnerven, welche von den Hauptnerven ausgehen. Die Extremitäten der Larven des vierten und hauptsächlich des fünften Stadiums weisen eine sehr starke Zunahme der Sinnesorgane auf. Diese letzteren haben dann verschiedene Grösse und stehen je nach Region des Beines mehr oder weniger dicht beisammen. Dieselben Verhältnisse finden sich auch bei den Nymphen und Imagines.Eine zahlen- und grössenmässige Regression der Sinnesorgane wurde bei der Entstehung der Pseudergaten festgestellt. Die Anatomie der Sinnesorgane des dritten Beinpaares ist derjenigen des mittleren Beinpaares ähnlich. Die vordere Fläche des vordersten Beinpaares ist der hinteren Fläche des mittleren Paares ähnlich und die hintere Fläche derjenigen der Vorderfläche des mittleren Beinpaares.

     

Synthèse d'ARN et de protéines dans des disques de patte de drosophile cultivés in vitro

Résumé Des disques imaginaux de patte, prélevés dans des larves de fin de 3e stade de drosophile, ont été cultivés dans le milieu M de Mandaron, en l'absence d'hormone ou en présence soit d'- soit de -ecdysone. L'incorporation de précurseurs marqués (³H-uridine,³H-leucine ou³H-proline) a été étudiée en fonction du stade de développement des disques.En l'absence d'hormone de mue, l'incorporation d'uridine décroît dès que les disques ont été explantés; l'incorporation de leucine et de proline ne décroît que 6 à 12 heures après l'explantation.- et -ecdysone stimulent l'incorporation des trois précurseurs; toutefois celle-ci varie en fonction du développement morphologique du disque.Les maxima et les minima d'incorporation d'uridine précèdent dans le temps ceux de la leucine et de la proline.Les maxima d'incorporation peuvent être mis en rapport avec des évènements morphologiques marquants du développement: évagination, sécrétion des cuticules nymphale et maginale.Il n'y a pas de différences significatives d'incorporation d'uridine en présence d'-ecdysone ou de -ecdysone; en revanche les maxima d'incorporation de leucine et de proline sont plus élevés en présence d'-ecdysone que de -ecdysone.Ces résultats montrent que l'-ecdysone—et à un degré moindre la -ecdysone—peuvent induire les synthèses de macromolécules nécessaires au développement des appendices in vitro.

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RNA and protein synthesis inDrosophila leg discs cultured in vitro

Summary Imaginal leg discs from late third instarDrosophila larvae were cultured in Mandaron's medium without hormone or with -ecdysone or -ecdysone. Incorporation of labelled precursors (tritiated uridine, tritiated leucine or tritiated proline) was studied as a function of the stage of in vitro disc development.In the absence of moulting hormone, uridine incorporation decreased as soon as the discs were explanted; leucine and proline incorporation however began to decrease only after 6 to 12 h.- and -ecdysone stimulated the incorporation of all three precursors; however the rate of the incorporation varied as a function of the morphological disc development.The maxima and minima of uridine incorporation preceeded in time those of proline and leucine incorporation.The peaks of incorporation were coincident with salient morphological events of development: evagination, secretion of pupal and imaginal cuticles.There were no significant differences in uridine incorporation in the presence of -ecdysone or -ecdysone. Leucine and proline incorporation maxima however were significantly higher in the presence of -ecdysone than of -ecdysone.The results show that -ecdysone—and to a lesser extent also -ecdysone—can induce the macromolecular syntheses required for the development of the appendage in vitro.

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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     

Menhirs et stèles de Corse. Une hypothèse chronologique

In Corsica, the first standing stones are related to Middle Neolithic. Later, during the Bronze Age, appear characteristic massive steles with arm figurations. Between those two limits, well settled, the chronology of other megalithic monuments remains much uncertain. The Sardinian chronology, proposed by E. Atzeni showed that in this island, the evolution from “aniconic menhirs” to “statues-menhirs” with dagger was related to Middle to Final Neolithic (Vth and IVth millenniums). Some examples taken in Europe confirm this chronology. In Corsica, we consider that a metamorphosis might have happen to Aravina stele (Lévie) showing that secondary transformation may have occurred on Neolithic steles. In the first stage, the monument is characterized by its apical rostrum, the engraving of the outline of the face and the “eyes”. During Bronze Age, it was modified by the carving of a sword. The comparison with other Sardinian and Maltese steles suggests a middle Neolithic age. This phase could correspond to an ancient phase of anthropomorphism of standing stones before the emergence of Final Neolithic statues-menhirs.     

Synthèse biostratigraphique du plio-pléistocène de Guadix-Baza (Province de Granada,Sud-Est de l'Espagne)

In the Guadix-Baza basin, a continental sequence 0214 ranging from the Upper Miocene (Upper Turolian) to the Middle Pleistocene (Cromerian) has been established. An essay of biozonation by means of the Rodent succession is proposed, based on the following biozones: Trilophomys castroi, Mimomys occitanus, Mimomys cappetai, Mimomys cf. reidi, Mimomys ostramosensis, Allophaiomys pliocaenicus, Mimomys savini and Arvicola cantiana.     

Obtention par gynogenèse in vitro de plantes haploïdes chlorophyliennes chez le blé dur

Morphogenic expression leading to green plant formation in unfertilized ovary culture (gynogenesis) was studied in durum wheat. After 4–5 weeks of culture in the optimal conditions tested, a creamy white callus grew out of the base of the ovary from which it was detached. After sub-cultures on a pre-regeneration then a regeneration medium, green zones appeared followed by shoot formation. A genotypic effect has been demonstrated. A study of various components of the induction media based on that of Murashige and Skoog showed that 2,4-dichlorophenoxyacetic acid was necessary for callus formation and green plant regeneration. Other factors, such as a thermal pretreatment (5–15 d at 5 °C) and an initial period of darkness (2–5 weeks) followed by light (16 h daily) were also favorable for gynogenesis. All plants formed were green and chromosome counts in root tips of regenerated plants showed the haploid number n = 14.     

Hypothèse : le modèle du lieu de rencontre pour la maladie des prions

Prions are responsible for spongiform diseases such as scrapie and bovine spongiform encephalopathy. It is now generally accepted that the disease mechanism involves the conversion from the normal form, PrP^C, to the pathogenic form, PrP^Sc, and that this isoform is infectious. In the case of scrapie, 15 different forms of the disease have been described and some of these different phenotypes can be conferred by infectious prions that are themselves encoded by normal genes. We propose here that a prion with an altered structure has a correspondingly altered preference for lipids; this altered preference creates a proteolipid domain containing different lipids and other factors such as chaperonins and enzymes responsible for post-translational modifications. Normal prions associated with this abnormal domain adopt the conformation dictated by its lipidic composition (and by the other factors present) and so acquire the lipidic preference of the original pathogenic prions. These transformed prions could then create new proteolipid domains. This process may be considered as semi-conservative replication in which prion and lipids are analogous to the Watson and Crick strands and the proteolipid domain to the double helix itself.     

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.     

Production d'aflatoxine par des souches d'Aspergillus flavus Link de différentes origines

Résumé 125 souches d'Aspergillus flavus Link ont été étudiées en matière de productionin vitro d'aflatoxine B. Ces souches se répartissent en deux groupes principaux: l'un se caractérise par une toxinogénèse forte, l'autre par une toxinogénèse très faible ou nulle. Le pourcentage de souches présentant une toxinogénèse élevée est plus fort parmi celles provenant d'arachide que parmi celles ayant pour origine le blé, le maïs ou des aliments composés destinés au bétail.

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The aflatoxin production of 125 isolates ofAspergillus flavus Link was studied. Among these isolates two principal groups were characterized: one with a high toxigenesis, the other with a weak or without toxigenesis. The percentage of highly toxigenic isolates was stronger amongA. flavus from groundnut thatA. flavus from wheat, maize or animal feedstuffs.

     

Le collagène du byssus de Mytilus edulis L.

Résumé L'autoradiographie révèle, au niveau du pied, une incorporation massive et sélective de la ³H-Proline dans la glande blanche de Mytilus edulis. Cette étude a permis de suivre le processus qui mène de la synthèse de la sécrétion dans la partie basale des cellules jusqu'a son émission dans le sillon pédieux où elle participe à la formation du filament. La collagénase détruit la presque totalité du marquage, attestant ainsi la nature collagénique du produit sécrété. Les autres glandes pédieuses ainsi que la glande du byssus proprement dite, située à la base du pied, montrent une incorporation très faible, sans commune mesure avec celle de la glande blanche. Ceci démontre de façon définitive que le collagène présent dans le filament prend naissance dans cette glande et justifie la dénomination de glande du collagène. Des contrôles réalisés dans différentes régions (bords du manteau, manteau, branchies) montrent que l'injection du précurseur dans le bord palléal constitue une méthode satisfaisante pour marquer de façon relativement rapide et différentielle le collagène de la glande.

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The collagen of the byssus in Mytilus edulis L.II. Autoradiographic study on the incorporation of ³H-Proline

Summary Autoradiographic studies reveal a strong specific incorporation of ³H-Proline in the white gland in the foot of Mytilus edulis. The author could trace the radioactive secretory product from its synthesis in the basal part of the cells down to its outflow into the pedial groove where it takes part in the formation of the filament. Purified collagenase takes out radioactivity from the sections. This observation confirms the collagenous nature of the secretion.The other foot-glands as well as the main byssus gland located at the base of the foot show but a very weak labelling not comparable with that of the white gland. This clearly evidences that the collagen occuring in the filament originates from the latter. The white gland may be properly called: collagen gland.Control sections through different parts of the body (mantle-edge, mantle, gills) confirm that our injection technique of the precursor into the palleal margin is a suitable method for a rather quick and specific labelling of the glandular collagen.

Cette note fait partie d'un travail pour l'obtention d'une thèse de doctorat.     

Cancer du testicule: BEP et spermatogenèse

The sperm characteristics of 44 men treated with two or more courses of BEP chemotherapy for non seminomatous germ cell testicular tumours were investigated before and 25.2 ± 19.4 months after chemotherapy. Before treatment, 54.5% of patients were oligozoospermic. The mean sperm characteristics did not differ before and after chemotherapy. However, following chemotherapy, the recovery of initial sperm count was more frequent after one year than before. During the first year, recovery was more frequent in patients treated with two than in those treated with more than two BEP cycles. In patients with good pre-treatment sperm count, sperm production was reduced by half after chemotherapy. In a subgroup of men who provided two sperm samples after chemotherapy, sperm production was better in the second sample than in the first. Our data suggest that sperm recovery is related to testicular function prior to therapy, to the time elapsed after chemotherapy and in the first year to the number of chemotherapy cycles. In conclusion, our study is reassuring concerning the long-term male reproductive toxicity of BEP. However, further studies are required to analyse the possible effects on sperm genetic material during the recovery period.     

Diminution de la capacité de surfusion au cours de l'embryogenèse et du développement larvaire chez un coléoptère

Potential cold resistance of non-diapause eggs and first instar larvae of Osmoderma eremita (Coleoptera, Cetoniidae, Trichiinae) during embryogenesis and post-embryonic growth was assessed by measuring individual supercooling points (SCP): sterile eggs had a mean SCP of −24.3 ± 2.0 °C; fertilized newly laid eggs a mean SCP of −23.4 ± 3.2 °C and eggs about to hatch a mean SCP of −9.2 ± 2.9 °C. Water absorption by fertilized eggs is a necessary requirement for the development of the embryo and results in an increase in weight and water content: fertilized newly laid eggs had a mean fresh weight of 10.687 ± 1.072 mg and a mean water content (expressed as a percentage of the dry weight) of 79.5 ± 10.83%; eggs about to hatch had a mean fresh weight of 19.127 ± 3.183 mg and a mean water content of 250.10 ± 74.15%. The ex-ovo larvae, hatched 30 days after oviposition, had a mean SCP of −10.1 ± 3.6 °C (no significant difference with eggs about to hatch) and had gained in weight (24.845 ± 3.911 mg) and in water content (499.72 ± 55.49%). Feeding 1st instar larvae had a decreased supercooling ability (mean SCP = −5.7 ± 0.4 °C) whereas their mean fresh weight (99.858 ± 53.091 mg) and mean water content (665.83 ± 82.74%) increased. The eggs and larvae of O. eremita are freezing intolerant. Before overwintering, all larvae switch to being freezing tolerant and can survive ice formation in their tissues and body fluids, whereas their mean SCP stays at around −5 °C. However, recent experiments in the winter of 1996 have shown that frozen larva mortality does occur at temperatures lower than about −12 °C.     

Variations du volume et teneur en ADN des noyaux deScapsipedus marginatus Afz. et Br. (Orthoptère,Gryllide) au cours de l'embryogenèse

Résumé Le volume moyen des noyaux dans l'uf deScapsipedus marginatus passe de 3101 ³ au stade 4 de la segmentation, à 40,71 ³ dans l'embryon à l'éclosion, avec une diminution constante tout au long de l'embryogenèse.Le volume nucléaire des neuroblastes se caractérise par sa constance. Les pleuropodes présentent un accroissement de 190 à 561 ³, puis une diminution brutale peu avant l'éclosion.Les noyaux de l'amnios dérivent des noyaux de la périphérie de l'écusson embryonnaire. Après une légère augmentation au cours de l'anatrepsis, leur volume diminue jusqu'à la disparition de cette annexe.La séreuse se caractérise par un fort accroissement du volume nucléaire au cours des trois premiers jours d'incubation, puis une diminution rapide pendant sa disparition.Les vitellophages subissent un important accroissement de leur volume nucléaire qui demeure considérable en fin de vie embryonnaire.L'évaluation de la teneur en ADN des différents noyaux au stade 96 heures montre que ceux qui accroissent leur volume sont polyploïdes. L'amnios demeure diploïde ainsi que les neuroblastes.Le rapport établi entre accroissement nucléaire, polyploïdie et activité physiologique montre que l'amnios ne semble pas être le siège d'une activité sécrétrice.L'estimation de la teneur en ADN des noyaux deGryllus domesticus et deLocusta migratoria au même stade de développement donne des résultats analogues. Alors que les degrés de ploïdie trouvés chezGryllus sont les mêmes que chezScapsipedus, ceux deLocusta sont plus importants. Les vitellophages dépassent 128 C.

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Volume variations and DNA content of the nuclei ofScapsipedus marginatus Afz. and Br. (Orthoptera, Gryllidae) during embryogenesis

Summary The average volume of the nuclei in the egg ofScapsipedus marginatus varies from 3101 ³ at the tetra-nucleate cleavage stage, to 40,7 ³ in the hatching embryo, with a constant decrease throughout development. The nuclear volume of neuroblasts remains constant; in the pleuropodia, it increases from 190 to 561 ³ and decreases rapidly before hatching.The nuclei of the amnion derive from peripheral nuclei of the germ disk. After a small increase during anatrepsis, their volume decreases until the degeneration of this membrane.The serosa shows a great nuclear volume increase during the first three days of incubation, then a rapid decrease during its disappearance. Yolk cells present an important increase of their nuclear volume which remains high.Estimation of DNA content of the different nuclei at about the 96 hour stage, shows that those whose volume increases are polyploid. Amnion nuclei remain diploid together with neuroblasts. The relation between nuclear increase, polyploidy and physiological functions shows that the amnion is not involved in a particular secretory activity.Estimation of DNA content of the nuclei ofGryllus domesticus andLocusta migratoria at the same developmental stage give comparable results. The degrees of polyploidy found inGryllus are the same as inScapsipedus. InLocusta they are higher, yolk cells attaining values up to 128 C.

     

Nouvelle Synthèse de l’α-Damascone

The gardenia absolute was separated into basic, phenolic, acidic, lactonic and neutral fractions and analysed by using GC, combined GC-MS, IR and NMR. A total of 130 components was identified. Among them, the characteristic constituents responsible for the sweet-green odor of this flower were jasmin lactone, cis-3-hexenol, esters of cis-3-hexenol, cis-3-hexenoic acid and tiglic acid.     

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).     

Anomalies postnatales du développement de la spermatogenèse associées aux troubles de la migration testiculaire

Cryptorchidism, a non-descended testis in its physiological intrascrotal location, is one of the most frequent congenital anomalies of the male genital system. The mechanisms of the normal descent of the testis are still unclear. Several etiological hypotheses have been proposed for cryptorchidism. Cryptorchidism is associated with a greater risk of testis cancer, and is also a cause of impairment in sperm parameters and fertility in the adult age. In this article, we review the cellular and hormonal events occurring from birth to puberty in isolated cases of congenital cryptorchidism that will later, in adulthood, alter both spermatogenesis and fertility.