Etude ultrastructurale de l'origine des plasmocytes ganglionnaires au cours de l'immunisation humorale

Résumé Après une injection unique d'antigène à des souris C 57 B1, la poussée plasmocytaire dans la médullaire ganglionnaire se développe parallèlement à la montée du taux des anticorps circulants du sérum. Ces plasmocytes semblent provenir principalement de la transformation de grandes cellules pyroninophiles. Celles-ci, présentes préalablement dans le cortex, pourraient provenir de la dislocation précoce des centres germinatifs. Elles ne peuvent se transformer en plasmocytes que dans la médullaire. Ces modifications ne pourraient se faire que lorsque la cellule pyroninophile est intégrée au sein d'un ilôt plasmocytaire, c'est-à-dire d'un ilôt dans lequel cette cellule pyroninophile entre étroitement en contact avec un macrophage. A côté de cette origine principale, des plasmocytes peuvent provenir directement de la transformation du lymphoblaste. Enfin, nous avons observé que certaines cellules réticulées se modifient après l'injection de l'antigène. Ces transformations aboutissent à la formation de cellules ayant plusieurs caractères du plasmocyte, sans cependant les présenter tous, d'oú le qualificatif de plasmocytoïde que nous leur avons donné.

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Summary After a single injection of sheep erythrocytes to C 57 Bl mice, the increase in the number of plasma cells in the medullary cords of lymph nodes parallels the humoral antibody titers.The appearance of these plasma cells has been followed ultrastructurally. Most of them arise by modification of the large pyroninophilic cells. These appear at first in the cortex, and could be formed by an early dislocation of the germinal centers. However, the transformation into plasma cells finds place only in the medulla. These changes seem to occur only when pyroninophilic cells are included in a rosette (ilôt plasmocytaire), where they surround a macrophage and develop close connections with it.Other plasma cells may originate directly from lymphoblasts.After the injection of the antigen, some reticular cells are modified into plasmacytoid cells sharing some, but not all, of the morphological characteristics of plasma cells.

     

Etude experimentale de l'immunite a mediation cellulaire au cours des dermatophyties

Résumé A différents temps après le début de l'infection, puis de la réinfection du cobaye par T. mentagrophytes, furent pratiqués des tests de détection de l'hypersensibilité retardée in vivo (intra dermo réaction) et in vitro (inhibition de la migration des macrophages péritonéaux) ainsi qu'un test destiné à mettre en évidence la secrétion de lymphotoxines actives vis à vis des éléments fongiques.Les résultats obtenus concernant l'évolution cinétique des réactions plaident en faveur de la plus grande sensibilité du test d'inhibition de la migration des macrophages pour la détection de l'hypersensibilité retardée. Ils confirment le rôle prépondérant des réactions de type cellulaire dans la résistance et soulignent la particularité de ce modèle expérimental oú se manifestent des phénomènes d'immunité locale. L'ensemble de nos résultats et, notamment, la démonstration de l'existence de médiateurs d'origine lymphocytaire toxiques pour les spores de T. mentagrophytes sont discutés dans le cadre de la réaction cutanée à l'agression parasitaire.     

Etude de l'evolution des activites des enzymes mitochondriaux de l'hepatocyte au cours du developpement du rat

Study on the evolution of mitochondrial enzyme activities in hepatocyte during rat development

Some constitutive enzymes of the three isolated fractions of mitochondria outer membrane, inner membrane and matrix, have been investigated in rat hepatocyte during a period varying from the foetal state to the 15th day after birth.

In the three mitochondrial fractions, activities of the studied enzymes present different evolutions. In the matrix, the tricarboxylic enzyme activities have already reached their normal values before birth. In the outer membrane, the NADH-cytochrome c reductase activity increases regularly, in the same way as that of the endoplasmic reticulum NADH-cytochrome c reductase. In the inner membrane, the oxygen consumption is very low before birth, then increases suddenly from the 5th to the 8th day after birth, when it reaches the normal values. The limiting factor of the respiratory chain activities is neither cytochrome oxidase nor the first dehydrogenases.     

Etude du métabolisme des acides nucléiques et des protéines au cours de l'initiation de racines adventives

Summary Changes in the metabolism of nucleic acids and proteins were followed during the initiation of adventitious roots of Cicer arietinum. During the first 24 h, several phases of activation of the metabolism were found. The use of inhibitors of RNA synthesis showed that an early phase of incorporation of precursors into RNA is essential for the initiation phenomena. This phase is more sensitive to inhibitors and activators (hormones) than all other phases. The rapid turn-over of RNA synthesized during the first 6 h and the inefficience of inhibitors after this time suggested that a stable (non-RNA) factor maintains the activation. This factor must be synthesized soon after the stimulus of cutting.     

Etude de la globuline des graines de Tournesol (Helianthus annuus L.) accumulation au cours de la maturation et localisation intracellulaire

Protein synthesis and accumulation in growing sunflower (Helianthus annuus L.cv.Airelle) seeds are studied. The salt soluble fraction, globulin, is the main soluble protein component. The earlier stages of seed development (10 days after flowering) are characterized by high M_r polypeptides (74, 58 and 44 kDa). Later stages mainly show nature globulin polypeptides. Thus, protein synthesis in seed occurs at a specific period of seed development which follows a period of fast cell divisions (0–14 days after flowering). Protein bodies are isolated and their protein composition analyzed. Globulin subunits are the main polypeptides of protein bodies soluble fraction. Mature globulin is only stored in protein bodies.      

Etude du processus de transformation des acides di-et tricarboxyliques chezPenicillium Brevi-compactum

Résumé L'étude du processus de transformation des acides di- et tricarboxyliques chezP. brevi-compactum a permis d'établir que le cycle deKrebs ne se déroule pas chez cette moisissure. Les résultats des recherches menées jusqu'à ce jour font au contraire supposer, avec grande vraisemblance, que le processus étudié est identique au schéma proposé parChrzaszcz etTiukow. Quant à l'acide α-cétoglutarique, il semble qu'il soit synthétisé par condensation oxydative d'une molécule d'acide pyruvique et d'une molécule d'acide acétique.     

Evolution des flavonoides au cours de la croissance des bractees de Poinsettia

The changes in flavonoids were studies during the growth of Poinsettia bracts. Pelargonidin glycosides appeared after cyanidin glycosides; the 3-rutinoside after the 3-monoglucoside. The 3-mono-glucosides were predominant at all times. The bracts contained kaempferol and quercetin, both as aglycones and glycosides. There was no direct relationship between the pathways of flavonol and anthocyanin biosynthesis, but two separate pathways corresponding to the 4′-monohydroxylated- and 3′,4′-dihydroxylated-, flavonoids. Flavanonols and isoflavones were detected but not characterized.     

Etude du phytochrome detectable,in vivo dans les graines de Cucurbita pepo L. au cours des differentes phases de la germination

Summary In dry gourd seeds all the phytochrome is in the P_fr form. The increase of phytochrome content from the beginning of hydration involves two phases, A and B, in the embryonic axis as well as in the cotyledons. Cycloheximide does not prevent the appearance of P_r during phase A. We assume that P_r is gradually released from an inactive complex. On the other hand phase B is inhibited by cycloheximide; this could mean that a de novo synthesis of P_r occurs.Some experiments indicate that the phytochrome which is localized in the embryonic axis may be involved only in the germinating process.The phytochrome which is synthesized during phase B disappears when the seeds are irradiated with red light, while the original phytochrome does not.According to our data it seems necessary to lay down a new and precise definition of the germination process.     

Etude des proteines an cours de la germination des graiues: Isolement et analyse des histories de radis Par

Histories of radish seedlings liave been characterised by comparison with pea histones extracted and purified under the same conditions. Submitted to acrylamide gel analysis the radish histones are resolved into main protein bands comparable to those of pea or calf thymus histones. However, protein bands of lesser importance which are not to be found in electrophoretic profils of pea or calf thymus histones, appear together with the main bands of radish histones. Study of these supplementary proteins through isoelectric focusing makes it possible to distinguish two groups: contaminating acid proteins and weakly basic proteins characterised by their high amide content.     

Synthèse des RNA au cours de la germination du radis

RNA synthesis in radish is studied during the first stages of germination. The radish seeds allowed to germinate in the dark, on distilled water, synthesize ribosomal RNA and accumulate a particular RNA, not incorporated in ribosomes. The results of ³²P incorporation in RNA of radish seedlings indicate a progressive formation of ribosomal RNA. Two species of rapidly labelled RNA are synthesized. With labelling time, their chromatographic behaviour on MAK columus evolves, while their electrophoretic characteristics remain stable. It is assumed that these two species are involved in ribosome formation. In vivo experiments with chloramphenicol support this conclusion. RNA which accumulates during germination, could be a particular type of ribosomal RNA which could be enable, under the definite culture conditions, to enter into ribosomal structures.