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.     

Synthèses ďacides nucléiques et de protéines au cours de ľinitiation de bourgeons adventifs sur des explantats de Cichorium intybus cultivés in vitro

Synthesis of nucleic acids and proteins during initiation of vegetative buds from explants of Cichorium intybus cultivated in vitro .
Explants of 6 mm diameter and 2 mm thickness from roots of Cichorium intybus L. (var. WitIoof cv. "Zoom"), grown in vitro in the presence of kinetin (l0_–6 M ), produced only buds. By comparing the histological events and the biochemical modifications which occurred during the neoformation of buds, it is possible to distinguish two distinct phases. The first phase starts immediately after the excision of the explants and continues for 30 h, when the mitotic index is at its highest. This corresponds to a phase of cellular activation, which is characterized by early synthesis of RNA, permitting the synthesis of proteins necessary for duplication of DNA and cell divisions. The second period starts after 30 h and ends after approximately 72 h of culture, at which time the first bud meristematic nodules were detected. This is a preparatory phase for organogenesis and above all related to synthesis of RNA and proteins.     

Influence ďune alimentation continue avec une solution glucosée sur ľévolution des glucides et des protéines dans les divers organes de la rose coupée (Rosa hybrida cv. Carina)

Influence of continuous supply with a solution of glucose on the changes in the content of soluble sugars and proteins in various organs of the cut rose (Rosa hybrida cv. Carina). Exogenous glucose continuously supplied to the cut rose is immediately converted into saccharose in the stem tissues. This saccharose migrates to the flower, where it is immediately hyd-rolysed, and to the leaves where its hydrolysis occurs more slowly. The reducing sugars resulting from the hydrolysis of saccharose in the flower and, therefore, possibly from the hydrolysis of saccharose in leaves, induce a large accumulation of hexoses (glucose and fructose) in the flower. The protein content does not depend on the level of reducing sugars in the flower.     

Étude du mécanisme d'établissement des liaisons glutaraldéhyde-protéines

Commercial aqueous 25 per cent glutaraldehyde solutions contain no stable derivative of this aldehyde, but compounds of variable molecular weight which easily revert to glutaraldehyde. The effect of pH on the reaction of glutaraldehyde with amino acids and on the stability of the products under acid conditions, shows the importance of the structure modification of the dialdehyde which occurs when pH increases, and even leads to precipitation in highly alkaline solutions. This precipitate results from aldol condensation of glutaraldehyde molecules. It contains aldehyd groups conjugated with ethylenic double bonds. Such a structure reacts with amino groups to give an imino bond, stabilized by resonance with the ethylenic bond, and does not undergo Michael-type addition reactions.Therefore, glutaraldehyde does not react with proteins under its free form, but as an unsaturated polymer, which gives imino bonds stabilized by conjugation.     

Les protéines des corps d'inclusion desBaculovirus

Résumé La comparaison des granules ou des protéines de granules desBaculovirus dePieris brassicae, Pygaera anastomosis, Hyphantria cunea, Carpocapsa pomonella, Mythimna unipuncta, Mamestra oleracea a été entreprise par les techniques d'électrophorèse, d'agglutination, d'immunofluorescence et de précipitation en gel. L'électrophorèse fait appara?tre l'étroite ressemblance qui existe entre les protéines des six sortes de corps d'inclusion. L'analyse immunochimique montre que chaque granule est bien distinct de tous les autres; elle peut servir de base à l'identification des divers virus.

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Summary The proteins ofBaculovirus capsules ofPieris brassicae, Pygaera anastomosis, Hyphantria cunea, Mamestra oleracea, Mythimna unipuncta andCarpocapsa pomonella are studied and compared. There is no significant difference in the composition of electrophoregrams of proteins extracted from capsules of six virus strains by means of a thioglycolate buffer, pH 10,5. Two chief zones (G and F bands) are identified in every one of these strains. Mobility of proteins (C proteins) contained in the G intermediate band is slightly identical, only C proteins ofPieris brassicae andPygaera anastomosis can be differentiated according to a slight difference between electrophoretic mobility. Agglutination and immunofluorescence techniques used for suspensions and smears of granules enable to recognize granules ofC. pomonella andM. unipuncta among the six types of granules. By the immunodiffusion technique, it is revealed that F antigens occurs in all strains and C antigens in five ones. In addition to these common antigens, there are specific antigens respectively named TPa, TPb, J, U, P antigens forP. anastomosis, P. brassicae, H. cunea, M. unipuncta andC. pomonella granules. Capsules taken in Hungary and France from larvae ofC. pomonella could not be differentiated by the techniques used. This work emphasizes both characters common to the group of viruses studied and differences sufficient for identifying every one of types studied.

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Avec la collaboration technique de LilianeCroizier.     

Transport axonal de protéines marquées dans le motoneurone géant de l'écrevisse

Isolated abdomens of crayfish were maintained in vitro and lysine (-³H) was intracellularly injected into one of the giant motoneuron of the ventral cord ganglia by iontophoresis. Membrane potentials ranging between -60 and -70 mV were recorded all along the experiment. Light microscope radioautographs showed an intense reaction over the injected nerve cell body and the initial segment of its axon; most of the surrounding tissues were free of radioactivity when the diffusion of the injected lysine (-³H) was prevented by adding cold lysine to the bathing medium. Some exchange of label was however noted with electrically coupled axons and glial sheaths. No radioactive protein could be traced in the numerous nerve endings of the neuromuscular junction. Nonetheless when a ligature was placed on the nerve root, the amount of accumulated radioactivity was increased from 3 to 6 h. in the axon of the injected motoneuron only. Electron microscope radioautographs indicate that the fast transported proteins were mainly associated with the endoplasmic reticulum and the axonal membrane. It is concluded that the visualization of the nerve endings was limited by the dispersion of the label into the numerous thin terminal branchs of the axon; however the combination of iontophoretic injection and radioautography permits to trace endogenous protein along the axon and to study molecular exchanges with other cells.     

Acides aminés libres et protéiques des divers types de rameaux du Periploca graeca: Rôle dans la circumnutation des tiges volubiles et compartimentation intracellulaire

Free and Bound Amino Acids in the Different Shoot Types of Periploca graeca: Role in the Circumnutation of Twining Shoots, and Cellular Compartmentation. A study has been made of amino acids of wall proteins, cytoplasmic TCA insoluble proteins and proteins of organelles in growing tissues from three types of shoots: short upright, twining, and creeping, all carried by the same specimen of Periploca graeca L. Each shoot type presents a specific pattern. The twining shoots are very rich in cytoplasmic TCA-insoluble proteins. The upright shoots distinguish themselves by a high level of proteins in the organelles and in the cell-wall. However, the composition of wallproteins is almost the same in the three types of shoots. This result excludes the existence of particular wall proteins (extensin, for example) in the twining and rapidly growing shoots. In these shoots the high level of free prolin is not a consequence of low incorporation in the proteins. Distribution of prolin, aspartic acid and glutamic acid between the cellular compartments (wall, hyaloplasm and organelles) has a specific pattern in each shoot type.     

Les protéines non hémoglobiniques érythrocytaires du poulet : Etude immunologique de leur évolution au cours du développement

By use of Laurell's method, the quantitative evolution of three antigenic components of chicken erythrocyte non-hemoglobin proteins has been followed during the course of development. One of the constituents has been characterized as the yellow component previously described and its evolution has been confirmed. The significance of these modifications is discussed.