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 relative de la BAP et de l'IBA sur la néoformation de bourgeons et de racines sur les plantules du Biota orientalis (Cupressacées)

Relative influence of BAP and IBA on the induction of adventitious buds and roots on plantelts of Biota orientalis (Cupressaceae)
Both cytokinin (BAP) and auxin (IBA) have an influence upon the intensity of adventitious bud induction in vitro on hypocotyls of Biota orientalis .
Increase in either the concentration or the length of contact with cytokinin enhances the mean number of neoformed buds per explant, while that of auxin results in an increase of the mean number of reactive explants as well as in the nature of neoformations. Auxin contributes to a restoration of the induction when the length of contact with cytokinin is too short. However, this synergism is only observed when the contract with IBA is simultaneous or follows that with contract with BAP.
Rhizogenesis is also influenced by the auxin-cytokinin balance. An increase in the duration of contact with IBA is always followed by an increased in the mean number of explants forming roots. This organogenesis may be partially or completely inhibited if the duration of contact with cytokinin – before, simultaneously or after that with auxin- exceeds two weeks.     

Acides-aminés et amines libres ďexplants foliaires de Nicotiana tabacum cultivés in vitro sur des milieux induisant la rhizogenèse ou la caulogenèse

Free amino acids and amines in leaf explants of Nicotiana tabacum cultivated in vitro on media inducing rhizogenesis or caulogenesis.
Foliar explants of Nicotiana tabacum cv. Xanthi n.c. were cultivated on three different media: (1) a basal medium without hormone, so that no differentiation occurred in the explants; (2) with auxin added; and (3) with auxin plus cytokinin added, where the additions (2) and (3) promote rhizogenesis and caulogenesis, respectively. The content of free amino acids and amines of the three kinds of explants were investigated. In the two media lacking cytokinin, the explants contained great amounts of five amino acids (asparagine, glutamine, proline, glutamic acid and histidine) and of one aromatic amine, tyramine. In the cytokinin containing medium, only two amines accumulated in the explants: one aliphatic polyamine (putrescine) and one aromatic amine (phenethylamine). The increase in amino acids began immediately on the first days of culture. It was related neither to a more active proteolysis nor to the breaking of the correlations from the mother plant. It was induced by the addition of nutritional elements into the medium. On the other hand, the accumulation of aromatic amines occurred after a few days of culture and was transitory. A decrease was observed after the first emergence of new organs. The relation between the accumulations of these aromatic compounds and formation of roots or shoots is discussed.     

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.     

Evolution des activités enzymatiques dans le tractus digestif au cours de la vie larvaire de la sole. Variations des protéinogrammes et des zymogrammes

The activities of digestive enzymes were studied during the course of larval development (from hatching to 30 days) in the sole, Solea solea. No glycosidase activity was present, but alkaline proteolytic activity increased from hatching to day 5, then decreased until day 15. In the acid range, proteolytic activity was relatively stable from the 10th to the 30th day. There were also changes in the number of esterase-like isozymes which increased between day 20 and 30, with minimum activity observed during metamorphosis.     

Phénolamides et induction florale de Cichorium intybus dans différentes conditions de culture en serre ou in vitro

Phenolamides and floral induction of Cichorium intybus in different conditions of culture in glass-room or in vitro. Three complexes between phenols and amines (phenolamides) have been found in Cichorium intybus L., a plant with an absolute requirement of vernalisation followed by long days for flowering. Upon hydrolysis, these complexes (A, B and C) liberate aromatic amines whose exact identification is in progress, but which are closely related to dopamine, tyramine and serotonin, respectively. In a first series of experiments, phenolamides were studied in the buds of plants grown in the greenhouse under varying conditions. Only buds from plants which flower in long days contained large amounts of these compounds. Much smaller amounts were found in buds at the end of vernalisation (at 2–4°C) before long-day treatment as well as in buds kept in the vegetative state after vernalisation by being grown in short days (8 h light) or in total darkness. In a second series of experiments, phenolamides were studied in bud-forming calli induced in vitro on explants of tuberised root. After sixteen days of culture in continuous light, large quantities of phenolamide were found in the buds and calli of the upper part of the explant, while the lower part which never produces buds contained much less. Buds formed under continuous light produce inflorescences in approximately one month. Various other culture conditions make it possible to maintain the explants in the vegetative state. This can be obtained by short-day conditions, or otherwise under continuous illumination by decreasing the sugar or increasing the NAA levels in the medium. After 13 days of culture, the phenolamide levels were much lower under all of these conditions, than under conditions favourable to floral induction. Compound C is absent or present in trace amounts in vegetative buds. The significance of the differences observed between floral and vegetative buds is supported by the sensitivity of the analytical techniques used. The accumulation of phenolamides in tissues of Cichorium intybus appears to be closely linked to floral induction. Under continuous light it begins very early in young buds and even in the calli that bear these buds.     

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.     

Esters hydroxycinnamiques et induction photopériodique florale in vitro chez Cichorium intybus

Hydroxycinnamic acid esters and photoperiodic flowering induction in vitro of Cichorium intybus.
In root tissues of Cichorium intybus L. cv. Witloof cultured in vitro, the photoinductive period occurs between the 8th and the 16th day after the start of the culture. The promotive light conditions are either long days (16 h photoperiod) or daily cycles of 9 h white + 15 h red light applied during the photoinductive period in an otherwise short day treatment. During the photoinductive period and under suitable irradiation conditions, the endogenous hydroxycinnamic acid esters (especially chlorogenic acid) show a regular development as from the 8th day, reaching a maximal level by the 16th day. The amount of these molecules then decreases rapidly, preceding the external expression of floral induction. When we apply non-inductive conditions [short days (9 h) or daily cycles of 9 h white + 15 h (far-red + red) light supplied from the 8th to the 16th day in otherwise short day conditions], the metabolic changes indicate the same pattern during the inductive period as mentioned above. However, a fundamental difference exists between the inductive and non-inductive conditions, so that the production of hydroxycinnamic acid esters is particularly high towards the end of the second week of in vitro development in the induced state. This increase is not primarily due to increased photosynthetic activity in long day conditions, since it occurs both in the long day treatments and in the treatments with daily cycles of 9 h white + 15 h red light, thus revealing the morphogenetic action of light via phytochrome. This accumulation of hydroxycinnamic acid esters is correlated with floral induction, which appears to be ineffective unless there is a certain minimum amount of these molecules in the tissues.     

Modalités de l'inhibition de la croissance et de la synthèse des acides nucléiques des plantules de blé par l'acide abscissique

The growth of wheat seedlings (Triticum sativum) is inhibited by abscisic acid (ABA). The inhibition increases with the concentration of ABA (from 10^-6M to 5 × 10^-5M) and is stronger in the case of coleoptiles and first leaves than in roots. In contrast, naphthaleneacetic acid (ANA), at 10^-5M, exerts its greatest inhibitory effect on the roots. The inhibitory effect of ABA on coleoptiles can be partially overcome by kinetin and to a much smaller degree by gibberellic acid. Neither of these two compounds, at 10^-5M, had any effect on the ABA-induced inhibition of root growth. The RNA and DNA contents per plant organ are considerably reduced after treatment of the seedlings with ABA, particularly in the coleoptiles and the first leaves. The incorporation of uracil-2-¹⁴C and uridine T (G) into RNA of treated seedlings is reduced in the case of coleoptiles and first leaves, but considerably enhanced in roots. The mechanism of the action of ABA is discussed in the light of these results.     

Origine et caracteres de la sécrétion d'aglycones flavonoliques par les bourgeons d'Aesculus hippocastanum

Flavonol aglycones are present in the oil excreted by buds of Aesculus hippocastanuml. and are probably synthesized in glandular hairs situated on the inner side of bud scales. Flavonols are most abundant in the hairs, being much less concentrated in all other scale tissues. Flavonol accumulation in the buds reaches a maximum both in the Spring and the Autumn and this is related to the accumulation of leaf flavonols and leucoanthocyanes and of scale and bark coumarins.     

Tomographie par émission de positons au F-fluorodeoxyglucose dans la mise en évidence de la maladie veineuse thromboembolique

Purpose

Association of venous thromboembolism (VTE) and inflammation reported in the literature may allow the use of FDG PET/CT in the detection of thrombotic process. Published studies remain limited and contradictory. The aim was, therefore, to evaluate the performance of FDG PET/CT for the detection of VTE.

Patients and methods

Patients included in a prospective study evaluating FDG PET/CT for the detection of malignancy in patients with idiopathic VTE were analysed (MVTEP, PHRC 2008). PET/CT images were interpreted initially without and then retrospectively with knowledge of VTE locations.

Results

Hundred and fourteen patients were included in MVTEP study from March 13th 2009 to July 1st 2010. Forty-six patients (median age: 74 years [20-87], 27 males, 19 females) were analysed. No abnormal uptake was initially reported in pulmonary vessels. The retrospective analysis of pulmonary embolism locations did not demonstrate any significant difference in FDG uptake between embolic sites and controlateral vessels (P = 0.883). Initial analysis of lower limbs vessels demonstrated sensitivity and specificity of PET/CT for deep venous thrombosis (DVT) diagnosis of 15 and 99%. The metabolic activity of DVT was significantly higher than the activity of controlateral vessels (P < 0.005) but without showing any significant SUV threshold for DVT diagnosis.

Conclusion

In conclusion, there is insufficient evidence to suggest that FDG PET/CT could be accurate in detection of VTE. These results need to be completed in a larger study with shorter delay between VTE and FDG PET/CT.     

La répartition spatiale des différents stades de Coccinella septempunctata dans un champ de blé: variation au cours de la saison

Résumé Au début du printemps les adultes de Coccinella septempunctata L. (Col., Coccinellidae) issus des sites d'hivernation, les larves et les nymphes qui en proviennent, fréquentent le sol et les parties basses du blé. En juin, les adultes nés dans le champ et leur descendance sont dispersés sur toute la hauteur des talles bien qu'une fraction non négligeable de leur population se rencontre à l'extrémité supérieure. La plupart des pontes sont déposées sous les mottes de terre, les pierres et les petites adventices qui constituent des sites privilégiés. Ces variations de la distribution de cette coccinelle peuvent être mises en relation avec le climat, en particulier la température, avec la thermophilie de cette espèce et avec la répartition sur les différentes parties des talles des 3 espèces de puceron qui se succèdent au cours de la saison. Ces observations sont importantes à considérer lors du choix ou de la mise au point d'une méthode d'échantillonnage.