Interactions between polyamine and ethylene metabolisms in a hormone autonomous sugarbeet callus

in Journal of Plant Physiology (2000), 157(1), 24-30

In a fully habituated non-organogenic sugarbeet callus (HNO) overproducing polyamines and underproducing ethylene (in comparison with its normal hormone-dependent counterpart), the question raised about a ... [more ▼]

In a fully habituated non-organogenic sugarbeet callus (HNO) overproducing polyamines and underproducing ethylene (in comparison with its normal hormone-dependent counterpart), the question raised about a possible competition between these two metabolites for their common precursor, S-adenosyl-methionine (SAM). The experimental strategy consisted in determining the effects of exogenous polyamines and inhibitors of polyamine biosynthetic pathway on growth, polyamine accumulation and ethylene production. Exogenous putrescine or spermidine decreased polyamine contents and ethylene production. Inhibitors of the diamine putrescine biosynthesis, DFMO and DFMA, induced a reduction of both polyamine content and ethylene production with an increase of HNO callus growth. However, when a mixture of the two inhibitors was used, an increase of ethylene production was observed without any effect on growth. The inhibitors of spermidine synthase (CHA) and of SAM decarboxylase (MGBG) also decreased polyamine content and ethylene production with different effects on growth according to the concentrations used. The combination of the two inhibitors (CHA + MGBG) increased ethylene production of the HNO callus. The effect of growth regulators (auxin and cytokinin) on growth and ethylene production of HNO callus is also discussed. These results suggest that polyamines affect directly the ethylene biosynthesis. In the absence of an exogenous hormonal control, the lower ethylene metabolism of HNO callus could not be explained by a competition with polyamines for their common precursor. [less ▲]

Interactions between systemic analgesics.

in Acta Anaesthesiologica Belgica (2001), 52(4), 395-401

Interactions between the cytochrome pathway and the alternative oxidase in isolated Acanthamoeba castellanii mitochondria.

in Journal of Bioenergetics & Biomembranes (2002), 34(1), 31-40

The steady-state activity of the two quinol-oxidizing pathways of Acanthamoeba castellanii mitochondria, the phosphorylating cytochrome pathway (i.e. the benzohydroxamate(BHAM)-resistant respiration in ... [more ▼]

The steady-state activity of the two quinol-oxidizing pathways of Acanthamoeba castellanii mitochondria, the phosphorylating cytochrome pathway (i.e. the benzohydroxamate(BHAM)-resistant respiration in state 3) and the alternative oxidase (i.e. the KCN-resistant respiration), is shown to be fixed by ubiquinone (Q) pool redox state independently of the reducing substrate (succinate or exogenous reduced nicotinamide adenine dinucleotide (NADH)), indicating that the active Q pool is homogenous. For both pathways, activity increases with the Q reduction level (up to 80%). However, the cytochrome pathway respiration partially inhibited (about 50%) by myxothiazol decreases when the Q reduction level increases above 80%. The decrease can be explained by the Q cycle mechanism of complex III. It is also shown that BHAM has an influence on the relationship between the rate of ADP phosphorylation and the Q reduction level when alternative oxidase is active, and that KCN has an influence on the relationship between the alternative oxidase activity and the Q reduction level. These unexpected effects of BHAM and KCN observed at a given Q reduction level are likely due to functional connections between the two pathways activities or to protein-protein interaction. [less ▲]

Interactions between the Meuse River and its heterogeneous alluvial deposits at a contaminated brownfield

Conference (2012, June 08)

Interactions between western lowland gorillas (Gorilla gorilla gorilla Savage & Wyman 1847) and timber exploitation: Preliminary insights in a Gabonese logging concession

Poster (2012, August 15)

Interactions between western lowland gorillas (WLG) and a timber exploitation were studied in Central Gabon. WLG densities were estimated in two sites with different logging histories (not logged vs ... [more ▼]

Interactions between western lowland gorillas (WLG) and a timber exploitation were studied in Central Gabon. WLG densities were estimated in two sites with different logging histories (not logged vs. logged one month before), and nesting behavior was described. Seeds dispersed by WLG were identified through fecal analysis and germination trials assessed seed viability after gut passage. Four treatments were realized for the most abundant species: passed seeds, passed seeds in fecal matrix, seeds surrounded by fresh pulp and seeds extracted from fresh fruits. Relatively high WLG densities were observed in the concession (3.7 weaned gorillas/km² in unlogged forest and 1.7 weaned gorillas/km² in logged forest). WLG nested preferentially in open areas (particularly open terra firme and swamp forest) and frequently used old logging road network for nesting and feeding. WLG dispersed sixteen species during the course of the study (February-May 2011). The most dispersed species was Santiria trimera (Burseraceae). The germination successes of S. trimera were significantly higher after gut passage (N=378; P<0.001) because of pulp removal and seed coat scarification. This pilot study suggests that timber exploitation and WLG conservation are not mutually exclusive. WLG are important agents of forest regeneration by dispersing seeds in logged areas. Nest sites in logging gaps could be particularly favorable for seedlings development. This consideration must encourage forest managers to strengthen WLG-conservative practices in their concessions. [less ▲]

Interactions d'un lipopeptide antimicrobien contenant des acides aminés atypiques avec des membranes biomimétiques

Scientific conference (2010)

Interactions de glycolipides avec des membranes biomimétiques

Scientific conference (2013, March 18)

Les surfactants à base de sucre sont des composés d’intérêt pour les domaines alimentaire, cosmétique et pharmaceutique de par leur origine naturelle, leur biodégradabilité élevée et leur biocompatibilité ... [more ▼]

Les surfactants à base de sucre sont des composés d’intérêt pour les domaines alimentaire, cosmétique et pharmaceutique de par leur origine naturelle, leur biodégradabilité élevée et leur biocompatibilité. Récemment, certains ont également montré un potentiel dans le domaine de la protection des plantes. Depuis quelques années, les surfactants de type bolaforme ont reçu une attention particulière surtout pour leur potentiel d’exploitation en tant qu’agent d’encapsulation ou de vectorisation de médicaments. Leur structure est composée de deux têtes polaires connectées par un bras espaceur hydrophobe. Parmi les bolaamphiphiles, ceux à base de sucre offrent l’avantage de fournir une hydrosolubilité importante et une cytotoxicité réduite. Une connaissance approfondie des propriétés tensioactives et membranaires de ces nouveaux tensioactifs est une clef importante dans la compréhension de leurs mécanismes, d’une part, et d’autre part, dans l’optique d’une démarche prédictive dans la conception d’agents tensioactifs ciblant une application précise, du domaine physico-chimique ou biologique. Les outils tels que la technique de la cuve de Langmuir, la calorimétrie de titration isotherme, la spectroscopie de fluorescence et la spectroscopie infra-rouge ont été exploités afin de mettre en évidence l’influence de la longueur du bras hydrophobe, de la présence d’insaturation, de la stéréochimie des carbones anomères et de la nature des sucres sur les propriétés interfaciales et d’interaction/déstabilisation des membranes biologiques des bolaformes de sucre. [less ▲]

Interactions des androgenes et des oestrogenes dans le controle de la reproduction

in Comptes Rendus de l'Académie des Sciences. Série III, Sciences de la Vie (1987), 305(14), 569-74

Castrated male quail were injected with the synthetic oestrogen, diethylstylbestrol (DES) or the synthetic androgen, methyltrienolone (R 1881) or both compounds simultaneously. Both R 1881 and DES ... [more ▼]

Castrated male quail were injected with the synthetic oestrogen, diethylstylbestrol (DES) or the synthetic androgen, methyltrienolone (R 1881) or both compounds simultaneously. Both R 1881 and DES activated male sexual behaviour, inhibited LH and FSH secretion and increased hypothalamic aromatase activity. Additive effects between R 1881 and DES were observed for the induction of brain aromatase and for the inhibition of FSH secretion. As a consequence, mechanisms mediated by androgen and estrogen receptors must be involved in the control of these reproductive characteristics. [less ▲]

Interactions du cadre juridique et des stratégies e-commerce: étude exploratoire dans le secteur de l'assurance

Conference (2004, May)

Prenant une place croissante dans la conduite des affaires, le commerce électronique, au travers des nouveaux modes de relations transactionnelles qu’il engendre, pose de nombreux défis stratégiques aux ... [more ▼]

Prenant une place croissante dans la conduite des affaires, le commerce électronique, au travers des nouveaux modes de relations transactionnelles qu’il engendre, pose de nombreux défis stratégiques aux entreprises et soulève de multiples interrogations juridiques. Alors que de nombreuses recherches étudient ces aspects relatifs au commerce électronique sous un angle unidisciplinaire, notre contribution entend aborder la question des stratégies e-commerce d’une façon davantage transversale, à l’encontre des courants stratégique et juridique. A partir de l’étude de cas concrets, issus du secteur de l’assurance, notre recherche exploratoire interroge la conception des stratégies B2C et entend cerner les interactions respectives du cadre juridique et de la stratégie d’affaires de l’entreprise sur les choix posés en matière de politique e-commerce. [less ▲]

Interactions entre glucocorticoïdes et sympathomimétiques et sensibilité à l'insuline chez l'homme

in Diabète & Métabolisme (1994), 20(suppl),