Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailOlfactory receptors are displayed on dog mature sperm cells
Vanderhaeghen, P.; Schurmans, Stéphane ULg; Vassart, G. et al

in Journal of Cell Biology (1993), 123

Olfactory receptors constitute a huge family of structurally related G protein-coupled receptors, with up to a thousand members expected. We have shown previously that genes belonging to this family were ... [more ▼]

Olfactory receptors constitute a huge family of structurally related G protein-coupled receptors, with up to a thousand members expected. We have shown previously that genes belonging to this family were expressed in the male germ line from both dog and human. The functional significance of this unexpected site of expression was further investigated in the present study. We demonstrate that a few dog genes representative of various subfamilies of olfactory receptors are expressed essentially in testis, with little or no expression in olfactory mucosa. Other randomly selected members of the family show the expected site of expression, restricted to the olfactory system. Antibodies were generated against the deduced amino acid sequence of the most abundantly expressed olfactory receptor gene in dog testis. The purified serum was able to detect the gene product (DTMT receptor) in late round and elongated spermatids, as well as in the cytoplasmic droplet that characterizes the maturation of dog sperm cells, and on the tail midpiece of mature spermatozoa. Western blotting further confirmed the presence of a 40-kD immunoreactive protein in the membrane of mature sperm cells. Altogether , these results demonstrate that the main expression site of a subset of the large olfactory receptor gene family is not olfactory mucosa but testis. This expression correlates with the presence of the corresponding protein during sperm cell maturation, and on mature sperm cells. The pattern of expression is consistent with a role as sensor for unidentified chemicals possibly involved in the control of mammalian sperm maturation, migration, and/or fertilization [less ▲]

Detailed reference viewed: 101 (5 ULg)
Full Text
Peer Reviewed
See detailOlfactory responses to aphid and host plant volatile releases: (E)-beta-farnesene an effective kairomone for the predator Adalia bipunctata.
Francis, Frédéric ULg; Lognay, Georges ULg; Haubruge, Eric ULg

in Journal of Chemical Ecology (2004), 30(4), 741-55

The volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. Using a four-arm olfactometer, the attraction of several ... [more ▼]

The volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. Using a four-arm olfactometer, the attraction of several combinations of three aphid (Myzus persicae, Acyrthosiphon pisum, and Brevicoryne brassicae) and three plant (Vicia faba, Brassica napus, and Sinapis alba) species toward Adalia bipunctata larvae and adults was observed. Both predatory larvae and adults were attracted only by A. pisum and M. persicae when they were crushed, whatever the host plant. (E)-beta-farnesene, the aphid alarm pheromone, was the effective kairomone for the ladybird. Plant leaves alone (V. faba, B. napus, and S. alba) or in association with nonstressed whole aphids (the three species) did not have any attraction for the predator. The B. brassicae specialist aphid is the only prey that was not attracted to A. bipunctata larvae and adults, even if they were crushed. Release of B. brassicae molecules similar to the host plant allelochemicals was demonstrated by GC-MS analysis. The lack of behavioral response of the ladybird at short distance toward the cruciferous specialist aphid was related only to the absence of (E)-beta-farnesene in the aphid prey volatile pattern. [less ▲]

Detailed reference viewed: 70 (16 ULg)
Full Text
Peer Reviewed
See detailOlfactory systems in mate recognition and sexual behavior.
Keller, Matthieu; Pillon, Delphine; Bakker, Julie ULg

in Vitamins and Hormones (2010), 83

Olfactory signals play an important role so that breeding efforts are synchronized with appropriate social and environmental circumstances. In this context, the mammalian olfactory system is characterized ... [more ▼]

Olfactory signals play an important role so that breeding efforts are synchronized with appropriate social and environmental circumstances. In this context, the mammalian olfactory system is characterized by the existence of several olfactory subsystems that have evolved to process olfactory information. While the vomeronasal (or accessory) olfactory system is usually conceived as being involved in the processing of pheromonal signals due to its close connections with the reproductive hypothalamus, the main olfactory system is, by contrast, considered as a general analyzer of volatile chemosignals, especially those that are used for the social identification of conspecifics. In fact, several recent sets of experiments suggest that both the main and accessory olfactory systems have the ability to process partly overlapping pheromonal chemosignals and that both systems converge at a downstream level of pheromonal processing. As a consequence, both systems have the ability to support complimentary aspects in mate discrimination and sexual behavior. However, the relative roles played by these systems and their interactions are at present still far from being understood. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailThe OLFR1 gene encoding the HGMP07E putative olfactory receptor maps to the 17p12-17p13 region of the human genome and reveals a MspI restriction fragment lenght polymorphism
Schurmans, Stéphane ULg; Muscatelli, F.; Miot, F. et al

in CytoGenetics & Cell Genetics (1993), 63

Olfactory receptors are believed to be encoded by an extremely large subfamily of G protein-coupled receptors. A human gene (OLFR1) encoding a member of this family was cloned from a genomic library by ... [more ▼]

Olfactory receptors are believed to be encoded by an extremely large subfamily of G protein-coupled receptors. A human gene (OLFR1) encoding a member of this family was cloned from a genomic library by cross-hybridization with a gene fragment obtained by the polymerase chain reaction. The nucleotide sequence of a 3.4-kb EcoRI fragment was determined, and the protein sequence was deduced from the single open reading frame. The gene was assigned by in situ hybridization of metaphase chromosomes to the 17p13-->p12 region of the human genome, in proximity to the tumor-suppressor gene encoding p53. When used as a probe on Southern blots under moderately stringent conditions, it hybridizes to at least three closely related genes. A restriction fragment length polymorphism was detected after MspI digestion. Mendelian segregation of the gene was assessed in three CEPH families, and linkage analysis confirmed the localization of the locus [less ▲]

Detailed reference viewed: 17 (5 ULg)
See detailOlgierd Kuty. Un parcours sociologique
Vrancken, Didier ULg

in Vrancken, Didier; Dubois, Christophe; Schoenaers, Frédéric (Eds.) Penser la négociation. Mélanges en hommage à Olgierd Kuty (2008)

Cet article retrace les principales étapes du parcours sociologique d'Olgierd Kuty. Depuis ses débuts, à une théorisation générale du droit, de l'organisation et de la société en passant par l'analyse des ... [more ▼]

Cet article retrace les principales étapes du parcours sociologique d'Olgierd Kuty. Depuis ses débuts, à une théorisation générale du droit, de l'organisation et de la société en passant par l'analyse des politiques sociales, les travaux d'Olgierd Kuty se sont déclinés autour d'une thématique transversale, celle de l'analyse de la négociation. [less ▲]

Detailed reference viewed: 54 (11 ULg)
Full Text
Peer Reviewed
See detailOligodendrocyte development and myelinogenesis are not impaired by high concentrations of phenylalanine or its metabolites.
Schoemans, Renaud; Aigrot, Marie-Stephane; Wu, Chaohong et al

in Journal of Inherited Metabolic Disease (2010), 33(2), 113-20

Phenylketonuria (PKU) is a metabolic genetic disease characterized by deficient phenylalanine hydroxylase (PAH) enzymatic activity. Brain hypomyelination has been reported in untreated patients, but its ... [more ▼]

Phenylketonuria (PKU) is a metabolic genetic disease characterized by deficient phenylalanine hydroxylase (PAH) enzymatic activity. Brain hypomyelination has been reported in untreated patients, but its mechanism remains unclear. We therefore investigated the influence of phenylalanine (Phe), phenylpyruvate (PP), and phenylacetate (PA) on oligodendrocytes. We first showed in a mouse model of PKU that the number of oligodendrocytes is not different in corpus callosum sections from adult mutants or from control brains. Then, using enriched oligodendroglial cultures, we detected no cytotoxic effect of high concentrations of Phe, PP, or PA. Finally, we analyzed the impact of Phe, PP, and PA on the myelination process in myelinating cocultures using both an in vitro index of myelination, based on activation of the myelin basic protein (MBP) promoter, and the direct quantification of myelin sheaths by both optical measurement and a bioinformatics method. None of these parameters was affected by the increased levels of Phe or its derivatives. Taken together, our data demonstrate that high levels of Phe, such as in PKU, are unlikely to directly induce brain hypomyelination, suggesting involvement of alternative mechanisms in this myelination defect. [less ▲]

Detailed reference viewed: 42 (7 ULg)
Peer Reviewed
See detailOligodendrocytes: From Development to Demyelinated Lesion Repair
Rogister, Bernard ULg; Belachew, Shibeshih ULg; Moonen, Gustave ULg

in Acta Neurologica Belgica (1999), 99(1), 32-9

Spontaneous but incomplete remyelination is observed after a demyelinating lesion. We know since ten years now that oligodendrocyte progenitors, (OP) and totipotent neural stem cells remain present in the ... [more ▼]

Spontaneous but incomplete remyelination is observed after a demyelinating lesion. We know since ten years now that oligodendrocyte progenitors, (OP) and totipotent neural stem cells remain present in the central nervous system of adult mammals. [less ▲]

Detailed reference viewed: 21 (6 ULg)
Peer Reviewed
See detailOligodendrogliome de la fosse postérieure : à propos d'un cas
Martin, Didier ULg; Dooms, G.; Flandroy et al

Conference (1990, March)

Detailed reference viewed: 11 (0 ULg)
See detailLes Oligoéléments en céréales
Destain, Jean-Pierre ULg; Bodson, Bernard ULg; Falisse, André et al

in Fumure et protection phytosanitaire des céréales (1988, February 25)

Detailed reference viewed: 15 (3 ULg)
Full Text
Peer Reviewed
See detailOligomerization and copolymerization of γ-butyrolactone - a monomer known as unable to homopolymerize, 1. Copolymerization with epsilon-caprolactone
Duda, Andrzej; Penczek, Stanislaw; Dubois, Philippe ULg et al

in Macromolecular Chemistry and Physics (1996), 197(4), 1273-1283

Copolymerization of γ-butyrolactone (γBL) with ε-caprolactone (εCL) initiated with aluminium isopropoxide trimer ([Al(OiPr)3 ]3, (A3)) is described. Copolymers with molecular weights ( ) up to 3 ; 104 and ... [more ▼]

Copolymerization of γ-butyrolactone (γBL) with ε-caprolactone (εCL) initiated with aluminium isopropoxide trimer ([Al(OiPr)3 ]3, (A3)) is described. Copolymers with molecular weights ( ) up to 3 ; 104 and containing up to 43 mol-% repeating units derived from γBL are prepared. Their molecular weight is controlled by the concentrations of the consumed comonomers and the starting concentration of initiator { = (86.09 ; [γBL]c + 114.14 ; [εCL]0)/3[Al(OiPr)3] + 60.10}. 13C NMR and DSC data are indicative of a pseudoperiodic or random copolymer structure. [less ▲]

Detailed reference viewed: 38 (6 ULg)
Full Text
Peer Reviewed
See detailOligophrenin 1 (OPHN1) gene mutation causes syndromic X-linked mental retardation with epilepsy, rostral ventricular enlargement and cerebellar hypoplasia
Bergmann, C.; Zerres, K.; Senderek, J. et al

in Brain (2003), 126(7), 1537-1544

We identified an oligophrenin 1 (OPHN1) gene mutation in a family with five brothers affected by a recognizable pattern of clinical and neuroradiological hallmarks. The distinctive phenotype comprised ... [more ▼]

We identified an oligophrenin 1 (OPHN1) gene mutation in a family with five brothers affected by a recognizable pattern of clinical and neuroradiological hallmarks. The distinctive phenotype comprised moderate to severe mental retardation, myoclonic-astatic epilepsy, ataxia, strabismus and hypogenitalism. Neuroimaging displayed fronto-temporal atrophy with rostral enlargement of the lateral ventricles, lower vermian agenesis and asymmetric cerebellar hypoplasia. Mutation analysis of the OPHN1 gene on Xq12 disclosed a genomic deletion of exon 19 causing a frameshift. Notably, OPHN1 mutations have been previously reported as a rare cause of non-syndromic X-linked mental retardation. Our findings, however, indicate that OPHN1 mutations result in a recognizable syndrome. In addition, identification of OPHN1 as a further gene associated with epileptic seizures will help to unravel aetiologic factors of epilepsy. [less ▲]

Detailed reference viewed: 2 (0 ULg)
Full Text
See detailOligopoles, collusion tacite et droit communautaire de la concurrence
Petit, Nicolas ULg

Book published by Bruylant (2008)

Detailed reference viewed: 87 (14 ULg)
Full Text
See detailThe Oligopoly Problem in EU Competition Law
Petit, Nicolas ULg

in GERADIN, D.; LIANNOS, I. (Eds.) Research Handbook in European Competition Law (2013)

This paper offers a complete overview of the oligopoly problem in competition law and economics, with a specific focus on European Union (EU) law. A related purpose of the paper is to challenge the ... [more ▼]

This paper offers a complete overview of the oligopoly problem in competition law and economics, with a specific focus on European Union (EU) law. A related purpose of the paper is to challenge the dominant view that merger control is the ultimate preventive remedy against tacit collusion. On close analysis, the merger-only enforcement paradigm against tacit collusion generates a systemic risk of type II errors. Part of this enforcement gap may, however, be alleviated through a more muscular enforcement of the rules on coordinated conduct (i.e. Article 101 TFEU) and on unilateral conduct (i.e. Article 102 TFEU). In this later respect, the paper formulates a possible theory of harm that would entitle agencies and courts to apply Article 102 TFEU to specific types of conduct by oligopolists. The concept of abuse of collective dominance may in particular be applied to the artificial tactics which oligopolists adopt to protect an observed collusive equilibrium from the natural, disruptive effect caused by an external shock (entry, natural disaster, change in tax rate, etc.). In this sense, the paper is different from other scholarly proposals that recommend applying rules on unilateral conduct to excessive oligopoly prices and/or facilitating practices. [less ▲]

Detailed reference viewed: 85 (7 ULg)
Full Text
Peer Reviewed
See detailOligosaccharide binding in family 8 glycosidases: Crystal structures of active-site mutants of the beta-1,4-xylanase pXyl from Pseudoaltermonas haloplanktis TAH3a in complex with substrate and product
De Vos, D.; Collins, T.; Nerinckx, W. et al

in Biochemistry (2006), 45(15), 4797-4807

The structures of inactive mutants D144A and E78Q of the glycoside hydrolase family 8 (GH-8) endo-beta-1,4-D-Xylanase (pXyl) from the Antarctic bacterium Pseudoalteromonas haloplanktis TAH3a in complex ... [more ▼]

The structures of inactive mutants D144A and E78Q of the glycoside hydrolase family 8 (GH-8) endo-beta-1,4-D-Xylanase (pXyl) from the Antarctic bacterium Pseudoalteromonas haloplanktis TAH3a in complex with its substrate xylopentaose (at 1.95 angstrom resolution) and product xylotriose (at 1.9 angstrom resolution) have been determined by X-ray crystallography. A detailed comparative analysis of these with the apoenzyme and with other GH-8 structures indicates an induced fit mechanism upon ligand binding whereby a number of conformational changes and, in particular, a repositioning of the proton donor into a more catalytically competent position Occurs. This has also allowed for the description of protein-ligand interactions in this enzyme and for the demarcation of subsites -3 to +3. An in-depth analysis of each of these subsites gives an insight into the structure-function relationship of this enzyme and the basis of xylose/glucose discrimination in family 8 glycoside hydrolases. Furthermore, the structure of the -1/+1 subsite spanning complex reveals that the substrate is distorted from its ground state conformation. Indeed, structural analysis and in silico docking Studies indicate that substrate hydrolysis in GH-8 members is preceded by a conformational change, away from the substrate ground-state chair conformation, to a pretransition state local minimum S-2(O) conformation. [less ▲]

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailLes oligosaccharides pectiques: production et applications possibles
Combo, Agnan Marie Michel ULg; Mario, Aguedo ULg; Paquot, Michel ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(1), 153-164

Les oligosaccharides pectiques ou POS sont des fragments de composition complexe issus de la dégradation chimique, physique ou enzymatique de la pectine. Du fait de l’intérêt de leurs propriétés ... [more ▼]

Les oligosaccharides pectiques ou POS sont des fragments de composition complexe issus de la dégradation chimique, physique ou enzymatique de la pectine. Du fait de l’intérêt de leurs propriétés biologiques, les oligosaccharides pectiques font l’objet de nombreuses études et trouvent aujourd’hui des applications dans des domaines aussi différents que la médecine, l’agriculture et l’industrie agro-alimentaire. Cet écrit présente la structure des pectines ainsi que les différents modes de production des POS en insistant particulièrement sur les différentes enzymes microbiennes permettant de les obtenir et sur les applications possibles de ces POS. [less ▲]

Detailed reference viewed: 27 (8 ULg)
Full Text
Peer Reviewed
See detailOlive mill wastewater valorization : use by non-conventional yeasts.
Gonçalves, C.; Lopes, M.; Aguedo, Mario ULg et al

in Nzihou, Ange; Lyberatos, Gerasimos (Eds.) Proceedings of the 2nd International Conference on Engineering for Waste Valorisation (2008)

The ability of the strains Yarrowia lipolytica and Candida rugosa to grow on Olive Mill Wastewater (OMW) based medium and to produce high-value compounds from OMW (such as enzymes), while degrading this ... [more ▼]

The ability of the strains Yarrowia lipolytica and Candida rugosa to grow on Olive Mill Wastewater (OMW) based medium and to produce high-value compounds from OMW (such as enzymes), while degrading this waste, was tested. Factors affecting cellular growth and OMW degradation were also studied, such as OMW composition, dilution and supplementation. OMW collected from 3-phase olive mill of the north region of Portugal were used and characterized chemical and biochemically. OMW with COD ranging from 100 g·L-1 to 200 g·L-1 were supplemented with yeast extract and ammonium chloride proportionally to its organic composition. Preliminary studies of OMW consumption were carried out in batch cultures of Y. lipolytica W29 and C. rugosa PYCC 3238. The strains were able to grow in the OMW used without dilution, to consume almost all of the sugars present in the media and to significantly reduce COD. Y. lipolytica W29 was less affected by operating conditions changes such as, stirring rate variation and OMW medium supplementation. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Full Text
See detailOliver PRIMAVESI et Katharina LUCHNER (Éd.), "The Presocratics from the Latin Middle Ages to Hermann Diels"
Gavray, Marc-Antoine ULg

in Antiquité Classique : Revue Interuniversitaire d'Etudes Classiques (2013), 82

Detailed reference viewed: 29 (0 ULg)