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 detailMutation de l'image, mutation de l'intention ? L'impact des représentations numériques en composition architecturale
Cunin, Maxime; Yang, Maria C.; Elsen, Catherine ULg

in de Boissieu, Aurélie; Deshayes, Catherine; Tufano, Antonella (Eds.) Mutations du Projet - Milieux et Cultures Numériques (2015, June)

Les architectes ont toujours eu recours à de multiples représentations pour générer, faire évoluer puis communiquer leurs concepts architecturaux (tant aux pairs qu’aux usagers, ou encore aux décideurs ... [more ▼]

Les architectes ont toujours eu recours à de multiples représentations pour générer, faire évoluer puis communiquer leurs concepts architecturaux (tant aux pairs qu’aux usagers, ou encore aux décideurs). Cet article envisage comment la représentation externe impacte la perception « naïve » d’une intention architecturale, les « non experts » assumant des rôles de plus fondamentaux au sein de certains mécanismes décisionnels. Comment l’image, en pleine mutation depuis l’ère du numérique, façonne-t-elle la perception des facteurs clés (ou « attributs ») d’une intention architecturale ? L’article résume les principaux résultats d’une enquête menée en ligne via l’interface « Amazon Mechanical Turk » et générant 790 échelles d’évaluation de 6 avant-projets architecturaux. Les résultats abordent l’analyse des données en regard des différentes attributs; en regard des trois types de représentation choisies et en regard enfin des inconsistances dont font preuve les architectes eux-mêmes, étant donné l’évaluation de leurs propres projets et représentations. Ils révèlent que les attributs ne sont pas équitablement propices à un transfert d’intention exclusivement graphique et que les formes plus abstraites de représentations constituent, dans certains contextes, le moyen le plus efficace pour le transfert fidèle d’une intention architecturale. [less ▲]

Detailed reference viewed: 27 (8 ULg)
See detailMutation de LH
Beckers, Albert ULg

Scientific conference (2007, June 30)

Detailed reference viewed: 3 (0 ULg)
See detailMutation de LH
Beckers, Albert ULg

Scientific conference (2007, May 26)

Detailed reference viewed: 4 (1 ULg)
Full Text
See detailMutation des systèmes partisans et résultats électoraux : Proportion congrue et gouvernabilité
Verjans, Pierre ULg

in Matagne, Geoffroy; Beaufays, Jean (Eds.) La Belgique en mutation : Systèmes politiques et politiques publiques (1968-2008) (2009)

Detailed reference viewed: 56 (4 ULg)
Full Text
Peer Reviewed
See detailMutation douce de l'enseignant en concepteur-tuteur dans des activités d'apprentissage totalement à distance. Communication présentée au Colloque TICE Méditérannée, Nice
Vandeput, Etienne ULg; Denis, Brigitte ULg

in Actes du colloque TICE Méditérannée (en ligne) (2004, November 26)

Experts in education and communication technology cannot speak about distance learning without calling up the new roles it springs up and the new relationships it generates. Its detractors claim that ... [more ▼]

Experts in education and communication technology cannot speak about distance learning without calling up the new roles it springs up and the new relationships it generates. Its detractors claim that, under these new conditions, this kind of learning requires significant and expansive means unlike a more classical one. Instead of giving up in front of such disheartening elements, the authors have been trying to measure how far a simple distance learning system (i.e. with little human, hardware and software means) can be implemented. In that way, they have been creating a learning environment basically based on a mixture of individual and collaborative works. Owing to both this mixture and the organization structure, the students can reach the fixed learning goals. Through these processes, they try to isolate practices, learners or teaching staff should be inspired by. They should, in that way, evolve slightly from a classical context to the design of learning scripts including efficient tutoring in a distance context. The course described in this paper is called “Analysis of distance learning environments”. The public consists of adults having enrolled for a DES in Education and Training Technology. To conduct this experiment, the authors have been setting themselves some rules and constraints in order to derive a general process that might be applied to various situations. These rules and constraints are very close to the usual learner’s working constraints. Recommendations focus on practices including careful preparation, coordination techniques betweenteachers and learner’s initiation into reflexivity. [less ▲]

Detailed reference viewed: 55 (11 ULg)
See detailMutation du gène AIP dans les FIPA
Beckers, Albert ULg

Scientific conference (2006, December 02)

Detailed reference viewed: 16 (0 ULg)
Peer Reviewed
See detailMutation in exon 5 of bovine prolactin gene is not associated with milk traits in Holstein bulls.
Parmentier, Isabelle; Gengler, Nicolas ULg; Laliberte, P. et al

in ASAS/ADSA Joint Meeting (2000, July)

Detailed reference viewed: 10 (0 ULg)
Peer Reviewed
See detailMutation in exon 5 of bovine prolactin gene is not associated with milk traits in Holstein bulls.
Parmentier, Isabelle; Gengler, Nicolas ULg; Laliberte, P. et al

in Journal of Animal Science (2000), 78(Suppl 1),

Detailed reference viewed: 7 (2 ULg)
Full Text
Peer Reviewed
See detailA mutation in the GTPase domain of the large subunit rRNA is involved in the suppression of a -1T frameshift mutation affecting a mitochondrial gene in Chlamydomonas reinhardtii
Matagne, René-Fernand ULg; Baurain, Denis ULg

in Molecular Genetics & Genomics (2001), 266(1), 103-108

The dum19 mutation isolated in Chlamydomonas reinhardtii is due to the deletion of one T at codon 152 of the mitochondrial cox1 gene sequence. Phenotypically, the dum19 mutant is characterized by a lack ... [more ▼]

The dum19 mutation isolated in Chlamydomonas reinhardtii is due to the deletion of one T at codon 152 of the mitochondrial cox1 gene sequence. Phenotypically, the dum19 mutant is characterized by a lack of cytochrome c oxidase activity and is unable to grow under heterotrophic conditions. A spontaneous pseudo-revertant that grows slowly in the dark was isolated from the dum19 mutant strain. A genetic and molecular analysis allowed us to demonstrate that the revertant phenotype is the consequence of two additional mutations that together act as a frameshift suppressor: an m mutation affecting a mitochondrial gene other than cox1 and an n mutation affecting a nuclear gene. On its own the n mutation does not act as a suppressor, whereas the m mutation very slightly compensates for the effect of the -1T mutation. Sequencing analysis showed that the m mutation affects the GTPase-associated domain of the large subunit (LSU) ofmitochondrial rRNA. Surprisingly, two substitutions, A1090 to G and A1098 to C, were found in the LSU rRNA of the revertant, the latter one being already present in the dum19 mutant strain itself. The A1090 to G substitution is thus involved in the suppression of the frameshift mutation, but it is not clear whether the change at position 1098 is also required for the expression of the suppressed phenotype. To our knowledge, this is the first example of a mutation in the GTPase-associated domain acting as a suppressor of a frameshift mutation. [less ▲]

Detailed reference viewed: 6 (1 ULg)
Full Text
Peer Reviewed
See detailTHE MUTATION LYS234HIS YIELDS A CLASS-A BETA-LACTAMASE WITH A NOVEL PH-DEPENDENCE
BRANNIGAN, J.; Matagne, André ULg; Jacob, Françoise et al

in Biochemical Journal (1991), 278(Part 3), 673-678

The lysine-234 residue is highly conserved in beta-lactamases and in nearly all active-site-serine penicillin-recognizing enzymes. Its replacement by a histidine residue in the Streptomyces albus G class ... [more ▼]

The lysine-234 residue is highly conserved in beta-lactamases and in nearly all active-site-serine penicillin-recognizing enzymes. Its replacement by a histidine residue in the Streptomyces albus G class A beta-lactamase yielded an enzyme the pH-dependence of which was characterized by the appearance of a novel pK, which could be attributed to the newly introduced residue. At low pH, the k(cat.) value for benzylpenicillin was as high as 50 % of that of the wild-type enzyme, demonstrating that an efficient active site was maintained. Both k(cat.) and k(cat.)/K(m) dramatically decreased above pH 6 but the decrease in k(cat.)/K(m) could not be attributed to larger K(m) values. Thus a positive charge on the side chain of residue 234 appears to be more essential for transition-state stabilization than for initial recognition of the substrate ground state. [less ▲]

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailMutation of a Single Envelope N-linked Glycosylation Site Enhances the Pathogenicity of Bovine Leukemia Virus
De Brogniez, Alix ULg; Bouzar, Amel-Baya; Jacques, Jean-Rock ULg et al

in Journal of Virology (2015), 89(17),

Viruses have co-evolved with their host to ensure efficient replication and transmission without inducing excessive pathogenicity that would indirectly impair their persistence. This is exemplified by the ... [more ▼]

Viruses have co-evolved with their host to ensure efficient replication and transmission without inducing excessive pathogenicity that would indirectly impair their persistence. This is exemplified by the bovine leukemia virus (BLV) system in which lymphoproliferative disorders develop in ruminants after latency periods of several years. In principle, the equilibrium reached between the virus and its host could be disrupted by emergence of more pathogenic strains. Intriguingly but fortunately, such a hyperpathogenic BLV strain was never observed in the field nor designed in vitro. In this study, we aimed at understanding the role of envelope N-linked glycosylation with the hypothesis that this posttranslational modification could either favor BLV infection by allowing viral entry or allow immune escape by using glycans as a shield. Using reverse genetics of an infectious molecular provirus, we have identified a N-linked envelope glycosylation site (N230) that limits viral replication and pathogenicity. Indeed, mutation N230E unexpectedly leads to enhanced fusogenicity and protein stability. Occurrence of this mutation may thus represent a potential threat associated with emergence of hyperpathogenic BLV strains and possibly of new variants of the related primate T-lymphotropic viruses. [less ▲]

Detailed reference viewed: 14 (5 ULg)
Full Text
Peer Reviewed
See detailMutation of the iron-sulfur cluster assembly gene IBA57 causes fatal infantile leukodystrophy.
DEBRAY, François-Guillaume ULg; Stumpfig, Claudia; Vanlander, Arnaud V. et al

in Journal of inherited metabolic disease (2015)

Leukodystrophies are a heterogeneous group of severe genetic neurodegenerative disorders. A multiple mitochondrial dysfunctions syndrome was found in an infant presenting with a progressive ... [more ▼]

Leukodystrophies are a heterogeneous group of severe genetic neurodegenerative disorders. A multiple mitochondrial dysfunctions syndrome was found in an infant presenting with a progressive leukoencephalopathy. Homozygosity mapping, whole exome sequencing, and functional studies were used to define the underlying molecular defect. Respiratory chain studies in skeletal muscle isolated from the proband revealed a combined deficiency of complexes I and II. In addition, western blotting indicated lack of protein lipoylation. The combination of these findings was suggestive for a defect in the iron-sulfur (Fe/S) protein assembly pathway. SNP array identified loss of heterozygosity in large chromosomal regions, covering the NFU1 and BOLA3, and the IBA57 and ABCB10 candidate genes, in 2p15-p11.2 and 1q31.1-q42.13, respectively. A homozygous c.436C > T (p.Arg146Trp) variant was detected in IBA57 using whole exome sequencing. Complementation studies in a HeLa cell line depleted for IBA57 showed that the mutant protein with the semi-conservative amino acid exchange was unable to restore the biochemical phenotype indicating a loss-of-function mutation of IBA57. In conclusion, defects in the Fe/S protein assembly gene IBA57 can cause autosomal recessive neurodegeneration associated with progressive leukodystrophy and fatal outcome at young age. In the affected patient, the biochemical phenotype was characterized by a defect in the respiratory chain complexes I and II and a decrease in mitochondrial protein lipoylation, both resulting from impaired assembly of Fe/S clusters. [less ▲]

Detailed reference viewed: 8 (4 ULg)
See detailMutation politiques et socioéconomiques latino-américaines
Santander, Sébastian ULg

Conference given outside the academic context (2009)

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailMutation update for the PORCN gene.
Lombardi, Maria Paola; BULK, Saskia ULg; Celli, Jacopo et al

in Human mutation (2011), 32(7), 723-8

Mutations in the PORCN gene were first identified in Goltz-Gorlin syndrome patients in 2007. Since then, several reports have been published describing a large variety of genetic defects resulting in the ... [more ▼]

Mutations in the PORCN gene were first identified in Goltz-Gorlin syndrome patients in 2007. Since then, several reports have been published describing a large variety of genetic defects resulting in the Goltz-Gorlin syndrome, and mutations or deletions were also reported in angioma serpiginosum, the pentalogy of Cantrell and Limb-Body Wall Complex. Here we present a review of the published mutations in the PORCN gene to date and report on seven new mutations together with the corresponding clinical data. Based on the review we have created a Web-based locus-specific database that lists all identified variants and allows the inclusion of future reports. The database is based on the Leiden Open (source) Variation Database (LOVD) software, and is accessible online at http://www.lovd.nl/porcn. At present, the database contains 106 variants, representing 68 different mutations, scattered along the whole coding sequence of the PORCN gene, and 12 large gene rearrangements, which brings up to 80 the number of unique mutations identified in Goltz-Gorlin syndrome patients. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailMutational analysis of the catalytic centre of the Citrobacter freundii AmpD N-acetylmuramyl-L-alanine amidase
Genereux, Catherine ULg; Dehareng, Dominique ULg; Devreese, Bart et al

in Biochemical Journal (2004), 377(Pt 1), 111-120

Citrobacter freundii AmpD is an intracellular 1,6-anhydro-N-acetylmuramyl-L-alanine amidase involved in both peptidoglycan recycling and beta-lactamase induction. AmpD exhibits a strict specificity for 1 ... [more ▼]

Citrobacter freundii AmpD is an intracellular 1,6-anhydro-N-acetylmuramyl-L-alanine amidase involved in both peptidoglycan recycling and beta-lactamase induction. AmpD exhibits a strict specificity for 1,6-anhydromuropeptides and requires zinc for enzymic activity. The AmpD three-dimensional structure exhibits a fold similar to that of another Zn2+ N-acetylmuramyl-L-alanine amidase, the T7 lysozyme, and these two enzymes define a new family of Zn-amidases which can be related to the eukaryotic PGRP (peptidoglycan-recognition protein) domains. In an attempt to assign the different zinc ligands and to probe the catalytic mechanism of AmpD amidase, molecular modelling based on the NMR structure and site-directed mutagenesis were performed. Mutation of the two residues presumed to act as zinc ligands into alanine (H34A and D164A) yielded inactive proteins which had also lost their ability to bind zinc. By contrast, the active H154N mutant retained the capacity to bind the metal ion. Three other residues which could be involved in the AmpD catalytic mechanism have been mutated (Y63F, E116A, K162H and K162Q). The E116A mutant was inactive, but on the basis of the molecular modelling this residue is not directly involved in the catalytic mechanism, but rather in the binding of the zinc by contributing to the correct orientation of His-34. The K162H and K162Q mutants retained very low activity (0.7 and 0.2% of the wildtype activity respectively), whereas the Y63F mutant showed 16% of the wild-type activity. These three latter mutants exhibited a good affinity for Zn ions and the substituted residues are probably involved in the binding of the substrate. We also describe a new method for generating the N-acetylglucosaminyl-1,6-anhydro-N-acetylmuramyl-tripeptide AmpD substrate from purified peptidoglycan by the combined action of two hydrolytic enzymes. [less ▲]

Detailed reference viewed: 41 (10 ULg)
Peer Reviewed
See detailMutational analysis of the p50 subunit of NF-kappa B and inhibition of NF-kappa B activity by trans-dominant p50 mutants.
Bressler, P.; Brown, K.; Timmer, W. et al

in Journal of Virology (1993), 67(1), 288-93

The NF-kappa B family of DNA-binding proteins regulates the expression of many cellular and viral genes. Each of these proteins has an N-terminal region that is homologous to the c-Rel proto-oncogene ... [more ▼]

The NF-kappa B family of DNA-binding proteins regulates the expression of many cellular and viral genes. Each of these proteins has an N-terminal region that is homologous to the c-Rel proto-oncogene product, and this Rel homology region defines both DNA binding and protein dimerization properties of the individual proteins. Most of the NF-kappa B family members have been shown to associate with themselves or with each other to form homodimers or heterodimers, and previous studies have shown that dimerization of NF-kappa B factors is necessary to provide a functional DNA binding domain. We have used site-directed mutagenesis to identify regions in the Rel homology domain of the p50/NF-kappa B protein that are important for DNA binding and protein dimerization. Our studies have identified mutations of p50 that interfere with DNA binding only and those that interfere with protein dimerization. Mutations of p50 which disrupt only DNA binding were still able to associate with other members of the NF-kappa B protein family. We demonstrate that such heterodimeric complexes inhibit transcriptional activation mediated in trans through a cis-acting kappa B motif; therefore, we have identified trans-dominant negative mutants of p50. [less ▲]

Detailed reference viewed: 2 (0 ULg)
Full Text
Peer Reviewed
See detailMutational Analysis Of The Tre2 Oncogene Encoding An Inactive Rabgap
Bizimungu, C.; Thomas, Annick ULg; Brasseur, Robert ULg et al

in Biotechnology Letters (2007), 29(12), 1927-37

The TRE2 oncoprotein is structurally related to the RabGAP (GTPase-activating protein) family. However, TRE2 seems enzymatically inactive. Two regions are important for its lack of GAP activity. First ... [more ▼]

The TRE2 oncoprotein is structurally related to the RabGAP (GTPase-activating protein) family. However, TRE2 seems enzymatically inactive. Two regions are important for its lack of GAP activity. First, the TBC domain, forming the catalytically active domain of RabGAPs, is non-functional in the oncoprotein. Also involved in TRE2 inactivity is the 93-aa region flanking the TBC domain on the C-terminal side. In order to identify the residues responsible for non-functionality, we performed hydrophobic cluster analysis of the oncoprotein sequence, combined with secondary structure prediction, receptor-binding domain analysis, and a tilted peptide calculation. These analyses were complemented with site-directed and random mutagenesis experiments. On the basis of our data, we hypothesize that the lack of secondary structure of the region flanking the TBC domain in TRE2 may explain why this region plays a role in the lack of GAP activity, even when a potentially functional TBC domain is present. [less ▲]

Detailed reference viewed: 12 (1 ULg)
Full Text
Peer Reviewed
See detailMutational analysis of the two zinc-binding sites of the Bacillus cereus 569/H/9 metallo-beta-lactamase
De Seny, Dominique ULg; Prosperi, Christelle ULg; Bebrone, Carine ULg et al

in Biochemical Journal (2002), 363(Pt 3), 687-696

The metallo-beta-lactamase BcII from Bacillus cereus 569/H/9 possesses a binuclear zinc centre. The mono-zinc form of the enzyme displays an appreciably high activity. although full efficiency is observed ... [more ▼]

The metallo-beta-lactamase BcII from Bacillus cereus 569/H/9 possesses a binuclear zinc centre. The mono-zinc form of the enzyme displays an appreciably high activity. although full efficiency is observed for the di-zinc enzyme. In an attempt to assign the involvement of the different zinc ligands in the catalytic properties of BcII, individual substitutions of selected amino acids were generated. With the exception of His(116) --> Ser (H116S), C221A and C221S, the mono- and di-zinc forms of all the other mutants were poorly active. The activity of H116S decreases by a factor of 10 when compared with the wild type. The catalytic efficiency of C221A and C221S was zinc-dependent. The monozinc forms of these mutants exhibited a low activity, whereas the catalytic efficiency of their respective di-zinc forms was comparable with that of the wild type. Surprisingly, the zinc contents of the mutants and the wild-type Bell were similar. These data suggest that the affinity of the beta-lactamase for the metal was not affected by the substitution of the ligand. The pH-dependence of the H196S catalytic efficiency indicates that the zinc ions participate in the hydrolysis of the beta-lactam ring by acting as a Lewis acid. The zinc ions activate the catalytic water molecule, but also polarize the carbonyl bond of the beta-lactam ring and stabilize the development of a negative charge on the carbonyl oxygen of the tetrahedral reaction intermediate. Our studies also demonstrate that Asn(233) is not directly involved in the interaction with the substrates. [less ▲]

Detailed reference viewed: 35 (8 ULg)
Full Text
Peer Reviewed
See detailMutational analysis of the zinc- and substrate-binding sites in the CphA metallo-beta-lactamase from Aeromonas hydrophila.
Bebrone, Carine ULg; Anne, Christine; Kerff, Frédéric ULg et al

in Biochemical Journal (2008), 414(1), 151-9

The subclass B2 CphA (Carbapenemase hydrolysing Aeromonas) beta-lactamase from Aeromonas hydrophila is a Zn(2+)-containing enzyme that specifically hydrolyses carbapenems. In an effort to evaluate ... [more ▼]

The subclass B2 CphA (Carbapenemase hydrolysing Aeromonas) beta-lactamase from Aeromonas hydrophila is a Zn(2+)-containing enzyme that specifically hydrolyses carbapenems. In an effort to evaluate residues potentially involved in metal binding and/or catalysis (His(118), Asp(120), His(196) and His(263)) and in substrate specificity (Val(67), Thr(157), Lys(224) and Lys(226)), site-directed mutants of CphA were generated and characterized. Our results confirm that the first zinc ion is in interaction with Asp(120) and His(263), and thus is located in the 'cysteine' zinc-binding site. His(118) and His(196) residues seem to be interacting with the second zinc ion, as their replacement by alanine residues has a negative effect on the affinity for this second metal ion. Val(67) plays a significant role in the binding of biapenem and benzylpenicillin. The properties of a mutant with a five residue (LFKHV) insertion just after Val(67) also reveals the importance of this region for substrate binding. This latter mutant has a higher affinity for the second zinc ion than wild-type CphA. The T157A mutant exhibits a significantly modified activity spectrum. Analysis of the K224Q and N116H/N220G/K224Q mutants suggests a significant role for Lys(224) in the binding of substrate. Lys(226) is not essential for the binding and hydrolysis of substrates. Thus the present paper helps to elucidate the position of the second zinc ion, which was controversial, and to identify residues important for substrate binding. [less ▲]

Detailed reference viewed: 43 (7 ULg)