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See detailIdentification, production et caractérisation de l’amylolysine, un lantibiotique de Type-B produit par Bacillus amyloliquefaciens GA1
Arguelles Arias, Anthony ULg

Doctoral thesis (2014)

Bacillus amyloliquefaciens GA1, antérieurement dénommée Bacillus subtilis GA1, est décrit dans la littérature comme étant une souche capable d’inhiber la croissance de nombreux micro-organismes. Afin ... [more ▼]

Bacillus amyloliquefaciens GA1, antérieurement dénommée Bacillus subtilis GA1, est décrit dans la littérature comme étant une souche capable d’inhiber la croissance de nombreux micro-organismes. Afin d’identifier les molécules responsables de ces activités biologiques, un séquençage partiel et aléatoire du génome de cette souche a été entrepris au laboratoire. Parallèlement à ce séquençage, nous avons entrepris une caractérisation globale des propriétés biologiques des métabolites secondaires produits par cette souche. La production de ces métabolites, essentiellement de type PKs et NRPs, a été mise en évidence par chromatographie liquide couplée à la spectrométrie de masse (LC-MS). Ainsi, nous avons pu mettre en évidence la présence de plusieurs clusters de gènes mais également la production de lipopeptides, polykétides et sidérophores. Lors du séquençage partiel du génome de B. amyloliquefaciens GA1, l’identification d’une séquence de 800 paires de bases (bp) homologue à celle d’un gène de Bacillus licheniformis ATCC 14580 codant pour une enzyme de modification d’un lantibiotique (« Lanthionine containing antibiotic »), nous a permis d’émettre l’hypothèse que B. amyloliquefaciens GA1 pourrait produire une molécule de type lantibiotique. Afin de vérifier cette hypothèse, nous avons entrepris l’identification, la purification et la caractérisation de ce peptide antibactérien. Pour permettre cette caractérisation, nous avons tout d’abord mis au point une méthode de production et de purification adaptée aux lantibiotiques. En parallèle, un séquençage des gènes responsables de la biosynthèse de ce lantibiotique, dénommé amylolysine, a également été réalisé. Les gènes responsables de la biosynthèse du lantibiotique sont au nombre de sept, formant quatre opérons, pour une taille totale de 9,6 kilobases (kb). La masse moléculaire du lantibiotique purifié, ainsi que les gènes de biosynthèse de celui-ci, nous ont confirmé que le lantibiotique produit par B. amyloliquefaciens GA1 est un lantibiotique qui n’avait pas encore été décrit dans la littérature. Nous avons mis en évidence le mode d’action de cette bactériocine de Type 1 et initier une étude structurale de cette dernière. Nos résultats ont démontrés que l’amylolysine est un lantibiotique de Type-B bien que son mode d’action soit atypique pour ce type de molécule. En effet, l’amylolysine est capable, à la fois, d’interagir avec le lipide II, ce qui inhibe la synthèse du peptidoglycane, et de former des pores dans la membrane des bactéries sensibles. Ce double mode d’action, décrit chez les lantibiotiques de Type-A, n’a jamais été décrit chez les lantibiotiques de Type-B, qui, en général ne sont pas capables de former des pores dans la membrane des bactéries. Enfin, dans le but de démontrer une application biotechnologique de l’amylolysine, sa capacité à inhiber la croissance de souches pathogènes, tel que Listeria monocytogenes, sur de la viande de volaille a été démontrée et comparée à la nisine, un lantibiotique utilisé en tant qu’agent de conservation dans l’industrie agro-alimentaire depuis de nombreuses années. En plus d’inhiber la croissance de L. monocytogenes, nous avons démontré que l’amylolysine est plus stable que la nisine par rapport aux protéases présentes naturellement dans la viande de volaille. Ce qui fait de l’amylolysine un excellent candidat pour l’utilisation de cette dernière en tant qu’agent de conservation. [less ▲]

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See detailIdentificazione di un sito polimorfico al locus del GH bovino tramite PCR-RFLP
Messina, Mariella; Gerin, Daniel; Renaville, Robert ULg et al

in Soc. ITAL Buiatria vol XXXIII (2001)

Detailed reference viewed: 21 (0 ULg)
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See detailIdentifier et contacter un informateur
Brahy, Rachel ULg; Lejeune, Christophe ULg

Scientific conference (2012, February 14)

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See detailIdentifier les structures locales de décision
Vermeulen, Cédric ULg

in Triplet, Patrick (Ed.) Manuel de gestion des aires protégées d'afrique de L'ouest (2009)

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See detailIdentifying and computing nonlinear normal modes
Cammarano, A.; Carrella, A.; Renson, Ludovic ULg et al

in Proceedings of the SEM IMAC XXX Conference (2012, February)

Non linear normal modes offer a rigorous framework, both mathematical and physical, for theoretical and experimental dynamical analysis. Albeit still in its infancy, the concept of non linear normal modes ... [more ▼]

Non linear normal modes offer a rigorous framework, both mathematical and physical, for theoretical and experimental dynamical analysis. Albeit still in its infancy, the concept of non linear normal modes has the potential of providing to both the academic and the industrial establishment a powerful tool for the analysis of non linear dynamical systems. However, in order to exploit the full potential of this theory (and its associated simulation capability), there is need to integrate it with other branches of non linear structural dynamics: namely, in order for the non linear normal modes of a real - physical - structure to be computed, there is need to identify and quantify its non linearity. In this paper, an identification method based on the measured Frequency Response Function (FRF) is employed to identify and quantify the system's non linearity before computing the system's non linear normal modes. [less ▲]

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See detailIdentifying and modeling the integrated design process of net Zero Energy buildings
Attia, Shady ULg; Walter, Emmanuel; Andersen, Marilyne

in Proceedings of the High Performance Buildings - Design and Evaluation Methodologies Conference (2013, June)

High Performance Buildings (HPB), including Net Zero Energy Buildings (NZEBs) and nearly Zero Energy Buildings (nZEB) are emerging as an important market in Europe and around the world. However, there are ... [more ▼]

High Performance Buildings (HPB), including Net Zero Energy Buildings (NZEBs) and nearly Zero Energy Buildings (nZEB) are emerging as an important market in Europe and around the world. However, there are very few studies that aim to model the process of HPBs and define key design processes, decisions and competencies of design teams. More importantly, there is hardly any documentation processes on tools currently being used to design high performance building. Therefore, the purpose of this paper is to identify, model and propose a generic integrated process maps for HPB. The generic process map focuses on the design phases steps, roles and tools used. The research methodology is based on literature review and a case study. With the help of a process modelling software (TIBCO), a Swiss office building (Green Office) is used to validate the produced process maps. The visual maps delivers insights on the integrated design process reporting on the means of improving the delivery of HPBs. [less ▲]

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See detailIdentifying beneficiaries of poverty alleviation programs
Mai, Lan Phuong ULg; Nguyen Mau, Dung; Lebailly, Philippe ULg

in Economics and Development Review = Kinh té̂ và phát triẻ̂n (2011), Special issue(July 2011), 29-36

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See detailIdentifying codes in vertex-transitive graphs
Gravier, Sylvain; Parreau, Aline ULg; Rottey, Sara et al

Conference (2014, July)

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the optimal integer and fractional solutions is between 1 and 2 log(|V|) where V is the ... [more ▼]

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the optimal integer and fractional solutions is between 1 and 2 log(|V|) where V is the set of vertices of the graph. We focus on vertex-transitive graphs for which we can compute the exact fractional solution. There are known examples of vertex-transitive graphs that reach both bounds. We exhibit infinite families of vertex-transitive graphs with integer and fractional identifying codes of order |V|^a with a in {1/4, 1/3, 2/5}. These families are generalized quadrangles (strongly regular graphs based on finite geometries). They also provide examples for metric dimension of graphs. [less ▲]

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See detailIdentifying codes in vertex-transitive graphs and strongly regular graphs
Gravier, Sylvain; Parreau, Aline; Rottey, Sara et al

in Electronic Journal of Combinatorics (2015), 22(4), 46

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the size of optimal integer and fractional solutions is between 1 and 2ln(|V|)+1 where V ... [more ▼]

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the size of optimal integer and fractional solutions is between 1 and 2ln(|V|)+1 where V is the set of vertices of the graph. We focus on vertex-transitive graphs for which we can compute the exact fractional solution. There are known examples of vertex-transitive graphs that reach both bounds. We exhibit infinite families of vertex-transitive graphs with integer and fractional identifying codes of order |V|^α with α∈{14,13,25}. These families are generalized quadrangles (strongly regular graphs based on finite geometries). They also provide examples for metric dimension of graphs. [less ▲]

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See detailIdentifying cows with subclinical mastitis by bulk single nucleotide polymorphism genotyping of tank milk
Blard, G.; Zhang, Zhiyan ULg; Coppieters, Wouter ULg et al

in Journal of Dairy Science (2012), 95(7), 4109-13

Mastitis remains the most important health issue in dairy cattle. Improved methods to identify cows developing subclinical mastitis would benefit farmers. We herein describe a novel method to determine ... [more ▼]

Mastitis remains the most important health issue in dairy cattle. Improved methods to identify cows developing subclinical mastitis would benefit farmers. We herein describe a novel method to determine the somatic cell counts (SCC) of individual cows by bulk genotyping a sample of milk from the milk tank with panels of genome-wide single nucleotide polymorphisms (SNP). We developed a simple linear model to estimate the contribution of individual cows to the genomic DNA present in the tank milk from 1) the known genotypes of individual cows for the interrogated SNP and 2) the ratio of SNP alleles in the tank milk. Using simulations, we estimate that 3,000, 50,000, and 700,000 SNP are sufficient to accurately (R(2)>0.98) estimate individual SCC in tanks containing milk from 25, 100, and 500 cows, respectively. Using actual data, we demonstrate that the SCC of 21 cows can be estimated with a coefficient of determination of 0.60 using approximately 9,000 SNP. The proposed method increases the value of the proposition of SNP genotyping individual cows for genomic selection purposes. [less ▲]

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See detailIdentifying early Earth microfossils in unsilicified sediments
Javaux, Emmanuelle ULg; Asael, Dan; Bekker, Andrey et al

in Geophysical Research Abstracts (2013), 15

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See detailIdentifying endophenotypes of autism: a multivariate approach
Segovia-Román, Fermín ULg; Holt, Rosemary; Spencer, Michael et al

in Frontiers in Computational Neuroscience (2014), 8

The existence of an endophenotype of autism spectrum condition (ASC) has been recently suggested by several commentators. It can be estimated by finding differences between controls and people with ASC ... [more ▼]

The existence of an endophenotype of autism spectrum condition (ASC) has been recently suggested by several commentators. It can be estimated by finding differences between controls and people with ASC that are also present when comparing controls and the unaffected siblings of ASC individuals. In this work, we used a multivariate methodology applied on magnetic resonance images to look for such differences. The proposed procedure consists of combining a searchlight approach and a support vector machine classifier to identify the differences between three groups of participants in pairwise comparisons: controls, people with ASC and their unaffected siblings. Then we compared those differences selecting spatially collocated as candidate endophenotypes of ASC. [less ▲]

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See detailIdentifying environmental risk factors for endemic cholera: a raster GIS approach
Ali, M.; Emch, M.; Donnay, Jean-Paul ULg et al

in Health & Place (2002), 8(3), 201-210

The bacteria that cause cholera are known to be normal inhabitants of surface water, however, the environmental risk factors for different biotypes of cholera are not well understood. This study ... [more ▼]

The bacteria that cause cholera are known to be normal inhabitants of surface water, however, the environmental risk factors for different biotypes of cholera are not well understood. This study identifies environmental risk factors for cholera in an endemic area of Bangladesh using a geographic information systems (GIS) approach. The study data were collected from a longitudinal health and demographic surveillance system and the data were integrated within a geographic information system database of the research area. Two study periods were chosen because they had different dominant biotypes of the disease. From 1992 to 1996 El Tor cholera was dominant and from 1983 to 1987 classical cholera was dominant. The study found the same three risk factors for the two biotypes of cholera including proximity to surface water, high population density, and poor educational level. The GIS database was used to measure the risk factors and spatial filtering techniques were employed. These robust spatial methods are offered as an example for future epidemiological research efforts that define environmental risk factors for infectious diseases. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailIdentifying Inflammatory Bowel Disease causative genes through trans-eQTLs mapping within GWAS loci
Docampo Martínez, Elisa ULg; Theatre, Emilie ULg; Dmitrieva, Joelia Borisnova ULg et al

Poster (2014, April 24)

Lifetime prevalence of inflammatory bowel disease (IBD) is reaching an alarming rate of >1/400 in industrialized societies. Improved understanding of disease pathogenesis is essential to develop more ... [more ▼]

Lifetime prevalence of inflammatory bowel disease (IBD) is reaching an alarming rate of >1/400 in industrialized societies. Improved understanding of disease pathogenesis is essential to develop more effective preventive, diagnostic and therapeutic measures. Genome-wide association studies (GWAS) have identified ~ 160 risk loci contributing to inherited predisposition to IBD, leading to the identification of new perturbed pathways and potential drug targets. Nevertheless, causative genes and variants remain unknown for the vast majority of risk loci. GWAS loci are likely to be regulatory and therefore alter expression levels of other genes. We hypothesize that if an IBD associated SNP is an expression quantitative loci (eQTL)-the " disease-association pattern " (DAP) should mirror the " eQTL association pattern " (EAP) of the causative gene if looking in the right target tissue(s). With this premise, our project aims to detect causative genes implicated in IBD's susceptibility through the evaluation of trans-eQTLs within GWAS loci. To this purpose, nine blood cell types and ileal, colonic and rectal biopsies have been collected for 330 healthy individuals of Northern European descent. All individuals have been genotyped with the OmniExpress Illumina array interrogating > 700K genetic variants. Transcriptome analysis has been conducted for all individuals and all cell/tissue types using Illumina HT12 arrays interrogating > 47,000 transcripts. Genotype and transcriptome data have undergone rigorous quality control. Transcriptome data have been pretreated variance stabilizing transformation, QQ normalization and correction for random and fixed effects in each cell type. Only expression probes mapped against Refseq have been considered. Genomic positions have been recovered and probes mapping to more than one genomic position (taking into account splice junctions with Tophat software) with a 96% identity have been discarded. Trans-eQTL mapping will be conducted on a SNP-by-SNP basis using linear regression (additive model) with PLINK software. In order to circumvent genome wide multiple testing penalty, we will test for a given SNP in the genome, any evidence for an excess of low p-values when testing its effect on the expression of genes located on other chromosomes or far away on the same chromosome. Confirmation of putative multigene transregulators will afterwards be performed by RNAseq experiments. We will then quantify the resemblance between DAP in the 160 GWAS-identified risk loci (raw data from IIBDGC plus imputed data) and " multigene trans-EAP " with Spearman's rank correlation. We will also evaluate the biological relevance of this list by performing a network analysis after adding the identified trans targets to the list of previously identified positional candidate genes (mapping to GWAS-identified IBD risk loci). Finally, as a the ultimate proof of causality, the selected genes will be resequenced in 3,000 IBD cases and 3,000 controls, using 600 DNA pools of 10 individuals with Illumina Truseq Amplicon. With this strategy, we expect to detect new causative variants that may constitute new drug targets for IBD. Latest results will be presented. [less ▲]

Detailed reference viewed: 57 (3 ULg)
See detailIdentifying Late Egyptian Virtual Relative Clauses
Sojic, Nathalie ULg

Conference (2016, February 19)

Ancient Egyptian so-called "virtual" relative clauses (VRC) are adverbial clauses that function like relative clauses. Descriptions provided by Late Egyptian grammars inform students of their existence ... [more ▼]

Ancient Egyptian so-called "virtual" relative clauses (VRC) are adverbial clauses that function like relative clauses. Descriptions provided by Late Egyptian grammars inform students of their existence and of the possibility to translate them accordingly. But they are not of a great help if one wants to grasp and describe the Late Egyptian relativization system in a linguistic perspective. The talk, given on the occasion of the international Crossroads V conference, aimed at providing interpretive guidelines based on syntax, pragmatics and Discourse Analysis. In my communication, I showed that Discourse Analysis proved to be very fruitful in clarifying some contexts of use of LEg VRCs as well as some interpretive processes. [less ▲]

Detailed reference viewed: 21 (1 ULg)