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See detailCharacterization of mycosubtilin, a natural antifungal agent, in membrane biomimetic systems
Nasir, Mehmet Nail ULg; Kouzayha, Achraf; Wattraint, Olivier et al

Poster (2008)

The emergence of several diseases which affects immune system (HIV infections, few cancers) and the expansion of immunosuppressive and chemical anticancer therapies increase mycosis frequency. Treatments ... [more ▼]

The emergence of several diseases which affects immune system (HIV infections, few cancers) and the expansion of immunosuppressive and chemical anticancer therapies increase mycosis frequency. Treatments currently used to cure mycoses meet problems such as antifungal agent toxicity or pathogenic strain resistance. Thus there is increasing interest for new medical applications of antifungal molecules. In this context, we investigated the behaviour of an antifungal lipopeptide, mycosubtilin, on cytoplasmic membranes. In this aim, biomimetic systems of biological membranes, such as lipid monolayers at the air-water interface and lipid multilayers were used. The interactions of mycosubtilin with these biomimetic systems were examined by different methods (kinetic isotherms, Brewster angle microscopy, FTIR spectroscopy and 1H HR- Magic Angle Spinning NMR). We demonstrated an original behaviour of mycosubtilin in the presence of sterol monolayer, suggesting a mycosubtilin-sterol affinity. We showed as well that mycosubtilin can interact with C=O ester residues and alkyl chains of phospholipids. Moreover, mycosubtilin has a preference for condensed phospholipid domains. [less ▲]

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See detailCharacterization of nanometer-scale roughness in SBA-15 mesoporous silica using image analysis of electron tomograms
Friedrich, Heiner; Gommes, Cédric ULg; de Jongh, Petra et al

Conference (2009, September)

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See detailCharacterization of Nest Sites of Chimpanzees (Pan troglodytes schweinfurthii) in Kibira National Park, Burundi
Hakizimana, Dismas; Hambuckers, Alain ULg; Brotcorne, Fany ULg et al

in African Primates (2015), 10

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites ... [more ▼]

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites by chimpanzees is available for other locations of the species’ range, this information is lacking for Kibira National Park. This is mainly due to the political troubles that prevailed in the country from 1993 until 2007, making study there difficult. To better protect this chimpanzee population, it is crucial to survey nest sites to identify the tree species, physical characteristics of the trees and habitat type that chimpanzees preferentially use for nesting. Therefore, in this study, we investigated: 1) the tree species used by chimpanzees for building their nests; 2) nest tree availability in the study area; 3) whether chimpanzee selection of a nest tree is based on physical characteristics such as diameter at breast height, lowest branch height, tree size and crown height; and 4) whether chimpanzees choose their nest sites according to topography and canopy types. We collected data monthly along 16 transects of 3 km each, from September 2011 to February 2013 (18 months). However, data related to the measurements of nests and nest trees were collected for only the last 12 months, from March 2012 to February 2013. We identified tree species used for nesting, and measured physical characteristics of trees used as opposed to surrounding trees unused. The results showed that chimpanzees select certain tree species to build their nests. Among the 32 species of trees bearing nests, chimpanzees used 12 species significantly more frequently than expected and 11 species significantly less frequently than expected. In addition, trees bearing nests were significantly larger and taller than the surrounding trees and had higher lowest branch and bigger canopies. [less ▲]

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See detailCharacterization of new bacterial glycoside hydrolases isolated from agricultural soils using a functional metagenomic approach
Biver, Sophie ULg; Dubois, Benjamin; Stroobants, Aurore ULg et al

Poster (2013, June 10)

Microorganisms play key roles in soil ecosystem functioning, notably through their ability to degrade plant cell wall polymers. For this, bacteria and fungi produce various enzymes such as cellulases ... [more ▼]

Microorganisms play key roles in soil ecosystem functioning, notably through their ability to degrade plant cell wall polymers. For this, bacteria and fungi produce various enzymes such as cellulases, xylanases, glucosidases, esterases or laccases. Finding new enzymes hydrolyzing cellulose, hemicellulose or lignin is not only interesting for a better understanding of the roles of the soil microflora still largely unknown but these enzymes are also useful for various biotechnological applications such as the production of renewable energy from lignocellulosic material. So here, we used a functional metagenomic approach to isolate new bacterial β-glucosidases, which were then biochemically characterized. The new enzymes were identified by functional analysis of agricultural-soil metagenomic libraries hosted in Escherichia coli and screened on medium containing esculin. After sequence analysis and preliminary estimation of the activity of the new β-glucosidases using p-nitrophenol derivatives on intact bacterial cells, the coding sequences of three of them were cloned into a bacterial expression vector so as to overproduce and purify them by affinity chromatography. The chosen enzymes show only 52-64% sequence identity to known family 3 (GH3) or 1 (GH1) glycoside hydrolases of different phyla (Actinobacteria, Acidobacteria and Proteobacteria). Analysis of the E. coli cells expressing each of them revealed that both GH1 proteins (ASEsc9 and ASEsc10) are thermophilic enzymes more active at mildly acidic to neutral pH while the GH3 enzyme (ASEsc6) is an alkaline, mesophilic, β-glucosidase also displaying xylosidase activity. Their coding sequences have been cloned in fusion with a carboxy-terminal His-tag and placed under the control of the IPTG-inducible promoter of the pET-30b vector. The proteins will be overproduced and purified for further characterization. [less ▲]

Detailed reference viewed: 287 (14 ULg)
See detailCharacterization of new fluorescent siderophores produced by Pseudomonas sp.
Jacques, Philippe ULg; Hautot, D.; Roblain, D. et al

Poster (1989, May)

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See detailCharacterization of non pigmented B16 melanoma cell-derived cytotoxic factors.
Siwek, B.; De Pauw-Gillet, Marie-Claire ULg; Quetin-Leclercq, J. et al

in Chemico-Biological Interactions (1997), 103(1), 59-73

We analyzed and tried to characterize substance(s) responsible for cytotoxic activities detected in culture media conditioned by non pigmented B16 melanoma cells (NPB16). The different cytological tests ... [more ▼]

We analyzed and tried to characterize substance(s) responsible for cytotoxic activities detected in culture media conditioned by non pigmented B16 melanoma cells (NPB16). The different cytological tests used showed that ultrafiltrated conditioned media (CM U1 fraction) contained several cytotoxic factors with a Mw lower than 1000 Da. These factors seemed to act either directly or indirectly on cell membranes, mitochondria, on the cell cycle and on protein and DNA synthesis. A cytotoxic activity could be found even after high dilution of CM U1. These cytotoxic factors were rapidly released by B16 cells in culture, independently of cell confluence. Their activities in the treated cells were also very fast and the cytotoxic effects were irreversible after only a few hours of treatment. These factors were not intermediate products during melanogenesis, neither polyamines, nor proteases. At least one of them seemed to be a small acidic and basic stable peptide without disulfide bounds but not heat stable. The synthesis of at least one of these cytotoxic factors was inhibited by cycloheximide and the cytotoxic activity was partially destroyed by pronase and trypsin, but not by pepsin. The cytotoxicity was not modified by copper complexants or free radical inhibitors (bovine serum albumin (BSA), tyrosine, superoxyde dismutase (SOD), catalase, vitamin E). Furthermore the levels of glutathione peroxydase activity and reduced glutathione did not change after treatment by CM U1 as compared to controls. [less ▲]

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See detailCharacterization of nonlinear aeroservoelastic behaviour
Dimitriadis, Grigorios ULg; Cooper, Jonathan Edware

in RTO-MP-036 Structural Aspects of Flexible Aircraft Control (1999, October)

The characterisation of the behaviour of nonlinear aeroelastic systems has become a very important re- search topic. Nevertheless, most of the work carried out to date concerns the development of unsteady ... [more ▼]

The characterisation of the behaviour of nonlinear aeroelastic systems has become a very important re- search topic. Nevertheless, most of the work carried out to date concerns the development of unsteady CFD solutions in the transonic region. Important though this work is, there is also a need for research which aims at understanding the behaviour of non- linear systems, particularly the occurance of Limit Cycle Oscillations (LCOs). The purpose of this pa- per is to study the stability of a simple aeroservoelas- tic system with nonlinearities in the control system. The work considers both structural and control law nonlinearities and assesses the stability of the system response by use of bifurcation diagrams. It is shown that simple feedback systems designed to increase the stability of the linearised system also stabilise the nonlinear system, although their effects can be less pronounced. Additionally, a nonlinear control law designed to limit the control surface pitch response was found to increase the flutter speed considerably by forcing the system to undergo limit cycle oscilla- tions instead of fluttering. Finally, friction was found to affect the damping of the system but not its sta- bility, as long as the amplitude of the frictional force is low enough not to cause stoppages in the motion. [less ▲]

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See detailCharacterization of olefins from enzymatically interesterified palm oil
Gibon, Véronique; Maes, Jeroen; Dijckmans, Peggy et al

Poster (2013)

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See detailCharacterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Frare, Erica; Mossuto, Maria F.; Polverino de Laureto, Patrizia et al

in Journal of Molecular Biology (2009)

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See detailCharacterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Frare, Erica; Mossuto, Maria F.; Polverino de Laureto, Patrizia et al

in Journal of Molecular Biology (2009), 387

has been analyzed by characterizing a series of distinct species formed on the aggregation pathway, specifically the amyloidogenic monomeric precursor protein, the oligomeric soluble prefibrillar ... [more ▼]

has been analyzed by characterizing a series of distinct species formed on the aggregation pathway, specifically the amyloidogenic monomeric precursor protein, the oligomeric soluble prefibrillar aggregates, and the mature fibrils. Particular attention has been focused on the analysis of the structural properties of the oligomeric species, since recent studies have shown that the oligomers formed by lysozyme prior to the appearance of mature amyloid fibrils are toxic to cells. Here, soluble oligomers of human lysozyme have been analyzed by a range of techniques including binding to fluorescent probes such as thioflavin T and 1-anilino-naphthalene-8-sulfonate, Fourier transforminfrared spectroscopy, and controlled proteolysis. Oligomers were isolated after 5 days of incubation of the protein and appear as spherical particles with a diameter of 8–17 nm when observed by transmission electron microscopy. Unlike the monomeric protein, oligomers have solventexposed hydrophobic patches able to bind the fluorescent probe 1-anilinonaphthalene- 8-sulfonate. Fourier transforminfrared spectroscopy spectra of oligomers are indicative of misfolded species when compared to monomeric lysozyme, with a prevalence of random structure but with significant elements of the β-sheet structure that is characteristic of the mature fibrils. Moreover, the oligomeric lysozyme aggregates were found to be more susceptible to proteolysis with pepsin than both the monomeric protein and the mature fibrils, indicating further their less organized structure. In summary, this study shows that the soluble lysozyme oligomers are locally unfolded species that are present at low concentration during the initial phases of aggregation. The nonnative conformational features of the lysozyme molecules of which they are composed are likely to be the factors that confer on them the ability to interact inappropriately with a variety of cellular components including membranes. [less ▲]

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See detailCharacterization of olive cake production in northern Morocco
El Otmani, Samira; Ayadi, Mohammed; Chentouf, Mouad et al

in 1st FARAH Day, Faculty of Veterinary Medicine (2014)

Detailed reference viewed: 40 (4 ULg)
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See detailCharacterization of ovine herpesvirus 2-induced malignant catarrhal fever in rabbits
Li; Cunha, C.W.; Gailbreath, K.L. et al

in Veterinary Microbiology (2011), 2

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See detailCharacterization of ovine herpesvirus 2-induced malignant catarrhal fever in rabbits
Li, Hong; Cunha, Cristina W.; Gailbreath, Katherine L. et al

in Veterinary Microbiology (2011), 150(3-4), 270-7

Malignant catarrhal fever (MCF) is a frequently fatal lymphoproliferative disease syndrome primarily of ruminant species, caused by gammaherpesviruses in the genus Macavirus. Ovine herpesvirus 2 (OvHV-2 ... [more ▼]

Malignant catarrhal fever (MCF) is a frequently fatal lymphoproliferative disease syndrome primarily of ruminant species, caused by gammaherpesviruses in the genus Macavirus. Ovine herpesvirus 2 (OvHV-2), carried by sheep, causes sheep-associated MCF worldwide, while Alcelaphine herpesvirus 1 (AlHV-1), carried by wildebeest, causes wildebeest-associated MCF, mainly in Africa. Diseases in rabbits can be induced by both viruses, which are clinically and pathologically similar; however, recent studies revealed different expression of viral genes associated with latency or lytic replication during clinical disease between the two viruses. In this study, we further characterized experimentally induced MCF in rabbits by nebulization with OvHV-2 from sheep nasal secretions to elucidate the course of viral replication, along with in vivo incorporation of 5-Bromo-2’-Deoxyuridine (BrdU), to evaluate lymphoproliferation. All six rabbits nebulized with OvHV-2 developed MCF between 24 and 29 days post infection. OvHV-2 DNA levels in peripheral blood leukocytes (PBL) remained undetectable during the incubation period and increased dramatically a few days before onset of clinical signs. During the clinical stage, we found that predominantly lytic gene expression was detected in PBL and tissues, and both T and B cells were proliferating. The data showed that the viral gene expression profile and lymphoproliferation in rabbits with OvHV-2 induced MCF were different from that in rabbits with AlHV-1 induced MCF, suggesting that OvHV-2 and AlHV-1 may play a different role in MCF pathogenesis. [less ▲]

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See detailCharacterization of OXA-29 from Legionella (Fluoribacter) gormanii: molecular class D beta-lactamase with unusual properties.
Franceschini, N.; Boschi, L.; Pollini, S. et al

in Antimicrobial agents and chemotherapy (2001), 45(12), 3509-16

A class D beta-lactamase determinant was isolated from the genome of Legionella (Fluoribacter) gormanii ATCC 33297(T). The enzyme, named OXA-29, is quite divergent from other class D beta-lactamases ... [more ▼]

A class D beta-lactamase determinant was isolated from the genome of Legionella (Fluoribacter) gormanii ATCC 33297(T). The enzyme, named OXA-29, is quite divergent from other class D beta-lactamases, being more similar (33 to 43% amino acid identity) to those of groups III (OXA-1) and IV (OXA-9, OXA-12, OXA-18, and OXA-22) than to other class D enzymes (21 to 24% sequence identity). Phylogenetic analysis confirmed the closer ancestry of OXA-29 with members of the former groups. The OXA-29 enzyme was purified from an Escherichia coli strain overexpressing the gene via a T7-based expression system by a single ion-exchange chromatography step on S-Sepharose. The mature enzyme consists of a 28.5-kDa polypeptide and exhibits an isoelectric pH of >9. Analysis of the kinetic parameters of OXA-29 revealed efficient activity (k(cat)/K(m) ratios of >10(5) M(-1) x s(-1)) for several penam compounds (oxacillin, methicillin, penicillin G, ampicillin, carbenicillin, and piperacillin) and also for cefazolin and nitrocefin. Oxyimino cephalosporins and aztreonam were also hydrolyzed, although less efficiently (k(cat)/K(m) ratios of around 10(3) M(-1) x s(-1)). Carbapenems were neither hydrolyzed nor inhibitory. OXA-29 was inhibited by BRL 42715 (50% inhibitory concentration [IC(50)], 0.44 microM) and by tazobactam (IC(50), 3.2 microM), but not by clavulanate. It was also unusually resistant to chloride ions (IC(50), >100 mM). Unlike OXA-10, OXA-29 was apparently found as a dimer both in diluted solutions and in the presence of EDTA. Its activity was either unaffected or inhibited by divalent cations. OXA-29 is a new class D beta-lactamase that exhibits some unusual properties likely reflecting original structural and mechanistic features. [less ▲]

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See detailCharacterization of paragangliomas : a single center cohort study
VROONEN, Laurent ULg; Maiga, Ibrahima ULg; PETROSSIANS, Patrick ULg et al

in Abstract book - 24th Meeting of the Belgian Endocrine Society (2014, October 18)

Detailed reference viewed: 26 (8 ULg)