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See detailVolatile Organic Chemicals in the Rhizosphere of Barley, and their Role on the Foraging Behavior of Wireworms (Coleoptera: Elateridae)
Barsics, Fanny ULg

Doctoral thesis (2015)

Many species of wireworms, the larvae of click beetles (Coleoptera: Elateridae), are known as worldwide belowground pests of a large range of crops including cereals. Pesticide based agricultural ... [more ▼]

Many species of wireworms, the larvae of click beetles (Coleoptera: Elateridae), are known as worldwide belowground pests of a large range of crops including cereals. Pesticide based agricultural practices seem to have allowed significant population reduction in the past, but there is an increasing need for alternative control methods. In the first Chapter of this work, we review the current knowledge concerning 1) Integrated Pest Management (IPM) of wireworms and 2) their chemical ecology. These reviews shed light on promising approaches to develop new management strategies, as well as gaps of knowledge to be filled in that purpose. One of them is investigated here. The research aim of this PhD thesis (detailed in Chapter II) is the identification of the volatile organic compounds (VOC) released by the roots and used by wireworms to locate their food source. To achieve this goal, we defined three objectives: 1) developing a behavioral assay suitable for the study of wireworm orientation behavior under exposure to root-produced VOC; 2) profiling VOC released in the rhizosphere, according to different growth conditions; and 3) evaluating the role of the identified VOC on wireworm foraging behavior. Our experimental model involved Agriotes sordidus Illiger wireworms and Hordeum distichon L. (spring barley). In Chapter III, we report on the developmental steps of an adequate olfactometric method for wireworms. This includes an initial setup, the “Y-shaped” olfactometer, and dual-choice pipes gathering the necessary upgrades to efficiently observe the behavior of wireworms exposed to a VOC source. By resorting to live roots in a variety of features, we attempted to highlight appropriate abiotic and biotic experimental parameters, as well as the limits to the use of our olfactometric devices. The bioassays confirmed the attraction of wireworms towards VOC emitted by live roots. With a first sampling method on excised roots, Solid – Phase Micro – Extraction (SPME – semi-quantitative), coupled to Gas Chromatography – Mass Spectrometry (GC-MS), we detected a high number of molecules that might act as semiochemicals on wireworms, notably in our bioassays. In the fourth Chapter, the bioassays were performed with selected VOC, detected during the chemical profiling. Firstly, we assessed if wireworms were attracted towards 2 pentylfuran, the main VOC highlighted with SPME. The molecule was submitted to the larvae by encapsulation in alginate beads. An adequate formulation allowed reaching an emission rate matching quantification estimates. In the aim to improve the VOC profiling, we also used Dynamic Head-Space Sampling (DHS), on roots ground in liquid nitrogen. It highlighted four volatile aldehydes. Their biological activity on wireworms was evaluated thanks to glass wool/triacetin-based dispensers, inserted in the dual-choice pipes. Through this work, we show that VOC produced by barley roots carry information useable by foraging wireworms. The two sampling methods indicate two different modalities of root-VOC production and are encouraging for further understanding of belowground VOC production and emission. The developed olfactometric method and related results open new perspectives to increase knowledge on wireworm ecology. Combined to other developments in research on their management, they could lead to interesting, innovative and ecological management practices. [less ▲]

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See detailPourquoi certaines réparations échouent-elles ? Un problème de compatibilité !
Courard, Luc ULg

Scientific conference (2015, February 12)

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See detailEncourager un vieillissement cognitif sain par un travail adapté (work shop)
Grotz, Catherine ULg; Adam, Stéphane ULg

Conference (2015, February 12)

L'objectif du workshop est d'apporter des éléments pratiques/cliniques en faveur d'un vieillissement cognitif de qualité, y compris une discussion des mesures à mettre en place en ce qui concerne l ... [more ▼]

L'objectif du workshop est d'apporter des éléments pratiques/cliniques en faveur d'un vieillissement cognitif de qualité, y compris une discussion des mesures à mettre en place en ce qui concerne l'employabilité de la population active plus âgée. [less ▲]

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See detailDevelopment of Hyphenated Methods for the Comprehensive Analysis of Complex Biological Samples
Brasseur, Catherine ULg

Doctoral thesis (2015)

The successful analysis of complex mixtures requires the combination of highly efficient separation techniques with advanced detection technologies to provide individual structural information. The ... [more ▼]

The successful analysis of complex mixtures requires the combination of highly efficient separation techniques with advanced detection technologies to provide individual structural information. The coupling of gas chromatography and mass spectrometry was one of the first steps in hyphenated method development. Nowadays, due to continuous hardware improvement, the term hyphenation has been extended to multidimensional separations and/or multiple detectors. The objective of the thesis is to develop hyphenated methods to extend the range of applications and propose solutions to improve the characterization of specifically selected complex samples. The main hyphenated technique that was used is comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS). Three thematic areas, presenting different levels and types of complexity were investigated: Forensic geotaphonomy with grave soil samples, lignocellulose biomass valorization with termite gut microbiota samples, and human monitoring for emerging organohalogen contaminants with blood samples. Data processing strategies were also developed in order to extract the relevant information from the large quantities of data produced. The different strategies included retention time alignment, comparative data processing, multivariate analysis using unsupervised learning algorithm such as principal component analysis (PCA), univariate analysis of variance (one-way ANOVA), and scripting for automated filtering of mass spectra. All developed methods allowed to successfully improve the characterization of samples originating from the different areas. For the first time, and because of the high level of specificity of GC×GC-TOFMS, the presence of methyl-branched alkane compounds was highlighted in grave soil samples, allowing to develop a screening method that has the capacity to differentiate between soils at proximity of buried decaying pig carcasses and control soils. This strategy could complement other approaches and contribute to aid forensic geotaphonomy investigators. In the biomass valorization area, more than 300 compounds were isolated and partly identified in the 1µL fluid volume available from the termite gut. A comparative study demonstrated that the adaptation of the termite system to non-optimal carbon sources is reflected in the metabolite profile. These results demonstrated the potential interest to investigate metabolite profiling with state-of-the-art separation science tools, to contribute to a better understanding of how termites efficiently degrades lignocellulose. In the human monitoring area, the analysis of serum samples using GC×GC-TOFMS and scripting allowed the efficient reduction of the data matrix from thousands of detected signals to a few important dozens, including the environmental contaminants of interest present in human blood plasma. Such an approach reduced data processing and reviewing time by several orders of magnitude while maintaining a high degree of identification power. This exploratory approach could result in the identification of emerging toxicants and help regulation bodies to gather better information before they rule on emerging issues. GC with high resolution mass spectrometry (HRMS) was also used, using a selective approach to evaluate human exposure to dechloranes, a family of emerging halogenated flame retardants recently reported as significantly present in the environment. A comprehensive approach was also developed using GC×GC coupled to high resolution TOFMS (HRTOFMS). The developed methodology will facilitate the monitoring of these emerging dechlorane contaminants and analogues in future exploratory studies. [less ▲]

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See detailQuand la clinique bouscule les concepts
Englebert, Jérôme ULg

Scientific conference (2015, February 11)

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See detailRisk of emergence of a hyperpathogenic bovine leukemia virus by mutation of a single envelope N-linked glycosylation site
De Brogniez, Alix ULg; Bouzar, Amel-Baya; Jacques, Jean-Rock ULg et al

Poster (2015, February 11)

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

- Introduction : Pathogens 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. Infection of sheep and cattle with BLV is a model system for the related human T-lymphotropic virus type 1 (HTLV-1) responsible for Adult T-cell Leukemia (ATL). - Aims : The goal of this work is to investigate the role of N-glycans of the viral envelope protein during viral replication and pathogenesis. - Methods and results : Using glycosylation inhibitors and lectins, we showed that N-glycosylation is involved in viral infection (i.e. cell-to-cell fusion). Using reverse genetics of an infectious molecular provirus, we next demonstrated that a particular N-linked envelope glycosylation site (N230) limits viral replication and pathogenicity in vitro and in vivo. We have thus generated a viral mutant that is more pathogenic than the wild type strain. - Conclusions : To our knowledge, this is the first time that a hyperpathogenic BLV has been identified. This unexpected observation has important consequences in terms of disease control and managing. Indeed, during evolution, pathogens and their hosts should achieve an equilibrium allowing the coexistence of the two species. Occurrence of this particular mutation may thus represent a potential threat associated with emergence of hyperpathogenic BLV strains and possibly of new variants of the related HTLV-1. [less ▲]

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See detailMener pratiquement ses entretiens: retour d'expériences
Parotte, Céline ULg

Learning material (2015)

Trucs et astuces pour mener pratiquement ses entretiens qualitatifs. Pratiquement, cette présentation a pour objectif de mettre l'étudiant en situation concrète: que faire? à quoi penser? comment me ... [more ▼]

Trucs et astuces pour mener pratiquement ses entretiens qualitatifs. Pratiquement, cette présentation a pour objectif de mettre l'étudiant en situation concrète: que faire? à quoi penser? comment me préparer? [less ▲]

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See detailCheckpoints modulation by the human T-lymphotropic virus type 1 (HTLV-1) Tax protein : towards new therapeutic approaches
Carpentier, Alexandre ULg; Barez, Pierre-Yves ULg; Boxus, Mathieu et al

Poster (2015, February 11)

HTLV-1 infects approximately 20 million people worldwide and causes several diseases. This virus is responsible for the adult T-cell leukemia (ATL) and for a chronic neuropathology (TSP/HAM). There is ... [more ▼]

HTLV-1 infects approximately 20 million people worldwide and causes several diseases. This virus is responsible for the adult T-cell leukemia (ATL) and for a chronic neuropathology (TSP/HAM). There is currently no satisfactory treatment for these diseases. Among the proteins encoded by HTLV-1, Tax appears to play an important role in the mechanisms leading to pathogenicity. We are interested in the mechanisms of cell transformation by HTLV-1 and more particularly in the interplay between the viral Tax oncoprotein and the DNA damage response (DDR). We demonstrate that transient expression of Tax results in DNA damage, cell cycle arrest and activation of the ATM-Chk2-p53 axis of the DDR. In fibroblasts, cell cycle arrest occurs at the G1 and G2 phases depending on the p53 background. Despite Tax expression hampers cell cycle progression, neither pro-apoptotic nor pro-senescent effects are observed. In contrast, HTLV-1 infected lymphocytes proliferate continuously and appear to be adapted to the checkpoints. This mechanism allows infected lymphocytes to proliferate despite the presence of genomic lesions. Those cells might thus rely on effective DNA repair mechanisms. Indeed, we show that Tax expressing cells activate the error free repair mechanism homologous recombination (HR). Inhibition of ATM, involved in DDR and DNA repair by HR, impedes Tax-mediated cellular transformation. Depending on these observations, we propose a novel therapeutic approach based on the principle of synthetic lethality. [less ▲]

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See detailReprogramming of replication origin firing and checkpoint adaptation in adult T-cell leukemia
Carpentier, Alexandre ULg; Barez, Pierre-Yves ULg; Boxus, Mathieu et al

Conference (2015, February 11)

Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects about twenty million individuals worldwide. HTLV-1 is the causative agent of different diseases among which the most common are the ... [more ▼]

Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects about twenty million individuals worldwide. HTLV-1 is the causative agent of different diseases among which the most common are the adult T-cell leukemia (ATL) and a neurodegenerative disorder called HAM/TSP (Human associated myelopathy/ Tropical spastic paraparesis). A key parameter of HTLV-1 pathogenesis is faster replication of provirus-carrying lymphocytes allowing clonal expansion of infected cell populations. The virally-encoded Tax oncoprotein plays an essential role in this process by interacting with DNA replication origins and accelerating S phase progression. By reprogramming the timing of origin firing, Tax also creates a replicative stress leading to DNA double strand breaks. This mechanism further triggers the DNA damage response (DDR) that induces cell cycle arrest and initiates either apoptosis or senescence. However, HTLV-1 infected cells have developed strategies to interfere with the DDR and are adapted to checkpoint control. These cells are thus able to proliferate despite occurrence of DNA damage. Based on these observations, we now propose a novel therapeutic approach based on the principle of synthetic lethality. [less ▲]

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See detailEnvironmental / climatic changes & the people ...
Ozer, Pierre ULg

Scientific conference (2015, February 11)

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See detailLes premiers enseignements de l'enquête auprès des élevages laitiers sur leurs évolutions technico-économiques
Beckers, Yves ULg; Vanwindekens, Frédéric ULg; Wyzen, Benoît et al

in Carrefour des Productions animales, 20ème édition "L'exploitation laitière wallonne de demain : du point de vue des acteurs aux propositions de la reccherche" (2015, February 11)

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See detailL'exploitation laitière de demain : présentation de l'enquête
Beckers, Yves ULg

Conference (2015, February 11)

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See detailL'exploitation laitière de demain : conclusions
Beckers, Yves ULg

Conference (2015, February 11)

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See detailFrom scientific expertise to lived experiences of genetic diseases. On patients’ organisations’ involvement in the construction of the medical evidence
Duysens, Fanny ULg

Conference (2015, February 11)

Genomic medicine is currently an expanding field. Based on the complete sequencing of the human genome, recent innovations promote the development of new protocols of diagnostic and treatments against ... [more ▼]

Genomic medicine is currently an expanding field. Based on the complete sequencing of the human genome, recent innovations promote the development of new protocols of diagnostic and treatments against hereditary genetic diseases. Thereby, they create opportunities which can disrupt the relationships between involved actors, such as patients and their relatives, concerned organisations, medical experts, as well as genomics specialists and health policy managers. This presentation exposes the baseline questions of a research project interested in some Belgian patients’ organisations’ involvement in issues related to genetic diseases within this current context, especially in the construction of the so-called "scientific and medical evidence". It addresses its expansion to patients' experiential knowledge which is based on their lived experiences of health and disease. [less ▲]

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See detailHDAC5 Depletion in Cancer Cells Induces an Oxidative Stress and Leads to a Metabolic Reprogramming toward Glucose and Glutamine Metabolism
Hendrick, Elodie ULg; Peixoto, Paul ULg; Polese, Catherine ULg et al

Poster (2015, February 11)

Histone deacetylases (HDAC) is a family of eighteen enzymes, which modulates the acetylation level of histones and non-histone proteins to regulate gene expression and chromatin structure. Broad-spectrum ... [more ▼]

Histone deacetylases (HDAC) is a family of eighteen enzymes, which modulates the acetylation level of histones and non-histone proteins to regulate gene expression and chromatin structure. Broad-spectrum inhibitors of these enzymes such as SAHA can inhibit tumor growth both in vitro and in vivo and are currently used as anti-cancer agents in clinic. For many years, we are investigating the specific role of individual HDAC members in cancer biology and we have recently demonstrated that specific depletion of HDAC5 using siRNA technology reduced cancer cells proliferation and survival1 The goal of this study is to further understand the molecular mechanisms of action of HDAC5 in cancer cells. Screening transcriptomic study demonstrated that HDAC5 depletion induces a down-regulation of subunits of the complex I of the mitochondrial respiratory chain (NDUFB5-NDUFA3) as well as anti-oxydant proteins (Ferritin, Metalothionein,¿) through modulation of mRNA stability. Therefore, HDAC5 depletion causes a significant increase of ROS production inducing both apoptosis and mechanisms of mitochondria quality control (mitophagy and mitobiogenesis). This HDAC5 depletion-induced mitochondrial dysfunction provokes metabolic adaptation associated with increased importance of glucose and glutamine. Indeed, interference with both glucose and glutamine supply in HDAC5-depleted cancer cells significantly increases apoptotic cell death suggesting that glucose or glutamine deprivation might be combined to HDAC5 inhibition as a therapeutic strategy to kill cancer cells. Our study demonstrated for the first time that specific HDAC5 inhibition induces metabolic reprogramming and provides insight into a valuable experimental strategy for manipulation of specific HDAC5 inhibition and glucose metabolism in therapy against cancer. 1.Peixoto, P. et al. HDAC5 is required for maintenance of pericentric heterochromatin, and controls cell-cycle progression and survival of human cancer cells. Cell death and differentiation, 2012; 1-14. Presenting author e-mail: elodie.hendrick@student.ulg.ac.be [less ▲]

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See detail“Problem Practices” in EU Competition Law
Petit, Nicolas ULg

Scientific conference (2015, February 10)

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Peer Reviewed
See detailTen years of Martian nitric oxide nightglow observations
Stiepen, Arnaud ULg; Gérard, Jean-Claude ULg; Gagné, Marie-Eve et al

in Geophysical Research Letters (2015)

Detailed reference viewed: 20 (4 ULg)